{"id":2227,"date":"2022-07-18T19:17:53","date_gmt":"2022-07-18T19:17:53","guid":{"rendered":"https:\/\/www.jpl.nasa.gov\/site\/jsgt\/jtrf\/?page_id=2227"},"modified":"2023-09-20T11:59:29","modified_gmt":"2023-09-20T11:59:29","slug":"jtrf2020-geocenter-scale-helmerts","status":"publish","type":"page","link":"https:\/\/www.jpl.nasa.gov\/site\/jsgt\/jtrf\/solutions\/jtrf2020\/values\/geocenter-scale\/","title":{"rendered":"JTRF2020 Geocenter & Scale"},"content":{"rendered":"\t\t
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\n\t\t\t\t\t\t\t\t\t\t\t\t\t\"JTRF_logo_w_shadow_2023-06-26_1500px\"\t\t\t\t\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t
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JTRF2020 Solution<\/p>\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t

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Geocenter and Scale<\/h1>\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t
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About JTRF2020 Geocenter and Scale<\/h2>\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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Below are tables and summary descriptions of the JTRF2020 geocenter and scale. For more in-depth information about the procedures used to compute the geocenter see Abbondanza et al. (2017)<\/a> and for the scale see Abbondanza et al. (2023)<\/a>.<\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t

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\n\t\t\t\n\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\tGeocenter<\/span>\n\t\t\t\t\t<\/span>\n\t\t\t\t\t<\/a>\n\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t
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\n\t\t\t\n\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\tScale<\/span>\n\t\t\t\t\t<\/span>\n\t\t\t\t\t<\/a>\n\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t
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Geocenter and Geocenter Motion<\/h2>\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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The origin (geocenter) of the JTRF2020 reference frame is the center-of-mass (CM) of the entire Earth system including atmosphere, oceans, and continental water. Satellites orbit about this CM. But satellite tracking systems are located on the surface of the Earth which is constantly deforming in response to the shifting load caused by the motion of the atmosphere, oceans, and continental water. The center of the network of the tracking stations (CN) is therefore constantly moving. The difference between CM and CN is known as geocenter motion.<\/p>\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t

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\n\t\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\"Sub-Network\t\t\t\t\t\t\t\t<\/a>\n\t\t\t\t\t\t\t\t\t\t\t
Sub-Network Used for JTRF2020 CM-CN<\/figcaption>\n\t\t\t\t\t\t\t\t\t\t<\/figure>\n\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t<\/section>\n\t\t\t\t
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How Do We Define Origin?<\/h3>\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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To define origin, the Helmert transformation parameter T<\/i>L<\/i><\/sub>(t)<\/strong> in the rank-deficient system of equations 5 of Abbondanza et al., 2017<\/a> is set to zero during the measurement update.<\/p>