{"id":64012,"date":"2025-04-08T15:52:28","date_gmt":"2025-04-08T15:52:28","guid":{"rendered":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/?p=64012"},"modified":"2025-04-09T21:10:47","modified_gmt":"2025-04-09T21:10:47","slug":"standing-wave-south-of-the-aleutian-islands","status":"publish","type":"post","link":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/archives\/64012","title":{"rendered":"Standing wave south of the Aleutian Islands"},"content":{"rendered":"\n<figure class=\"wp-block-video\"><video height=\"932\" style=\"aspect-ratio: 1320 \/ 932;\" width=\"1320\" controls loop src=\"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-content\/uploads\/sites\/5\/2025\/04\/goeswest_abi_radf_true_color_night_s20250407170021_e20250408040021_f67.mp4\"><\/video><figcaption class=\"wp-element-caption\">True Color imagery from GOES-18, 1700 UTC 7 April &#8211; 0400 UTC 8 April 2025<\/figcaption><\/figure>\n\n\n\n<p>GOES-18 True Color imagery during the day on 7 April, above, shows the development of a standing wave downwind of the elevated topography on the Aleutian peninsula between King Salmon and Perryville.  (Note also the faint signal of volcanic ash as discussed <a href=\"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/archives\/64004\">here<\/a>) What atmospheric conditions support the development of these clouds? Soundings from King Salmon AK at <a href=\"https:\/\/weather.uwyo.edu\/cgi-bin\/sounding?region=naconf&amp;TYPE=GIF%3ASKEWT&amp;YEAR=2025&amp;MONTH=04&amp;FROM=0712&amp;TO=0800&amp;STNM=70326\">1200 UTC\/7 April and 0000 UTC\/8 April<\/a>, below, taken from the <a href=\"https:\/\/weather.uwyo.edu\/upperair\/sounding_legacy.html\">University of Wyoming Sounding site<\/a>, show very strong northerly winds at low-levels and near dry-adiabatic conditions at 1200 UTC. At 0000 UTC, the low-level winds are relaxing but the steep low-level lapse rate persists. By 0000 UTC, Aleutians are starting to be affected by a system dropping down from the north as evidenced by changes in the cloudiness in the animation shown above. The inversion is between 850 and 900 mb, around 1000 m above Sea Level. Only a few peaks in this area of the Aleutians reach above 1 km (<a href=\"https:\/\/en-gb.topographic-map.com\/map-vzh14\/Aleutian-Islands\/?center=56.68641%2C-157.76367&amp;zoom=7\">link<\/a>).<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><a href=\"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-content\/uploads\/sites\/5\/2025\/04\/KingSalmonAK2025040712_0800.70326.skewt_.parc_.gif\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"410\" src=\"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-content\/uploads\/sites\/5\/2025\/04\/KingSalmonAK2025040712_0800.70326.skewt_.parc_-1024x410.gif\" alt=\"\" class=\"wp-image-64015\" srcset=\"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-content\/uploads\/sites\/5\/2025\/04\/KingSalmonAK2025040712_0800.70326.skewt_.parc_-1024x410.gif 1024w, https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-content\/uploads\/sites\/5\/2025\/04\/KingSalmonAK2025040712_0800.70326.skewt_.parc_-300x120.gif 300w, https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-content\/uploads\/sites\/5\/2025\/04\/KingSalmonAK2025040712_0800.70326.skewt_.parc_-768x307.gif 768w, https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-content\/uploads\/sites\/5\/2025\/04\/KingSalmonAK2025040712_0800.70326.skewt_.parc_-1536x614.gif 1536w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><\/a><figcaption class=\"wp-element-caption\">King Salmon Alaska soundings, 1200 UTC on 7 April (left) and 0000 UTC on 8 April (right) (Click to enlarge)<\/figcaption><\/figure>\n\n\n\n<p>Day Cloud Phase Distinction imagery during the day on 7 April, below, suggests that the standing wave cloud is glaciated.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1524\" height=\"1008\" src=\"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-content\/uploads\/sites\/5\/2025\/04\/G18DCPD-20250407_1700_to_0408_0400anim.gif\" alt=\"\" class=\"wp-image-64017\"\/><figcaption class=\"wp-element-caption\">GOES-18 Day Cloud Phase Distinction RGB, 1700 UTC 7 April &#8211; 0400 UTC 8 April 2025 (Click to enlarge)<\/figcaption><\/figure>\n\n\n\n<p>Mid-level Water Vapor infrared imagery (6.95 \u00b5m), below, also shows the development of the standing waves. Surface observations show very strong northerly winds off the Bering Sea.