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Zhibo Zhang (UMBC GEST) June 7 th ,2010 Celebrating GEST’s 10 th Anniversary . Effects of ice particle size vertical inhomogeneity on the passive remote sensing of ice clouds. Many thanks to: Steven Platnick (NASA GSFC), Ping Yang (Texas A&M University), - PowerPoint PPT Presentation
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GEST 10th Anniversary 1
EFFECTS OF ICE PARTICLE SIZE VERTICAL INHOMOGENEITY ON THE PASSIVE REMOTE SENSING OF ICE CLOUDS
Zhibo Zhang (UMBC GEST)June 7th,2010Celebrating GEST’s 10th Anniversary
Many thanks to:Steven Platnick (NASA GSFC), Ping Yang (Texas A&M University), Andrew K. Heidinger (NOAA NESDIS) and Jennifer Comstock (PNNL)
Outline 2
Outline
Background Exciting discoveries Summary
Background 3
What happens in the night?MODIS daytime granule Product size ~40M
Optical thicknessEffective radius
MODIS nighttime granule Product size ~4M
Optical thicknessEffective radius
? ?
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
Background 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 6
MODIS cloud retrieval algorithm
Plane-parallelVertical
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 & aggregationCould cloud particle size inhomogeneity lead cause inconsistency between the solar and infrared methods?
Exciting Discoveries 7
Thin cloudsSolar method IR method
•Both methods tend to underestimate the effective size.•IR method is worse due to higher degree of nonlinearity.
Exciting Discoveries 8
Thick clouds (1)Solar method IR method
•Solar method is highly sensitive to cloud particle at cloud top•IR method is relatively insensitive to cloud vertical inhomogeneity.
Exciting Discoveries 9
Thick Clouds (2)
Cloud particle size
Cloud top
Cloud baseIR < solar IR ~ solar
Summary 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…Take-home message• Cloud particle inhomogeneity could
lead to inconsistency between solar and IR methods.
• Be cautious when comparing or combining the two methods.
GEST 10th Anniversary 11
Happy Birthday, GEST!
This talk is based on Zhang et al 2010 JGR (Will be highlighted in EOS)