The impact of deep convection on the West African summer monsoon climate: a regional climate model sensitivity study

2011 ◽  
Vol 137 (659) ◽  
pp. 1417-1430 ◽  
Author(s):  
M. B. Sylla ◽  
F. Giorgi ◽  
P. M. Ruti ◽  
S. Calmanti ◽  
A. Dell'Aquila
Keyword(s):  
Regional Climate Model ◽  
Summer Monsoon ◽  
Climate Model ◽  
Deep Convection ◽  
Regional Climate ◽  
Sensitivity Study ◽  
West African ◽  
Monsoon Climate ◽  
The West ◽  
The Impact

scholarly journals Regional Climate Model Sensitivity to Domain Size for the Simulation of the West African Summer Monsoon Rainfall

2012 ◽  
Vol 2012 ◽  
pp. 1-17 ◽  
Author(s):  
Nana A. K. Browne ◽  
Mouhamadou B. Sylla
Keyword(s):  
Atlantic Ocean ◽  
Regional Climate Model ◽  
Summer Monsoon ◽  
Climate Model ◽  
Monsoon Rainfall ◽  
Regional Climate ◽  
Summer Monsoon Rainfall ◽  
West African ◽  
The West ◽  
The Impact

We use the International Centre for Theoretical Physics (ICTP) Regional Climate Model (RegCM3) to study the impact of different domain sizes on the simulation of the West African summer monsoon rainfall and circulation features. RegCM3 simulates drier conditions over the default domain (RegCM-D1) and its westward extension (RegCM-D2), much less dryness over the eastward extended domain (RegCM-D3) and excessive wetness in the domain extended northward into the extratropical regions (RegCM-D4). This overestimation is related to the existence of larger source of humidity due to the inclusion of a more significant portion of the Atlantic Ocean and to a weakening of the African Easterly Jet (AEJ), which both favor stronger westerlies advecting moisture towards the land. The best performance is, however, captured in the RegCM-D3 experiment, and this originates from a simulation of moderate westerly moisture fluxes along with a stronger AEJ and occurrences of more frequent African Easterly Waves (AEWs). Therefore, the choice of the domain for regional climate model simulation of the West African summer monsoon rainfall is of critical importance, and caution needs to be taken to account for the main regional forcings including mostly the necessary humidity sources of the tropical Atlantic Ocean and the AEWs genesis region upstream of Sudanese Highlands.

scholarly journals Diagnosing Land–Atmosphere Interaction from a Regional Climate Model Simulation over West Africa

2010 ◽  
Vol 11 (2) ◽  
pp. 467-481 ◽  
Author(s):  
Bart J. J. M. van den Hurk ◽  
Erik van Meijgaard
Keyword(s):  
Soil Moisture ◽  
Regional Climate Model ◽  
Climate Model ◽  
Hydrological Cycle ◽  
Regional Climate ◽  
West African ◽  
The West ◽  
Near Surface ◽  
Monsoon Area ◽  
Atmosphere Interaction

Abstract Land–atmosphere interaction at climatological time scales in a large area that includes the West African Sahel has been explicitly explored in a regional climate model (RegCM) simulation using a range of diagnostics. First, areas and seasons of strong land–atmosphere interaction were diagnosed from the requirement of a combined significant correlation between soil moisture, evaporation, and the recycling ratio. The northern edge of the West African monsoon area during June–August (JJA) and an area just north of the equator (Central African Republic) during March–May (MAM) were identified. Further analysis in these regions focused on the seasonal cycle of the lifting condensation level (LCL) and the convective triggering potential (CTP), and the sensitivity of CTP and near-surface dewpoint depressions HIlow to anomalous soil moisture. From these analyses, it is apparent that atmospheric mechanisms impose a strong constraint on the effect of soil moisture on the regional hydrological cycle.

scholarly journals Feedback of observed interannual vegetation change: a regional climate model analysis for the West African monsoon

2016 ◽  
Vol 48 (9-10) ◽  
pp. 2837-2858 ◽  
Author(s):  
Cornelia Klein ◽  
Jan Bliefernicht ◽  
Dominikus Heinzeller ◽  
Ursula Gessner ◽  
Igor Klein ◽  
...  
Keyword(s):  
Regional Climate Model ◽  
Vegetation Change ◽  
Climate Model ◽  
Regional Climate ◽  
West African Monsoon ◽  
Model Analysis ◽  
West African ◽  
The West ◽  
African Monsoon

scholarly journals Improving the Simulation of the West African Monsoon Using the MIT Regional Climate Model