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1524\" height=\"1008\" src=\"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-content\/uploads\/sites\/5\/2025\/04\/G18Band09Obs-20250407_1340_to_20250408_0610anim.gif\" alt=\"\" class=\"wp-image-64018\"\/><figcaption class=\"wp-element-caption\">GOES-18 Mid-Level water vapor (band 9, 6.95 \u00b5m) infrared imagery along with surface observations, 1340 UTC 7 April 2025 &#8211; 0610 UTC 8 April 2025 (Click to enlarge)<\/figcaption><\/figure>\n\n\n\n<p>The toggle below between VIIRS and GOES-18 ABI visible (0.64 \u00b5m) imagery highlights the importance of VIIRS data at high latitudes. There is a significant parallax shift in the GOES-18 imagery such that the standing wave is shown to be over the mountains, rather than displaced to the south as in the VIIRS imagery (and, likely, in reality). VIIRS data also allows the use to see the shadow of the higher clouds on the terrain below; the oblique view from GOES-18 misses that feature.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1524\" height=\"1008\" src=\"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-content\/uploads\/sites\/5\/2025\/04\/VIIRSI01_G18Band2Meso2-20250407_2301toggle.gif\" alt=\"\" class=\"wp-image-64020\"\/><figcaption class=\"wp-element-caption\">VIIRS I01 and GOES-18 Band 2 visible (0.64 \u00b5m) imagery, 2300 UTC on 7 April 2025 (Click to enlarge)<\/figcaption><\/figure>\n\n\n\n<p>The animation below compares zoomed-in VIIRS imagery from Visible (I01, 0.64 \u00b5m), shortwave infrared (I04, 3.87 \u00b5m) and longwave infrared (I05, 11.45 \u00b5m) channels.  Solar reflectance of 3.74 \u00b5m energy means the clouds and surface are warm &#8212; but note how the shadow of the clouds &#8212; where little solar reflection occurs &#8212; are relatively cold!<\/p>\n\n\n\n<figure class=\"wp-block-image size-large is-resized\"><img loading=\"lazy\" decoding=\"async\" width=\"1155\" height=\"838\" src=\"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-content\/uploads\/sites\/5\/2025\/04\/SuomiNPPNPPI01_I03_I04-20250407_230122.gif\" alt=\"\" class=\"wp-image-64021\" style=\"width:783px;height:auto\"\/><figcaption class=\"wp-element-caption\">VIIRS imagery from Suomi NPP;  I01 (0.64 \u00b5m), I04 (3.74  \u00b5m) and I05 (11.45 \u00b5m) at 2301 UTC on 7 April 2025 (Click to enlarge)<\/figcaption><\/figure>\n\n\n\n<p>VIIRS data can be used to create Day Cloud Phase Distinction RGBs, as shown in the animation below (courtesy Carl Dierking, GINA), and the multiple JPSS Satellites (Suomi NPP, NOAA-20 and NOAA-21) means excellent temporal resolution.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><a href=\"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-content\/uploads\/sites\/5\/2025\/04\/VIIRS_DCPD_250407_2021_250408_0016.gif\"><img loading=\"lazy\" decoding=\"async\" width=\"1182\" height=\"791\" src=\"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-content\/uploads\/sites\/5\/2025\/04\/VIIRS_DCPD_250407_2021_250408_0016.gif\" alt=\"\" class=\"wp-image-64030\"\/><\/a><figcaption class=\"wp-element-caption\">VIIRS Day Cloud Phase Distinction RGB, 2120 UTC 7 April &#8211; 0016 UTC 8 April 2025 (Click to enlarge);  animation courtesy Carl Dierking, GINA<\/figcaption><\/figure>\n\n\n\n<p>JPSS Satellites carry infrared and microwave sounders, and data from those sounders are used to create vertical profiles of moisture and temperature, i.e., NUCAPS soundings. The animation below shows three soundings near the standing wave.  There is a strong inversion upstream of the standing wave cloud, and the inversion is not so pronounced downstream of the cloud.  The boundary layer in all three soundings is dry adiabatic.