ORCID Profile
0000-0003-2181-0638
Current Organisation
Nanjing University of Information Science and Technology
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Publisher: Springer Science and Business Media LLC
Date: 04-02-2011
Publisher: Springer Science and Business Media LLC
Date: 21-07-2013
DOI: 10.1038/NCLIMATE1945
Publisher: American Meteorological Society
Date: 15-03-2011
Abstract: Surface air temperature (SAT) over the globe, particularly the Northern Hemisphere continents, has rapidly risen over the last 2–3 decades, leading to an abrupt shift toward a warmer climate state after 1997/98. Whether the terrestrial warming might be caused by local response to increasing greenhouse gas (GHG) concentrations or by sea surface temperature (SST) rise is recently in dispute. The SST warming itself may be driven by both the increasing GHG forcing and slowly varying natural processes. Besides, whether the recent global warming might affect seasonal-to-interannual climate predictability is an important issue to be explored. Based on the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) climate prediction system in which only observed SSTs are assimilated for coupled model initialization, the present study shows that the historical SST rise plays a key role in driving the intensified terrestrial warming over the globe. The SST warming trend, while negligible for short lead predictions, has substantial impact on the climate predictability at long lead times (& yr) particularly in the extratropics. The tropical climate predictability, however, is little influenced by global warming. Given a perfect warming trend and/or a perfect model, global SAT and precipitation could be predicted beyond two years in advance with an anomaly correlation skill above ∼0.6. Without assimilating ocean subsurface observations, model initial conditions show a strong spurious cooling drift of subsurface temperature this is caused by large negative surface heat flux d ing arising from the SST-nudging initialization. The spurious subsurface cooling drift acts to weaken the initial SST warming trend during model forecasts, leading to even negative trends of global SAT and precipitation at long lead times and hence deteriorating the global climate predictability. Concerning the important influence of the subsurface temperature on the global SAT trend, future efforts are required to develop a good scheme for assimilating subsurface information particularly in the extratropical oceans.
Publisher: Bureau of Meteorology
Date: 2015
DOI: 10.22499/4.0011
Publisher: American Geophysical Union (AGU)
Date: 26-07-2023
DOI: 10.1029/2023GL104406
Abstract: Wintertime precipitation, especially snowstorms, significantly impacts people's lives. However, the current forecast skill of wintertime precipitation is still low. Based on data augmentation (DA) and deep learning, we propose a DABU‐Net which improves the Global Forecast System wintertime precipitation forecast over southeastern China. We build three independent models for the forecast lead times of 24, 48, and 72 hr, respectively. After using DABU‐Net, the mean Root Mean Squared Errors (RMSEs) of the wintertime precipitation at the three lead times are reduced by 19.08%, 25.00%, and 22.37%, respectively. The threat scores (TS) are all significantly increased at the thresholds of 1, 5, 10, 15, and 20 mm day −1 for the three lead times. During heavy precipitation days, the RMSEs are decreased by 14% and TS are increased by 7% at the lead times within 48 hr. Therefore, combining DA and deep learning has great prospects in precipitation forecasting.
Publisher: American Geophysical Union (AGU)
Date: 16-03-2012
DOI: 10.1029/2012GL051037
Publisher: http://www.bom.gov.au/research/research-reports.shtml
Date: 2015
DOI: 10.22499/4.0010
Publisher: American Geophysical Union (AGU)
Date: 25-03-2019
DOI: 10.1029/2019GL082280
Publisher: American Geophysical Union (AGU)
Date: 06-11-2022
DOI: 10.1029/2021JD036216
Abstract: Year‐to‐year forecasts of the Arctic climate conditions have drawn much interest in recent decades. This study investigates the primary drivers responsible for interannual variations (without multi‐decadal trends) of air temperature at 2 m (T2m) and sea ice concentration (SIC) over the Barents‐Kara Seas (BKS) during September from 1950 to 2021. The Arctic Dipole (AD), a leading factor in the BKS variability, plays an important role via influencing large‐scale atmospheric circulations and local thermodynamical feedbacks (i.e., vapor and albedo feedbacks). During a negative AD phase, the positive surface air temperature advection anomalies warm up the BKS region and promote sea ice melting, which in turn maintains the below‐normal sea ice and warmer‐than‐normal conditions via positive vapor and albedo feedbacks. Moreover, our results suggest that the sea surface temperature (SST) variability in the midlatitudes of the North Atlantic in the preceding month could also be an important driver of the SIC variability over the BKS area. The anomalous temperature advections from the surface to the upper troposphere are accompanied by a Rossby wave‐type atmospheric response, which intensifies the energy exchanges between the ocean and the atmosphere. Local SST anomalies associated with the surface heat flux anomalies further persist in the following month and influence sea ice variations due to their long‐lasting memory. A better understanding of the mechanisms of interannual climate variabilities over the BKS region in boreal early autumn is helpful to improving the Arctic regional climate predictions.
Publisher: Elsevier BV
Date: 09-2009
Publisher: Proceedings of the National Academy of Sciences
Date: 29-05-2024
Abstract: It has been widely believed that the tropical Pacific trade winds weakened in the last century and would further decrease under a warmer climate in the 21st century. Recent high-quality observations, however, suggest that the tropical Pacific winds have actually strengthened in the past two decades. Precise causes of the recent Pacific climate shift are uncertain. Here we explore how the enhanced tropical Indian Ocean warming in recent decades favors stronger trade winds in the western Pacific via the atmosphere and hence is likely to have contributed to the La Niña-like state (with enhanced east–west Walker circulation) through the Pacific ocean–atmosphere interactions. Further analysis, based on 163 climate model simulations with centennial historical and projected external radiative forcing, suggests that the Indian Ocean warming relative to the Pacific’s could play an important role in modulating the Pacific climate changes in the 20th and 21st centuries.
