Aspects of Cloud Horizontal Variability From Higher-Level MODIS Products
Abstract
We have analyzed two full months (July 2003 and January 2004) of MODIS Atmosphere Level-3 data from the Terra and Aqua satellites in order to characterize the apparent horizontal heterogeneity in cloud optical properties at global scales. We have layed the foundation of a global cloud inhomogeneity climatology from 1 km retrievals sampled every 5 km by determining statistics of cloud variability at spatial scales of 1° x1° and at daily and monthly time scales. Specifically, we have studied geographical, diurnal and seasonal changes of various measures of cloud optical thickness variability both over land and ocean as well as its dependence on cloud type and cloud phase. Some of the highlights of the findings are that cloud inhomogeneity appears to be weaker over land than over ocean (mainly for Terra), smaller for local morning (Terra) than local afternoon (Aqua), about the same for liquid and ice clouds on a global scale, but with wider PDFs and larger latitudinal variations for ice. We have also found that global values of inhomogeneity parameters are virtually identical for both January and July, while the hemispheric values are in almost perfect seasonal correspondance: northern hemisphere (NH) winter equals southern hemisphere (SH) winter and NH summer matches SH summer. Overall, clouds are more inhomogeneous during the winter. This presentation will also discuss whether Level-3 data are appropriate for examining whether any of the apparent cloud variability behaviour described above can be linked to the influence on the retrievals of well-known morphological features of particular cloud types and the geometry of the radiometric observations.
- Publication:
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AGU Spring Meeting Abstracts
- Pub Date:
- May 2004
- Bibcode:
- 2004AGUSM.U21A..07O
- Keywords:
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- 3359 Radiative processes;
- 3360 Remote sensing