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Title: The precipitation response to the desiccation of Lake Chad

Located in the semi-arid African Sahel, Lake Chad has shrunk from a surface area of 25000 km2 in 1960 to about 1350 km2 due to a series of droughts and anthropogenic influences. The disappearance of such a large open-water body can be expected to have a noticeable effect on the meteorology in the surroundings of the lake. The impact could extend even further to the west as westward propagating convective systems pass Lake Chad in the rainfall season. This study examines the sensitivity of the regional hydrology and convective processes to the desiccation of the lake using a regional atmospheric model. Three Lake Chad scenarios are applied reflecting the situation in 1960, the current situation and a potential future scenario in which the lake and the surrounding wetlands have disappeared. The model simulations span the months July-September in 2006, which includes the rainfall season in the Lake Chad area. Total precipitation amounts and the components of the hydrological cycle are found to be hardly affected by the existence of the lake. A filled Lake Chad does, however, increase the precipitation at the east side of the lake. The model results indicate that the boundary layer moisture and temperature are significantlymore » altered downwind of the lake. By investigating a mesoscale convective system (MCS) case, this is found to affect the development and progress of the system. At first, the MCS is intensified by the more unstable boundary layer air but the persistence of the system is altered as the cold pool propagation becomes less effective. The proposed mechanism is able to explain the differences in the rainfall patterns nearby Lake Chad between the scenarios. This highlights the local sensitivity to the desiccation of Lake Chad whereas the large-scale atmospheric processes are not affected.« less
Authors:
; ;
Publication Date:
OSTI Identifier:
1044788
Report Number(s):
BNL--98144-2012-JA
Journal ID: ISSN 0035-9009; QJRMAM; R&D Project: 2014-BNL-EE630EECA-Budg; KP1701000; TRN: US201214%%834
DOE Contract Number:
DE-AC02-98CH10886
Resource Type:
Journal Article
Resource Relation:
Journal Name: Quarterly Journal of the Royal Meteorological Society; Journal Volume: 138; Journal Issue: 664
Research Org:
BROOKHAVEN NATIONAL LABORATORY (BNL)
Sponsoring Org:
USDOE SC OFFICE OF SCIENCE (SC)
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; AIR; BOUNDARY LAYERS; CHAD; DROUGHTS; HYDROLOGY; LAKES; METEOROLOGY; MOISTURE; PRECIPITATION; SEASONS; SENSITIVITY; SURFACE AREA; WETLANDS