Publisher: Meteorological Society of Japan
Date: 2014
Publisher: Springer Science and Business Media LLC
Date: 24-02-2013
Publisher: Springer Science and Business Media LLC
Date: 09-2011
DOI: 10.1038/477544A
Publisher: Oxford University Press
Date: 26-10-2016
DOI: 10.1093/ACREFORE/9780190228620.013.82
Abstract: This is an advance summary of a forthcoming article in the Oxford Research Encyclopedia of Climate Science. Please check back later for the full article. The tropical Indian Ocean is unique in several aspects. Unlike the Pacific and the Atlantic Oceans, the Indian Ocean is bounded to the north by a large landmass, the Eurasian continent. The large thermal heat contrast between the ocean in the south and the land in the north induces the world’s strongest monsoon systems in South and East Asia, in response to the seasonal migration of solar radiation. The strong and seasonally reversing surface winds generate large seasonal variations in ocean currents and basin-wide meridional heat transport across the equator. In contrast to the tropical Pacific and the Atlantic, where easterly trade winds prevail throughout the year, westerly winds (albeit with a relatively weak magnitude) blow along the equatorial Indian Ocean, particularly during the boreal spring and autumn seasons, generating the semi-annual Yoshida-Wyrtki eastward equatorial ocean currents. As a consequence of the lack of equatorial upwelling, the tropical Indian Ocean occupies the largest portion of the warm water pool (with Sea Surface Temperature [SST] being greater than 28 °C) on Earth. The massive warm water provides a huge potential energy available for deep convections that significantly affect the weather-climate over the globe. It is therefore of vital importance to discover and understand climate variabilities in the Indian Ocean and to further develop a capability to correctly predict the seasonal departures of the warm waters and their global teleconnections. The Indian Ocean Dipole (IOD) is the one of the recently discovered climate variables in the tropical Indian Ocean. During the development of the super El Niño in 1997, the climatological zonal SST gradient along the equator was much reduced (with strong cold SST anomalies in the east and warm anomalies in the west). The surface westerly winds switched to easterlies, and the ocean thermocline became shallow in the east and deep in the west. These features are reminiscent of what are observed during El Niño years in the Pacific, representing a typical coupled process between the ocean and the atmosphere. The IOD event in 1997 contributed significantly to floods in eastern Africa and severe droughts and bushfires in Indonesia and southeastern Australia. Since the discovery of the 1997 IOD event, extensive efforts have been made to lead the rapid progress in understanding the air-sea coupled climate variabilities in the Indian Ocean and many approaches, including simple statistical models and comprehensive ocean-atmosphere coupled models, have been developed to simulate and predict the Indian Ocean climate. Essential to the discussion are the ocean-atmosphere dynamics underpinning the seasonal predictability of the IOD, critical factors that limit the IOD predictability (inter-comparison with El Niño-Southern Oscillation [ENSO]), observations and initialization approaches that provide realistic initial conditions for IOD predictions, models and approaches that have been developed to simulate and predict the IOD, the influence of global warming on the IOD predictability, impacts of IOD-ENSO interactions on the IOD predictability, and the current status and perspectives of the IOD prediction at seasonal to multi-annual timescales.
Publisher: American Meteorological Society
Date: 07-2007
DOI: 10.1175/JCLI4161.1
Abstract: The Indian summer monsoon (ISM) is one of the main components of the Asian summer monsoon. It is well known that one of the starting mechanisms of a summer monsoon is the thermal contrast between land and ocean and that sea surface temperature (SST) and moisture are crucial factors for its evolution and intensity. The Indian Ocean, therefore, may play a very important role in the generation and evolution of the ISM itself. A coupled general circulation model, implemented with a high-resolution atmospheric component, appears to be able to simulate the Indian summer monsoon in a realistic way. In particular, the features of the simulated ISM variability are similar to the observations. In this study, the relationships between the ISM and tropical Indian Ocean (TIO) SST anomalies are investigated, as well as the ability of the coupled model to capture those connections. The recent discovery of the Indian Ocean dipole mode (IODM) may suggest new perspectives in the relationship between ISM and TIO SST. A new statistical technique, the coupled manifold, is used to investigate the TIO SST variability and its relation with the tropical Pacific Ocean (TPO). The analysis shows that the SST variability in the TIO contains a significant portion that is independent from the TPO variability. The same technique is used to estimate the amount of Indian rainfall variability that can be explained by the tropical Indian Ocean SST. Indian Ocean SST anomalies are separated in a part remotely forced from the tropical Pacific Ocean variability and a part independent from that. The relationships between the two SSTA components and the Indian monsoon variability are then investigated in detail.
Publisher: Elsevier BV
Date: 06-2022
Publisher: American Geophysical Union (AGU)
Date: 07-2008
DOI: 10.1029/2008GL034122
Publisher: American Meteorological Society
Date: 10-09-2014
DOI: 10.1175/JCLI-D-14-00258.1
Abstract: The effects of declining anthropogenic aerosols in representative concentration pathway 4.5 (RCP4.5) are assessed in four models from phase 5 the Coupled Model Intercomparison Project (CMIP5), with a focus on annual, zonal-mean atmospheric temperature structure and zonal winds. For each model, the effect of declining aerosols is diagnosed from the difference between a projection forced by RCP4.5 for 2006–2100 and another that has identical forcing, except that anthropogenic aerosols are fixed at early twenty-first-century levels. The response to declining aerosols is interpreted in terms of the meridional structure of aerosol radiative forcing, which peaks near 40°N and vanishes at the South Pole. Increasing greenhouse gases cause lified warming in the tropical upper troposphere and strengthening midlatitude jets in both hemispheres. However, for declining aerosols the vertically averaged tropospheric temperature response peaks near 40°N, rather than in the tropics. This implies that for declining aerosols the tropospheric meridional temperature gradient generally increases in the Southern Hemisphere (SH), but in the Northern Hemisphere (NH) it decreases in the tropics and subtropics. Consistent with thermal wind balance, the NH jet then strengthens on its poleward side and weakens on its equatorward side, whereas the SH jet strengthens more than the NH jet. The asymmetric response of the jets is thus consistent with the meridional structure of aerosol radiative forcing and the associated tropospheric warming: in the NH the latitude of maximum warming is roughly collocated with the jet, whereas in the SH warming is strongest in the tropics and weakest at high latitudes.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 03-2019
Abstract: The El Niño-Southern Oscillation (ENSO), which originates in the Pacific, is the strongest and most well-known mode of tropical climate variability. Its reach is global, and it can force climate variations of the tropical Atlantic and Indian Oceans by perturbing the global atmospheric circulation. Less appreciated is how the tropical Atlantic and Indian Oceans affect the Pacific. Especially noteworthy is the multidecadal Atlantic warming that began in the late 1990s, because recent research suggests that it has influenced Indo-Pacific climate, the character of the ENSO cycle, and the hiatus in global surface warming. Discovery of these pantropical interactions provides a pathway forward for improving predictions of climate variability in the current climate and for refining projections of future climate under different anthropogenic forcing scenarios.
Publisher: Springer Science and Business Media LLC
Date: 25-04-2008
Publisher: American Geophysical Union (AGU)
Date: 02-2013
DOI: 10.1029/2012JC008352
Publisher: Springer Science and Business Media LLC
Date: 16-12-2008
Publisher: Springer Science and Business Media LLC
Date: 22-05-2010
Publisher: Springer Science and Business Media LLC
Date: 12-12-2022
DOI: 10.1038/S41467-022-35412-0
Abstract: As one of the most predominant interannual variabilities, the Indian Ocean Dipole (IOD) exerts great socio-economic impacts globally, especially on Asia, Africa, and Australia. While enormous efforts have been made since its discovery to improve both climate models and statistical methods for better prediction, current skills in IOD predictions are mostly limited up to three months ahead. Here, we challenge this long-standing problem using a multi-task deep learning model that we name MTL-NET. Hindcasts of the IOD events during the past four decades indicate that the MTL-NET can predict the IOD well up to 7-month ahead, outperforming most of world-class dynamical models used for comparison in this study. Moreover, the MTL-NET can help assess the importance of different predictors and correctly capture the nonlinear relationships between the IOD and predictors. Given its merits, the MTL-NET is demonstrated to be an efficient model for improved IOD prediction.
