1. Zhibo Zhang (UMBC GEST) June 7 th,2010 Celebrating GEST’s 10 th Anniversary Many thanks to: Steven Platnick (NASA GSFC), Ping Yang (Texas A&M University), Andrew K. Heidinger (NOAA NESDIS) and Jennifer Comstock (PNNL) 1 GEST 10th Anniversary

2. Outline  Background  Exciting discoveries  Summary 2 Outline

3. What happens in the night? Background 3 MODIS daytime granule Product size ~40M Optical thicknessEffective radius MODIS nighttime granule Product size ~4M Optical thicknessEffective radius ??

4. Background 4 Infrared approach is needed (and already funded by NASA) to fill the nighttime gap in MODIS cloud product But, does the infrared approach provide the same cloud property retrievals as the solar approach? If not, what are the potential reasons? Our research focuses on the effect of cloud particle size vertical inhomogeneity

5. Ice cloud vertical inhomogeneity Microphysical processes that could lead to ice particle size vertical inhomogeneity. 1) Condensation growth; 2) Size sorting; 3) Coalescence & aggregation Background 5

6. MODIS cloud retrieval algorithm 6 Background Plane-parallel Vertical homogenous Cloud in MODIS retrieval algorithm Real cloud Ice Particle model Ice clouds in reality Microphysical processes that could lead to ice particle size vertical inhomogeneity. 1) Condensation growth; 2) Size sorting; 3) Coalescence & aggregation Could cloud particle size inhomogeneity lead cause inconsistency between the solar and infrared methods?

7. Thin clouds Exciting Discoveries 7 Solar method IR method Both methods tend to underestimate the effective size. IR method is worse due to higher degree of nonlinearity.

8. Thick clouds (1) Exciting Discoveries 8 Solar method IR method Solar method is highly sensitive to cloud particle at cloud top IR method is relatively insensitive to cloud vertical inhomogeneity.

9. Thick Clouds (2) Exciting Discoveries 9 Cloud particle size Cloud top Cloud base IR < solar IR ~ solar

10. Summary If cloud particle size is vertically inhomogeneous……  For thin clouds, both solar and IR methods tend to underestimate the effective radius  For thick clouds, it depends… Summary 10 Take-home message Cloud particle inhomogeneity could lead to inconsistency between solar and IR methods. Be cautious when comparing or combining the two methods.

11. Happy Birthday, GEST! GEST 10th Anniversary 11 This talk is based on Zhang et al 2010 JGR (Will be highlighted in EOS)