{"id":4287,"date":"2010-01-02T12:49:14","date_gmt":"2010-01-02T12:49:14","guid":{"rendered":"http:\/\/cimss.ssec.wisc.edu\/satellite-blog\/?p=4287"},"modified":"2010-01-04T05:04:20","modified_gmt":"2010-01-04T05:04:20","slug":"terraining-induced-clouds-over-the-brooks-range-in-alaska","status":"publish","type":"post","link":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/archives\/4287","title":{"rendered":"Terrain-induced clouds over the Brooks Range in Alaska"},"content":{"rendered":"
\"POES<\/a>

POES AVHRR 10.8 \u00c2\u00b5m IR images + surface temperatures (F)<\/p><\/div>\n

McIDAS images of POES AVHRR 10.8 \u00c2\u00b5m IR channel data (above)<\/em><\/strong> showed the development of a large terrain-induced “banner cloud” over the eastern part of the Brooks Range in northeastern Alaska on 01 January – 02 January 2010<\/strong>. The IR cloud top brightness temperature values were as cold as -65\u00c2\u00ba C (darker red color enhancement)<\/em> around 20:26 UTC, which suggested very high cloud tops (GOES-11 10.7 \u00c2\u00b5m IR<\/a><\/strong> cloud top brightness temperatures were as cold as -58\u00c2\u00ba C at that time). The terrain of the Brooks Range was acting as an obstacle to the northerly flow aloft (ECMWF 700 hPa winds<\/a><\/strong> | 500 hPa winds<\/a><\/strong>), which helped to initiate the formation of the banner cloud.<\/p>\n

This cloud feature was also apparently thick enough to have a dramatic influence on surface temperatures — note that the temperature at Arctic Village (station identifier PARC)<\/em> rose from -35\u00c2\u00ba F<\/strong> before the cloud feature developed to +1\u00c2\u00ba F<\/strong> after the cloud feature had been overhead for several hours. A surface meteorogram plot<\/a><\/strong> indicated that this temperature rise occurred during a period of light winds, so warm air advection could not account for the warming; instead, the thick cloud deck acted as a blanket to stop radiational cooling over that particular site.<\/p>\n

CIMSS has been evaluating and testing a variety of CLAVR-x<\/a><\/strong> AVHRR cloud products in AWIPS, which can be used to further characterize this banner cloud that formed over the Brooks Range. The Cloud Type product (below)<\/em><\/strong> classified the feature as a combination of Cirrus, Multi-level Cirrus, and Opaque Ice Cloud categories (yellow, orange, and red color enhancements)<\/em>, which is not surprising given the very cold appearance on IR imagery. <\/p>\n

\"AVHRR<\/a>

AVHRR Cloud Type product<\/p><\/div>\n

The AVHRR Cloud Top Temperature (CTT) product (below)<\/em><\/strong> showed that the tops of the cirrus feature were even colder than what was indicated by the IR imagery, with CTT values as low as -76\u00c2\u00ba C<\/strong> at 20:20 UTC. <\/p>\n

\"AVHRR<\/a>

AVHRR Cloud Top Temperature product<\/p><\/div>\n

The AVHRR Cloud Top Height product (below)<\/em><\/strong> showed that the tops of the banner cloud feature were generally around 8 km (cyan color enhancement).<\/em> This height was close to the altitude of the tropopause, as indicated on the Barrow AK rawinsonde data<\/a><\/strong>.<\/p>\n

\"AVHRR<\/a>

AVHRR Cloud Top Height product<\/p><\/div>\n

As an aside, the eastern Arctic Slope region of Alaska was experiencing blizzard conditions during this period — at Barter Island (station identifier PABA)<\/em> along the coast, winds gusted as high as 72 mph. The strong westerly winds were in response to a tightening pressure gradient in advance of an approaching cold front (surface pressure and frontal analysis<\/a><\/strong>).<\/p>\n","protected":false},"excerpt":{"rendered":"

McIDAS images of POES AVHRR 10.8 \u00c2\u00b5m IR channel data (above) showed the development of a large terrain-induced “banner cloud” over the eastern part of the Brooks Range in northeastern Alaska on 01 January – 02 January 2010. The IR cloud top brightness temperature values were as cold as -65\u00c2\u00ba C (darker red color enhancement) […]<\/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":[37,22,26],"tags":[],"class_list":["post-4287","post","type-post","status-publish","format-standard","hentry","category-arctic","category-avhrr","category-poes"],"acf":[],"_links":{"self":[{"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/posts\/4287","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=4287"}],"version-history":[{"count":14,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/posts\/4287\/revisions"}],"predecessor-version":[{"id":4301,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/posts\/4287\/revisions\/4301"}],"wp:attachment":[{"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/media?parent=4287"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/categories?post=4287"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/tags?post=4287"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}