Mean zonal wind (contour interval = 1 m s −1) within the layer between 750 and 500 hPa during August 2006 from (a) Meteosat-8 atmospheric motion vectors gridded using 2° × 2° resolution, and the (b) AMMA and (c) pre-AMMA analyses. The black dots indicate the locations of the AMMA radiosonde stations. (a) The mean analysis for the AMMA experiment and (b) the difference between the two experiments (AMMA minus pre-AMMA) for the total column water vapor (kg m −2) from the 00 UTC analyses during August 2006. (a) The mean analysis for the AMMA experiment and (b) the difference between the two experiments (AMMA minus pre-AMMA) for the zonal wind at 700 hPa from the 00 UTC analyses during August 2006. The black dots show the locations of the AMMA radiosonde stations. The gray shading in (c) indicates the difference in mean wind speed and the arrows depict the mean difference in wind vectors. The difference between the AMMA and pre-AMMA experiments for the (b) mean temperature at 925 hPa (K) and (c) mean wind from the 00 UTC analyses. (a) Mean temperature (K) at 925 hPa for August 2006 based on 00 UTC analyses from the AMMA experiment. The black dots depict the locations of the AMMA radiosonde stations. Mean specific humidity analysis increments (g kg −1) at (a) model level 84 (near 925 hPa) and (b) model level 79 (near 850 hPa) for August 2006 based on both the 00 UTC analyses from the AMMA experiment. Numbers on the left indicate the number of observations available around a given level.
Mean vertical profile of radiosonde observation–background departures (OB–BG, solid line) and radiosonde observation–analysis departures (OB–AN, dashed line) of the specific humidity (g kg −1) for the AMMA analysis over (a) the whole West African region (5°–30°N, 20°W–20☎) and (b) the Sahel region (12°–22°N, 20°W–20☎). The arrows depict the mean wind vector analysis at the same level and time. Mean zonal wind analysis increments at 700 hPa for August 2006 based on both the 00 UTC analyses from the AMMA experiment (shaded). The black dots depict the location of the AMMA radiosonde stations. (b) Mean wind vector analysis (see arrow legend) and mean wind speed (see grayscale) at 925 hPa from 00 UTC during August 2006 (AMMA experiment). (a) Mean temperature analysis increments at 925 hPa for August 2006 based on the 00 UTC analyses from the AMMA experiment (gray shades) the arrows depict the wind analysis increments and the black lines are the vertical velocity analysis increment contours of 0.025 Pa s −1 (solid line) and −0.025 Pa s −1 (dashed line) at the same level and time. Only the number of TEMP messages available varies between the two experiments presented in this paper, particularly the radiosondes.
Radiosondes are highlighted with a large cross and circle small red dots are dropsondes. Map showing spatial coverage of conventional observation types (SYNOP from land and ship meteorological stations, aircrafts, and buoys TEMP from radiosondes and dropsondes and PILOT from balloons) used in the ECMWF analysis experiments below 500 hPa during August 2006. (2008), (c) American Meteorological Society. The “monsoon” transects are denoted by solid lines, the “zonal” and northern transects are dashed–dotted, and the “southern quadrilateral” is dashed. The observed mean annual precipitation amount for the period 1961–90 is contoured (up to 2000 mm yr −1, based on the Variability Analysis of Surface Climate Observations (VASClimo) dataset ( Beck et al. Color indicates the planned operational frequencies in 2006: white indicates operational (once per day) with no GTS communications, black indicates once per day, magenta twice per day, green four times per day (Tamanrasset) or variable (Dano), and red four times per day during SOPs 1–3, with eight times per day during IOPs. Shapes denote a station’s status: circles are reactivated stations (or those reconnected to the GTS) and triangles are stations that operated temporarily in 2006 (Praia is not shown, as it is very close to Sal, in the Cape Verde Islands).
“Tamba” is Tambacounda and “Ouaga” is Ouagadougou, Burkina Faso. Key stations in the AMMA radiosonde network.
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