Precipitation sensitivity to regional SST in a regional climate simulation during the West African monsoon for two dry years

2004 ◽  
Vol 22 (2-3) ◽  
pp. 249-266 ◽  
Author(s):  
C. Messager ◽  
H. Gall�e ◽  
O. Brasseur
Keyword(s):  
Regional Climate ◽  
West African Monsoon ◽  
West African ◽  
Climate Simulation ◽  
Regional Climate Simulation ◽  
The West ◽  
African Monsoon

scholarly journals Dynamics of the West African Monsoon Jump

2007 ◽  
Vol 20 (21) ◽  
pp. 5264-5284 ◽  
Author(s):  
Samson M. Hagos ◽  
Kerry H. Cook
Keyword(s):  
Climate Model ◽  
Regional Climate ◽  
West African Monsoon ◽  
Lower Troposphere ◽  
West African ◽  
Moisture Convergence ◽  
The West ◽  
African Monsoon ◽  
Sahel Region ◽  
Continental Interior

Abstract The observed abrupt latitudinal shift of maximum precipitation from the Guinean coast into the Sahel region in June, known as the West African monsoon jump, is studied using a regional climate model. Moisture, momentum, and energy budget analyses are used to better understand the physical processes that lead to the jump. Because of the distribution of albedo and surface moisture, a sensible heating maximum is in place over the Sahel region throughout the spring. In early May, this sensible heating drives a shallow meridional circulation and moisture convergence at the latitude of the sensible heating maximum, and this moisture is transported upward into the lower free troposphere where it diverges. During the second half of May, the supply of moisture from the boundary layer exceeds the divergence, resulting in a net supply of moisture and condensational heating into the lower troposphere. The resulting pressure gradient introduces an inertial instability, which abruptly shifts the midtropospheric meridional wind convergence maximum from the coast into the continental interior at the end of May. This in turn introduces a net total moisture convergence, net upward moisture flux and condensation in the upper troposphere, and an enhancement of precipitation in the continental interior through June. Because of the shift of the meridional convergence into the continent, condensation and precipitation along the coast gradually decline. The West African monsoon jump is an example of multiscale interaction in the climate system, in which an intraseasonal-scale event is triggered by the smooth seasonal evolution of SSTs and the solar forcing in the presence of land–sea contrast.

Land surface coupling in regional climate simulations of the West African monsoon

2009 ◽  
Vol 33 (6) ◽  
pp. 869-892 ◽  
Author(s):  
Allison L. Steiner ◽  
Jeremy S. Pal ◽  
Sara A. Rauscher ◽  
Jason L. Bell ◽  
Noah S. Diffenbaugh ◽  
...  
Keyword(s):  
Land Surface ◽  
Regional Climate ◽  
West African Monsoon ◽  
West African ◽  
The West ◽  
African Monsoon ◽  
Climate Simulations ◽  
Surface Coupling

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.

A regional climate modeling study of the effect of desert dust on the West African monsoon

2008 ◽  
Vol 113 (D12) ◽  
Author(s):  
A. Konare ◽  
A. S. Zakey ◽  
F. Solmon ◽  
F. Giorgi ◽  
S. Rauscher ◽  
...  
Keyword(s):  
Climate Modeling ◽  
Regional Climate ◽  
West African Monsoon ◽  
Regional Climate Modeling ◽  
West African ◽  
The West ◽  
African Monsoon ◽  
Desert Dust ◽  
Modeling Study

scholarly journals Simulation of the West African monsoon onset using the HadGEM3-RA regional climate model

2014 ◽  
Vol 43 (3-4) ◽  
pp. 575-594 ◽  
Author(s):  
Ismaïla Diallo ◽  
Caroline L. Bain ◽  
Amadou T. Gaye ◽  
Wilfran Moufouma-Okia ◽  
Coumba Niang ◽  
...  
Keyword(s):  
Regional Climate Model ◽  
Climate Model ◽  
Regional Climate ◽  
West African Monsoon ◽  
Monsoon Onset ◽  
West African ◽  
The West ◽  
African Monsoon

scholarly journals On What Scale Can We Predict the Agronomic Onset of the West African Monsoon?

2016 ◽  
Vol 144 (4) ◽  
pp. 1571-1589 ◽  
Author(s):  
Rory G. J. Fitzpatrick ◽  
Caroline L. Bain ◽  
Peter Knippertz ◽  
John H. Marsham ◽  
Douglas J. Parker
Keyword(s):  
West Africa ◽  
Noise Analysis ◽  
West African Monsoon ◽  
West African ◽  
New Method ◽  
The West ◽  
African Monsoon ◽  
Spatial Consistency ◽  
Local Stakeholders ◽  
Local Rainfall

Abstract Accurate prediction of the commencement of local rainfall over West Africa can provide vital information for local stakeholders and regional planners. However, in comparison with analysis of the regional onset of the West African monsoon, the spatial variability of the local monsoon onset has not been extensively explored. One of the main reasons behind the lack of local onset forecast analysis is the spatial noisiness of local rainfall. A new method that evaluates the spatial scale at which local onsets are coherent across West Africa is presented. This new method can be thought of as analogous to a regional signal against local noise analysis of onset. This method highlights regions where local onsets exhibit a quantifiable degree of spatial consistency (denoted local onset regions or LORs). It is found that local onsets exhibit a useful amount of spatial agreement, with LORs apparent across the entire studied domain; this is in contrast to previously found results. Identifying local onset regions and understanding their variability can provide important insight into the spatial limit of monsoon predictability. While local onset regions can be found over West Africa, their size is much smaller than the scale found for seasonal rainfall homogeneity. A potential use of local onset regions is presented that shows the link between the annual intertropical front progression and local agronomic onset.

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