ORCID Profile
0000-0002-9985-3876
Current Organisations
Universidade de São Paulo
,
Global Center on Adpatation
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Publisher: Elsevier BV
Date: 11-2015
Publisher: Copernicus GmbH
Date: 27-03-2017
Abstract: Abstract. As the largest water conservancy project, Three Gorges Dam starts its impoundment in 2003 and henceforth the efficient operation of a multi-purpose dam has aroused a great concern on the effectiveness on flood control and water management over Yangtze River Basin. In this paper, we consider the relationship between rainfall from 136 weather stations and streamflow from 5 hydrological stations including Cuntan, Yichang, Luoshan, Hankou and Datong. Meanwhile, the spatial average rainfall over 21 subbasins was computed. The analysis of the correlation demonstrated that the correlation of spatial average rainfall and streamflow for each station is consistent with that between rainfall by stations and streamflow. Then, two options were selected to develop the linear models, including option a) using rainfall by stations to forecast streamflow and option b) using spatial average rainfall to forecast streamflow. The canonical correlation analysis enabled a large degree of spatially coherent information of rainfall by linear transforms to maximize the correlation of rainfall and streamflow for developing linear models. The model resulting from option b) best fits the observations. Coefficient of determination for each model and statistics such as reduction of error, coefficient of efficiency under cross validation serve as a test of good performance of the model. An analysis of streamflow characteristics across the stations illustrated that the streamflow of Cuntan and Yichang have different modes of variability from that of the rest stations below the dam. The comparison of risk type changes between observations and predictions during the post-dam period showed the dam effectively relieved the risk of upstream while not always played a positive role in risk mitigation of downstream. The spatial and temporal patterns of rainfall anomalies over the whole basin helps to explain how the dam impact the streamflow. Some applications as to possible operational strategies are discussed.
Publisher: American Geophysical Union (AGU)
Date: 04-2017
DOI: 10.1002/2016WR019632
Publisher: American Geophysical Union (AGU)
Date: 2023
DOI: 10.1029/2022JC019168
Abstract: The Deep Western Boundary Current (DWBC) is the main component of the deep limb of the Atlantic Meridional Overturning Circulation (AMOC). Off northeast Brazil, the DWBC breaks up into southwestward‐propagating anticyclones. In this study, we investigate the breakup mechanism with hydrographic observations, eddy‐resolving numerical model outputs, and theory. Here, we present a quasi‐synoptic map of geostrophic velocities and stream function at the DWBC core level between 2.5°S and 11°S. We observe, in horizontal distributions of velocities, that the DWBC breakup site is linked to a topographic feature of the Brazilian continental margin centered at 8°S: the Pernambuco Plateau (PP). Moreover, both observations and model outputs hint at a possible DWBC separation near the PP preceding anticyclone genesis. We test, with three different theories from the literature, whether or not the DWBC separates at 8°S. The results of the tests converge to indicate that the DWBC undergoes a local and intermittent inertial separation while contouring the PP. Downstream of its separation at the plateau, the DWBC sheds eddies similarly to previously reported laboratory experiments. In addition, a regional analysis of energy transfer shows that barotropic instability significantly contributes to the anticyclones growth between 8°S and 13°S. Analysis of the energy budget and separation of waters related to the AMOC pathways into the basin interior provide a better understanding for later studies about heat fluxes and ventilation in the deep tropical South Atlantic.
No related grants have been discovered for Xun Sun.