Earth Observations and Statistics: Unlocking Sociodemographic Knowledge through the Power of Satellite Images

North Korea's COVID-19 policy dilemma: epidemic prevention conflicting with trade

BACKGROUND

Amidst the COVID-19 pandemic, striking a delicate balance between sustaining economic activity and safeguarding public health has become a crucial concern. The border closures for COVID-19 prevention have further intensified concerns for North Korea, which conducts over 90% of its trade with China and Russia, countries sharing its borders.

METHODS

This study aims to scrutinize North Korea's response to these competing imperatives by examining the impact of border closures on the country's trade dynamics with China and Russia. This study employed the difference-in-difference (DID) method to analyze transformations in North Korea's economic activity before and after the border closures, utilizing trade data and nighttime satellite imagery captured in 2019 and 2020.

RESULTS

The results reveal that North Korea actively reoriented its trade priorities towards Russia and accorded precedence to its epidemic prevention system over its economy during the pandemic. A noticeable increase in imports of food and pharmaceuticals was observed, indicating a significant rise in the inflow of these essential commodities.

CONCLUSION

The findings of this study suggest that during the early stages of the COVID-19 pandemic, North Korea placed significant policy emphasis on preserving public health. However, due to economic hardships and food shortages, if the pandemic persists in the long term, it indicates the possibility of partial or complete lifting of border closures to mitigate these challenges.

Assessment of the Mechanisms of Summer Thermal Environment of Waterfront Space in China’s Cold Regions

Water is an essential part of the urban ecosystem and plays a vital role in alleviating urban heat island (UHI) problems. The contribution toward UHI mitigation made by bodies of water needs to be ascertained to establish waterfront thermal environment construction standards. In this study, the thermal environment of the waterfront space of Tianjin in the cold regions of China was the research object. Through a survey including 141 valid questionnaires and the field measurement of four typical waterfront spaces in Tianjin, the thermal demand characteristics of recreational use for the waterfront environment and the influence of water on microclimate are discussed, supplemented by results from low-altitude infrared remote sensing technology, which was mainly used to obtain a wider range of infrared thermal images with higher accuracy. To improve the urban heat island effect and the quality of the ecological environment, this paper used outdoor thermal environment simulation software to quantitatively analyze the thermal environmental impact of outdoor public activity spaces around the representative urban body of water and proposes the optimization scheme of the waterfront space’s thermal environment. The results show that, based on the factors of water itself, the most economical water width was 70–80 m, and the cooling effect intensity of water had an essential correlation with the distance between the measured site and the water center. In terms of the environmental factors around the water, when the green lawn of the waterfront space was 12 m and the water shore’s geometric form was S-shaped, this could improve the cooling effect of water significantly. Waterfront activity spaces should focus on thermal comfort on the east and south water shores. It is expected that this study could provide practical implications and useful guidance for the planning and design of urban waterfront space in China’s cold regions.

6+: A Novel Approach for Building Extraction from a Medium Resolution Multi-Spectral Satellite

For smart, sustainable cities and urban planning, building extraction through satellite images becomes a crucial activity. It is challenging in the medium spatial resolution. This work proposes a novel methodology named ‘6+’ for improving building extraction in 10 m medium spatial resolution multispectral satellite images. Data resources used are Sentinel-2A satellite images and OpenStreetMap (OSM). The proposed methodology merges the available high-resolution bands, super-resolved Short-Wave InfraRed (SWIR) bands, and an Enhanced Normalized Difference Impervious Surface Index (ENDISI) built-up index-based image to produce enhanced multispectral satellite images that contain additional information on impervious surfaces for improving building extraction results. The proposed methodology produces a novel building extraction dataset named ‘6+’. Another dataset named ‘6 band’ is also prepared for comparison by merging super-resolved bands 11 and 12 along with all the highest spatial resolution bands. The building ground truths are prepared using OSM shapefiles. The models specific for extracting buildings, i.e., BRRNet, JointNet, SegUnet, Dilated-ResUnet, and other Unet based encoder-decoder models with a backbone of various state-of-art image segmentation algorithms, are applied on both datasets. The comparative analyses of all models applied to the ‘6+’ dataset achieve a better performance in terms of F1-Score and Intersection over Union (IoU) than the ‘6 band’ dataset.