1. TReSS (Transportable Remote Sensing Station) in Tamanrasset Overview of TReSS Status of implementation on April 1 st 2006 Operations in the framework of the AMMA lidar network

2. TReSS team: –Cyrille Flamant (IPSL/SA, CNRS, Paris, France) –Juan Cuesta (IPSL/LMD, CNRS, Palaiseau, France) –Pierre Flamant (IPSL/LMD, Palaiseau, France) –Dimitri Edouart (IPSL/LMD, Palaiseau, France) –Claude Loth (IPSL/LMD, Palaiseau, France) –Jacques Pelon (IPSL/SA, CNRS, Paris, France) Support teams: gratefully acknowledged ! –Algéria: OMN in Algers and Tamanrasset –France: L. Gomes (CNRM) & K. Desboeufs (LISA) & M. Legrand (LOA) TReSS science objectives and teams Main objective: Improved knowledge of heat low dynamics and aerosol radiative properties in the heat low region Ancillary objective: CAL/VAL for CALIPSO and the A-Train Funded by API & CNES & IPSL

3. What is TReSS? TReSS is an autonomous and high-performance system designed to observe radiative and structural properties of clouds and aerosol layers, as well as atmospheric boudary layer dynamics. The standard payload is made of the following instruments: 1) a multi-wavelength elastic backscatter Mini-Lidar operating at 532 and 1064 nm (with diverse polarization capability at 532 nm), 2) a sun-photometer, 3) an IR radiometer, 3) a full sky visible channel web-type camera. For the AMMA SOP period, the platform capability will be enhanced with: an Optical Depth Sensor (for daytime and nighttime measurements), a CLIMAT radiometer a sonic anemometer a GRIMM for size distribution measurements a nephelometer operating at 880 nm filters for chemical speciation (in collaboration with LISA) The above instrumentation will also be enhanced by the measurements conducted routinely by the Météo Algérienne: balloon soundings (x4 during the SOP), surface Meteorological measurements, radiative measurements, ozone integrated column

4. TReSS measurements Aerosol and molecular extinction coefficient profiles (30 m vertical resolution, 10 s temporal resolution)  km -1 Aerosol layers optical and geometrical depths  unitless and m ABL depth  m Thick cloud base altitude  m Thin cloud optical and geometrical depths (15 m res)  unitless and m Total aerosol optical depth at 8 wavelengths from the sunphotometer (340, 380, 440, 500, 670, 870, 936 and 1020 nm) and 2 wavelengths (330-400 and 780-1100 nm) for the ODS  unitless Integrated water vapor content  kg m -2 IR irradiance in the 8-13µm, 11.5-12.5 µm, 10.5-11.5 µm, 8.2-9.2 µm and 9.5-11.5 µm ranges  W m -2 Full-sky visible images (10 s temporal resolution) Surface sensible heat flux (5 min. temporal resolution)  W m -2 Aerosol size distribution between 0.1 and 5 µm (3-6 hourly)  µm 3 µm -2 Aerosol phase fonction in the 45°-90° ranges (5 min. res)  sr -1

5. Schedule of AMMA SOP operation SOP 0 (almost) Installation & first measurements SOP 2a1 SOP 2a2 SOP 1a

6. Status of implementation The multi-wavelength backscatter Mini-Lidar  seriously damaged during transportation between Algers and Tamanrasset New laser and new telescope are needed!! Replacement scheduled for SOP 1a Sun-photometer  operational since 16/02/06 (data transmitted to AERONET and available on the web) CLIMAT radiometer  operational since 17/02/06 (data transmitted to M. Legrand at LOA via internet) Sonic anemometer  operational since 18/02/06 (installed on 10 m mast) Size distribution measurements  operational since 18/02/06 Failure Operational

7. Status of implementation Full sky visible channel web-type camera IR radiometer Nephelometer Tested / will be running during lidar operations Optical Depth Sensor (for daytime and nighttime measurements) Filters for chemical speciation To be installed / tested (before SOP 1a)

8. TReSS-lidar measurements in the framework of the lidar network Important issues associated with networking : to document the diurnal cycle of relevant variables in the heat low region (ABL structure, aerosol content and properties, etc..), to document diurnal cycle of relevant variables NORTH and SOUTH of the ITF, to document the diurnal cycle of relevant variables before and after the passage of MCSs (not really relevant for TReSS, but….), validation CALIPSO products over the Sahara, which will in turn be used to analyze the mesoscale/large scale variability of the PBL/SAL and aerosol properties.  IOPs: Day J: continuous Days J-1 & J+1: continuous ??  Outside IOPs: 4 h around 12 z (flexible)