## 1 Introduction  
The development of technology in earth observation, ground monitoring, deep detection, and social network and mobile voluntary data collection has boosted the approaches to obtain geospatial data. Rich geospatial data can better support research on natural resources, ecological environment change and its sustainable development, and national strategic decision-making [1]. To promote the acquisition and wide use of geospatial data, a large number of geospatial data are available to the public through portals or websites online by government departments, research institutions, or enterprises [2; 3]. Geospatial data portals or websites (hereafter referred to as geospatial data sharing website, GDSW) refer to the human-to-machine interface performing as a single point-of-access to geospatial data. It is the bridge between geospatial data providers and users, and typically employed as a web-based graphical user interface (GUI) equipped with functionalities for accessing geospatial data [4; 5]. At present, the main approach to sharing geospatial data on the web is to access GDSW directly [6; 7; 8], such as NASA's Earth Observing System Data and Information System (EOSDIS), Global Change Master Directory (GCMD, [[http://gcmd.nasa.gov](http://gcmd.nasa.gov)]([http://gcmd.nasa.gov](http://gcmd.nasa.gov)), last accessed: 15 September 2021), and Global Land Analysis & Discovery (GLAD, [[https://glad.umd.edu/dataset](https://glad.umd.edu/dataset)]([https://glad.umd.edu/dataset](https://glad.umd.edu/dataset)), last accessed: 15 September 2021) [9]. However, users are currently limited to using datasets provided by data websites they are familiar with instead of the ones that are more suitable for their requirements [9; 10; 11]. The main reason is that, so far, no websites have been found to provide a comprehensive index of all geospatial data [11]. Although there are integrated data websites, such as the Global Change Master Directory (GCMD), the data provided by these are not enough, because the data on this website mainly come from various departments of National Aeronautics and Space Administration (NASA), and there are other websites that contain a lot of geospatial data. Additionally, the current GDSWs hosted by different organizations have various forms of data release--for example, they are published based on different standards--which leads to the isolated existence of GDSW on the web, thus bringing great challenges for users to discover geospatial data for research and decision support applications [12; 13]. Therefore, the precise discovery of GDSWs is the foundation and prerequisite for precisely mining and utilizing open geospatial data, which can greatly save scientists' time in finding geospatial data, bring great convenience to researchers and related personnel, and effectively improve the utilization of geospatial data. There are two types of GDSW: one is based on the open geospatial consortium (Inc., OGC), that is, an open-standard data website [14], and the other one is non-open-standard [15], which does not depend on OGC standard when publishing geospatial data. According to the published GDSW based on the OGC standard, whether the website is a geospatial data website can be evaluated by sending a specific request (see [16] for details). Although the open-standard website can identify geospatial data websites precisely and quickly using a simple method, it cannot find data websites that are not published based on OGC standards. There are a large number of non-standard geospatial data websites in the network [8], which illustrates that the method is incomplete in identifying GDSW. For non-open-standard websites, users search through keywords, and search engines use precise or fuzzy matching to search the whole network and return a series of results [17], and then identify whether there are GDSWs in the results one by one.