TY - JOUR
T1 - Influence of Lake Malawi on regional climate from a double-nested regional climate model experiment
AU - Diallo, Ismaïla
AU - Giorgi, Filippo
AU - Stordal, Frode
N1 - Funding Information:
We thank the two anonymous reviewers for their constructive comments and suggestions which helped to improve the quality of this manuscript. This research was funded under the project SOCOCA (Socioeconomic Consequences of Climate Change in sub-equatorial Africa, http://www.mn.uio.no/geo/english/research/projects/sococa/index.html ), sponsored by the Research Council of Norway. This research was conducted while the first author was employed by the Abdus Salam International Centre for Theoretical Physics (ICTP). The final stage of the writing has been performed at the University of California, Los Angeles (UCLA). Support from the U.S. National Science Foundation grants AGS-1419526 is gratefully acknowledged. RegCM4 simulations outputs for this paper are archived by the Earth System Physics (ESP) section of the Abdus Salam ICTP and can be obtained by contacting the corresponding author (Dr. Ismaïla Diallo; [email protected]).
Publisher Copyright:
© 2017, Springer-Verlag GmbH Germany.
PY - 2018/5/1
Y1 - 2018/5/1
N2 - We evaluate the performance of the regional climate model (RCM) RegCM4 coupled to a one dimensional lake model for Lake Malawi (also known as Lake Nyasa in Tanzania and Lago Niassa in Mozambique) in simulating the main characteristics of rainfall and near surface air temperature patterns over the region. We further investigate the impact of the lake on the simulated regional climate. Two RCM simulations, one with and one without Lake Malawi, are performed for the period 1992–2008 at a grid spacing of 10 km by nesting the model within a corresponding 25 km resolution run (“mother domain”) encompassing all Southern Africa. The performance of the model in simulating the mean seasonal patterns of near surface air temperature and precipitation is good compared with previous applications of this model. The temperature biases are generally less than 2.5 °C, while the seasonal cycle of precipitation over the region matches observations well. Moreover, the one-dimensional lake model reproduces fairly well the geographical pattern of observed (from satellite measurements) lake surface temperature as well as its mean month-to-month evolution. The Malawi Lake-effects on the moisture and atmospheric circulation of the surrounding region result in an increase of water vapor mixing ratio due to increased evaporation in the presence of the lake, which combines with enhanced rising motions and low-level moisture convergence to yield a significant precipitation increase over the lake and neighboring areas during the whole austral summer rainy season.
AB - We evaluate the performance of the regional climate model (RCM) RegCM4 coupled to a one dimensional lake model for Lake Malawi (also known as Lake Nyasa in Tanzania and Lago Niassa in Mozambique) in simulating the main characteristics of rainfall and near surface air temperature patterns over the region. We further investigate the impact of the lake on the simulated regional climate. Two RCM simulations, one with and one without Lake Malawi, are performed for the period 1992–2008 at a grid spacing of 10 km by nesting the model within a corresponding 25 km resolution run (“mother domain”) encompassing all Southern Africa. The performance of the model in simulating the mean seasonal patterns of near surface air temperature and precipitation is good compared with previous applications of this model. The temperature biases are generally less than 2.5 °C, while the seasonal cycle of precipitation over the region matches observations well. Moreover, the one-dimensional lake model reproduces fairly well the geographical pattern of observed (from satellite measurements) lake surface temperature as well as its mean month-to-month evolution. The Malawi Lake-effects on the moisture and atmospheric circulation of the surrounding region result in an increase of water vapor mixing ratio due to increased evaporation in the presence of the lake, which combines with enhanced rising motions and low-level moisture convergence to yield a significant precipitation increase over the lake and neighboring areas during the whole austral summer rainy season.
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U2 - 10.1007/s00382-017-3811-x
DO - 10.1007/s00382-017-3811-x
M3 - Article
AN - SCOPUS:85026489702
SN - 0930-7575
VL - 50
SP - 3397
EP - 3411
JO - Climate Dynamics
JF - Climate Dynamics
IS - 9-10
ER -
