16 September 1996

NOAA 12 at 12:42 UT cloud heights and emissivity.
NOAA 14 at 19:07 UT cloud heights and emissivity.
GOES 8 analysis at 11:46 and 12:46 UT.
MPEG IR movie 10:45-13:15 UT.
MPEG Visible channel movie
HSRL from 11:00-12:30 UT.

Summary

NOAA 12 at 12:42 UT.

A anvil from an isolated Cb passed east of the lidars. The edge crossed the HSRL from approximately 11:00 to 12:45 UTC. Clouds were moving south from about 345 degrees. These clouds appeared to be a decaying anvil. There was an active Cb to the west just into the Gulf.

Lidars and the Radar, both show a single layer from 9-12.0 km. NOAA 12 reported 9.7-11.0 km for the cloud east of EVG. GOES 8 reported 7.6-11.0 km for the cloud. NOAA 12 tended to report about 1.3 km higher than GOES 8. The most noticable is the 11.0 km report directly south of EVG where NOAA 12 reported 11.0 and GOES 8 flanked it on each side with 9.7 reports. To the east, 9.8 km NOAA 12 report was next to a 8.6 km GOES 8 report, indicating good agreement between the satellites.

Effective Emissivity was higher for GOES 8 than NOAA 12. GOES 8 guaged this cloud EE=47-90% while NOAA 12 found 14-15%. Temperatures on the VISR image indicate the coldest part of the cloud was 239 K which passed to the east of EVG. This was about an altitude of 10 km. The part that passed over EVG was 249-253 K. 249 K corresponds to to an EE=0.86 or O.D.=3.9 for a Tsfc=294 K. Look for the HSRL to find part of this cloud saturating, i.e. O.D.>3.0. The NOAA 12 EE=15% corresponds to a visible optical depth of 0.3.

NOAA 14 at 19:07 UT

Clouds continued to move from the north. However, in the afternoon Cb's developed up wind and to the northeast of EVG. An anvil started crossing EVG around 20:00 UT. Only the HSRL was available on the quick look. It indicated most of the cloud was between 12.0-13.9 km with very light returns up to 15.5 km.

NOAA 14 heights were from 12.5 - 15.9 km for the main mass northeast of EVG. GOES 8 reported 11.0 - 14.2 km for the same mass. It should be noted that the GOES 8 and NOAA 14 obs were 40 minutes apart. I had to use the 19:46 UT GOES 8 ob. The 18:46 ob was not available. In that time there was considerable southward movement in the Ci.

Effective Emissivity ranged from 28-93% on NOAA 14 and 67-98% on GOES 8. This corresponds to visible optical depths of 0.7-5.3 for NOAA 14 and 2.2-6.0 for GOES 8.