The 2006 Rainy Season over the GOURMA meso-site (Mali)

Transcription

1 SOP Meeting, Toulouse, Nov Instruments and data sets, Status & Highlights The 2006 Rainy Season over the GOURMA meso-site (Mali) E. Mougin, M. Arjounin, F. Baup, E. Ceschia, L. Diarra, V. Demarez P. derosnay, S. Guibert, C. Gruhier, F. Guichard, P. Hiernaux, M. Koité F. Lavenu, L. Kergoat, V. LeDantec, T.M. Mabilo, S. Mangiarotti M.N. Mulhaupt, O. Samain, J. Seghieri, N. Soumaguel, F. Timouk Photo: Doug Parker

2 GOURMA Instruments and Data Sets

3 Gourma 2006: Status of Instruments, Rainfall stations Ekia (16.0 N) Bilantao (15.3 N) Nessouma (15.3 N) EVOLUTION OF RAIN GAUGES. MESO-SCALE Total = 28 stations NATIONAL MANUAL CRX10 PLUVIO 91 5 Status Description Automatic raingauges 11 Automatic Stations Start Location Date Nessouma 2004 Bilantao 2004 Kelma 2006 Kirnya 2005 Kobou 2005 Bangui Mallam 2005 Ekia 2005 Tin tadeini 2005 In Zaket 2006 Agoufou mid slope 2002 Agoufou (down slope) 2005 Data capture : 95%

4 Gourma 2006: Status of Instruments, Meteorological stations Agoufou (15.3 N, 1.5 W) Bamba (17.1 N, 1.3 W) Status Description Automatic Weather stations Start Location Date Agoufou 2002 Bamba 2004 Data capture : 95%

5 Gourma 2006: Status of Instruments, SM stations Meso-scale Network Soil Moisture Station In Zaket 16.6 N Depth: 5cm 2.50m Start Description Location Date Automatic soil moisture Agoufou Upslope 2005 Agoufou mid slope 2006 Agoufou down slope 2005 Agoufou (sapflow) 2005 Bangui Mallam 2005 Kelma (lowland) 2005 Ekia 2005 In Zaket 2005 Bamba stations + 4 (Flux) Data capture: 94%

6 Gourma 2006: Status of Instruments, Flux stations Agoufou (15.3 N) Eguerit (15.5 N) Bamba (17.1 N) Kelma (15.2 N) Description Network of 4 flux stations 2 Sensible Heat 2 Sensible Heat CO 2 H 2 O Automatic Weather Stations CEH Status Start Location Date Bamba (HF)? 2005 Agoufou (CO2+HO2) H only H only 2005 Kelma (C02+HO2) H only 2005 Eguerit (HF) 2005 Bamba???????? 2005 Agoufou 2005 Kelma 2005 Eguerit 2005 Flux-2006: H only ( 50%) Met-2006: ( 20 to 40%)

7 Gourma 2006: Status of Instruments, Sapflow station (Agoufou) Sampled evergreen and deciduous trees January 2006 Sap flow measures provide an estimation of transpiration from trees Heated probe Reference probe 1- Combretum glutinosum 2- Balanites aegyptiacum 3- Acacia raddiana 4- Acacia senegalensis Start Description location Date Sap flow station Agoufou 2006 Acacia senegal 320 Agoufou " Acacia senegal 317 (dead) Agoufou " Acacia raddiana 318 Agoufou " Balanites aegyptiaca 316 Agoufou " Combretum glutinosum 315 Agoufou " Data capture: 98%

8 GOURMA 2006 Highlights

9 Gourma 2006: Rainfall LONG TERM VARIABILITY HOMBORI (15.3 N) ANOMALY (mm) YEARS Long Term mean : 374 mm Hombori : 370 mm

10 Gourma 2006: Rainfall Period Seasons 440 mm 305 mm Late starting Observations 2006: 1. Late starting, but normal (Hombori) to exceeding rain (Agoufou) 2. High intra-seasonal variability (2006 / 2005)

