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

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).

Objectives

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 0.1 – 5 µm)

Dropsondes (F-F20 & BAe 146):• Wind, temperature, humidity, pressure profiles

Doppler wind lidar WIND (D-F20):• Wind profiles 4 km / 250 m• Atmospheric reflectivity at 10 µm resol 4 km / 250 m(~ aerosol concentration in the range 5 - 15 µm)

Observational plateforms / Instruments (1/2)Operated from above the PBL between 6 and 7.5 km

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 Number size distribution (0.3 et 20 µm diameter)

6-s resolution Good

Spectral nephelometer Particle scattering and backscattering coefficients

1-s resolution Good

Spectral aethalometer Particle absorption coefficient

2-min resolution Good

AVIRAD (ATR) :Optical, physical & chemical properties of aerosols 0.3 – 20 µm

In situ mean and turbulent variables (ATR)HYGRO (ATR):Physico-chemical properties of aerosols 10 nm – 2 µmas well as their hygroscopic properties (CN, CCN, ions, BC, OC)

Observational plateforms / Instruments (2/2)Operated within the PBL

SOP 1a (1-15 June 2006):• F/F20 with WV DIAL LEANDRE 2 + dropsondes• F/ATR with AVIRAD and HYGRO aerosol packages

ITD too far north: ATR could not detail vertical structure on both sides of the ITD

ATR focus of vertical structure south of ITDATR crossed the ITD only once (8 June)

F-F20: 5 I1.1 missions / 45 dropsondesATR: 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

Valid 050606 12Z

Wet-bulb temperature and winds at 925 hPa – Arpege Tropique

ITD

Heat Low characterisation from 0600 Z WASA (N. Ascencio)

Latitude Intensity hPa

SurfaceLongitude

West

East

12N

27N 1002

1005

1009

06 07 08 09 06 07 08 09

F-F20 flight tracks ATR flight tracks

ATR flight trackon 8 June 2006

ITD

Summary of flight tracks

5 June 2006 case

1100Z 1300Z 1500Z

1900Z1700Z 2100Z

MSG/SEVERI

Inter-tropical discontinuity & Heat Low survey – 5 june 2006

LEANDRE 2 reflectivity: 1428 –1532 UTC

MSG IR 10.8µ 1500 UTC Arpege tropique wet bulb temp 1200 UTC

Leading edge of dust stormFalcon 20 track ITD

Saharan aerosol layer

Niamey

Clouds

19 18 17 16 15Latitude (°N)

0

3

6

Alt

itud

e (k

m a

gl)

Internalboundary layer

Dust injection

Dust mixingbehind front

19.6°N 19°N

18°N18.5°N

F-F20 Dropsondes over Sahara

19.6°N 19°N

18°N18.5°N

F-F20 Dropsondes over Sahara

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

ATR: 7 I1.1 missionsD-F20: 3 I1.1 missions + 2 transit flights

SOP 2a1Dates 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 ??

Valid 030706 12Z

Wet-bulb temperature and winds at 925 hPa – Arpege Tropique

ITD

Heat Low characterisation from 0600 Z WASA (N. Ascencio)

Latitude Intensity hPa

SurfaceLongitude

West

East

12N

27N 1002

1005

1009

06 07 08 09 06 07 08 09

F-F20 flight tracksATR flight tracks

ITD

Summary of flight tracks

07/07/2006 10/07/2006LEANDRE LEANDRE

WINDWIND

AEJ

monsoon monsoon

Aerosol uptake

07/07/2006 10/07/2006ECMWF analyses

ATR 42 : HYGRO & AVIRAD aerosol packages

7 July 2006

7 July 2006

10 July 2006

Uncorrected

scattering coeff

Aerosol concentration

size distribution

13 July 2006

30th of June – TransferDjerba to Niamey

North-South cross section of the tropospheric wind field from the Mediterranean sea to Niamey…

Monsoon

ITD Harmattan

AEJ

Low-level, south winds

From the westFrom the east

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

Use of boundary-layer pressurizedballoon for ITD studies

BLPB #5, 6 and 8 reached the ITD for several days documenting its thermodynamics and diurnal cycle

BLPB #5 terminated 03/07/06BLPB #6 terminated 04/07/06 BLPB #8 terminated 15/07/06

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

ATR: 10 I1.1 missionsBAe 146: 1 I1.1 missions / 16 dropsondes

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

Heat Low characterisation from 0600 Z WASA (N. Ascencio)

Latitude Intensity hPa

SurfaceLongitude

West

East

12N

27N 1002

1005

1009

06 07 08 09 06 07 08 09

Valid 210806 12Z

Wet-bulb temperature and winds at 925 hPa – Arpege Tropique

ITDSHL

F-F20 flight trackon 21/08/06

Priorities1- Study of the evolution during the SOP of the mousson/harmattaninterface (entrainment process, wind shear, etc..)

Priority cases : June 5-6 and 15 (SOP 1a), July 2-12-13 (SOP 2a1), and August 12-13-16-17 (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 loadingPosition of SHL