{"id":1447,"date":"2008-11-22T23:59:17","date_gmt":"2008-11-22T23:59:17","guid":{"rendered":"http:\/\/cimss.ssec.wisc.edu\/satellite-blog\/?p=1447"},"modified":"2019-03-26T18:42:50","modified_gmt":"2019-03-26T18:42:50","slug":"extremely-cold-cloud-top-temperatures","status":"publish","type":"post","link":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/archives\/1447","title":{"rendered":"Extremely cold cloud-top temperatures over Australia"},"content":{"rendered":"

\"MTSAT-1R<\/a>

MTSAT-1R Infrared (10.8 \u00b5m) images [click to enlarge]<\/p><\/div>
\nHat-tip to blog reader Boris Konon for sending us this in an email:<\/p>\n

Noted a large area of extremely cold cloud tops on a thunderstorm complex over northern Australia 17-23z 11\/22.\u00a0 So cold it went off our IR color table scale we use here at WSI for MTSAT!<\/p><\/blockquote>\n

MTSAT-1R Infrared (10.8 \u00b5m) images (above)<\/strong><\/em> did indeed show an area of convection that exhibited an unusually large canopy of cloud top temperatures colder than -80\u00baC<\/strong> (shades of violet to purple)<\/em> on 22 November 2008<\/strong>. The coldest infrared brightness temperature seen with this particular thunderstorm complex was 174.78 K (-98.37\u00baC)<\/strong>, just off the northern coast of Australia at 2030 UTC.<\/p>\n

A comparison of MTSAT-1R Visible and Infrared images at 2030 UTC (below)<\/strong><\/em> showed that there were a number of overshooting tops within the area of cold cloud-top temperatures, as the convective system was beginning to move offshore across the Gulf of Carpenteria. This squall line was responsible for producing 25-50 mm of rainfall (BOM rainfall analysis<\/a>)<\/strong> and wind gusts to 96 km\/h (52 knots) at Bradshaw and 68 km\/h (37 knots) at Gove (thanks to Jeff Callaghan, Australian Bureau of Meteorology for that information!)<\/em>.<\/p>\n

\"MTSAT-1R<\/a>

MTSAT-1R Visible and Infrared images [click to enlarge]<\/p><\/div>A closer view using 1-km resolution NOAA-15 AVHRR Infrared (10.8 \u00b5m) imagery (below)<\/strong><\/em> revealed a bit more detail in the cloud-top temperature structure around 1956 UTC. Unfortunately, the image was marred by a large number of “noise” pixels — but the coldest reliable cloud-top infrared brightness temperature seen on this AVHRR image was 170.2 K (-102.95\u00baC)<\/strong>, located within the farthest southeast cold pixel cluster (IR brightness temperatures of -100\u00baC and colder are enhanced in the yellow to brown colors at the end of the scale)<\/em>. If this cloud-top brightness temperature is accurate, it rivals what is believed to be the coldest satellite-sensed cloud top temperature value noted in the literature: -102.2\u00baC in Ebert and Holland, 1992. <\/strong><\/a><\/p>\n

\"NOAA-15<\/a>

NOAA-15 AVHRR Infrared (10.8 \u00b5m) image [click to enlarge]<\/p><\/div>Rawinsonde data from Darwin Airport at 0000 UTC on 23 November 2008 (below)<\/strong><\/em> indicates that the tropopause was at a very high altitude (around 100 hPa, approximately 16.0 km)<\/em>. Such a high and cold tropopause is not unusal in the tropics — especially in that particular region, as studies have shown that the average tropopause level is quite high and quite cold over the western tropical Pacific Ocean.<\/p>\n

\"Darwin,<\/a>

Darwin, Australia rawinsonde report [click to enlarge]<\/p><\/div>\n","protected":false},"excerpt":{"rendered":"

Hat-tip to blog reader Boris Konon for sending us this in an email: Noted a large area of extremely cold cloud tops on a thunderstorm complex over northern Australia 17-23z 11\/22.\u00a0 So cold it went off our IR color table scale we use here at WSI for MTSAT! MTSAT-1R Infrared (10.8 \u00b5m) images (above) did […]<\/p>\n","protected":false},"author":18,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[22,20,3],"tags":[],"class_list":["post-1447","post","type-post","status-publish","format-standard","hentry","category-avhrr","category-mtsat","category-severe-convection"],"acf":[],"_links":{"self":[{"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/posts\/1447","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=1447"}],"version-history":[{"count":22,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/posts\/1447\/revisions"}],"predecessor-version":[{"id":32602,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/posts\/1447\/revisions\/32602"}],"wp:attachment":[{"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/media?parent=1447"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/categories?post=1447"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/tags?post=1447"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}