Publisher: American Meteorological Society
Date: 08-2003
DOI: 10.1175/2413.1
Abstract: Using outputs of a high-resolution ocean general circulation model, upper-ocean heat content budget and mixed layer heat budget are analyzed to investigate the reason for the 1988–89 decadal warming event in the northern North Pacific. The model reproduces realistic upper-ocean temperature changes in comparison with observational data. This analysis suggests that the horizontal mean geostrophic advection of anomalous temperature is the main contributor to the heat content increase around 1988–89, and surface heat flux forcing is the main contributor to increasing mixed layer temperature. The anomalous geostrophic advection of mean temperature plays a negative role in the increase of both the upper-ocean heat content and mixed layer temperature in midlatitudes around 1988–89. Another negative contribution to the mixed layer temperature increase is provided by the Ekman advection. In the Kuroshio Extension region, the warm upper-ocean heat content anomaly appears in 1987–88, in which the mean geostrophic advection also plays a dominant role. South of Japan the decadal warming appears even earlier, around 1985–86. The anomalous Kuroshio transport shows a decadal decreasing trend since the early 1980s and therefore cannot explain the late 1980s warming event in midlatitudes. The 1988–89 event is found to be closely linked with the decadal change of the Kuroshio path south of Japan. It is found that subtropical Rossby waves may influence the decadal temperature changes south of Japan.
Publisher: Elsevier BV
Date: 11-2012
Publisher: American Meteorological Society
Date: 15-02-2008
Abstract: The effect of atmospheric horizontal resolution on tropical variability is investigated within the modified Scale Interaction Experiment (SINTEX) coupled model, SINTEX-Frontier (SINTEX-F), developed jointly at Istituto Nazionale di Geofisica e Vulcanologia (INGV), L’Institut Pierre-Simon Laplace (IPSL), and the Frontier Research System. The ocean resolution is not changed as the atmospheric model resolution is modified from spectral resolution 30 (T30) to spectral resolution 106 (T106). The horizontal resolutions of the atmospheric model T30 and T106 are investigated in terms of the coupling characteristics, frequency, and variability of the tropical ocean–atmosphere interactions. It appears that the T106 resolution is generally beneficial even if it does not eliminate all the major systematic errors of the coupled model. There is an excessive shift west of the cold tongue and ENSO variability, and high resolution also has a somewhat negative impact on the variability in the east Indian Ocean. A dominant 2-yr peak for the Niño-3 variability in the T30 model is moderated in the T106 as it shifts to a longer time scale. At high resolution, new processes come into play, such as the coupling of tropical instability waves, the resolution of coastal flows at the Pacific–Mexican coasts, and improved coastal forcing along the coast of South America. The delayed oscillator seems to be the main mechanism that generates the interannual variability in both models, but the models realize it in different ways. In the T30 model it is confined close to the equator, involving relatively fast equatorial and near-equatorial modes, and in the high-resolution model, it involves a wider latitudinal region and slower waves. It is speculated that the extent of the region that is involved in the interannual variability may be linked to the time scale of the variability itself.
Publisher: American Geophysical Union (AGU)
Date: 14-06-2023
DOI: 10.1029/2022JD037041
Abstract: This study aims to detect atmospheric rivers (ARs) around the world by developing a deep‐learning ensemble method using AR catalogs of the ClimateNet data set. The ensemble method, based on 20 semantic segmentation algorithms, notably reduces the bias of the testing data set, with its intersection over union score being 1.7%–10.1% higher than that of in idual algorithms. This method is then applied to the Coupled Model Intercomparison Project Phase 6 (CMIP6) datasets to quantify AR frequency and its related precipitation in the historical period (1985–2014) and future period (2070–2099) under the Shared Socioeconomic Pathways 5–8.5 warming scenario. The six key regions, which are distributed in different continents of the globe and greatly influenced by ARs, are particularly highlighted. The results show that CMIP6 multi‐model mean with the deep‐learning ensemble method reasonably reproduces the observed AR frequency. In most key regions, both heavy precipitation (90–99 percentile) and extremely heavy precipitation ( percentile) are projected to increase in a warming climate mainly due to the increased AR‐related precipitation. The AR contributions to future heavy and extremely heavy precipitation increase range from 145.1% to 280.5% and from 36.2% to 213.5%, respectively, indicating that ARs should be taken into account to better understand the future extreme precipitation changes.
Publisher: American Geophysical Union (AGU)
Date: 08-2014
DOI: 10.1002/2013JC009713
Publisher: Springer Science and Business Media LLC
Date: 25-11-2011
Publisher: American Meteorological Society
Date: 15-05-2007
DOI: 10.1175/JCLI4132.1
Abstract: The Indian Ocean Dipole (IOD) has profound socioeconomic impacts on not only the countries surrounding the Indian Ocean but also various parts of the world. A forecast system is developed based on a relatively high-resolution coupled ocean–atmosphere GCM with only sea surface temperature (SST) information assimilated. Retrospective ensemble forecasts of the IOD index for the past two decades show skillful scores with up to a 3–4-month lead and a winter prediction barrier associated with its intrinsic strong seasonal phase locking. Prediction skills of the SST anomalies in both the eastern and western Indian Ocean are higher than those of the IOD index this is because of the influences of ENSO, which is highly predictable. The model predicts the extreme positive IOD event in 1994 at a 2–3-season lead. The strong 1997 cold signal in the eastern pole, however, is not well predicted owing to errors in model initial subsurface conditions. The real-time forecast system with more ensembles successfully predicted the weak negative IOD event in the 2005 boreal fall and La Niña condition in the 2005/06 winter. Recent experimental real-time forecasts showed that a positive IOD event would appear in the 2006 summer and fall accompanied by a possible weak El Niño condition in the equatorial Pacific.
Publisher: Springer Science and Business Media LLC
Date: 23-12-2011
Publisher: American Geophysical Union (AGU)
Date: 29-03-2008
DOI: 10.1029/2007GL032793
Publisher: American Geophysical Union (AGU)
Date: 27-03-2009
DOI: 10.1029/2008JD011096
Publisher: American Geophysical Union (AGU)
Date: 15-10-2001
DOI: 10.1029/2000JC000471
Publisher: American Geophysical Union (AGU)
Date: 12-12-2022
DOI: 10.1029/2022GL101339
Abstract: Currently, the Arctic is undergoing a significant warming, which has exerted widespread impacts on global climate. Although many mechanisms responsible for the Arctic warming have been proposed, the impacts of the multi‐decadal change of tropical sea surface temperature receive little attention. Here we use numerical experiments to elucidate that the Indian Ocean (IO) warming may contribute to the Arctic warming. Through enhancing the Atlantic Meridional Overturning Circulation, the IO warming remotely induces more ocean heat transport from the North Atlantic to the Arctic. The resulted upper ocean warming dominates the surface warming in the Arctic. Additionally, despite the net negative contribution of the atmospheric heat transport, more warm air is conveyed into the Kara Seas, North Eurasia, and North America sectors, contributing to the local warming. The results propose a new mechanism to interpret the Arctic warming and indicate the important remote impacts of the tropical IO warming.
