{"id":439,"date":"2007-07-29T23:55:34","date_gmt":"2007-07-29T23:55:34","guid":{"rendered":"http:\/\/cimss.ssec.wisc.edu\/satellite-blog\/2007\/07\/29\/river-valley-fog-in-the-upper-midwest-region\/"},"modified":"2007-08-02T13:54:03","modified_gmt":"2007-08-02T13:54:03","slug":"river-valley-fog-in-the-upper-midwest-region","status":"publish","type":"post","link":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/archives\/439","title":{"rendered":"River valley fog in the Upper Midwest region"},"content":{"rendered":"

\"AWIPS<\/a><\/p>\n

The low-lying areas of the Wisconsin River<\/strong><\/a> and other tributaries that drain into the upper Mississippi River are favored areas for nocturnal valley fog formation, as shown by the MODIS “fog\/stratus product” and topography image comparison (above)<\/strong><\/em>.<\/p>\n

AWIPS images of the MODIS and GOES-12 fog\/stratus product from 29 July 2007<\/strong><\/a> (below)<\/strong><\/em> demonstrated important differences in the detection of these narrow fingers of river valley fog (yellow to orange enhancement)<\/em> that were forming during the nighttime hours over parts of southwestern Wisconsin, southeastern Minnesota, and northeastern Iowa. The 1-km resolution MODIS fog\/stratus product at 07:50 UTC (below, left)<\/strong><\/em> was able to give a more precise indication of the areas where fog was beginning to form, while the corresponding 4-km resolution GOES-12 fog\/stratus product at 08:01 UTC (below, right)<\/strong><\/em> could only provide a vague signal that fog was starting to develop over portions of the region.<\/p>\n

\"AWIPS<\/a><\/p>\n

The fog continued to increase in depth and areal coverage later that night, with surface visibility eventually dropping to 0.15 miles<\/strong> at Wisconsin sites Lone Rock KLNR<\/strong> and Boscobel KOVS<\/strong> (0.01 inch<\/strong> of precipitation was also recorded at each location as mist developed) — and as the fog thickened, the GOES-12 fog\/stratus product did begin to exhibit a better signal of the fog structure (especially over the lower Wisconsin River valley: Java animation<\/strong><\/em><\/a>).<\/p>\n

A comparison of the AWIPS GOES-12 fog\/stratus product and GOES-12 visible channel image at 13:15 UTC (below)<\/strong><\/em> shows that much of the river valley fog was still present after sunrise; however, note that after sunrise the fog features on the GOES-12 fog\/stratus product began to change in appearance from yellow or orange enhanced features (11-3.9\u00c2\u00b5m brightness temperature difference values around -7\u00c2\u00ba to -8\u00c2\u00ba C)<\/em> to darker gray enhanced features (11-3.9\u00c2\u00b5m brightness temperature difference values of around -4\u00c2\u00ba to -5\u00c2\u00ba C)<\/em> — this is due to the fact that the 3.9\u00c2\u00b5m channel is very sensitive to solar radiation reflected off the tops of water droplet cloud features (such as fog), which increases<\/em> the brightness temperature value sensed by the 3.9\u00c2\u00b5m detectors (and therefore decreases<\/em> the 11-3.9\u00c2\u00b5m brightness temperature difference that constitutes the fog\/stratus product). Because of the solar reflection issue, the fog\/stratus product is not valid during daytime hours.<\/p>\n

\"AWIPS<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

The low-lying areas of the Wisconsin River and other tributaries that drain into the upper Mississippi River are favored areas for nocturnal valley fog formation, as shown by the MODIS “fog\/stratus product” and topography image comparison (above). AWIPS images of the MODIS and GOES-12 fog\/stratus product from 29 July 2007 (below) demonstrated important differences in […]<\/p>\n","protected":false},"author":18,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[13,19,12],"tags":[],"class_list":["post-439","post","type-post","status-publish","format-standard","hentry","category-fog-detection","category-goes-12","category-modis"],"acf":[],"_links":{"self":[{"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/posts\/439","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/users\/18"}],"replies":[{"embeddable":true,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/comments?post=439"}],"version-history":[{"count":0,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/posts\/439\/revisions"}],"wp:attachment":[{"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/media?parent=439"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/categories?post=439"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/tags?post=439"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}