AMMA SOP. ITD and HL survey flights (I1.1)

Transcription

1 AMMA SOP ITD and HL survey flights (I1.1) Observational plateforms / Instruments: F-F20: H2O DIAL lidar LEANDRE 2 and Dropsondes D-F20: Doppler wind lidar WIND ATR: AVIRAD, HYGRO and in situ (mean&turbulent var.) BAe146: Dropsondes

2 Objectives Datasets acquired during I1.1 missions will contribute to improve knowlege of: the structure of the ITD (inter-tropical discontinuity), the monsoon / harmattan / african easterly jet (AEJ) interactions prior to and after the so-called monsoon onset, the uptake and transport of desert dusts in saharan and sub-saharan regions, the role of desert dust radiative forcing on dynamics in the saharan and sahelian regions, the role of albedo heterogeneities in creating mesoscale circulations in the saharan planetary boundary layer (PBL).

3 Observational plateforms / Instruments (1/2) Operated from above the PBL between 6 and 7.5 km DIAL lidar LEANDRE 2 (F-F20): Water vapor mixing ratio profiles 25 km / 600 m (at best) Atmospheric reflectivity at 730 nm resol 1 km / 15 m (~ aerosol concentration in the range µm) Dropsondes (F-F20 & BAe 146): Wind, temperature, humidity, pressure profiles Doppler wind lidar WIND (D-F20): Windprofiles 4 km / 250 m Atmospheric reflectivity at 10 µm resol 4 km / 250 m (~ aerosol concentration in the range 5-15 µm)

4 Observational plateforms / Instruments (2/2) In situ mean and turbulent variables (ATR) Operated within the PBL HYGRO (ATR): Physico-chemical properties of aerosols 10 nm 2 µm as well as their hygroscopic properties (CN, CCN, ions, BC, OC) AVIRAD (ATR) : Optical, physical & chemical properties of aerosols µm Instruments Aerosol property Data availability Data quality Sampling on bulk filters Bulk aerosol composition ~ 80 filters Good Sampling on 4-stage impactors Size-segregated aerosol composition ~ 20 impacteurs, that is 20 x 4 = 80 filters Good GRIMM particle counter Spectral nephelometer Spectral aethalometer Number size distribution (0.3 et 20 µm diameter) Particle scattering and backscattering coefficients Particle absorption coefficient 6-s resolution Good 1-s resolution Good 2-min resolution Good

5 SOP 1a (1-15 June 2006): F/F20 with WV DIAL LEANDRE 2 + dropsondes F/ATR with AVIRAD and HYGRO aerosol packages F-F20: 5 I1.1 missions / 45 dropsondes ATR: 7 I1.1 missions SOP 1a Dates 4/06 5/06 6/06 7/06 8/06 11/06 12/06 15/06 F-F20 ATR A: Interesting stand-alone case B: Useful results in combination with other cases/aircraft C: Good data but unlikely to be useful D: Partial data collection but unlikely to be useful for original objectives E: No useful data ITD too far north: ATR could not detail vertical structure on both sides of the ITD ATR focus of vertical structure south of ITD ATR crossed the ITD only once (8 June)

6 Wet-bulb temperature and winds at 925 hpa Arpege Tropique Valid Z ITD

7 1005 Heat Low characterisation from 0600 Z WASA (N. Ascencio) 27N 1002 Latitude Intensity hpa 12N 1009 East Longitude Surface West

8 Summary of flight tracks ITD ATR flight track on 8 June 2006 F-F20 flight tracks ATR flight tracks

9 5 June 2006 case

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11 1100Z 1300Z 1500Z MSG/SEVERI 1700Z 1900Z 2100Z

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14 Altitude (km agl) Inter-tropical discontinuity & Heat Low survey 5 june Saharan aerosol layer Falcon 20 track Internal boundary layer Leading edge of dust storm LEANDRE 2 reflectivity: UTC Clouds Latitude ( N) Dust injection Dust mixing behind front ITD Niamey MSG IR 10.8µ 1500 UTC Arpege tropique wet bulb temp 1200 UTC