Publisher: American Geophysical Union (AGU)
Date: 22-12-2022
DOI: 10.1029/2022GL101571
Abstract: The interactions between El Niño‐Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) are known to have great implications for global climate variability and seasonal climate predictions. Observational analysis suggests that the ENSO–IOD inter‐basin connection is time‐varying and related to the Atlantic Multidecadal Oscillation (AMO) with weakened ENSO–IOD relationship corresponding to AMO warm phases. A suite of Atlantic pacemaker simulations successfully reproduces the decadal fluctuations in ENSO–IOD relationship and its link to the AMO. The warm sea surface temperature (SST) anomalies associated with the AMO drive a series of Indo‐Pacific mean climate changes through tropical‐wide teleconnections, including the La Niña‐like mean SST cooling over the central Pacific and the deepening of mean thermocline depth in the eastern Indian Ocean. By modulating ocean–atmosphere feedback strength, those mean state changes decrease both ENSO litude and the Indian Ocean sensitivity to ENSO forcing, therefore decoupling the IOD from ENSO.
Publisher: American Geophysical Union (AGU)
Date: 29-04-2022
DOI: 10.1029/2021GL097687
Abstract: This paper reports that there has been a significant relationship between the quasi‐biennial oscillation (QBO) in zonal wind at 50 hPa in summer and precipitation in August in northern China since the late 1970s. The correlation coefficient between them reaches up to −0.61 during 1979–2018. Associated with the easterly (westerly) phase of the QBO, there is a meridional dipole pattern of zonal wind from the stratosphere to troposphere over the Northwest Pacific in August with the easterly (westerly) anomalies in 25–50°N and westerly (easterly) anomalies in 50–65°N. This meridional zonal‐wind dipole favors the strengthening (weakening) of the tropospheric Japan Sea high in the QBO easterly (westerly) phase, causing an increase (decrease) of the water vapor transportation from the Northwest Pacific to northern China and thus more (less) precipitation in these regions. The finding of this study has import implications for predicting the summer precipitation in northern China in the future.
Publisher: American Meteorological Society
Date: 2008
Abstract: Using a fully coupled global ocean–atmosphere general circulation model assimilating only sea surface temperature, the authors found for the first time that several El Niño–Southern Oscillation (ENSO) events over the past two decades can be predicted at lead times of up to 2 yr. The El Niño condition in the 1997/98 winter can be predicted to some extent up to about a 1½-yr lead but with a weak intensity and large phase delay in the prediction of the onset of this exceptionally strong event. This is attributed to the influence of active and intensive stochastic westerly wind bursts during late 1996 to mid-1997, which are generally unpredictable at seasonal time scales. The cold signals in the 1984/85 and 1999/2000 winters during the peak phases of the past two long-lasting La Niña events are predicted well up to a 2-yr lead. Amazingly, the mild El Niño–like event of 2002/03 is also predicted well up to a 2-yr lead, suggesting a link between the prolonged El Niño and the tropical Pacific decadal variability. Seasonal climate anomalies over vast parts of the globe during specific ENSO years are also realistically predicted up to a 2-yr lead for the first time.
Publisher: Springer Science and Business Media LLC
Date: 22-01-2013
Publisher: American Meteorological Society
Date: 15-09-2008
Abstract: In this second part of a two-part paper, the mechanism for the litude asymmetry of SST anomalies (SSTA) between positive and negative Indian Ocean dipole (IOD) events is investigated through the diagnosis of coupled model simulations. Same as the observed in Part I, a significant negative skewness appears in the IOD east pole (IODE) in September–November (SON), whereas there is no significant skewness in the IOD west pole (IODW). A sensitivity experiment shows that the negative skewness in IODE appears even in the case when the ENSO is absent. The diagnosis of the model mixed layer heat budget reveals that the negative skewness is primarily induced by the nonlinear ocean temperature advection and the asymmetry of the cloud–radiation–SST feedback, consistent with the observation (Part I). However, the simulated latent heat flux anomaly is greatly underestimated in IODE during the IOD developing stage [June–September (JJAS)]. As a result, the net surface heat flux acts as strong thermal d ing. The underestimation of the latent heat flux anomaly in the IODE is probably caused by the westward shift of along-coast wind anomalies off Sumatra.
Publisher: Springer Science and Business Media LLC
Date: 12-06-2017
DOI: 10.1038/NCLIMATE3304
Publisher: Springer Science and Business Media LLC
Date: 18-04-2018
Publisher: Authorea, Inc.
Date: 24-08-2023
DOI: 10.22541/ESSOAR.169290554.48887852/V1
Abstract: Accurate seasonal precipitation forecasts, especially for extreme events, are crucial to preventing meteorological hazards and its potential impacts on national development, social stability, and security. However, the intensity of summer precipitation is often significantly underestimated in many current dynamical models. This study uses a deep learning method called Cycle-Consistent Generative Adversarial Networks (CycleGAN) to enhance the seasonal forecast skill of the Nanjing University of Information Science & Technology Climate Forecast System (NUIST-CFS1.0) in predicting June-July-August precipitation in southeastern China. The results suggest that the CycleGAN-based model significantly improves the accuracy in predicting the spatial-temporal distribution of summer precipitation than traditional quantile mapping (QM) method. Due to the use of unpaired day-to-day correction models, we can pay more attention to the frequency, intensity, and duration of extreme precipitation events in the climate dynamical model forecast. This study expands the potential applications of deep learning models to improving seasonal precipitation forecasts.
Publisher: Springer Science and Business Media LLC
Date: 23-10-2009
Publisher: Springer Science and Business Media LLC
Date: 18-10-2023
Publisher: American Geophysical Union (AGU)
Date: 06-11-2021
DOI: 10.1029/2021GL095309
Abstract: The recently discovered Chile Niño/Niña is an intrinsic coupled climate mode in the southeast Pacific, which influences both regional climate and marine ecosystem. Using Scale Interaction Experiment‐Frontier version 2 seasonal prediction system, it is shown that the Chile Niño/Niña can be skillfully predicted up to 3‐month lead. Although the occurrences and related climate impacts of the Chile Niño/Niña are captured by the prediction system, the predicted magnitudes are weaker than observations in the ensemble mean. Further analyses of the inter‐member relationships indicate that the Chile Niño/Niña predictability depends on how well the coastal ocean‐atmosphere‐land positive feedback among alongshore surface winds, coastal upwelling and the sea surface temperature anomalies is captured. The insufficient reproduction of this essential feedback is responsible for the underestimated magnitude. Therefore, accurately predicting the Chile Niño/Niña remains a challenge. Improving model resolution and ensemble size may be a key to enhancing prediction skills of the coastal climate modes along the eastern boundary upwelling systems.
