A42A-04
Determination of Cloud Thermodynamic Phase with Ground Based, Polarimetrically Sensitive, Passive Sky Radiometers
Thursday, 17 December 2015: 11:05
3002 (Moscone West)
Kirk D Knobelspiesse1, Bastiaan van Diedenhoven2, Alexander Marshak3, Stephen E Dunagan1, Brent N Holben3 and Ilya Slutsker4, (1)NASA Ames Research Center, Moffett Field, CA, United States, (2)Columbia University of New York, Palisades, NY, United States, (3)NASA Goddard Space Flight Center, Greenbelt, MD, United States, (4)Science Systems and Applications, Inc., Lanham, MD, United States
Abstract:
When observed from the ground, optically thick clouds minimally polarize light, while the linear polarization direction (angle) of optically thin clouds contains information about thermodynamic phase. For instruments such at the Cimel radiometers that comprise the AErosol RObotic NEtwork (AERONET), these properties can also be exploited to aid cloud optical property retrievals. Using vector radiative transfer simulations, we explore the conditions most favorable to cloud thermodynamic phase determination, then test with actual AERONET data. Results indicate that this technique may be appropriate for some, but not all, conditions, and motivate a deeper investigation about the polarization direction measurement capability of Cimel instruments, which to date have been primarily used to determine degree of polarization. Recent work explores these measurement issues using a newly installed instrument at the NASA Ames Research Center in Moffett Field, California.
