************************************************************************ IERS Message No. 520 January 27, 2025 ************************************************************************ Announcing JTRF2020-u2022 Dear JTRF Users, We are pleased to announce that JTRF2020-u2022, the JPL-Caltech first update of JTRF2020, is ready to be released and distributed to the community. JTRF2020-u2022 has been computed by running SREF -the square-root information filter and smoother algorithm developed at JPL to estimate terrestrial reference frames- in update mode. In computing JTRF2020-u2022, SREF adopts the conceptual framework of Bayesian update inherent to any Kalman filter formulation: the latest estimate of JTRF2020 state and its covariance (YEAR 2020, DOY 366, GPS Week 2138) gets uploaded and subsequently updated by assimilating at daily intervals the extended frame inputs made available by IGS (IGSR3-igr3.atx), IVS (ivs2023b), ILRS (ilrsav86), and IDS (idswd23) from 2021 through the end of 2022 (DOY 330, GPS Week 2237). Afterwards, with SREF running in forecast mode, station positions are predicted through the end of 2027 (DOY 365, GPS Week 2503). JTRF2020-u2022 consists of 2556 daily "gzipped" SINEX files in 'VARIANCE-COVARIANCE' format containing geocentric coordinates along with their full covariance from 931 stations, the full JTRF2020 network. It is worth observing that, although new space-geodetic stations acquiring observations after the end of 2020 have been made available and included in the frame inputs by the Technique Centers, JTRF2020-u2022 does not adopt them. The first 695 SINEX files of JTRF2020-u2022 span the updated frame-defining interval from 2021 (DOY 001, GPS Week 2138) through the end of 2022 (DOY 330, GPS Week 2237). The remaining 1861 SINEX files relate to the forecast interval from 2022 (DOY 332 GPS Week 2238) through the end of 2027 (DOY 365, GPS Week 2503) during which SREF stopped assimilating frame inputs and started operating in forecast mode. For those of you interested in JTRF2020-u2022, its daily SINEX files (containing station positions only) can be accessed from the following URL: https://sideshow.jpl.nasa.gov/pub/JPL_SREF_Products/ JTRF2020_Latest_Updated_Forecasts [Please note the line wrap in this link.] Note that the parent directory JTRF2020_Latest_Updated_Forecasts contains in turn four additional sub-directories named GNSS, VLBI, SLR, DORIS each of which hosts 2556 SINEX files characterized by (*) GNSS Stations only in ./JPL_SREF_Products/JTRF2020_Latest_Updated_Forecasts/GNSS (*) VLBI Stations only in ./JPL_SREF_Products/JTRF2020_Latest_Updated_Forecasts/VLBI (*) SLR Stations only in ./JPL_SREF_Products/JTRF2020_Latest_Updated_Forecasts/SLR (*) DORIS Stations only in ./JPL_SREF_Products/JTRF2020_Latest_Updated_Forecasts/DORIS There is a fifth sub-directory ./JPL_SREF_Products/JTRF2020_Latest_Updated_Forecasts/FULL which stores 2556 SINEX files with station positions from 931 stations (the full JTRF2020 network) along with their full covariance (including the inter-technique covariances). The daily SINEX files available at https://sideshow.jpl.nasa.gov/pub/JPL_SREF_Products/ JTRF2020_Latest_Updated_Forecasts/ [Please note the line wrap in this link.] have been grouped in sub-directories categorized by year. For instance, the sub-directory https://sideshow.jpl.nasa.gov/pub/JPL_SREF_Products/ JTRF2020_Latest_Updated_Forecasts/GNSS/2022 [Please note the line wrap in this link.] stores the GNSS-only JTRF2020-u2022 SINEX files for the year 2022. The JTRF2020-u2022 SINEX files under JPL_SREF_Products/ JTRF2020_Latest_Updated_Forecasts [please note the line wrap in this link] are all characterized by unique, non-ambiguous file names adopting the following convention: YYYY-MM-DD-noon_jtrf2020_u2022_techID.snx.gz where (*) YYYY is a 4-digit integer value denoting the