{"id":30749,"date":"2018-11-16T23:58:41","date_gmt":"2018-11-16T23:58:41","guid":{"rendered":"http:\/\/cimss.ssec.wisc.edu\/satellite-blog\/?p=30749"},"modified":"2018-11-18T15:34:48","modified_gmt":"2018-11-18T15:34:48","slug":"dry-air-within-an-atlantic-subtropical-ridge","status":"publish","type":"post","link":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/archives\/30749","title":{"rendered":"Dry air within an Atlantic subtropical ridge"},"content":{"rendered":"

\"GOES-16<\/a>

GOES-16 Low-level (7.3 \u00b5m),<\/em> Mid-level (6.9 \u00b5m)<\/em> and Upper-level (6.2 \u00b5m)<\/em> Water Vapor images [click to play animation | MP4<\/strong><\/a>]<\/p><\/div>GOES-16 (GOES-East)<\/em> Low-level (7.3 \u00b5m<\/strong><\/a>), Mid-level (6.9 \u00b5m<\/strong><\/a>) and Upper-level (6.2 \u00b5m<\/strong><\/a>) Water Vapor images (above)<\/strong><\/em> showed a large region of very dry air within a subtropical ridge over the central North Atlantic Ocean on 16 November 2018. Infrared brightness temperatures<\/strong><\/a> were unusually warm (brighter yellow to red enhancement)<\/em> on all 3 Water Vapor bands, especially along the western edge of the dry air.<\/p>\n

A GOES-16 Upper-level Water Vapor image at 1700 UTC (below)<\/strong><\/em> showed a swath of NUCAPS<\/strong><\/a> sounding availability close to that time. The swath passed directly over the driest air within the subtropical ridge.<\/p>\n

\"GOES-16<\/a>

GOES-16 Upper-level Water Vapor image at 1700 UTC, with a swath of NUCAPS sounding availability [click to enlarge]<\/p><\/div>One of the green (high-quality) NUCAPS soundings within the arc of driest air (below)<\/strong><\/em> revealed a remarkably dry profile above the trade wind inversion — dewpoint values were -50\u00baC and colder within the 500-620 hPa layer, and dewpoint depressions were about 50\u00baC near the 550 hPa level.<\/p>\n

\"NUCAPS<\/a>

NUCAPS sounding profile within the driest air [click to enlarge]<\/p><\/div>Even though the middle to upper tropozphere was quite dry, note that the Total Precipitale Water (TPW) value calculated from the NUCAPS profile was 0.73 inch — there was still abundant tropical moisture within the marine boundary layer of the warm central Atlantic. The GOES-16 TPW product (below)<\/strong><\/em> showed minimum values of 0.6-0.8 inch in the region of driest air on the Water Vapor imagery (1800 UTC comparison<\/strong><\/a>). In contrast, TPW values over a large portion of the Lower 48 states were 0.6 inch or less, even in regions that appeared to be “moist” on the Water Vapor imagery.<\/p>\n

\"GOES-16<\/a>

GOES-16 Upper-level Water Vapor + Total Precipitable Water [click to play animation | MP4<\/strong><\/a>]<\/p><\/div>\n","protected":false},"excerpt":{"rendered":"

GOES-16 (GOES-East) Low-level (7.3 \u00b5m), Mid-level (6.9 \u00b5m) and Upper-level (6.2 \u00b5m) Water Vapor images (above) showed a large region of very dry air within a subtropical ridge over the central North Atlantic Ocean on 16 November 2018. Infrared brightness temperatures were unusually warm (brighter yellow to red enhancement) on all 3 Water Vapor bands, […]<\/p>\n","protected":false},"author":18,"featured_media":30752,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[74,79,49],"tags":[],"class_list":["post-30749","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-goes-16","category-microwave","category-suomi_npp"],"acf":[],"_links":{"self":[{"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/posts\/30749","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=30749"}],"version-history":[{"count":1,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/posts\/30749\/revisions"}],"predecessor-version":[{"id":30750,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/posts\/30749\/revisions\/30750"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/media\/30752"}],"wp:attachment":[{"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/media?parent=30749"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/categories?post=30749"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/tags?post=30749"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}