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lmd_Seze1987_abstracts.html

1987 .

(4 publications)

G. Seze and M. Desbois. Cloud Cover Analysis from Satellite Imagery Using Spatial and Temporal Characteristics of the Data. Journal of Applied Meteorology, 26:287-303, February 1987. [ bib | DOI | ADS link ]

New developments of a cloud classification scheme based on histogram clustering by a statistical method are presented. Use of time series of geostationary satellite pictures as well as for construction of composite images representative of the surface properties and then for the identification of significative cloud classes is discussed. Spatial variances are introduced as additional parameters of the classification, with the aim to better separate clouds from the surface and the different kinds of more or less homogeneous cloud classes.

L. Picon, M. Desbois, and G. Sèze. Use of meteosat ISCCP B2 data for the study of interannual variations of climatic elements in Africa. Advances in Space Research, 7:199-202, 1987. [ bib | DOI | ADS link ]

Composite monthly images corresponding to West African rainy seasons of 1983, 1984, and 1985, have been constructed from ISCCP B2 Meteosat data. Average and standard deviation images from thermal infrared and water vapor channels are studied. In the thermal infrared, differences between the three years appear principally in the mean structure of the ITCZ, North-South extend, northward boundary, longitudinal variations of the convection. In the water vapor channel, well defined “dry” areas appear, showing the location and extent of subsidence regions on a large scale. These locations and extents also vary from year to year.

F. Drake, G. Sèze, M. Desbois, and A. Henderson-Sellers. European ISCCP sector surface and satellite retrieved cloud comparison. Advances in Space Research, 7:159-161, 1987. [ bib | DOI | ADS link ]

A comparison between surface-observed total, low and high cloud amount and retrievals from METEOSAT radiance data made using the cluster technique of Desbois et al. has been undertaken. Observations for 12.00 GMT for the 20 day period 22nd July to 10th August 1983 were compared with retrievals made from METEOSAT radiances measured at 11.30 GMT. The comparisons for total and low cloud amount were made for 204 stations covering France, southern Britain and West Germany although high cloud amount comparisons were not possible for France, so only 114 stations were used. The location and time period were selected to coincide with one of the regions designated for the validation phase of the International Satellite Cloud Climatology Project, ISCCP. The results are generally good: for total cloud amount 30% of retrievals were fully in agreement and 64% of the differences were within +/-1 okta. As anticipated, the surface observations offered additional information oin low cloud cover in multi-layer situations. Surface observers were also found to identify thin cirrus which was not detected by the satellite retrieval and to detect small gaps in cloud decks and small clouds missed by the satellite retrieval.

G. Sèze and W. Rossow. Time-cumulated visible and infrared histograms used as descriptor of cloud cover. Advances in Space Research, 7:155-158, 1987. [ bib | DOI | ADS link ]

To study the statistical behavior of clouds for different climate regimes, the spatial and temporal stability of VIS-IR bi-dimensional histograms is tested. Also, the effect of data sampling and averaging on the histogram shapes is considered; in particular the sampling strategy used by the International Satellite Cloud Climatology Project is tested.

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