## 3 Results and Discussion  
To address the problem of cloud cover, we propose a solution that uses cloud cover information provided by GEO meteorological satellites to guide mission planning for LEO optical imaging satellites. In the traditional mission planning, a 24-h observation schedule is developed by the ground control center and uploaded to the GEO-LEO satellites. Thus, the GEO-LEO satellites cooperation is based on an initial schedule. During the execution of the observation schedule by the LEO optical imaging satellites, the GEO meteorological satellite performs autonomous mission planning for the LEO optical imaging satellites based on the acquired cloud cover information. In the scenario, we set the cloud threshold to 65% and extract the time period of CLM from 0:00 to 9:00 (UTC time). The observation time of the GEO meteorological satellite under this time period is from 08:00 to 17:00 at local time, which meets the basic requirement for optical imaging. The number of CLM data during this time period is 15, which means there are 15 planning cycles. The number of tasks adjusted by onboard autonomous planning, the number of tasks successfully adjusted to the cloud-free window, and the number of tasks fail to adjust to the cloud-free window in the 15 planning cycles are shown in the Table 4. \begin{table}
\begin{tabular}{c c} \hline \hline
**Parameters** & **FY-4A** \\ \hline Orbit type & GEO \\ Orbit attitude & 36,000 km \\ Longitude of sub-satellite point & 104.7\({}^{\circ}\)E \\ Spatial resolution under full-disk & 4 km \\ Time resolution & 15 min \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Main parameters of FY-4A satellite. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Parameters** & **GF-1** & **GF-2** \\ \hline Orbit type & Sun-synchronous Orbit & Sun-synchronous Orbit \\ Orbit attitude & 645 km & 631 km \\ Orbit inclination & 98.0506\({}^{\circ}\) & 97.9080\({}^{\circ}\) \\ Swath & 60 km & 45 km \\ Maximum rolling angle & \(\pm\)35\({}^{\circ}\) & \(\pm\)35\({}^{\circ}\) \\ Spatial resolution (PAN, MSS) & 2 m, 16 m & 1 m, 4 m \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Main parameters of and GF-1/2 satellite. As can be seen from the table, there are 325 tasks in initial schedule, the onboard autonomous planning adjustment means that if the GEO-LEO satellites cooperation scheme is not used and the LEO optical imaging satellites perform observation according to the initial schedule, 70.46% of the images will contain over 65% cloud cover. By using the GEO-LEO satellites cooperation and autonomous onboard planning, 30.15% (98/325) tasks are successfully adjusted to cloud-free windows, it means the 98 tasks meet the operational constraints of mathematical model and are adjusted under onboard autonomous planning algorithm, which has improved the effectiveness of data acquisition. Meanwhile, 40.31% (131/325) tasks fail to adjust to the cloud-free window, it means the weather conditions of the 131 tasks are highly cloudy (over 65%), meanwhile the 131 tasks cannot meet the operational constraints of mathematical model. The 131 tasks will still be executed according to the initial schedule under high probability of acquiring cloudy images, consider that the images with over 65% may contain the region of interest. In addition, the task adjustments during each autonomous planning cycle are shown in Figure 5.  
In the above experiment, we set the cloud cover threshold as 65%. In order to test the influence of different cloud cover thresholds on onboard autonomous planning. We used 10 cloud thresholds from 5-95% with a value taken at 10% intervals, and the test results are shown in the Table 5. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Type** & **Number of Tasks** & **Adjustment Ratio** \\ \hline Initial schedule & 325 & / \\ Onboard autonomous & 229 & 70.46\% \\ planning adjustment & 98 & 30.15\% \\ Adjust to cloud-free window & 131 & 40.31\% \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Adjustments of the initial schedule by onboard autonomous planning.