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dorisreport             11-Mar-2025 21:38:59 Message No 6610
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Author: "Lemoine, Frank G. (GSFC-61A0)" <frank.g.lemoine@nasa.gov>
Subject: Delivery of gscwd60 SINEX files (2021-2024)


Dear Colleagues,

To support the preparation of the next extension of ITRF2020 (ITRF2020-u202=
4), we have recently
submitted an updated series of SINEX files from January 2021 to December 20=
24, the series wd60.
This series, gscwd60, is an update of the previous operational series (wd58=
) over this time period.
The delivery to the IDS data centers, recently completed, included 209 SINE=
X files
 from 2021-DOY003  (January 3, 2021) to 2024-DOY364 (Dec. 29, 2024).

 We implemented the following changes w.r.t the wd58 series:
 (1) The Cryosat-2 and Saral normal equations based on DORIS/V2 data were r=
eplaced
      with DORIS/RINEX data.
 (2) We updated the background gravity model to use the COSTG_FSM gravity m=
odel in=20
       this period of time (Peter et al., 2022). We replaced  the low degre=
e terms (C20, C21, S21, C30)  for each data arc,
      using  low-degree  solutions for the Geopotential coefficients based =
on SLR tracking of
      the spherical geodetic satellites.  These solutions are provided by B=
ryant Loomis (GSFC)
     and are part of the normal delivery to the GRACE FO project, known as =
GRACE Technical=20
     Note 14 (Loomis et al., 2020).

 (3) Although this has minimal impact on any of the POD calculations, we fo=
und it expedient
    to update the planetary ephemeris to DE440, from the prior model used o=
ver this=20
    time period (DE430).

 We note that in addition, both the prior operational series (wd58) and thi=
s new
  series (wd60) use the MSIS2 atmosphere density model (Emmert et al. 2021)=
,=20
   and the Conrad et al. (2023) macromodel for Sentinel-6A.

 Sincerely,
 NASA GSFC DORIS Analysis Center (GSC)
   Frank Lemoine, Douglas Chinn, Nikita Zelensky

References
=3D=3D=3D=3D=3D=3D=3D=3D=3D
Conrad A,  Desai S.D., Haines B.J., Axelrad P. (2023).  =93Extending the GP=
S IIIA antenna calibration for=20
    precise orbit determination of low Earth orbit satellites=94,=20
    J. Geodesy, 97:35, doi: 10.1007/s00190-023-01718-0.'

Emmert J.T., Drob D.P., Picone J.M. et al. (2021).=20
    "NRLMSIS 2.0: A Whole-Atmosphere Empirical Model=20
     of Temperature and Neutral Species Densities"
    Earth and Space Sci., 8(3), doi: 10.1029/2020EA001321

Loomis B.D. Rachlin K.E. Wiese  D.N.  Landerer, F.W., and Luthcke, S.B. (20=
20).
   =93Replacing GRACE/GRACE-FO C30 with satellite laser ranging:=20
   Impacts on Antarctic Ice Sheet mass change=94,=20
   Geophys Res Lett., 47, e2019GL085488, doi: 10.1029/2019GL085488.

Park R.S., Folkner W.M., Williams J.G., Boggs D.H. (2021).=20
  "The JPL Planetary and Lunar Ephemerides DE440 and DE441"
    Astronomical Journal, 161(3), doi: 10.3847/1538-3881/abd414.

 Peter H., Meyer U., Lasser M., and J=E4ggi A., (2022).=20=20
   =93COST-G gravity field models for precise orbit
    determination of Low Earth Orbiting Satellites=94,=20
    Adv. Space Res., 69(12), 4155=964168, doi: 10.1016/j.asr.2022.04.005.




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