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1088\" height=\"720\" src=\"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-content\/uploads\/sites\/5\/2025\/04\/I01NUCAPS_Soundings_23UTC_7April2025step.gif\" alt=\"\" class=\"wp-image-64023\"\/><figcaption class=\"wp-element-caption\">NUCAPS profiles at 3 separate locations (indicated by the blue boxes), ca. 2300 UTC on 7 April 2025 (click to enlarge)<\/figcaption><\/figure>\n\n\n\n<p>My thanks to Aaron Jacobs, WFO Juneau and Carl Dierking, GINA, for alerting me to this interesting case, and supplying imagery and suggestions. Aaron also forwarded along the following screen captures of <a href=\"https:\/\/weathercams.faa.gov\/map\/-161.49302,55.52557,-152.13816,58.272\">FAA Webcams<\/a> at <a href=\"https:\/\/weathercams.faa.gov\/map\/-160.71178,54.89023,-151.35692,57.68157\/airport\/AJC\/details\/camera\">Chignik Bay<\/a> and <a href=\"https:\/\/weathercams.faa.gov\/map\/-161.49928,54.47061,-152.14442,57.29145\/airport\/PEV\/details\/camera\">Perryville<\/a> shown below.<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><a href=\"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-content\/uploads\/sites\/5\/2025\/04\/ChignikBay_SouthEast_04072025.gif\"><img loading=\"lazy\" decoding=\"async\" width=\"640\" height=\"480\" src=\"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-content\/uploads\/sites\/5\/2025\/04\/ChignikBay_SouthEast_04072025.gif\" alt=\"\" class=\"wp-image-64045\"\/><\/a><figcaption class=\"wp-element-caption\">Webcam imagery, Chignik Bay, looking southeast, 1735 &#8211; 2208 UTC on 7 April 2025 (Click to enlarge)<\/figcaption><\/figure>\n\n\n\n<figure class=\"wp-block-image size-full\"><a href=\"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-content\/uploads\/sites\/5\/2025\/04\/Perryville_East_04072025.gif\"><img loading=\"lazy\" decoding=\"async\" width=\"640\" height=\"480\" src=\"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-content\/uploads\/sites\/5\/2025\/04\/Perryville_East_04072025.gif\" alt=\"\" class=\"wp-image-64046\"\/><\/a><figcaption class=\"wp-element-caption\">Webcam imagery, Perryville AK, looking east, ca. 1500-2300 UTC on 7 April 2025 (Click to enlarge)<\/figcaption><\/figure>\n\n\n\n<figure class=\"wp-block-image size-full\"><a href=\"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-content\/uploads\/sites\/5\/2025\/04\/Perryville_NorthWest_04072025.gif\"><img loading=\"lazy\" decoding=\"async\" width=\"640\" height=\"480\" src=\"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-content\/uploads\/sites\/5\/2025\/04\/Perryville_NorthWest_04072025.gif\" alt=\"\" class=\"wp-image-64047\"\/><\/a><figcaption class=\"wp-element-caption\">Webcam imagery, Perryville, AK, looking northwest, 1600-2200 UTC on 7 April 2025 (Click to enlarge)<\/figcaption><\/figure>\n","protected":false},"excerpt":{"rendered":"<p>GOES-18 True Color imagery during the day on 7 April, above, shows the development of a standing wave downwind of the elevated topography on the Aleutian peninsula between King Salmon and Perryville. (Note also the faint signal of volcanic ash as discussed here) What atmospheric conditions support the development of these clouds? Soundings from King [&hellip;]<\/p>\n","protected":false},"author":19,"featured_media":64022,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[37,114,78,83,49,48],"tags":[],"class_list":["post-64012","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-arctic","category-goes-18","category-noaa-20","category-nucaps","category-suomi_npp","category-viirs"],"acf":[],"_links":{"self":[{"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/posts\/64012","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\/19"}],"replies":[{"embeddable":true,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/comments?post=64012"}],"version-history":[{"count":13,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/posts\/64012\/revisions"}],"predecessor-version":[{"id":64052,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/posts\/64012\/revisions\/64052"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/media\/64022"}],"wp:attachment":[{"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/media?parent=64012"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/categories?post=64012"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/tags?post=64012"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}