Regional And Mesoscale Meteorology Team
Daily Satellite Discussion
Thursday July 10, 1997
Today's images focus on mid-day imagery over Central America depicting the predominance of sunglint over the region. The first two images show composites of maximum radiance for 1-15 June 1997 for 3.9 micrometers (channel 2). Imagery at 1715 and 1815 GMT for each day during the first two weeks in June were used to develop this composite. The RAMSDIS enhancement has been used which shows bright areas as highly reflective and/or warm and dark areas as less reflective and/or cool. During this period, the sun's declination was greater than 20 deg N latitude. Note how the region of sun glint moves from 1715 to 1815 GMT. The glint is indicative of calm wind regions over the ocean. The darker regions over land interiors indicate regions of persistent cloudiness over the period. Note in the 1815 image, a bright region of glint over land in north east Costa Rica and glint over Lake Nicaragua. The glint over land is reflecting off river and wet surfaces. The next two images depict composites of minimum radiance (poorly reflective and cold surfaces) at the same times for 1-15 June 1997 for 3.9 micrometers (channel 2). Note that cloud covered some of the same glint regions over this two week period. Note also the bright region in the upper right portion of the image indicating a warmer, relatively cloud free region. The third set of images show the average radiance over the same two week period in the beginning of June 1997 for 3.9 micrometers (channel 2). Note that glint over land shows up in this imagery. The final two images show visible 1 km imagery over Costa Rica for 3 June 1997 at 1715 and 1815 GMT. In the 1715 image, the brightest region is to the east of Costa Rica although a brightning can be seen over the entire image. In the 1815 image, glint over the north-east portion of Costa Rica can be seen which highlights rivers, wet areas and adds strong contrast to the coast. A very calm region of strong glint can be detected on Lake Nicaragua.
Bernadette Connell