11 Gourma 2006: Total Rainfall Gourma meso-site Strong North-South gradient : 2 mm/km 7.5 Hombori super-site 15.5 BAMBA (mm) 17 OURMA-RHAROUS 6.5 TINT 16 HEKYA 5.5 DIMA AGOUFOU HOMBORI KYNIA NESS HOMBORI DARA KILM GOUN SEBA TARA BILA KELM DARI DOUN AGOUFOU EBAN (mm) KOBOU High local variability : 60%

12 Gourma 2006: Soil moisture AMSR Supersite Averaged Soil Moisture Product August 8 Sept. 17

13 Gourma 2006: Surface Radiative Budget Net radiation = LW -LW + SW -SW Agoufou 2006 Rainy season: Strong increase after mid-july 2006 Period High interannual variability with stronger increase of Rnet for wet years (2003, 2005) compared to dry years (2002, 2004) Jul Aug Wet Year Dry Year

14 Gourma 2006: Surface Radiative Budget Albedo = SW / SW Jul Aug Agoufou 2006 Rainy season: Strong decrease after mid-july 2006 Period High interannual variability with stronger decrease for wet years (2003, 2005) compared to dry years (2002, 2004) 2005 Jun Jul Aug Wet Year Dry Year 2004

15 Gourma 2006: Tethered Balloon in the CBL Convective Boundary Layer growth August 19 9h 17h Virtual potential Temperature (θv) vs pressure CBL rather low, following significant rainfall over a well vegetated area. Data capture: August 12-31

16 Gourma 2006: Seasonal change of vegetation, Hombori JULY -2006: desperately seeking green vegetation Super-site overflight Hombori: July 28, 2006 Field survey Hombori: July 17, 2006

17 Gourma 2006: Interannual change of vegetation, Agoufou GRASSLAND Soil Moisture June 06 May 29 July 17 LAI July 15 August 19 DOY August 20

18 Gourma 2006: Interannual change of vegetation, Kelma ACACIA FOREST August 02 LAI July 24 August 30 August 21 DOY September 19 September 20

19 Gourma 2006: Surface fluxes, Kelma 1 m 3 /m 3 Rain Soil moisture mm 20 Acacia Forest site 0,9 0,8 Rain Soil Water content -50 cm ,7 Soil Water content -10 cm 14 0,6 12 0,5 10 0,4 8 0,3 6 0,2 4 0, Jul 15-Jul 20-Jul 25-Jul 30-Jul 4-Aug 9-Aug W/ m² Sensible Heat Fluxes Net Radiation ma x Flooded Sensible Heat Flux 10-Jul 15-Jul 20-Jul 25-Jul 30-Jul 4-Aug 9-Aug

20 Gourma 2005: Inter-sites variation, H fluxes W/m² Grassland 600 Rnet max Sensible Heat Flux juin 11-juin 21-juin 1-juil. 11-juil. 21-juil. 31-juil. 10-août 20-août 30-août Erosion surface

21 Gourma 2006: Sapflow fluxes from trees, Agoufou Seasonal variation flux de s eve HV (-5cm) 40 Flux (mv) TDR (mv) Strong seasonal variation dependent on leaf phenology and Soil Moisture Content in the root zone Soil Moisture Daily variation jours 0.25 Water stress Strong daily variation dependent on SWC flux (mv) No Water stress h 17h heure

22 Gourma 2006: Summary Rainy season Late starting, followed by heavy rains from mid-july to mid-august (60% of total rainfall) and finally normal to exceeding total rainfall Surface Radiative properties (Net radiation): typical of wet year (2005, 2003) Late starting of vegetation (trees and herbs) but fast growth and finally a total cover close to that observed in 2005 (even better for trees) Instruments and Data Sets Operational network : Data collection >95% (rainfall, soil moisture, vegetation) Flux stations : 50%, complemented by sap flow measurements on trees.