{"id":47261,"date":"2022-07-20T18:34:25","date_gmt":"2022-07-20T18:34:25","guid":{"rendered":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/?p=47261"},"modified":"2022-08-01T15:39:15","modified_gmt":"2022-08-01T15:39:15","slug":"sar-winds-over-tropical-cyclone-estelle-in-the-eastern-pacific","status":"publish","type":"post","link":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/archives\/47261","title":{"rendered":"Using SAR Winds to center-fix Tropical Cyclone Estelle in the Eastern Pacific"},"content":{"rendered":"\n<figure class=\"wp-block-image size-large\"><a href=\"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-content\/uploads\/sites\/5\/2022\/07\/G17Band02_Band13-20220720_0150toggle.gif\"><img loading=\"lazy\" decoding=\"async\" width=\"1129\" height=\"754\" src=\"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-content\/uploads\/sites\/5\/2022\/07\/G17Band02_Band13-20220720_0150toggle.gif\" alt=\"\" class=\"wp-image-47262\" \/><\/a><figcaption>OGES-17 Visible (Band 2, 0.64 \u00b5m) and Infrared (Band 13, 10.3 \u00b5m) at 0150 UTC on 20 July 2022 (click to enlarge)<\/figcaption><\/figure>\n\n\n\n<p>GOES-17 visible and infrared imagery shows Tropical Storm Estelle over the eastern Pacific to the west-southwest of Baja California.  Although there are regions of strong convection, satellite presentation of the storm suggests a modest tropical storm.  Center-fixing a storm such as this (with just one image vs. an animation!) is complicated by both parallax (GOES-17 is overhead at 0<sup>o<\/sup>N, 137.2<sup>o<\/sup>W) and the lack of an easily-discerned eye feature in this system.<\/p>\n\n\n\n<p>Instruments that view surface winds, via Scatterometry or via Synthetic Aperture Radar (SAR), can offer better center fixes.  Consider the toggle below of Radarsat-2 SAR winds over Estelle.  SAR Winds (available <a href=\"https:\/\/www.star.nesdis.noaa.gov\/socd\/mecb\/sar\/AKDEMO_products\/APL_winds\/wind_images_nic\/sarwinds_daily_now.html?date=20220720\">here<\/a>; SAR winds over Tropical Systems can be found <a href=\"https:\/\/www.star.nesdis.noaa.gov\/socd\/mecb\/sar\/AKDEMO_products\/APL_winds\/tropical\/index.html?year=2022&amp;storm=EP062022_ESTELLE\">here<\/a>.) show a lopsided storm, with most of the strong winds on the poleward side of the center.  The <a href=\"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-content\/uploads\/sites\/5\/2022\/07\/RSAT2_GSS_2022_07_20_01_50_16_0711597016_116.07W_19.86N_VH_C-8_GFS05CDF_wind.png\">SAR winds that use 0.5-degree GFS wind data as a first guess<\/a> show a characteristic hourglass feature near the center that advertises an ambiguity between the first guess winds and the observations.  That feature is missing in the <a href=\"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-content\/uploads\/sites\/5\/2022\/07\/RSAT2_GSS_2022_07_20_01_50_16_0711597016_116.07W_19.86N_VV_C5_GFS025CDF_wind.png\">SAR wind field that is a product of the 0.25-degree GFS winds<\/a>, suggesting that the 0.25-degree wind field is more accurate.  Both fields show a rather baggy center at or just south of 20<sup>o<\/sup>N.<\/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\/2022\/07\/RSAT2_GSS_2022_07_20_01_50_16_0711597016_116.07W_19.86N_VV_C5_GFS05_GFS025CDF_windtoggle.gif\"><img loading=\"lazy\" decoding=\"async\" width=\"1826\" height=\"1955\" src=\"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-content\/uploads\/sites\/5\/2022\/07\/RSAT2_GSS_2022_07_20_01_50_16_0711597016_116.07W_19.86N_VV_C5_GFS05_GFS025CDF_windtoggle.gif\" alt=\"\" class=\"wp-image-47263\" \/><\/a><figcaption>RSAT-2 SAR Winds over Estelle benchmarked by 0.5-degree and 0.25-degree model output, 0150 UTC on 20 July 2022;  note the different color scales used in the two images (Click to enlarge)<\/figcaption><\/figure>\n\n\n\n<p>Scatterometry from MetopB and HY2B between 1730 UTC 19 July and 0230 UTC 20 July, respectively show a storm moving west-northwest, passing north of 20<sup>o<\/sup>N just after 0230 UTC.<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"775\" height=\"891\" src=\"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-content\/uploads\/sites\/5\/2022\/07\/asc_b_20220719_1741_hy_2b_20220720_02_98_flag_togglec.gif\" alt=\"\" class=\"wp-image-47271\" \/><figcaption>ASCAT (MetopB) and HY2B Scatterometry winds at 1730 (19 July) and 0230 (20 July), respectively.<\/figcaption><\/figure>\n","protected":false},"excerpt":{"rendered":"<p>GOES-17 visible and infrared imagery shows Tropical Storm Estelle over the eastern Pacific to the west-southwest of Baja California. Although there are regions of strong convection, satellite presentation of the storm suggests a modest tropical storm. Center-fixing a storm such as this (with just one image vs. an animation!) is complicated by both parallax (GOES-17 [&hellip;]<\/p>\n","protected":false},"author":19,"featured_media":47266,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[80,104,25,2],"tags":[],"class_list":["post-47261","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-goes-17","category-sar","category-satellite-winds","category-tropical-cyclones"],"acf":[],"_links":{"self":[{"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/posts\/47261","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=47261"}],"version-history":[{"count":11,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/posts\/47261\/revisions"}],"predecessor-version":[{"id":47421,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/posts\/47261\/revisions\/47421"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/media\/47266"}],"wp:attachment":[{"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/media?parent=47261"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/categories?post=47261"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-json\/wp\/v2\/tags?post=47261"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}