Coastal observations of weather features in Senegal during the African Monsoon Multidisciplinary Analysis Special Observing Period 3

Jenkins, Gregory S.; Kucera, Paul A.; Joseph, Everette; Fuentes, José D.; Gaye, Amadou Thierno; Gerlach, John; Roux, Frank; Viltard, Nicolas; Papazzoni, Mathieu; Protat, Alain; Bouniol, Dominique; Reynolds, A. E.; Arnault, Joël; Badiane, Daouda; Kebe, Fadel; Camara, Moctar; Sall, Saïdou Moustapha; Ndiaye, S. A.; Dème, Abdoulaye

doi:10.1029/2009jd013022

Cited by 18 publications

(11 citation statements)

References 44 publications

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“…Previous studies indicated distinct differences in the dynamic and thermodynamic characteristics of MCSs that propagate through West Africa and, in some cases, over the Atlantic Ocean [ DeLonge et al ., ; Jenkins et al ., ; Guy et al ., ]. Previous studies employed satellite and radar data to examine convection and rainfall in West Africa [ Fuentes et al ., ; Nicholls and Mohr , ; Guy and Rutledge , ].…”

Section: Introductionmentioning

confidence: 98%

The relationship between the Guinea Highlands and the West African offshore rainfall maximum

Hamilton

Young

Evans

et al. 2017

Geophysical Research Letters

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Satellite rainfall estimates reveal a consistent rainfall maximum off the West African coast during the monsoon season. An analysis of 16 years of rainfall in the monsoon season is conducted to explore the drivers of such copious amounts of rainfall. Composites of daily rainfall and midlevel meridional winds centered on the days with maximum rainfall show that the day with the heaviest rainfall follows the strongest midlevel northerlies but coincides with peak low‐level moisture convergence. Rain type composites show that convective rain dominates the study region. The dominant contribution to the offshore rainfall maximum is convective development driven by the enhancement of upslope winds near the Guinea Highlands. The enhancement in the upslope flow is closely related to African easterly waves propagating off the continent that generate low‐level cyclonic vorticity and convergence. Numerical simulations reproduce the observed rainfall maximum and indicate that it weakens if the African topography is reduced.

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Section: Introductionmentioning

confidence: 98%

The relationship between the Guinea Highlands and the West African offshore rainfall maximum

Hamilton

Young

Evans

et al. 2017

Geophysical Research Letters

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“…The SAL is characterized by dry (low relative humidity), stable air (an inversion above the marine boundary layer), a midlevel easterly jet and reduced visibilities from enhanced dust [ Carlson and Prospero , 1972; Karyampudi and Carlson , 1988; Dunion and Velden , 2004]. The SAL is evident from vertical profiles of temperature, dew point and relative humidity from coastal cities of Mauritania, Senegal [ Jenkins et al , 2010] and the Cape Verde Islands [ Zipser et al , 2009]. Recent lidar measurements have detected aerosols suspended in the SAL exiting West Africa is typically found between 2 and 6 km [ Léon et al , 2009].…”

Section: Introductionmentioning

confidence: 99%

Observations and simulation of a Saharan air layer event with a midtropospheric dust layer at Dakar, Senegal, 6-7 July 2010

et al. 2011

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[1] On 3 July 2010 a large dust event was initiated over the Saharan Desert in Southern Algeria with the westward movement of an intensifying thermal low. Increases in Aerosol Optical Depth (AOD) in Algeria, Niger, Senegal and Cape Verde show the progression of the dust event with an AOD of 3.5 to 4 found in Senegal on 7 July. The surface total and direct shortwave radiative fluxes are reduced by more than 200 W m −2 and 300 W m −2 respectively compared to the previous day. Furthermore, there is an increase in diffuse shortwave radiation of 50-150 W m −2 when compared to the previous day. On 7 July, satellite based lidar observations confirm a uniform dust layer at approximately 5 km near the top of the Saharan Air layer where relative humidity values are greater than 50%. A WRF-GOCART simulation show additional sources of dust perturbed over Eastern and Western Mauritania during 6 and 7 July with elevated dust concentrations aloft in concert with satellite measurements on the morning of 7 July. The warm temperatures are associated with the thermal low creating sloping isentropes to the south, which allows the SAL air mass and dust aerosols to rise above the monsoon layer over Senegal.

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“…The present analysis deals with rainfall data of the Dakar raingauge network, located in the region of Dakar (Senegal) in the vicinity of the coast (Jenkins et al, 2010). The rain-gauge network ( Figure 1) We first consider precipitating events.…”

Section: Rain-gauge Datamentioning

confidence: 99%

An analysis of the diurnal cycle of precipitation over Dakar using local rain‐gauge data and a general circulation model

Sané

Bonazzola

Rio

et al. 2012

Quart J Royal Meteoro Soc

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The representation of the diurnal cycle of local deep convection in two versions of the Laboratoire de Météorologie Dynamique-Zoom (LMDZ) General Circulation Model is evaluated using rainfall observations of a rain-gauge network in Senegal. An interpretation of the observed rainfall diurnal modes is attempted by partitioning rainfall as a function of rain-rate intensities and the origin, age and size of associated cloud systems. Our analysis shows a complex multipeak diurnal cycle and a large spatial variability over the rain-gauge domain of typically 100 km. Our results are consistent with the picture of a diurnal cycle of high convective rain rates associated with young and small cloud systems generated in the vicinity of the rain gauges, peaking in late afternoon and superimposed with precipitation associated with long propagative mesoscale convective systems or squall lines with no preferential time over the rain-gauge network. It is shown that these local observations of convection and rain can be used to evaluate the representation of the diurnal cycle of precipitation in a general circulation model with a typical horizontal resolution of 100 km. Two versions of the LMDZ model, including different parametrizations of boundary-layer turbulence, convection and clouds, are compared with observations. In the new parametrization, considering the role of boundary-layer thermals in deep convection preconditioning and the role of cold pools in its sustainment allows us realistically to shift the maximum of precipitation and cloud cover to late afternoon.

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Coastal observations of weather features in Senegal during the African Monsoon Multidisciplinary Analysis Special Observing Period 3

Cited by 18 publications

References 44 publications

The relationship between the Guinea Highlands and the West African offshore rainfall maximum

The relationship between the Guinea Highlands and the West African offshore rainfall maximum

Observations and simulation of a Saharan air layer event with a midtropospheric dust layer at Dakar, Senegal, 6-7 July 2010

An analysis of the diurnal cycle of precipitation over Dakar using local rain‐gauge data and a general circulation model

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