# Data Analysis of the TK-1G Sounding Rocket Installed with a Satellite Navigation System
## 4 Data Processing and Analysis
### Result Analysis
#### 4.2.2 Analysis of the Meteorological Data  
To further gauge the detection precision of the rocket, this paper draws a comparison between China's reference atmospheric data, ECMWF-T799 (European Centre for Medium-Range Weather Forecasts) model data and satellite remote sensing data, and rocket sounding data. The rocket sonde data has been smoothed before comparison. The reference atmosphere used in this paper refers to China's GJB5601-2006 reference atmosphere. With ranges of 15\({}^{\circ}\) N-50\({}^{\circ}\) N, 75\({}^{\circ}\) E-130\({}^{\circ}\) E, it displays the atmospheric parameters up to 80 km above the ground. The horizontal resolution is 5\({}^{\circ}\)\(\times\) 5\({}^{\circ}\). Vertical intervals: 0.5 km, within 10 km above the ground; 1 km, 10 km to 30 km and 2 km, and 30 km to 80 km. Readings of monthly and annual average atmospheric temperature, pressure, humidity, density, and wind field are given through a comprehensive analysis of the distribution features of the atmospheric parameters [22]. The ECMWF-T799 (hereafter referred to as T799) analyses are derived from global four-dimensional assimilation of various atmospheric observations into the ECMWF model. Six-hourly output products have \(\Delta\)h of 0.25\({}^{\circ}\) and 91 vertical levels from the surface to 0.01 hPa. The vertical resolution \(\Delta\)z is ~0.4 km in the lower stratosphere and ~1-2 km in the stratosphere, respectively. It can offer meteorological parameters such as temperature, pressure, wind direction, wind speed, and so on [23]. Due to the limitations of spatial resolution, we have used the T799 forecasting data of the grid point (105.50\({}^{\circ}\) E, 38.75\({}^{\circ}\) N), which is nearest to the launch site and the rocket detection data, to draw a comparison. TIMED (Thermosphere-Ionosphere-Mesosphere Energetics and Dynamics) satellite, whose orbital period is 97 min, operates at a height of 625 km above the ground with inclination of about 74.1\({}^{\circ}\) from the equator. Being one of the four instruments placed onboard the TIMED satellite, SABER (Sounding of the Atmosphere using Broadband Emission Radiometry) serves as a radiometer that measures infrared emissions from 1.27 mm to 15.2 mm from lower stratosphere to lower thermosphere [24]. SABER has the ability to measure temperature, pressure, density, and other parameters by dint of satellite infrared limb sounding technique with ten channels [25]. The comparison of the wind speed and direction obtained from the rocket sonde with the reference atmospheric data is shown, respectively, in Figures 4 and 5. As shown in the figures, their tendency is consistent. \begin{table}
\begin{tabular}{c c c c c c} \hline
**Altitude (km)** & **60** & **50** & **40** & **30** & **20** \\ \hline TK-1 average fall velocity \({}^{*}\) & 136.0 & 82.9 & 36.0 & 15.9 & 6.2 \\ TK-1G (20150703) & 34.0 (59.6 km) & 73.8 & 31.5 & 14.3 & 5.6 \\ TY-4B (20140316) & 157.6 & 71.6 & 34.4 & 13.5 & 5.7 \\ \hline \end{tabular} \({}^{*}\)Mean value of five qualification tests of TK-1 in November 2004.  
\end{table} 
Table 3: Comparison of the fall velocities of different sounding rockets. The comparison between the temperature data collected from the rocket sonde and the reference atmospheric data is shown in Figure 8, from which we can see the temperature curve of the rocket sonde shares similar tendency with that of the reference atmosphere. Also, the temperature curve of the rocket sonde mainly locates in the 3\(\sigma\) variance envelope curves of the reference atmosphere. The temperature profiles obtained from the rocket sonde and the SABER are shown in Figure 9. From the figure, we can see consistency between the two curves, which dovetail nicely in terms of their detailed features. Figure 8: The temperature profiles (10–60 km) obtained from the rocket sonde (red) and the reference atmosphere (black). The blue dotted line represents the 3\(\sigma\) variance of reference atmosphere. Figure 7: The wind direction profiles (10–60 km) obtained from the rocket sonde (red) and the T799 (blue).