# Spatialization and Analysis of China's GDP Based on NPP/VIIRS Data from 2013 to 2023
## 5 Discussion
### Dynamic Analysis of GDP Spatial and Temporal Changes
#### 5.2.2 Differences in Economic Development of Major Urban Agglomerations  
The major urban agglomerations in mainland China include the Beijing-Tianjin-Hebei, Yangtze River Delta, and Pearl River Delta urban agglomerations, as shown in Figure 7, which are economically developed regions. The Beijing-Tianjin-Hebei urban agglomeration includes Beijing, Tianjin, the entire territory of Hebei, and Anyang City in Henan Province. The Yangtze River Delta urban agglomeration includes 27 prefecture-level cities in Shanghai, Jiangsu, Zhejiang, and Anhui. The Pearl River Delta urban agglomeration includes Guangzhou, Foshan, Zhaoqing, Shenzhen, Dongguan, Huizhou, Zhuhai, Zhongshan, and Jiangmen City in Guangdong Province, and is the smallest of the three urban agglomerations. By calculating the GDP data of the three major urban agglomerations in 2013 and 2023, and obtaining the official GDP data, and comparing them, we obtain Table 7. From the official data, the GDP of the Yangtze River Delta urban agglomeration grew the fastest, with a growth rate of 67.95%; from the NTL data, the GDP growth rate of the Beijing-Tianjin-Hebei urban agglomeration was 1.49% faster than that of the Yangtze River Delta. The Beijing-Tianjin-Hebei urban agglomeration and the Yangtze River Delta urban agglomeration have a large area of more than 200,000 square kilometers, while the Pearl River Delta urban agglomeration covers an area of only 56,000 square kilometers. From the perspective of the unit area, the official GDP of the Pearl River Delta urban agglomeration in 2023 is about 1967.857 billion yuan; the GDP calculated by NTL is about 1565.368 billion yuan; and the GDP of the Beijing-Tianjin-Hebei urban agglomeration is about one-quarter of that \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**GDP/Million Yuan** & **0–5** & **5–10** & **10–50** & **50–100** & **>100** \\ \hline
2013 & 95.34\% & 1.88\% & 2.12\% & 0.50\% & 0.16\% \\
2015 & 95.87\% & 1.59\% & 1.84\% & 0.44\% & 0.26\% \\
2018 & 95.34\% & 1.86\% & 2.02\% & 0.50\% & 0.27\% \\
2021 & 94.25\% & 2.39\% & 2.40\% & 0.60\% & 0.35\% \\
2023 & 94.80\% & 2.12\% & 2.18\% & 0.49\% & 0.42\% \\ \hline \hline \end{tabular}
\end{table} 
Table 6: The proportion of GDP in different levels. Figure 7: GDP of the three major urban agglomerations in 2023.  
of the Pearl River Delta urban agglomeration. The GDP per unit area of the Pearl River Delta urban agglomeration is the highest among the three urban agglomerations, and its economic activities are the most active. Overall, over the past 11 years, the official GDP growth rate has been 11.57% faster than the GDP under NTL. The RE of the total GDP in 2023 is \(-\)0.13, which is within the controllable range. From the overall changes in the high-value-GDP areas (GDP greater than 100 million), between 2013 and 2023, the Beijing-Tianjin-Hebei urban agglomeration added 3557.43 km\({}^{2}\), the Yangtze River Delta urban agglomeration added 9381.65 km\({}^{2}\), and the Pearl River Delta urban agglomeration added 4191.24 km\({}^{2}\). From the expansion rate of the high-value-GDP areas, the Yangtze River Delta region has the fastest expansion rate, which is 852.88 km\({}^{2}\)/a; and the Beijing-Tianjin-Hebei region has the slowest expansion rate, which is 323.40 km\({}^{2}\)/a. From the expansion rate per unit area of the high-value-GDP areas, the Pearl River Delta region has the fastest expansion rate, which is about 4.8 times that of the Beijing-Tianjin-Hebei region and 1.8 times that of the Yangtze River Delta region. From the geographical location analysis, the Pearl River Delta region is close to Hong Kong and Macao, and has excellent ports, and foreign trade industry development and prosperity, and, thus, the fastest development rate. The Yangtze Delta, with Shanghai as the center, is located in the plain area, through the Yangtze River; the transport industry is developed, and the industrial characteristics of each city are obvious; the industry is complete, and the development of urban groups is good.