{"id":9166,"date":"2011-11-14T21:00:34","date_gmt":"2011-11-14T21:00:34","guid":{"rendered":"http:\/\/cimss.ssec.wisc.edu\/satellite-blog\/?p=9166"},"modified":"2011-11-15T19:12:21","modified_gmt":"2011-11-15T19:12:21","slug":"mysterious-gravity-wave-over-the-eastern-pacific-ocean","status":"publish","type":"post","link":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/archives\/9166","title":{"rendered":"Mysterious Gravity Wave Over the Eastern Pacific Ocean"},"content":{"rendered":"

We received the following email from Ken Waters of the National Weather Service forecast office in Phoenix, Arizona<\/a><\/strong>:<\/p>\n

I noticed something interesting in this morning’s visible imagery off the Baja California coast.<\/p>\n

Here’s a link: https:\/\/docs.google.com\/open?id=0B2ktDMIN5qWfODI2OTYzYjgtZjJkMS00MTU5LTk2ODctYzdhNzY5M2Y2MWIx<\/a><\/p>\n

I’m looking at the apparent wave pattern that’s going “upstream” towards the northeast whereas the low level flow is mostly towards the south. Is that a gravity wave? If so, what causes it? The vis can only go so far back so I looked at the IR and couldn’t find anything obvious.<\/p><\/blockquote>\n

Great question Ken — it certainly appears to be some sort of internal gravity wave, but what caused it and why was it propagating against<\/em> the ambient flow shall remain a bit of a mystery until we can dig into this case a bit further. One more event for the “What the heck is this?” blog category.<\/p>\n

\"GOES-15<\/a>

GOES-15 6.5 \u00c2\u00b5m water vapor channel images + GOES-15 0.63 \u00c2\u00b5m visible channel images<\/p><\/div>\n

McIDAS images of GOES-15 6.5 \u00c2\u00b5m water vapor channel data (prior to daylight)<\/em> and then GOES-15 0.63 \u00c2\u00b5m visible channel data after sunrise (above)<\/em><\/strong> on 14 November 2011<\/a><\/strong> tell us one thing: this gravity wave was apparently fairly deep in the vertical, since it exibited a signal on both the water vapor channel imagery (which generally senses radiation from the middle troposphere: San Diego 12:00 UTC rawinsonde water vapor chanel weighting function profile<\/a><\/strong>)<\/em> as well as on the lower-tropospheric cloud features seen on the visible channel imagery.<\/p>\n

Note that there was a second packet of shorter-wavelength gravity waves that could be seen in the far southwestern portion of the GOES-15 visible image satellite scene toward the end of the animation. This second packet of gravity waves was very evident on a 500-meter resolution Aqua MODIS Red\/Green\/Blue (RGB) true color image at 21:21 UTC (below)<\/em><\/strong>.<\/p>\n

\"Aqua<\/a>

Aqua MODIS true color image<\/p><\/div>\n

Gravity waves are usually ducted within a well-defined temperature inversion. A look at the 12:00 UTC rawinsonde profile from San Diego, California (below)<\/em><\/strong> did indicate the presence of a few inversions that might have been capable of ducting such a gravity wave — but the inversions existed at multiple levels.<\/p>\n

\"San<\/a>

San Deigo, California 12:00 UTC rawinsonde profile<\/p><\/div>\n

An AWIPS image of 18:00 UTC MODIS 0.65 \u00c2\u00b5m visible channel data with overlays of 1-hour interval MADIS satellite winds (below)<\/em><\/strong> did not reveal any atmospheric motion vectors with a southwesterly component – but these would likely have been rejected by the winds quality control algorithms, since such a motion would have differed too greatly from the model first guess wind fields at 850 hPa<\/a><\/strong>, 500 hPa<\/a><\/strong>, 300 hPa<\/a><\/strong>, and 250 hPa<\/a><\/strong>.<\/p>\n

\"MODIS<\/a>

MODIS 0.65 \u00c2\u00b5m visible channel image + MADIS 1-hour interval satellite winds<\/p><\/div>\n

Regarding the effect of the gravity wave seen on the lower-tropospheric clouds bands, a MODIS 11.0 \u00c2\u00b5m IR image detected cloud top IR brightness temperatures around +4\u00c2\u00baC, which on a RUC model sounding at that location apparently corresponded to a cloud top height around 12,550 feet (below)<\/em><\/strong> — however, this value seemed to be a bit high judging from the appearance of the cloud band features on the GOES and MODIS visible and IR imagery.<\/p>\n

\"MODIS<\/a>

MODIS 11.0 \u00c2\u00b5m IR image + RUC model sounding<\/p><\/div>\n

On the other hand, POES AVHRR Cloud Type and Cloud Top Height products indicated that these low-level cloud bands were water droplet clouds, with cloud top heights of around 1 km (below)<\/em><\/strong> — much more typical for marine boundary layer cloud features over this region.<\/p>\n

\"POES<\/a>

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

\"POES<\/a>

POES AVHRR Cloud Top Height product<\/p><\/div>\n","protected":false},"excerpt":{"rendered":"

We received the following email from Ken Waters of the National Weather Service forecast office in Phoenix, Arizona: I noticed something interesting in this morning’s visible imagery off the Baja California coast. Here’s a link: https:\/\/docs.google.com\/open?id=0B2ktDMIN5qWfODI2OTYzYjgtZjJkMS00MTU5LTk2ODctYzdhNzY5M2Y2MWIx I’m looking at the apparent wave pattern that’s going “upstream” towards the northeast whereas the low level flow is […]<\/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":[22,43,12,26,45,25,38],"tags":[],"class_list":["post-9166","post","type-post","status-publish","format-standard","hentry","category-avhrr","category-goes-15","category-modis","category-poes","category-redgreenblue-rgb-images","category-satellite-winds","category-what-the-heck-is-this"],"acf":[],"_links":{"self":[{"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/posts\/9166","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=9166"}],"version-history":[{"count":12,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/posts\/9166\/revisions"}],"predecessor-version":[{"id":9178,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/posts\/9166\/revisions\/9178"}],"wp:attachment":[{"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/media?parent=9166"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/categories?post=9166"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/tags?post=9166"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}