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MODIS Cloud Properties



MODIS-only cloud property interpolation

MODIS-only cloud property interpolation example

 Hour
01020304 05060708 09101112 13141516 17181920 21222324
D
a
y
1IIIIIIIII MIIIIII IIIII MII
2IIIIIIIII MIIIIII IIIII MII
3IIIIIIIII MIIIIII IIIII MII
...  
31IIIIIIIII MIIIIII IIIII MII
M=MODIS measurement
I=Linearly interpolated between MODIS measurements
Hour bins are defined as 01 is between local time 0-1AM, hour2 is 1-2AM, hour24 is 23-24PM
  • Valid MODIS-Cloud observed properties are binned into 24 hourly increments for the day.
  • The remaining hourly bins are filled using linear interpolation.
  • For example day 2, hour increment 5 is linearly interpolated from day 1 hour 22 and day 2 hour 10.
  • Monthly or daily cloud amount mean is the average of all hourly increments
  • Cloud properties are weighted by cloud fraction to derive the mean.
  • Cloud optical depth is averaged in terms of log optical depth.
  • Daytime cloud properties are only averaged from hourly increments that have a SZA<90°.

MODIS/GEO cloud property interpolation

  • MODIS/GEO is similar to the MODIS-only cloud property interpolation, except it includes 3-GMT hourly GEO derived cloud properties.
  • Not all cloud properties are retrieved by GEO (check here for list of GEO properties) link to external site for those properties not retrieved by GEO, MODIS-only cloud property interpolation is implemented.

MODIS-only and MODIS/GEO cloud property interpolation comparison

MODIS-only and MODIS/GEO cloud property interpolation example

Hour+:30 00010203 04050607 08091011 12131415 16171819 20212223
MergeGIIGII GIIGMI GIIGII GIIGMI
MODISIIIIIIIIII MIIIIIIIII IIMI
M=MODIS measurement
G=GEO measurement
I=Linearly interpolated between MODIS and GEO measurements
Hour bins are defined as 0 is between local time 0-1AM, hour1 is 1-2AM, hour23 is 23-24PM
  • The Merge row shows the MODIS/GEO measured and interpolated cloud properties.
  • The MODIS row shows the MODIS-only measured and interpolated cloud properties.
  • MODIS cloud properties are more accurate than GEO derived cloud properties, since MODIS uses multiple channels and GEO is a 2 channel, VIS and IR retrieval.
  • The daytime cloud retrievals are based on the visible, 3.7µm and IR MODIS channels and are more reliable than the nighttime cloud retrievals only based on the IR MODIS channels, however they are interpolated between day and night.
  • GEO cloud properties are more accurate than MODIS interpolated cloud properties, since they take into account changing meteorology.

CERES Data Product Information

 
  Image: NASA Logo NASA Official: Dr. Norman Loeb
Page Curator: Edward Kizer
Page Last Modified: 10/16/2017 11:04:36 EST
Site Last Modified: 11/07/2017 17:18:43 EST