Publisher: American Meteorological Society
Date: 12-2012
Abstract: In light of the growing recognition of the role of surface temperature variations in the Indian Ocean for driving global climate variability, the predictive skill of the sea surface temperature (SST) anomalies associated with the Indian Ocean dipole (IOD) is assessed using ensemble seasonal forecasts from a selection of contemporary coupled climate models that are routinely used to make seasonal climate predictions. The authors assess predictions from successive versions of the Australian Bureau of Meteorology Predictive Ocean–Atmosphere Model for Australia (POAMA 15b and 24), successive versions of the NCEP Climate Forecast System (CFSv1 and CFSv2), the ECMWF seasonal forecast System 3 (ECSys3), and the Frontier Research Centre for Global Change system (SINTEX-F) using seasonal hindcasts initialized each month from January 1982 to December 2006. The lead time for skillful prediction of SST in the western Indian Ocean is found to be about 5–6 months while in the eastern Indian Ocean it is only 3–4 months when all start months are considered. For the IOD events, which have maximum litude in the September–November (SON) season, skillful prediction is also limited to a lead time of about one season, although skillful prediction of large IOD events can be longer than this, perhaps up to about two seasons. However, the tendency for the models to overpredict the occurrence of large events limits the confidence of the predictions of these large events. Some common model errors, including a poor representation of the relationship between El Niño and the IOD, are identified indicating that the upper limit of predictive skill of the IOD has not been achieved.
Publisher: American Geophysical Union (AGU)
Date: 08-12-2022
DOI: 10.1029/2022GL100916
Abstract: Ocean waves, especially extreme waves, are vital for air‐sea interaction and shipping. However, current wave models still have significant biases. Based on a numerical wave model and a deep learning model, a BU‐Net by adding batch normalization layers to a U‐Net, we accurately predict the significant wave height (SWH) of the Northwest Pacific Ocean. For each day in 2017–2021, we conducted a 3‐day hindcast experiment using WAVEWATCH3 (WW3) to obtain the SWH forecasts at lead times of 24, 48, and 72 hr, forced by GFS real‐time forecast surface winds. After using BU‐Net, the mean Root Mean Squared Errors (RMSEs) of the SWH forecast from WW3 at lead times of 24, 48, and 72 hr are reduced by 40%, 38%, and 30%, respectively. During typhoon passages, the drop percentages of RMSEs all exceed 20% for three lead times. Therefore, combining numerical models and deep learning is very promising in wave forecasting.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 05-08-2011
Abstract: Indian summer monsoon changes during the Pleistocene were influenced by dynamic effects originating in both hemispheres.
Publisher: American Meteorological Society
Date: 15-06-2012
DOI: 10.1175/JCLI-D-11-00396.1
Abstract: The growth and decay mechanisms of subtropical dipole modes in the southern Indian and South Atlantic Oceans and their impacts on southern African rainfall are investigated using results from a coupled general circulation model originally developed for predicting tropical climate variations. The second (most) dominant mode of interannual sea surface temperature (SST) variations in the southern Indian (South Atlantic) Ocean represents a northeast–southwest oriented dipole, now called subtropical dipole mode. The positive (negative) SST interannual anomaly pole starts to grow in austral spring and reaches its peak in February. In austral late spring, the suppressed (enhanced) latent heat flux loss associated with the variations in the subtropical high causes a thinner (thicker) than normal mixed layer thickness that, in turn, enhances (reduces) the warming of the mixed layer by the climatological shortwave radiation. The positive (negative) pole gradually decays in austral fall because the mixed layer cooling by the entrainment is enhanced (reduced), mostly owing to the larger (smaller) temperature difference between the mixed layer and the entrained water. The increased (decreased) latent heat loss due to the warmer (colder) SST also contributes to the decay of the positive (negative) pole. Although further verification using longer observational data is required, the present coupled model suggests that the South Atlantic subtropical dipole may play a more important role in rainfall variations over the southern African region than the Indian Ocean subtropical dipole.
Publisher: Copernicus GmbH
Date: 22-11-2016
Abstract: Abstract. Robust projections and predictions of climate variability and change, particularly at regional scales, rely on the driving processes being represented with fidelity in model simulations. The role of enhanced horizontal resolution in improved process representation in all components of the climate system is of growing interest, particularly as some recent simulations suggest both the possibility of significant changes in large-scale aspects of circulation as well as improvements in small-scale processes and extremes. However, such high-resolution global simulations at climate timescales, with resolutions of at least 50 km in the atmosphere and 0.25° in the ocean, have been performed at relatively few research centres and generally without overall coordination, primarily due to their computational cost. Assessing the robustness of the response of simulated climate to model resolution requires a large multi-model ensemble using a coordinated set of experiments. The Coupled Model Intercomparison Project 6 (CMIP6) is the ideal framework within which to conduct such a study, due to the strong link to models being developed for the CMIP DECK experiments and other model intercomparison projects (MIPs). Increases in high-performance computing (HPC) resources, as well as the revised experimental design for CMIP6, now enable a detailed investigation of the impact of increased resolution up to synoptic weather scales on the simulated mean climate and its variability. The High Resolution Model Intercomparison Project (HighResMIP) presented in this paper applies, for the first time, a multi-model approach to the systematic investigation of the impact of horizontal resolution. A coordinated set of experiments has been designed to assess both a standard and an enhanced horizontal-resolution simulation in the atmosphere and ocean. The set of HighResMIP experiments is ided into three tiers consisting of atmosphere-only and coupled runs and spanning the period 1950–2050, with the possibility of extending to 2100, together with some additional targeted experiments. This paper describes the experimental set-up of HighResMIP, the analysis plan, the connection with the other CMIP6 endorsed MIPs, as well as the DECK and CMIP6 historical simulations. HighResMIP thereby focuses on one of the CMIP6 broad questions, “what are the origins and consequences of systematic model biases?”, but we also discuss how it addresses the World Climate Research Program (WCRP) grand challenges.
Publisher: American Meteorological Society
Date: 07-2007
DOI: 10.1175/JCLI4164.1
Abstract: Using 200 yr of coupled general circulation model (CGCM) results, causes for the termination of Indian Ocean dipole (IOD) events are investigated. The CGCM used here is the Scale Interaction Experiment-Frontier Research Center for Global Change (SINTEX-F1) model, which consists of a version of the European Community–Hamburg (ECHAM4.6) atmospheric model and a version of the Ocean Parallelise (OPA8.2) ocean general circulation model. This model reproduces reasonably well the present-day climatology and interannual signals of the Indian and Pacific Oceans. The main characteristics of the intraseasonal disturbances (ISDs)/oscillations are also fairly well captured by this model. However, the eastward propagation of ISDs in the model is relatively fast in the Indian Ocean and stationary in the Pacific compared to observations. A sudden reversal of equatorial zonal winds is observed, as a result of significant intraseasonal disturbances in the equatorial Indian Ocean in November–December of IOD events, which evolve independently of ENSO. A majority of these IOD events (15 out of 18) are terminated mainly because of the 20–40-day ISD activity in the equatorial zonal winds. Ocean heat budget analysis in the upper 50 m clearly shows that the initial warming after the peak of the IOD phenomenon is triggered by increased solar radiation owing to clear-sky conditions in the eastern Indian Ocean. Subsequently, the equatorial jets excited by the ISD deepen the thermocline in the southeastern equatorial Indian Ocean. This deepening of the thermocline inhibits the vertical entrainment of cool waters and therefore the IOD is terminated. IOD events that co-occur with ENSO are terminated owing to anomalous incoming solar radiation as a result of prevailing cloud-free skies. Further warming occurs seasonally through the vertical convergence of heat due to a monsoonal wind reversal along Sumatra–Java. On occasion, strong ISD activities in July–August terminated short-lived IOD events by triggering downwelling intraseasonal equatorial Kelvin waves.
