analysis of surface meteorological data at the Gourma sites focus on radiative fluxes & thermodynamics at diurnal & interannual time scales automatic weather station of Agoufou, 2002  now wind speed, T, RH, radiative fluxes etc, 15-min sampling no pressure nor wind direction, some holes mostly outside the monsoon season aeronet sunphotometer of Agoufou, 2003  now aerosol optical depths, precipitable water, daytime & cloud free conditions automatic weather station of Bamba 2004  now with wind direction ECMWF-IFS « Agoufou grid-point » time and time-height series, horizontal resolution ~ 40 km, 60 vertical levels initially, check of data consistency characterisation of the site valuable Northern Sahel ground truth/modelling purpose (diagnostics) objectives data & products F. Guichard, L. Kergoat, F. Timouk, F. Baup, F. Lavenu & E. Mougin

185 mm water vapour mixing ratio (qv) 2m AGL 430 mm cumulative precipitation mm day of year Jul rainfall per event Aug Agoufou qv (g.kg -1 ) mm

JulAug Agoufou day of year net radiation 3-day running mean seasonal variations of net radiation Rnet = LW  - LW  + SW  - SW  interannual variability with stronger increase of Rnet for wet years (2003,2005) compared to dry years (2002,2004) partly explained by a stronger decrease of upward longwave flux for wet years... but not the whole story surface radiative budget 2005 rainfall per event

Jul Aug Agoufou day of year albedo 3-day running mean seasonal variations of ALBEDO = SW  / SW  again interannual variability with stronger increase of Rnet for wet years (2003,2005) compared to dry years (2002,2004) differences also before the monsoon season surface radiative budget, suite more on albedo to come with Olivier & Laurent rainfall per event 2005

interannual variations of surface radiative fluxes LW  -LW  SW  -SW  Rnet LWnet SWnet dLW  -dLW  dSW  -dSW  dRnet dLWnet dSWnet Agoufou August average (W.m -2 )  Rnet ) ~ W.m -2 for Rnet values~ 120 W.m -2 dominated by  IR  ) less IR  flux from a surface that is cooler during wet years weaker albedo in [2003 & 2005]/[2002 &2004] more that compensates SW  decrease of [2003 & 2005]/[2002 &2004] decrease of SW  consistent with a more cloudy atmosphere during wet years (deviation from the 4-year mean)

ECMWF model 2005 ECMWF model 2004 data 2005 data dLW  -dLW  dSW  -dSW  dRnet dLWnet dSWnet (deviation from given cstes) model ~ok for 2004, not for 2005 because does too much the same for both years

Bamba m-temperature (K) 2m-vater vapour mixing ratio (g/kg) Agoufou 2004 Agoufou 2005 associated thermodynamics significant afternoon decrease of water vapour mixing ratio for dry years would be broadly consistent with higher sensible heat fluxes 2004/2005 & simple convective boundary layer dynamics saturation afternoon (13-16h LT) all points August

July August Bamba 2004Agoufou 2004 Agoufou 2005 diurnal cycle of  e (equivalent potential temperature ~ moist enthalpy, with T& q) no increase of  e during daytime for dry years (flat cycle) because of large daytime drying (may further enhances evaporation of precip) links with diurnal cycle of convection over land & convective indexes used for modelling, although nature of link not necessarily simple magnitude of convective destabilisation from low levels, intensity of convection  e (K) precipitation at Bamba fct(hour of day)

Jul-Aug 5-day running mean Bamba 2004Agoufou 2004 Agoufou 2003 also larger time scale variability & nature of thetae (wetter versus drier) 2m-water vapour mixing ratio (g/kg) 2m-temperature (°C)  e=350K

Agoufou July-August 2005, daily values dataECMWF model 2m-water vapour mixing ratio (g/kg) 2m-temperature (°C) worse for low  e regimes, possible links with –missing- processes? T- qv- T+ qv-  e=347K

Plcl (mb) LWnet (W.m -2 ) JJAS 2005 daily values data ECMWF model summary, perspectives useful dataset, clear signals in meteorological data to my knowledge, not so numerous such datasets over the area synthetic diagnostics for analysing & evaluating atmospheric models too (e.g. same vein as Betts) – some caution required ECMWF: seasonal variations rather good, reasonable T & water vapour, but –for Eric- precipitation very wrong; likely other distinct stories for climate models. manage to write down a description/characterisation of the site(s) as provided by these data

63 mm 185 mm Agoufou 2004 Bamba 2004 Bamba 2004 albedo=0.4 Agoufou 2004 albedo albedo=0.4