Contribution of the airborne and ground-based lidar LAUVA. to AMMA SOP-0

Transcription

1 Contribution of the airborne and ground-based lidar LAUVA to AMMA SOP-0 P. Chazette, F. Dulac and J. Sanak ULA Pilot: F. Toussaint Acknowledgements: C. Flamant, J. Pelon, V. Cassé, J-L Redelsperger, AOC and Niamey airport author. Funding by CNES

2 The backscatter lidar LAUVA Air cond. Electronics Optics Ground version Wavelength (Nd:YAg) Mean energy per pulse Pulse repetition rate Pulse duration Beam diameter Divergence Reception diameter Filter bandwidth Field of view Detector Detection mode Vertical resolution Dimensions of the optical head Weight of the optical head Weight of the electronics Electric supply Consumption 355 nm 16 mj 20 Hz 7 ns 20 mm < 0.2 mrad 150 mm 0.5 nm 4 mrad Photomultiplicator Analog 1.5 m 45 cm (H) x 28 cm (W) x 18 cm (D) ~9 kg ~20 kg 220 V < 500 W Patented CEA-CNRS licensed to Leosphere (Easy-lidar,

3 The field campaign Niamey international airport Observation period: 23 Jan. 02 Feb Ground-based during night time + 1 day (27 Jan.) In-flight during day time

4 N I G E R The playground N B Flight area O T Ground-based monitoring N: Niamey int. airport T: La Tapoa airfield (1 night) N I G E R I A B: Banizoumbou station D D: Djougou station

5 Examples of ground-based data Niamey airport: Jan. La Tapoa: Jan.

6 Niamey airport: 31 Jan.-1 Feb. Dust exported from Sahara desert? Dust and/or local sources

7 Niamey airport: 1-2 Feb. Dust arrival in the BL during the night Lidar POLIS of Munich University (B. Heese measurements) ~8% depolarisation

8 Ultra-Light Aircraft (ULA) characteristics and payload ULA payload the backscatter lidar LAUVA (355 nm) a GPS an artificial horizon a PTU sonde a wide-band scatterometer operating at 880 nm ULA general characteristics Air Création competition machine Horizontal pointing during ascent and descent, nadir pointing on cruise True airspeed: 17 to 40 m/s (60 to 145 km/h) Ascent speed: up to 365 ft/min (110 m/min) Descent speed: 825 ft/min (250 m/min) Endurance: 3 hr (max 4 hr at 20 m/s) Maximum scientific payload: 120 kg Maximum altitude: 5.8 km

9 Airborne measurements 13 + flights from 24 Jan. to 1 Feb Duration: 46 to 169 mn Max. altitude: 3.5 to 5.6 km N B Including: T 3 profiles at Niamey in coincidence with BAe-146 (26 & 28 Jan., 1 Feb.) and about 100 km of common track to SE (1 Feb.) 2 flights to Banizoumbou with descents over the station (25 & 26 Jan.) failure of tentative coincidence with the surface lidar (31 Jan.) 2 N-S transects to and from La Tapoa (29 and 30 Jan.)

10 Example: flight from La Tapoa to Niamey (30/01) Ascent over La Tapoa and descent over Niamey airport Nadir shooting mode Horizontal shooting mode La Tapoa airfield

11 A large scale multilayered aerosol structure 1000 m 2000 m 3500 m Hysplit back-trajectories Biomass burning aerosol from Benin/Nigeria Ascent Descent Mixing of aerosol from lack Tchad area Dust aerosols from Sahara desert La Tapoa Niamey Relative humidity

12 Derived profiles of aerosol properties Ascent (La Tapoa) Descent (Niamey) Aerosol extinction coefficient at 355 nm retrieved from horizontal shooting Angström exponent between 355 and 880 nm synergy between the airborne lidar and scatterometer and the ground-based sunphotometer Ascent Descent

13 Backscatter to extinction ratio (BER) BER = ω o P Π product of the single scattering albedo of aerosols by their backscatter function Biomass burning aerosols a lidar parameter controlled by aerosol properties (absorption, scattering, size, chemical composition) Dust/biomass burning aerosols Niamey La Tapoa Dust/Urban aerosols

14 Perspectives for data exploitation Manuscript on the ULA lidar A new approach for aerosol profiling with a lidar onboard an ultra light aircraft and application to the African Monsoon Multidisciplinary Analysis (AMMA). P. Chazette et al., J. Environ. Sci. Technol. Collaborative work on airborne data coincident BAe in situ measurements (profiles of refractive index) Collaborative work on ground-based monitoring coincident ARM and Banizoumbou data (variability, BER profile, )