15 19.6 N 19 N 18.5 N 18 N F-F20 Dropsondes over Sahara

16 19.6 N 19 N 18.5 N 18 N F-F20 Dropsondes over Sahara

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18 SOP 2a1 (1-15 July 2006): F/F20 with WV DIAL LEANDRE 2 + dropsondes D/F20 with Doppler wind LIDAR WIND F/ATR with AVIRAD and HYGRO aerosol packages F-F20: 3 I1.1 missions / 31 dropsondes D-F20: 3 I1.1 missions + 2 transit flights ATR: 7 I1.1 missions SOP 2a1 Dates 30/06 1/07 2/07 3/07 6/07 7/07 10/07 12/07 13/07 14/07 F-F20 D-F20 ATR A: Interesting stand-alone case B: Useful results in combination with other cases/aircraft C: Good data but unlikely to be useful D: Partial data collection but unlikely to be useful for original objectives E: No useful data ITD too far north: ATR could not detail vertical structure on both sides of the ITD post-onset??

19 Wet-bulb temperature and winds at 925 hpa Arpege Tropique Valid Z ITD

20 1005 Heat Low characterisation from 0600 Z WASA (N. Ascencio) 27N 1002 Latitude Intensity hpa 12N 1009 East Longitude Surface West

21 Summary of flight tracks ITD ATR flight tracks F-F20 flight tracks

22 07/07/ /07/2006 LEANDRE LEANDRE Aerosol uptake AEJ WIND WIND monsoon monsoon

23 ECMWF analyses 07/07/ /07/2006

24 ATR 42 : HYGRO & AVIRAD aerosol packages 10 July July 2006 Uncorrected scattering coeff 7 July July 2006 Aerosol concentration size distribution

25 30th of June Transfer Djerba to Niamey North-South cross section of the tropospheric wind field from the Mediterranean sea to Niamey AEJ ITD Harmattan From the east From the west Monsoon Low-level, south winds

26 14th of July Transfer Niamey to Agadir above the Heat-Low

27 Use of boundary-layer pressurized balloon for ITD studies BLPB #5, 6 and 8 reached the ITD for several days documenting its thermodynamics and diurnal cycle BLPB #5 terminated 03/07/06 BLPB #6 terminated 04/07/06 BLPB #8 terminated 15/07/06

28 SOP 2a2 (17 July 21 August 2006): F/F20 with WV DIAL LEANDRE 2 + dropsondes UK/BAe 146 with dropsondes F/ATR with CVI and HYGRO aerosol packages & chemistry package F-F20: 1 I1.1 missions / 11 dropsondes BAe 146: 1 I1.1 missions / 16 dropsondes ATR: 10 I1.1 missions SOP 2a2 Dates 17/07 05/08 06/08 07/08 12/08 13/08 14/08 15/08 16/08 17/08 19/08 21/08 F-F20 BAe ATR A: Interesting stand-alone case B: Useful results in combination with other cases/aircraft C: Good data but unlikely to be useful D: Partial data collection but unlikely to be useful for original objectives E: No useful data ITD too far north: ATR could not detail vertical structure on both sides of the ITD

29 1005 Heat Low characterisation from 0600 Z WASA (N. Ascencio) 27N 1002 Latitude Intensity hpa 12N 1009 East Longitude Surface West

30 Wet-bulb temperature and winds at 925 hpa Arpege Tropique Valid Z F-F20 flight track on 21/08/06 SHL ITD

31 Priorities 1- Study of the evolution during the SOP of the mousson/harmattan interface (entrainment process, wind shear, etc..) Priority cases : June 5-6 and 15 (SOP 1a), July (SOP 2a1), and August (SOP 2a2) The link with the heat low characteristics (position, intensity, extent) will have to be assessed 2- Analysis of the ITD structure obtained from lidar remote sensing measurements and dropsondes for the period 30 June - 17 July 2006 (F-F20, D-F20 & BAe 146) Period when the SHL was seen to grow and deepen in the NWP analyses, just before the begining of the rainy season in Sahel (the so-called monsoon onset) African easterly wave activity was also found to be pronounced during this period in the region of the heat low 3- Why was the ITD so difficult to detect from lidar measurements during SOP 1a as opposed to SOP 2a1? Dust loading Position of SHL