1. OVERVIEW OF THE DATA OBTAINED DURING ASTAR 2007 (ARCTIC MIXED-PHASE CLOUDS) & CIRCLE-2 (MID-LATITUDE CIRRUS) Alfons Schwarzenboeck, Guillaume Mioche, Christophe Gourbeyre, Jean – Francois Fournol, Guy Febvre, Jean – François Gayet Institut für Physik der Atmosphäre Flight facility Oberpfaffenhofen http://www.pa.op.dlr.de/aerosol/astar2007/ http://www.pa.op.dlr.de/pazi-falcon/circle2/

2. ASTAR 2007 (Longyearbyen 25 Mars – 19 Avril)

3. ● Cloud Particle imager (CPI) : High resolution measurement of the cloud particle shape (2.3 µm pixel size) ● Polar Nephelometer (PN) : Measurement of the scattering phase function of the cloud particles (3 µm < D < ~ 1 mm) ● PMS FSSP-100 or 2D-C probes : Particle size distribution (and shape) of particles (3 µm < d < 800µm) The cloud in-situ measurements onboard the AWI Polar 2 aircraft ● Nevzorov probe (AWI) : Liquid / ice water content ● AMALi (AWI) 355nm & 532nm (// & ^), Spectral Albedometer (Univ. of Mainz)

4. Overview of the observations Date Take-off time (UT) Landing Time (UT) ObservationsCloud types 2 April14:4517:00Cloud observations Mixed-phase stratiform cloud 3 April11:5514:45Cloud observations Mixed-phase stratiform cloud 7 April8:2011:30CALIPSO (cloud) validation Mixed-phase stratiform cloud 8 April9:1512:15 Alternate Remote sensing/ Cloud observations Mixed-phase stratiform cloud 9 April8:1511:20 Alternate Remote sensing/ Cloud observations CALIPSO (cloud validation) Mixed-phase stratiform cloud 10 April11:0014:00 Alternate Remote sensing/ Cloud observations Mixed-phase stratiform cloud 14 April11:4514:30 Alternate Remote sensing/ Cloud observations Cirrus layer 14 April15:5017:50 Alternate Remote sensing/ Cloud observations Cirrus layer 16 April8:3011:30 Cloud observations CALIPSO (cloud validation) Mixed-phase stratiform cloud ● 7 flights are related to mixed-phase stratocumulus clouds including 3 flights coordinated with the CALIPSO trace, and 2 flights are related to cirrus layers. ● Remote sensing observations concern AMALi Lidar (AWI) and Albedometer (Univ. of Mainz)

5. Calipso track interception A A C C Example of Polar 2 Flight plan and measurements (7 April 2007)

6. NOAA 18 RGB Channel 10:10 UTC CALIPSO Track Polar 2 flight mission

7. In situ observations

8. 11:00 UT

9. 9:08 LT

10. Asymmetry parameter LWC (g/m3) Ice particle conc. (l-1) Effective diam. (um) Supercooled water Ice crystals Cloud top : -23°C

11. Conc : 50 cm-3 Ext : 20 km-1 LWC : 0.14 g/m3 Deff :17.5  m PMS FSSP size distribution Theoretical scattering phase function (FSSP) Example of measurements in water cloud : FL 1450 m / -20°C

12. Conc : 50 cm-3 Ext : 20 km-1 LWC : 0.14 g/m3 Deff :17.5  m g : 0.836 PMS FSSP size distribution Theoretical scattering phase function (FSSP) ● Measured scattering phase function (Polar Nephelometer) Example of measurements in water cloud : FL 1450 m / -20°C

13. Example of measurements below the cloud (precipitation) : FL 600 m / -13°C Polar Nephelometer CPI FSSP Ice particle conc : 10 l-1 Extinction : 2 km-1 IWC : 20 mg/m-3 Deff : 70  m g : 0.775

14. 0 500  m CPI images obtained below the cloud (precipitation)

15. Conclusions and outlook ● Several mixed-phase stratocumulus clouds have been observed with similar properties, i.e. supercooled water droplets in the upper layer (of a few hundred meters depth) with ice crystals precipitating down to the surface. ● The cloud top layers varied between 1000 m / -15°C and 2000 m / -23°C ● The water - ice partition was observed with different magnitude. Furthermore different supercooled water-droplet properties were evidenced (50 cm-3 / 18  m to 200 cm-3 / 11  m). ● Two Polar-2 flights has been devoted for the validation of CALIPSO cloud- products with transects performed along the satellite trace including numerous cloud vertical profiles and a third flight was carried out very close to the satellite trace. ● Several vertical profiles are therefore available for the validation of the cloud products (level 2a, i.e. extinction coefficient, particle phase, effective diameter, …)