Publisher: American Geophysical Union (AGU)
Date: 05-2006
DOI: 10.1029/2005GL024916
Publisher: American Geophysical Union (AGU)
Date: 04-2005
DOI: 10.1029/2004GL021980
Publisher: Elsevier BV
Date: 04-2005
Publisher: Springer Science and Business Media LLC
Date: 29-09-2013
Publisher: Research Square Platform LLC
Date: 02-08-2023
DOI: 10.21203/RS.3.RS-3222878/V1
Abstract: The northwestern Pacific monsoon trough (NWPMT) deeply impacts socio-economic development and human security over East Asia by supplying moisture to the summer monsoon rainfall and modulating tropical cyclone activities. However, considerable inter-model spreads in the Coupled Model Inter-comparison Project Phase 6 models make the future projection of the NWPMT less reliable. Here, we find that the inter-model spread of the NWPMT change is significantly correlated with the central equatorial Pacific sea surface temperature change, and mainly determined by the equatorial thermocline sharpness in the historical simulations. According to the emergent constraint method, the central equatorial Pacific SST would warm up about 8% slower than the multi-model mean with 56% uncertainty reduced. Correspondingly, the NWPMT would slacken westward with 36% uncertainty reduced. Results here emphasize the importance of examining and reducing systematic model biases in simulating subsurface fields that have been overlooked in past literatures, before achieving more reliable future projections.
Publisher: American Geophysical Union (AGU)
Date: 02-2019
DOI: 10.1029/2018EF001093
Publisher: American Geophysical Union (AGU)
Date: 08-09-2023
DOI: 10.1029/2023JD039039
Publisher: American Meteorological Society
Date: 11-2008
Abstract: The Indian summer monsoon rainfall has complex, regionally heterogeneous, interannual variations with huge socioeconomic impacts, but the underlying mechanisms remain uncertain. The upwelling along the Somalia and Oman coasts starts in late spring, peaks during the summer monsoon, and strongly cools the sea surface temperature (SST) in the western Arabian Sea. They restrict the westward extent of the Indian Ocean warm pool, which is the main moisture source for the monsoon rainfall. Thus, variations of the Somalia–Oman upwelling can have significant impacts on the moisture transport toward India. Here the authors use both observations and an advanced coupled atmosphere–ocean general circulation model to show that a decrease in upwelling strengthens monsoon rainfall along the west coast of India by increasing the SST along the Somalia–Oman coasts, and thus local evaporation and water vapor transport toward the Indian Western Ghats (mountains). Further observational analysis reveals that such decreases in upwelling are caused by anomalously weak southwesterly winds in late spring over the Arabian Sea that are due to warm SST/increased precipitation anomalies over the Seychelles–Chagos thermocline ridge of the southwestern Indian Ocean (and vice versa for years with strong upwelling/weak west Indian summer monsoon rainfall). The latter SST recipitation anomalies are often related to El Niño conditions and the strength of the Indonesian–Australian monsoon during the previous winter. This sheds new light on the ability to forecast the poorly predicted Indian monsoon rainfall on a regional scale, helped by a proper ocean observing/forecasting system in the western tropical Indian Ocean.
Publisher: Springer Science and Business Media LLC
Date: 30-10-2007
Publisher: Public Library of Science (PLoS)
Date: 03-2016
Publisher: Springer Science and Business Media LLC
Date: 08-01-2008
Publisher: Springer Science and Business Media LLC
Date: 21-11-2011
Publisher: American Meteorological Society
Date: 07-2007
DOI: 10.1175/JCLI4168.1
Abstract: The decadal variation in the tropical Indian Ocean is investigated using outputs from a 200-yr integration of the Scale Interaction Experiment-Frontier Research Center for Global Change (SINTEX-F1) ocean–atmosphere coupled model. The first EOF mode of the decadal bandpass- (9–35 yr) filtered sea surface temperature anomaly (SSTA) represents a basinwide mode and is closely related with the Pacific ENSO-like decadal variability. The second EOF mode shows a clear east–west SSTA dipole pattern similar to that of the interannual Indian Ocean dipole (IOD) and may be termed the decadal IOD. However, it is demonstrated that the decadal air–sea interaction in the Tropics can be a statistical artifact it should be interpreted more correctly as decadal modulation of interannual IOD events (i.e., asymmetric or skewed occurrence of positive and negative events). Heat budget analysis has revealed that the occurrence of IOD events is governed by variations in the southward Ekman heat transport across 15°S and variations in the Indonesian Throughflow associated with the ENSO. The variations in the southward Ekman heat transport are related to the Mascarene high activities.
Publisher: Springer Science and Business Media LLC
Date: 21-02-2010
DOI: 10.1038/NGEO760
Publisher: Springer Science and Business Media LLC
Date: 15-05-2014
DOI: 10.1038/NCOMMS4712
Abstract: The monitoring and prediction of climate-induced variations in crop yields, production and export prices in major food-producing regions have become important to enable national governments in import-dependent countries to ensure supplies of affordable food for consumers. Although the El Niño/Southern Oscillation (ENSO) often affects seasonal temperature and precipitation, and thus crop yields in many regions, the overall impacts of ENSO on global yields are uncertain. Here we present a global map of the impacts of ENSO on the yields of major crops and quantify its impacts on their global-mean yield anomalies. Results show that El Niño likely improves the global-mean soybean yield by 2.1-5.4% but appears to change the yields of maize, rice and wheat by -4.3 to +0.8%. The global-mean yields of all four crops during La Niña years tend to be below normal (-4.5 to 0.0%). Our findings highlight the importance of ENSO to global crop production.
Publisher: Springer Science and Business Media LLC
Date: 03-06-2010
Publisher: Wiley
Date: 07-06-2013
DOI: 10.1002/MET.1402
Publisher: American Meteorological Society
Date: 15-09-2007
DOI: 10.1175/JCLI4275.1
Abstract: Using outputs from the SINTEX-F1 coupled GCM, the thermodynamics of ENSO events and its relation with the seasonal cycle are investigated. Simulated El Niño events are first classified into four groups depending on during which season the Niño-3.4 sea surface temperature anomaly (SSTA) index (5°S–5°N, 120°–170°W) reaches its peak. Although the heat content of the tropical Pacific decreases for all four types, the tropical Pacific loses about twice as much during an El Niño that peaks during winter compared with one that peaks during summer. The surface heat flux, the southward heat transport at 15°S, and the Indonesian Throughflow heat transport contribute constructively to this remarkable seasonal difference. It is shown that the Indonesian Throughflow supplies anomalous heat from the Indian Ocean, especially during the summer El Niño–like event. Changes in the basic state provided by the seasonal cycle cause differences in the atmospheric response to the SSTA, which in turn lead to the difference between the surface heat flux and the meridional heat transport anomaly.
