1 June 2001
imagery from GOES-8

Bob Rabin
Visible loop 1

Window channel (10.7 microns)

  Water vapor (6.7 microns)

  Near IR (3.9 microns)

 Dirty window (13.3 microns)

  Window - water vapor (10.7-6.7 microns)

The images have been remapped to a equal latitude-longitude projection.  The shift in the location of the clouds with respect to the map is due to the effects of parallax, which has not been taken into account here.



    Unlike the 9 Oct 2001 case, the brightness temperature difference (10.7 - 6.7 microns) is negative in local regions over the thunderstorm tops.  The observations are similar to that reported in previous studies using METEOSAT (Schmetz et al., 1997). The brightness temperature in the water vapor band was often observed to be warmer (by as much as 6-8 K) than in the window band above cold top convective clouds. This observation was explained by stratospheric water vapor which emits radiation at higher stratospheric temperatures than the emitted radiation at cloud top. Their results suggested that the magnitude of the difference in brightness temperature depends on the lapse rate above the tropopause. Moreover, the greatest differences are expected when cloud tops are located at the tropopause.

   The most negative differences (-2 degs C) exist above some of the coldest (presumably, higher than the tropopause).
Schmetz, J., S.A. Tjemkes, M. Gube, L. van de Berg, 1997: Monitoring deep convection and convective overshooting with METEOSAT. Adv. Space Res., Vol. 19, No. 3, pp433-441.



    Note that to animate the full time period requires the download of 53 images. It may take a while before the movie is set up and ready to run, depending on network speed & the amount of memory available to your computer.  The loops use a  Java Applet  written by Tom Whittaker at the Cooperative Institute for Meteorological Satellite Studies ( CIMSS ) at the University of Wisconsin-Madison.

    Choose from the entries in Table 1 to compare individual bands and brightness temperature differences at indicated times (UTC). GOES-8 & GOES-8 comparisons are available when available. .

Table 1