Upwelling of cold water along the eastern shore of Lake Michigan

September 7th, 2011
Comparison of 8-day average MODIS SST (left) and 07 September MODIS SST (right)

Comparison of 8-day average MODIS SST (left) and 07 September MODIS SST (right)

 

A comparison of the MODIS 8-day average Sea Surface Temperature (SST) ending on 06 September 2011 (above, left) with the MODIS SST product on 07 September 2011 (above, right) revealed a dramatic cooling of the near-shore waters just off the east coastline of Lake Michigan. Persistent strong northerly daytime winds (gusting in the 20-30 mph range) induced an upwelling of colder water from below the surface, with 07 September values as cold as 6.8ºC (44ºF) at one location (Latitude/Longitude 43.63 North/81.96 West) — compared to the previous 8-day average SST of 22.8ºC (73ºF) at that same location. Unfortunately, the MODIS Cloud Mask that is applied to the SST product mistakenly identifies the strongest SST gradient as a cloud, and blanks out the SST product along the far western fringe of the ribbon of colder water.

AWIPS images of MODIS 0.65 µm visible channel and 11.0 µm IR channel data (below) showed greater detail in the ribbon of colder waters, with a series of eddies forming along the northern edge of the feature. Since no Cloud Mask is applied to the IR image, the full westward extent of the cold water feature can be seen.

 

MODIS 0.65 µm visible channel and 11.0 µm IR channel images

MODIS 0.65 µm visible channel and 11.0 µm IR channel images

 

A sequence of four MODIS 11.0 µm IR images (below) shows the evolution of the eddy features along the western edge of the cold water. Note that the land surfaces exhibit cool IR brightness temperatures (blue to cyan color enhancement) on the first 2 night-time images (03:10 UTC and 07:21 UTC, or 10:10 pm and 2:21 am local time), but on the 2 daytime images (16:45 UTC and 18:27 UTC, or 11:45 am and 1:27 pm local time) urban areas and regions with less dense vegetation heat up and exhibit much warmer IR brightness temperatures (orange to red color enhancement). However, the Lake Michigan IR brightness temperatures generally remain constant during this time period.

MODIS 11.0 µm IR images

MODIS 11.0 µm IR images

 

CIMSS participation in GOES-R Proving Ground activities includes making a variety of MODIS images and products available for National Weather Service offices to add to their local AWIPS workstations. Currently there are 49 NWS offices receiving MODIS imagery and products from CIMSS. In addition, the VISIT training lesson “MODIS Products in AWIPS” is available to help users understand these products and their applications to weather analysis and forecasting.

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