Time series analysis includes two modules: “time series data” and “animation.”
2.4.5.1 Time series data
It includes points, lines, and polygons time series button.
First, it needs to query the data from the database for time series analysis, including the time range, products, etc. If the “load selected image” is checked at the same time, the data queried will be loaded into the 3D geosphere in the form of layers.
Point time series analysis: Use “mouse click” to select a point on the image or directly input the longitude and latitude of a point, and then click “import” (as shown in Figure 2-36). It will output the sequence value of the sampling point in the selected time period successively, and draw the time series diagram (as shown in Figure 2-37).
Figure 2‑36. Time series query results
Figure 2‑37. Results of temporal variation of selected point
Line time series analysis: Click “draw line(s) on screen,” and mouse click on the image several times and double-click to end; then, the system returns a line sequence diagram (Figure 2-38). The user can also click the “import” button to import the .txt file containing the longitude and latitude coordinates of the point, and corresponding values along the selected line (the format is shown in Figure 2-39). The plots can show wither spatial average, or temporal average, along a selected line.
1) Spatial average along a selected line. The x-axis is the sequence number of each grid point on the polygonal line relative to the starting point, and the y-axis is the time average results in the statistical sequence (as shown in Figure 2-40).
2) Temporal average along a selected line. The x-axis is the time series, and the y-axis is the average value of all grid points on the polygonal line (Figure 2- 41).
The statistical mean, range and standard deviation can be set to display or not.
Figure 2‑38. The monthly average chlorophyll concentration in the Bay of Bengal in December 2005 obtained from the ESACCI data set with 4-km resolution. The white line represents the polygonal line for line time series analysis, which passes through the algal bloom area.
Figure 2‑39. File format for import
Polygon time series analysis: Click the "polygon" button, and click the image and double-click the end to dray a polygon (Figure 2-42), or click on the "import" button to import the .txt file containing the latitude and longitude coordinates of the polygon points (as shown in Figure 2-39). The software will, in turn, output the selected time series data of the user-defined polygon area, and the basic statistical information of the grid points contained in the polygon region will be plotted as time series (Figure 2-43). The statistical mean, range and standard deviation can be set to display or not.
For the above time series result plot, users can click the X/Y axis to adjust the minimum value, maximum value, primary number, and secondary number of coordinate axis to redraw the plot (Figure 2-44). The results can be saved to the local directory in image and text format through the “export plot” or “export data” buttons.
Figure 2‑44. Adjust X/Y axis
2.4.5.2 Animation
After clicking the "image animation" button, the image animation dialog box will pop up, and the product query results will appear (as shown in Figure 2-45)
.
Figure 2‑45. Query results dialog
Click the "OK" button, and the products queried will be loaded into the 3D geosphere in the form of layers. After all products are loaded successfully, the animation play panel will pop up. During playback, click the pause (or stop) button to pause (or stop) the current animation. An animation is shown in Figure 2-46.
Figure 2‑46. Product time continuous animation
Wind field dynamic simulation: Click "vector data" button to pop up the ocean wind field visual dialog box (as shown in Figure 2-47).
Figure 2‑47. Ocean wind field dialog box
Users can select the corresponding conditions, such as “product level,” “product,” and “time range” for product query and selection, and then set animation parameters (Figure 2-48). The result is shown in Figure 2-49.
Figure 2‑48. Determine animation display speed
Figure 2‑49. Wind animation