16. CIRCLE-2 (Oberpfaffenhoffen 7 – 27 Mai)

17. ● Cloud Particle imager (CPI) : High resolution measurement of the cloud particle shape (2.3 µm pixel size). ● Polar Nephelometer (PN) : Measurement of the scattering phase function of the cloud particles (3 µm < D < ~ 1 mm). ● PMS FSSP-300 and 2D-C probes : Particle size distribution (and shape) of particles (1 µm < d < 1 mm). ● Lidar WALES (DLR) 532nm & 1064nm (// & ^), Spectral Albedometer (Univ. of Mainz) The cloud in-situ measurements onboard the DLR Falcon aircraft

18. Date Measurement period Flight operation Cloud type CloudSat CALIPSO interception In situ Probes RALI Coordinated Flight F = French G = German Start Time (UTC) End Time (UTC) 13 May11:0014:40Creil - Creil No Ci - Convection YESN/AOK NO (F) 14 May 11:00 16:00 14:40 16:50 OP – Leipzig Leipzip - OP Broken Ci YES NO No CPI N/A NO (G) 16 May 08:00 12:20 16:50 10:00 15:30 18:30 OP – Brest Brest – Brest Brest - OP Frontal Ci NO YES NO OK - YES - 20 May12:4014:40OP - OPOutflow CiNOOKN/ANO (G) 20 May12:4014:40Creil – CreilBroken CiYESN/AOKNO (F) 22 May 10:20 14:30 13:40 16:20 OP – Esbjerg Esbjerg - OP Frontal Ci NO OK N/ANO (G) 23 May 08:30 12:15 16:40 10:20 15:20 18:30 OP – Bilbao Bilbao – Bilbao Bilbao – OP Outflow Ci NO YES NO OK N/ANO (G) 25 May 07:00 11:20 16:10 09:00 15:00 17:40 OP – Brest Brest – Brest Brest - OP Broken Ci Ci layer Ouflow Ci NO YES NO OK - YES - 26 May11:0514:00OP - OPOutflow CiYESOK RASTA OK NO LNG - YES - Overview of the observations

19. A B Example of data obtained on 16 May

20. Point A Point B Altitudes need to be confirmed

21. Point A CALIPSO Point B FL 11800m / -59°C FL 11400m / -56°C

22. Point A Point B Extinction Coef. (PN). Scale 0 – 0.5 km-1

23. Ice crystals from CPI : Plate is the dominant shape but with no 22° Halo on PN ? 0 200  m

24. Ice Particle concentration = 1.2 cm-3 Ice water content = 1.5 mg/m3 Extinction coefficient = 0.30 km-1 Effective diameter = 11 mm Asymmetry parameter = 0.784 Measured phase function Theoretical phase function (FSSP + Mie) A smoothed scattering phase function is observed despite rather geometrical shape of ice crystals (see CPI images). Therefore, the internal lattice structure of the crystals plays a dominant role on optical properties.

25. Oberpfaffenhofen to Brest flight 22° halo occurrence (when > 1) Halo No Halo 16 May FL 7000 m / -30°C

26. 22° halo 22 ° Halo occurrence => pristine ice crystals Extinction Coef. = 0.80 km-1 Asym. Parameter = 0.779

27. Smooth scattering phase function => Irregular shaped ice particles Ext. Coeff. = 0.35 km-1 Asym. Param. = 0.765

28. CloudSat-1B_CPR RASTA (calibrated) 26 MAY : Overpass Temporal Evolution ?

30. Conclusions and outlook ● Over 7 operational days, 15 flights have been carried out in various Cirrus clouds. 5 flights were perfectly co-ordinated with the CALIPSO overpasses including 3 flights also co-ordinated with the French SAFIRE Falcon. ● The observations address different cirrus types (optically thin to very dense) with extinction varying from about 0.15 km-1 to more than 5 km-1). ● The in situ cloud instruments worked well and a first evaluation of the data show an excellent coherence between the different observations. ● The ensemble of observations gathered during CIRCLE2 (Lidar WALES on board the DLR Falcon and RALI system onboard the SAFIRE Falcon) constitutes an unique material to get new insights in Cirrus interactions with radiation and for the Calipso, CloudSat and MSG validations.