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Table 3 Setups for the data assimilation experiments

From: Improving the estimation of thermospheric neutral density via two-step assimilation of in situ neutral density into a numerical model

ID

completion (%)

\(\Lambda _h\) (km)

\(p_0\)

obs. loc.

median difference \((\frac{\text {g}}{\text {cm}^3})\)

RMSE \((\frac{\text {g}}{\text {cm}^3})\)

     

CHAMP

GRACE

CHAMP

GRACE

01

100

\(\infty\)

1.0

No

− 9.6e−16

− 7.1e−17

2.3e−15

1.2e−16

02

100

\(\infty\)

2.0

No

− 2.9e−16

− 5.3e−17

1.8e−15

1.0e−16

03

100

\(\infty\)

3.0

No

4.9e−17

− 4.2e−17

1.7e−15

9.7e−17

04

25

\(\infty\)

4.0

No

    

05

100

150

3.0

No

− 2.8e−16

− 5.1e−17

1.8e−15

1.0e−16

06

100

300

3.0

No

− 1.1e−16

− 4.8e−17

1.8e−15

1.0e−16

07

100

600

3.0

No

− 3.4e−17

− 4.5e−17

1.7e−15

9.9e−17

08

100

300

4.0

No

9.7e−17

− 4.1e−17

1.7e−15

9.6e−17

09

53

150

6.0

No

    

10

54

200

4.5

No

    

11

100

\(\infty\)

3.0

Yes

− 1.3e−15

− 7.9e−17

2.6e−15

1.3e−16

12

100

300

4.0

Yes

− 1.2e−15

− 7.4e−17

2.5e−15

1.3e−16

OLS 1

100

   

− 1.8e−15

− 9.8e−17

3.1e−15

1.6e−16

OLS 2

100

   

− 1.4e−15

− 9.1e−17

2.7e−15

1.6e−16

OLS 3

100

   

− 1.8e−16

− 5.1e−17

2.4e−15

1.4e−16

  1. A ’completion’ of 100% means that the experiment ran to the end without any errors. Values below 100% indicate that the TIE-GCM crashed after the corresponding percentage of the experiment’s intended duration. \(\Lambda _h\) is the half life parameter for weighting the densities on the data grid based ob the vertical distance to CHAMP (see Eq. 9). \(p_0\) is the constant weighting factor introduced in Eq. 7. We abbreviate observation localization with ’obs. loc.’. ’median difference’ refers to the median of the differences between ensemble mean and accelerometer derived density of the corresponding satellite. The RMSE is computed using the difference between ensemble mean and accelerometer derived density. The statistics are only computed for experiments with 100% completion to ensure comparability