Publisher: Copernicus GmbH
Date: 07-11-2013
DOI: 10.5194/ACP-13-10883-2013
Abstract: Abstract. All the representative concentration pathways (RCPs) include declining aerosol emissions during the 21st century, but the effects of these declines on climate projections have had little attention. Here we assess the global and hemispheric-scale effects of declining anthropogenic aerosols in RCP4.5 in CSIRO-Mk3.6, a model from the Coupled Model Intercomparison Project Phase 5 (CMIP5). Results from this model are then compared with those from other CMIP5 models. We calculate the aerosol effective radiative forcing (ERF, including indirect effects) in CSIRO-Mk3.6 relative to 1850, using a series of atmospheric simulations with prescribed sea-surface temperatures (SST). Global-mean aerosol ERF at the top of the atmosphere is most negative in 2005 (−1.47 W m−2). Between 2005 and 2100 it increases by 1.46 W m−2, i.e., it approximately returns to 1850 levels. Although increasing greenhouse gases (GHGs) and declining aerosols both exert a positive ERF at the top of the atmosphere during the 21st century, they have opposing effects on radiative heating of the atmosphere: increasing GHGs warm the atmosphere, whereas declining aerosols cool the atmosphere due to reduced absorption of shortwave radiation by black carbon (BC). We then compare two projections for 2006–2100, using the coupled atmosphere-ocean version of the model. One (RCP45) follows the usual RCP4.5 the other (RCP45A2005) has identical forcing, except that emissions of anthropogenic aerosols and precursors are fixed at 2005 levels. The global-mean surface warming in RCP45 is 2.3 °C per 95 yr, of which almost half (1.1 °C) is caused by declining aerosols. The warming due to declining aerosols is almost twice as strong in the Northern Hemisphere as in the Southern Hemisphere, whereas that due to increasing GHGs is similar in the two hemispheres. For precipitation changes, the effects of declining aerosols are larger than those of increasing GHGs due to decreasing atmospheric absorption by black carbon: 63% of the projected global-mean precipitation increase of 0.16 mm per day is caused by declining aerosols. In the Northern Hemisphere, precipitation increases by 0.29 mm per day, of which 72% is caused by declining aerosols. Comparing 13 CMIP5 models, we find a correlation of –0.54 (significant at 5%) between aerosol ERF in the present climate and projected global-mean surface warming in RCP4.5 thus, models that have more negative aerosol ERF in the present climate tend to project stronger warming during 2006–2100. A similar correlation (–0.56) is found between aerosol ERF and projected changes in global-mean precipitation. These results suggest that aerosol forcing substantially modulates projected climate response in RCP4.5. In some respects, the effects of declining aerosols are quite distinct from those of increasing GHGs. Systematic efforts are needed to better quantify the role of declining aerosols in climate projections.
Publisher: American Geophysical Union
Date: 19-03-2013
DOI: 10.1029/147GM12
Publisher: Stockholm University Press
Date: 08-2007
Publisher: Springer Science and Business Media LLC
Date: 22-11-2013
Publisher: Springer Science and Business Media LLC
Date: 26-07-2012
Publisher: American Geophysical Union (AGU)
Date: 30-11-2021
DOI: 10.1029/2021GL095516
Abstract: The multi‐model ensemble mean sea surface temperature (SST) of CMIP5 models shows an El Niño‐like Pacific warming (PW) trend, contradictory with the observational result which manifests a La Niña‐like PW pattern. Here, we demonstrate that these two SST PWs coexist in the CMIP5 models and they are largely determined by the model's tropical Indo‐Pacific SST gradient. When the Pacific warms faster than the Indian Ocean (IO), the model tends to project an El Niño‐like PW pattern. In contrast, a La Niña‐like warming trend prevails if a more rapid IO warming is simulated. We suggest that the PW pattern in an in idual model is nonstationary and may transform from a La Niña‐like to an El Niño‐like when its interbasin SST gradient changes with more robust warming in the Pacific, and vice versa. Our conclusions shed great light on the future SST PW pattern change projected by the coupled models.
Publisher: American Geophysical Union (AGU)
Date: 12-2003
DOI: 10.1029/2003GL018649
Publisher: Copernicus GmbH
Date: 12-04-2016
DOI: 10.5194/GMD-2016-66
Abstract: Abstract. Robust projections and predictions of climate variability and change, particularly at regional scales, rely on the driving processes being represented with fidelity in model simulations. The role of enhanced horizontal resolution in improved process representation in all components of the climate system is of growing interest, particularly as some recent simulations suggest the possibility for significant changes in both large-scale aspects of circulation, as well as improvements in small-scale processes and extremes. However, such high resolution global simulations at climate time scales, with resolutions of at least 50 km in the atmosphere and 0.25° in the ocean, have been performed at relatively few research centers and generally without overall coordination, primarily due to their computational cost. Assessing the robustness of the response of simulated climate to model resolution requires a large multi-model ensemble using a coordinated set of experiments. The Coupled Model Intercomparison Project 6 (CMIP6) is the ideal framework within which to conduct such a study, due to the strong link to models being developed for the CMIP DECK experiments and other MIPs. Increases in High Performance Computing (HPC) resources, as well as the revised experimental design for CMIP6, now enables a detailed investigation of the impact of increased resolution up to synoptic weather scales on the simulated mean climate and its variability. The High Resolution Model Intercomparison Project (HighResMIP) presented in this paper applies, for the first time, a multi-model approach to the systematic investigation of the impact of horizontal resolution. A coordinated set of experiments has been designed to assess both a standard and an enhanced horizontal resolution simulation in the atmosphere and ocean. The set of HighResMIP experiments is ided into three tiers consisting of atmosphere-only and coupled runs and spanning the period 1950-2050, with the possibility to extend to 2100, together with some additional targeted experiments. This paper describes the experimental set-up of HighResMIP, the analysis plan, the connection with the other CMIP6 endorsed MIPs, as well as the DECK and CMIP6 historical simulation. HighResMIP thereby focuses on one of the CMIP6 broad questions: “what are the origins and consequences of systematic model biases?”, but we also discuss how it addresses the World Climate Research Program (WCRP) grand challenges.
Publisher: American Meteorological Society
Date: 06-08-2013
DOI: 10.1175/JCLI-D-12-00645.1
Abstract: The prediction skill of dynamical downscaling is evaluated for climate forecasts over southern Africa using the Advanced Research Weather Research and Forecasting (WRF) model. As a case study, forecasts for the December–February (DJF) season of 2011/12 are evaluated. Initial and boundary conditions for the WRF model were taken from the seasonal forecasts of the Scale Interaction Experiment-Frontier Research Center for Global Change (SINTEX-F) coupled general circulation model. In addition to sea surface temperature (SST) forecasts generated by nine-member ensemble forecasts of SINTEX-F, the WRF was also configured to use SST generated by a simple mixed layer Price–Weller–Pinkel ocean model coupled to the WRF model. Analysis of the ensemble mean shows that the uncoupled WRF model significantly increases the biases (errors) in precipitation forecasted by SINTEX-F. When coupled to a simple mixed layer ocean model, the WRF model improves the spatial distribution of precipitation over southern Africa through a better representation of the moisture fluxes. Precipitation anomalies forecasted by the coupled WRF are seen to be significantly correlated with the observed precipitation anomalies over South Africa, Zimbabwe, southern Madagascar, and parts of Zambia and Angola. This is in contrast to the SINTEX-F global model precipitation anomaly forecasts that are closer to observations only for parts of Zimbabwe and South Africa. Therefore, the dynamical downscaling with the coupled WRF adds value to the SINTEX-F precipitation forecasts over southern Africa. However, the WRF model yields positive biases (& °C) in surface air temperature forecasts over the southern African landmass in both the coupled and uncoupled configurations because of biases in the net heat fluxes.
