1. Multiple Scattering and CLOUDNET D.Donovan, J. Pelon and M. Haeffelin

2. Multiple scattering

3. Beam tends to spread out in Clouds

4. Effective extinction is reduced ½ energy goes into forward diffraction peak. For large particles and large FOV's F(z)=0.5

5. Dependence on size

6. Applicatio n to Real Data

7. An ice cloud example FOV 5mrad ? FOV 0.5 mrads Alignment ?

8. An lower cloud example GreenIR Overload ? Pick-up noise ?

9. A low water cloud example Green IR Alignment and overload Pickup-noise ?

10. So…inconclusive Hints that it may still work ! Need better data. Examining quick looks not enough ! Alignment drifts Non-linearity and Signal-induced-noise and noise pick-up Need purpose acquired data with signals within linear range of the system and attention to alignment !

11. Retrieval Procedure (for thick clouds) To get optical depth

12. Low water clouds (often missed by radars) Small FOV should be small as possible Large FOV of 2.5-3.0 microns sensitive to variations between 5-25 microns Feasible ! Should be attempted

13. Semi-analytical model (Eloranta)