GFR processing standards at IfE. Igor Koch, Jakob Flury, Akbar Shabanloui COST-G meeng, 14 Jan 2019, ISSI Bern

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1 GFR processing standards at IfE Igor Koch, Jakob Flury, Akbar Shabanloui COST-G meeng, 14 Jan 2019, ISSI Bern

2 GRACE-SIGMA New compact so)ware package for gravity,eld recovery from GRACE sensor data Implemented in MATLAB from scratch [M. Naeimi et al., 2018] Compeve run me Variaonal equaons approach 2

3 GFR overview [Naeimi et al., 2018] 3

4 Variational equations approach Important aspects: Numerical integraon Force modeling Adjustment strategy 4

5 Numerical integration Modi,ed Gauss-Jackson integrator Without correcon step (contribuon to the posion vector below 1E-12 m) Mulstep integraon method ( RK4 for inializaon) Vectorized computaon of ephemerides, STM and SM More informaon: M. Naeimi: A modied Gauss-Jackson method for the numerical integraon of the variaonal equaons, poster, EGU 2018, Vienna. 5

6 Force modeling Eect Model Reference Gravity,eld GIF48 (d/o: 300) Ries et al., 2011 Third bodies Moon and Sun, Ephemerides: DE405 Standish, 1998 Solid Earth des IERS Convenons Pet a. Luzum, 2010 Ocean des EOT11a including minor waves (d/o: 80) Rieser et al., 2012 Solid Earth pole des IERS Convenons Pet a. Luzum, 2010 Ocean pole des IERS Convenons (d/o: 60) Pet a. Luzum, 2010 Relavisc IERS Convenons Pet a. Luzum, 2010 Non-dal AOD1B RL05 (d/o: 100) Flechtner et al., 2015 Non-gravitaonal Linear acceleraon measurements Case et al,

7 Force modeling In order to decrease the computaonal me, the major part of the force edects is calculated once using the L1B reduced dynamic orbits During orbit improvement these edects are not re-computed Only acceleraons due to the geopotenal and non-gravitaonal acceleraons are evaluated every iteraon 7

8 Adjustment strategy 1. Pre-adjustment 2. Main adjustment Esmated parameters: - Inial state vectors - Accelerometer biases Esmated parameters: - Inial state vectors - Accelerometer biases - Empirical KBR parameters - Spherical harmonics 3 it. 1 it. 8

9 Stochastic modeling Orbit (30 sec) + KBRR (5 sec) 1E-02 m 1E-07 m/s relave weighng of normal matrices 1 NEQ orbit 1E10 NEQ KBRR 9

10 Arcwise NEQ stacking 10

11 Arcwise NEQ stacking 3h 11

12 Arcwise NEQ stacking 3h 3d 12

13 Arcwise NEQ stacking 3h 3h 3d 3d 10d 13

14 Arcwise NEQ stacking 3h 3h 3d 3d 10d 20d 14

15 Arcwise NEQ stacking 3h 3h 3d 3d 10d 20d 31d 15

16 Arcwise NEQ stacking 3h 3d No regulariza on 16

17 Published solutions First batch of spherical harmonics using the presented strategy for the period can be found on IfE and also on ICGEM website 17

18 Exemplary EWHs (2008) CSR GFZ LUH m Jan Feb Mar Apr Gauss,lter (350 km) C20: TN SLR values 18

19 Exemplary EWHs (2008) CSR GFZ LUH m May Jun Jul Aug Gauss,lter (350 km) C20: TN SLR values 19

20 Exemplary EWHs (2008) CSR GFZ LUH m Sep Oct Nov Dec Gauss,lter (350 km) C20: TN SLR values 20

21 Comparison of degree standard deviations ( ) Results are in a good agreement with GFZ, CSR and JPL soluons 21

22 EWH Greenland ( ) Gauss,lter (350 km) C20: TN SLR values 22

23 EWH Amazonas ( ) Gauss,lter (350 km) C20: TN SLR values 23

24 Future plans Force models: atmospheric des, AOD1B RL06, FES2014, dynamic empiric parameters Parametrizaon: arc length, scale factors Data: L1B RL06 Range rate residuals analysis Code extending for GRACE-FO 24

25 References Case et al. (2010): GRACE level 1B data product user handbook (JPL D-22027), Technical report. Naeimi et al. (2018): IfE monthly gravity,eld soluons using the variaonal equaons, EGU 2018, Vienna. Naeimi (2018): A modi,ed Gauss-Jackson method for the numerical integraon of the variaonal equaons, poster, EGU 2018, Vienna. Pet and Luzum (2010): IERS Convenons (2010), IERS technical note 36, Verlag des Bundesamts für Kartographie und Geodäsie, Frankfurt am Main. Ries et al. (2011): Mean background gravity,elds for GRACE processing, GRACE Science Team Meeng Ausn, TX, August Rieser et al. (2012): The ocean de model EOT11a in spherical harmonics representaon, Technical report. Standish (1998): JPL planetary and lunar ephemerides, DE405/LE405, Jet Propulsion Laboratory InteroOce Memorandum IOM 312.F

26 Thank you for your a*enon! 26