Publisher: Springer Science and Business Media LLC
Date: 11-11-2011
Publisher: American Meteorological Society
Date: 02-2010
Abstract: Climate variability in the tropical Indo-Pacific sector has undergone dramatic changes under global ocean warming. Extreme Indian Ocean dipole (IOD) events occurred repeatedly in recent decades with an unprecedented series of three consecutive episodes during 2006–08, causing vast climate and socioeconomic effects worldwide and weakening the historic El Niño–Indian monsoon relationship. Major attention has been paid to the El Niño influence on the Indian Ocean, but how the IOD influences El Niño and its predictability remained an important issue to be understood. On the basis of various forecast experiments activating and suppressing air–sea coupling in the in idual tropical ocean basins using a state-of-the-art coupled ocean–atmosphere model with demonstrated predictive capability, the present study shows that the extreme IOD plays a key role in driving the 1994 pseudo–El Niño, in contrast with traditional El Niño theory. The pseudo–El Niño is more frequently observed in recent decades, coincident with a weakened atmospheric Walker circulation in response to anthropogenic forcing. The study’s results suggest that extreme IOD may significantly enhance El Niño and its onset forecast, which has being a long-standing challenge, and El Niño in turn enhances IOD and its long-range predictability. The intrinsic El Niño–IOD interaction found here provides hope for enhanced prediction skill of both of these climate modes, and it sheds new light on the tropical climate variations and their changes under the influence of global warming.
Publisher: American Geophysical Union (AGU)
Date: 29-09-2022
DOI: 10.1029/2022GL099781
Abstract: As a dominant climate mode of the southeast Indian Ocean, Ningaloo Niño/Niña has paramount impacts on regional climate and marine ecosystems. Using outputs from the latest phase of Coupled Model Intercomparison Project (CMIP6), we have systematically evaluated the simulation of Ningaloo Niño/Niña in the state‐of‐the‐art coupled models. Eighteen out of 28 CMIP6 models well reproduce the spatial pattern and seasonality of Ningaloo Niño/Niña, whereas the simulated litudes show large spread across the models. Main processes of the oceanic and atmospheric El Niño‐Southern Oscillation teleconnections and the coastal Bjerknes feedback are successfully captured by most of the CMIP6 models, but their uncertainties in the simulation are responsible for the inter‐model difference in litude. The CMIP6 models are also skillful in reproducing the regional climate impacts of Ningaloo Niño/Niña. Compared to Coupled Model Intercomparison Project Phase 5, a larger fraction of models in CMIP6 well reproduce the Ningaloo Niño/Niña, which provides a good hope for projecting its future changes.
Publisher: Springer Science and Business Media LLC
Date: 23-05-2017
DOI: 10.1038/S41598-017-01479-9
Abstract: Multi-year La Niña events often induce persistent cool and wet climate over global lands, altering and in some case mitigating regional climate warming impacts. The latest event lingered from mid-2010 to early 2012 and brought about intensive precipitation over many land regions of the world, particularly Australia. This resulted in a significant drop in global mean sea level despite the background upwards trend. This La Niña event is surprisingly predicted out to two years ahead in a few coupled models, even though the predictability of El Niño-Southern Oscillation during 2002–2014 has declined owing to weakened ocean-atmosphere interactions. However, the underlying mechanism for high predictability of this multi-year La Niña episode is still unclear. Experiments based on a climate model that demonstrates a successful two-year forecast of the La Niña support the hypothesis that warm sea surface temperature (SST) anomalies in the Atlantic and Indian Oceans act to intensify the easterly winds in the central equatorial Pacific and largely contribute to the occurrence and two-year predictability of the 2010–2012 La Niña. The results highlight the importance of increased Atlantic-Indian Ocean SSTs for the multi-year La Niña’s predictability under global warming.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 10-2021
Abstract: Decadal climate variability and change affects nearly every aspect of our world, including weather, agriculture, ecosystems, and the economy. Predicting its expression is thus of critical importance on multiple fronts. Power et al . review what is known about tropical Pacific decadal climate variability and change, the degree to which it can be simulated and predicted, and how we might improve our understanding of it. More accurate projections will require longer and more detailed instrumental and paleoclimate records, improved climate models, and better data assimilation methods. —HJS
Publisher: American Meteorological Society
Date: 07-2005
DOI: 10.1175/JCLI3404.1
Abstract: The cold tongue in the tropical Pacific extends too far west in most current ocean–atmosphere coupled GCMs (CGCMs). This bias also exists in the relatively high-resolution SINTEX-F CGCM despite its remarkable performance of simulating ENSO variations. In terms of the importance of air–sea interactions to the climatology formation in the tropical Pacific, several sensitivity experiments with improved coupling physics have been performed in order to reduce the cold-tongue bias in CGCMs. By allowing for momentum transfer of the ocean surface current to the atmosphere [full coupled simulation (FCPL)] or merely reducing the wind stress by taking the surface current into account in the bulk formula [semicoupled simulation (semi-CPL)], the warm-pool/cold-tongue structure in the equatorial Pacific is simulated better than that of the control simulation (CTL) in which the movement of the ocean surface is ignored for wind stress calculation. The reduced surface zonal current and vertical entrainment owing to the reduced easterly wind stress tend to produce a warmer sea surface temperature (SST) in the western equatorial Pacific. Consequently, the dry bias there is much reduced. The warming tendency of the SST in the eastern Pacific, however, is largely suppressed by isopycnal diffusion and meridional advection of colder SST from south of the equator due to enhanced coastal upwelling near Peru. The ENSO signal in the western Pacific and its global teleconnection in the North Pacific are simulated more realistically. The approach as adopted in the FCPL run is able to generate a correct zonal SST slope and efficiently reduce the cold-tongue bias in the equatorial Pacific. The surface easterly wind itself in the FCPL run is weakened, reducing the easterly wind stress further. This is related with a weakened zonal Walker cell in the atmospheric boundary layer over the eastern Pacific and a new global angular momentum balance of the atmosphere associated with reduced westerly wind stress over the southern oceans.
Publisher: American Geophysical Union (AGU)
Date: 25-10-2023
DOI: 10.1029/2023GL105175
Publisher: Springer Science and Business Media LLC
Date: 16-09-2008
Publisher: Springer Science and Business Media LLC
Date: 20-04-2012
Location: China
No related grants have been discovered for Jing-Jia Luo.