# Evaluating the Accuracy of Magnetospheric Magnetic Field Models Using Cluster Spacecraft Magnetic Field Measurements

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## Abstract

**:**

## 1. Introduction

## 2. Data Set

## 3. Results

## 4. Discussion

## 5. Conclusions

## Author Contributions

## Funding

## Data Availability Statement

## Conflicts of Interest

## References

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**Figure 1.**Total number of magnetic field measurements included in the analysis in individual spatial bins. The size of the bins is $0.1\times 0.1{R}_{E}$. (

**a**) Daytime (LT 9–15 h). (

**b**) Dawn/dusk (LT 3–9 and 15–21 h). (

**c**) Night (LT 21–24 and 0–3 h).

**Figure 2.**Average differences between the measured and model magnetic field magnitudes are color coded as a function of the location using the color scale on the right-hand side. The individual columns correspond to different local times, while the individual rows correspond to different external magnetic field models. (

**a**–

**c**) Tsyganenko 89 external magnetic field model. (

**d**–

**f**) Tsyganenko 96 external magnetic field model. (

**g**–

**i**) Tsyganenko 01 external magnetic field model. (

**j**–

**l**) Tsyganenko and Andreeva 15B external magnetic field model. (

**m**–

**o**) Tsyganenko and Andreeva 15N external magnetic field model.

**Figure 3.**The same as Figure 2, but for average angular differences between the measured and model magnetic field directions.

**Figure 4.**The same as Figure 2, but for average magnitudes of vector differences between measured and model magnetic field directions.

**Figure 5.**Geomagnetic latitude of min-B equator evaluated using an external magnetic field model as a function of the min-B equator geomagnetic latitude determined using four-point Cluster spacecraft measurements. Each symbol corresponds to a single equatorial crossing of the Cluster spacecraft constellation. The diagonal dashed line corresponds to the 1:1 dependence. The respective Pearson correlation values are given. (

**a**) Tsyganenko 89 external magnetic field model; (

**b**) Tsyganenko 96 external magnetic field model; (

**c**) Tsyganenko 01 external magnetic field model; (

**d**) Tsyganenko and Andreeva 15B external magnetic field model; (

**e**) Tsyganenko and Andreeva 15N external magnetic field model.

**Figure 6.**(

**a**) Histogram of geomagnetic latitudes of min-B equators determined using four-point Cluster spacecraft measurements; (

**b**) Histogram of differences between min-B equator geomagnetic latitudes determined using Cluster spacecraft measurements and min-B equator geomagnetic latitudes calculated using the Tsyganenko 89 external magnetic field model; (

**c**) The same as (

**b**), but for the Tsyganenko 96 external magnetic field model; (

**d**) The same as (

**b**), but for the Tsyganenko 01 external magnetic field model; (

**e**) The same as (

**b**), but for the Tsyganenko and Andreeva 15B external magnetic field model; (

**f**) The same as (

**b**), but for the Tsyganenko and Andreeva 15N external magnetic field model.

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Němec, F.; Kotková, M.
Evaluating the Accuracy of Magnetospheric Magnetic Field Models Using Cluster Spacecraft Magnetic Field Measurements. *Universe* **2021**, *7*, 282.
https://doi.org/10.3390/universe7080282

**AMA Style**

Němec F, Kotková M.
Evaluating the Accuracy of Magnetospheric Magnetic Field Models Using Cluster Spacecraft Magnetic Field Measurements. *Universe*. 2021; 7(8):282.
https://doi.org/10.3390/universe7080282

**Chicago/Turabian Style**

Němec, František, and Marie Kotková.
2021. "Evaluating the Accuracy of Magnetospheric Magnetic Field Models Using Cluster Spacecraft Magnetic Field Measurements" *Universe* 7, no. 8: 282.
https://doi.org/10.3390/universe7080282