2014 ◽  
Vol 27 (6) ◽  
pp. 2209-2229 ◽  
Author(s):  
Eun-Soon Im ◽  
Rebecca L. Gianotti ◽  
Elfatih A. B. Eltahir
Keyword(s):  
Regional Climate Model ◽  
Land Surface ◽  
Climate Model ◽  
Regional Climate ◽  
West African Monsoon ◽  
Convective Cloud ◽  
West African ◽  
The West ◽  
African Monsoon ◽  
Convection Schemes

Abstract This paper presents an evaluation of the performance of the Massachusetts Institute of Technology (MIT) regional climate model (MRCM) in simulating the West African monsoon. The MRCM is built on the Regional Climate Model, version 3 (RegCM3), but with several improvements, including coupling of Integrated Biosphere Simulator (IBIS) land surface scheme, a new surface albedo assignment method, new convective cloud and convective rainfall autoconversion schemes, and a modified scheme for simulating boundary layer height and boundary layer clouds. To investigate the impact of these more physically realistic representations when incorporated into MRCM, a series of experiments were carried out implementing two land surface schemes [IBIS with a new albedo assignment, and the Biosphere–Atmosphere Transfer Scheme (BATS)] and two convection schemes (Grell with the Fritsch–Chappell closure, and Emanuel in both the default form and modified with the new convective cloud cover and a rainfall autoconversion scheme). The analysis primarily focuses on comparing the rainfall characteristics, surface energy balance, and large-scale circulations against various observations. This work documents significant sensitivity in simulation of the West African monsoon to the choices of the land surface and convection schemes. Despite several deficiencies, the simulation with the combination of IBIS and the modified Emanuel scheme with the new convective cloud cover and a rainfall autoconversion scheme shows the best performance with respect to the spatial distribution of rainfall and the dynamics of the monsoon. The coupling of IBIS leads to representations of the surface energy balance and partitioning that show better agreement with observations compared to BATS. The IBIS simulations also reasonably reproduce the dynamical structures of the West African monsoon circulation.

scholarly journals Regional climate model experiments to investigate the Asian monsoon in the Late Miocene

2011 ◽  
Vol 7 (2) ◽  
pp. 841-886
Author(s):  
H. Tang ◽  
A. Micheels ◽  
J. Eronen ◽  
M. Fortelius
Keyword(s):  
Regional Climate Model ◽  
Summer Monsoon ◽  
Late Miocene ◽  
Asian Monsoon ◽  
Climate Model ◽  
Regional Climate ◽  
Regional Model ◽  
Global Model ◽  
Monsoon Climate ◽  
Northern Tibetan Plateau

Abstract. The Late Miocene (11.6–5.3 Ma) is a crucial period for the Asian monsoon evolution. However, the spatiotemporal changes of the Asian monsoon system in the Late Miocene are still ambiguous, and the mechanisms responsible for these changes are debated. Here, we present a simulation of the Asian monsoon climate (0 to 60° N and 50 to 140° E) in the Tortonian (11–7 Ma) using the regional climate model CCLM3.2. We employ relatively high spatial resolution (1° × 1°) and adapt the physical boundary conditions such as topography, land-sea distribution and vegetation in the regional model to represent the Late Miocene. As climatological forcing, the output of a Tortonian run with a fully-coupled atmosphere-ocean general circulation model is used. Our results show a stronger-than-present E-Asian winter monsoon wind in the Tortonian, as a result of the enhanced mid-latitude westerly wind of our global forcing and the lowered northern Tibetan Plateau in the regional model. The summer monsoon circulation is generally weakened in our regional Tortonian run compared to today. However, the changes of summer monsoon precipitation exhibit major regional differences. The precipitation decreases in N-China and N-India, but increases in S-China, the western coast and the southern tip of India. This can be attributed to the combined effect of both the regional topographical changes and the other forcings related to our global model. The spread of the dry summer conditions over N-China and NW-India further implies that the monsoonal climate may not be fully established over these regions in the Tortonain. Compared with the global model, the high resolution regional model highlights the spatial differences of the Asian monsoon climate in the Tortonian, and better characterizes the convective activity and its response to topographical changes. It therefore provides a useful and compared to global models complementary tool to improve our understanding of the Asian monsoon evolution in the Late Miocene.

Sign in / Sign up

Export Citation Format

Share Document