University of Wisconsin-Madison Space Science and Engineering Center

CIMSS Satellite Blog

The last day of Summer…

September 21st, 2008

AWIPS images of MODIS visible, snow/ice, and Land Suface Temperature

What do you do on the last day of meteorological summer if you’re in southeastern Nunavut or far northern Manitoba in Canada? You watch fresh snow cover melt! AWIPS images of the MODIS visible channel, snow/ice channel, and Land Surface Temperature product on 21 September 2008 (above) showed that significant snow cover was in place across that region (which had fallen a few days earlier). The many lakes in that area were still not frozen, and appeared very dark against the surrounding snow cover on the visible image. The slightly darker signal on the near-IR snow/ice image confirmed the presence of snow cover; Land Surface Temperature values were at or just below freezing at many locations (darker green colors), where presumably there was somewhat more snow cover.

The snow cover analysis from Environment Canada (below) indicated that as much as 12 cm (5 inches) of snow was on the ground in that region.

Snow cover analysis

Posted in Arctic, MODIS, Winter weather | Comments Off

River valley fog over Missouri and Arkansas

September 17th, 2008

GOES-12 fog/stratus and low cloud base products + MODIS fog/stratus product

AWIPS images of the 4-km resolution GOES-12 fog/stratus and Low Cloud Base products and the 1-km resolution MODIS fog/stratus product (above) showed fingers of river valley fog that had formed over parts of southern Missouri and northern Arkansas at around 08 UTC (3am local time) on 17 September 2008. The soil was moist across that particular region due to heavy rainfall associated with the passage of the remnants of Hurricane Ike 3 days earlier, creating an environment favorable for the formation of radiation fog. Many of the fingers of river valley fog had formed in areas located between the METAR surface reporting stations, so there were not a lot of reports of fog across the region at that time.

Posted in Fog detection, GOES-12, MODIS | Comments Off

Gravity wave over Indiana, Ohio, and Michigan

September 15th, 2008

GOES-13 visible images

Blog reader Michael Lawson wrote:

Hi, I am a meteorologist working with Meridian Environmental Technology in Grand Forks, ND. A co-worker noticed a gravity wave feature in the visible over northern Indiana/northwest Ohio during the afternoon of September 15, 2008. Clouds moving into the feature would dissipate then reform once they propagated through the other side. Thought it would make an interesting topic!

Thanks for the tip, Michael. GOES-13 visible imagery (above) did indeed show the wave as it propagated northwestward (against the ambient flow) across northern Indiana/Ohio into southern Lower Michigan on 15 September 2008.

The dissipation of the stratocumulus cloud field with the passage of the wave might be explained by examining the rawinsonde data from Wilmington, Ohio (below) — note the presence of very dry air aloft, which could have been briefly mixed downward as the wave moved through (similar to what was seen with an apparent hydraulic jump over lower Michigan and southern Ontario on 08 May 2008).