The B3 data is derived from the raw satellite data by averaging in space and time to a 3hr seperation of the images at a 30km spatial resolution, each pixel is registered to the surface of the Earth and calibrated to temperature. For this study B3 data derived from the geostationary satellites GMS and METEOSAT have been smoothed using a spherical smoothing kernal (Hodges, 1995) onto a 1.5 degree grid. This removes the smaller spatial scales associated with individual clouds but keeps the spatial scale of cloud clusters associated with the mesoscale features.
Two periods have been explored, a GMS DJF for 87/88 and a METEOSAT JJAS for 1988. The results of the tracking are shown in the following results for different time filtering of the tracks, the colored points indicate the strength at each 3hr postion in units of *100 degrees Kelvin below 273K:
b. Tracks with lifetimes > 1.5 day
b. Tracks with lifetimes > 1.0 day
c. Tracks with lifetimes > 1.5 day
d. Tracks with lifetimes > 2.0 day
Note that the mesoscale features in the Atlantic (METEOSAT) seem to be more coherent and abundent than those in the Pacific (GMS). Also notice that a track has been found which recurves northward in mid-atlantic, this is hurricane Helene. The track of hurricane Helene determined by TRACK (3hr time step) and from an archive of hurricane tracks from the National Hurricane Center (6hr time step) can be seen in Helene. The colours for the METEOSAT result are as before, while those of the second track represent nothing but the position at each 6hr time step.
1. Eight Year Statistics For July
2. Eight Year Statistics For August
2. Rossow, W. B., and R. A. Schiffer, "ISCCP Cloud Data Products", Bull. Amer. Met. Soc., v72, 1-20.
3. Hodges, K. I., "Spherical Nonparametric Estimators Applied to the UGAMP Model Integration for AMIP", Mon. Weath. Rev., V 124, pp 2914-2932.