Gregorian Year (*) MM is a 2-digit integer value denoting the Month (*) DD is a 2-digit integer value denoting the Day of the Month (*) techID is a lowercase string denoting the technique (i.e. gnss, vlbi, slr, doris). Please, note that for the JTRF2020-u2022 SINEX files under ./JPL_SREF_Products/JTRF2020_Latest_Updated_Forecasts/FULL the string _techID is not defined (i.e. YYYY-MM-DD-noon_jtrf2020_u2022.snx.gz). GNU wget, as well as cURL, can be used to download the JTRF2020-u2022 files. Here is a couple of examples: (1) mkdir ./GNSS & wget -b -r -np -P ./GNSS -R "*index.html*" "*.snx" -nH --cut-dirs=4 https://sideshow.jpl.nasa.gov/pub/ JPL_SREF_Products/JTRF2020_Latest_Updated_Forecasts/GNSS/2027 [Please note the line wraps in this command and link.] (2) mkdir ./GNSS & wget -b -r -np -P ./GNSS -R "*index.html*" "*.snx" -nH --cut-dirs=4 https://sideshow.jpl.nasa.gov/pub/ JPL_SREF_Products/JTRF2020_Latest_Updated_Forecasts/GNSS [Please note the line wraps in this command and link.] (1) will download in background mode the GNSS-only JTRF2020-u2022 SINEX files for the year 2027 in the directory ./GNSS/2027. (2) will download in background mode the GNSS-only JTRF2020-u2022 SINEX files the whole sub-directory JTRF2020-u2022/GNSS. The Users are advised that daily EOPs have been removed from the SINEX files gathered in https://sideshow.jpl.nasa.gov/pub/JPL_SREF_Products/ and will be made available as a separate JTRF2020-u2022 product. As of this writing, the URL https://www.jpl.nasa.gov/site/jsgt/jtrf/ is being populated with the entire set of JTRF2020-u2022 products. We'll be sending out an official email to the community as soon as the JTRF2020 website gets fully populated with all of the JTRF2020-u2022-related files and products. For those users eager to test time series products out, we made available station position time series expressed in the the same ASCII file format consistently adopted throughout the JTRF website. Such time series can ben found at the following URL: https://sideshow.jpl.nasa.gov/pub/JPL_SREF_Products JTRF2020_Additional_Products/jtrf2020-u2022/stations/ [Please note the line wraps in this command and link.] The structure of the sub-directories under jtrf2020-u2022/stations is self-explanatory with the usual distinction in XYZ and ENU time series products. It is worth observing that the sub-directories contain time series data for all of the 931 stations constituting JTRF. Such time series are constructed by "merging" the JTRF2020 with the JTRF2020-u2022 time series products. We wish to acknowledge the crucial contributions provided by the Technique Services (IVS, ILRS, IGS, IDS) and their tremendous efforts put into the re-analyses of the space-geodetic databases. We also would like to thank the ITRS Combination Centres at IGN and DGFI for their gracious support throughout the JTRF2020-u2022 analyses. For any comment, question or specific request, please do feel free to contact us. We will be delighted to accommodate your requests and to help you integrate JTRF products into your reduction procedures. We hope you will be able to enjoy JTRF2020-u2022 and we really look forward to having your feedback. With our warmest regards, Claudio Abbondanza, on behalf of the TRF Team at JPL-Caltech Richard Gross C Abbondanza T Chin M Heflin ************************************************************************ IERS Messages are edited and distributed by the IERS Central Bureau. If not stated otherwise, the IERS is only the distributor of the message and is not responsible for its content. To submit texts for distribution, please write to . To subscribe or unsubscribe, please create an IERS account or modify it: https://www.iers.org/Login/Login/EN/login_node.html or write to . Archives: http://www.iers.org/IERS/Messages ************************************************************************