**2. Data Processing and Calibration**

*2.1. Remote Sensing Image Processing*

In the haze spatial evolution, the haze in the immediate vicinity will be highly correlated to the appropriate length of time. In order to analyze the temporal and spatial

evolution characteristics of haze, the input of the model needs to involve different regions. Therefore, we chose Beijing as the research object according to the administrative division. Beijing is the capital of China and has severe haze pollution [28]. There are 36 air pollutant monitoring stations relatively evenly distributed in different parts of Beijing, which provide us with historical haze concentration data for different regions [1]. Based on the available data from the ground stations, the time span is chosen as 2013 to 2015.

In this paper, we collect two types of dataset:


We preprocess the remote sensing satellite images in Beijing to improve the model's classification prediction accuracy and data consistency. We use ENVI 5.0 software (L3Harris Geospatial, Boulder, CO, USA) to process satellite images: radiation correction, geometric correction, area extraction and synthesis, RGB image synthesis, and image cutting.


After the synthesized RGB satellite image Figure 1b is cut, Figure 1c contains nine blocks of the same size, and we sort them from left to right and from top to bottom in Block 1 to Block 9. The administrative divisions contained in different blocks are shown in Table 2.

**Figure 1.** (**a**) is the satellite image with full channel information, and (**b**) is the synthesized RGB image. (**c**) is cut into nine equally sized blocks based on (**b**).

**Table 1.** Spatial resolution and wavelength interval of each channel in MOD021KM.



