Background Under the dual carbon goals framework, the demand for clean energy continues to grow significantly. China has become the world’s largest photovoltaic (PV) production base and application market. However, the construction of large-scale PV power field may exert specific impacts on the thermal environment of both the immediate and surrounding areas. Land surface temperature (LST) serves as a crucial indicator for evaluating PV power fields’ environmental impacts. This study therefore focuses on the " Junma Power Field ", the world’s largest photovoltaic power field featuring a panel array pattern, to systematically assess LST variations before and after its construction.

Methods The study is based on the Google Earth Engine platform. Landsat 8 images with cloud cover < 5% were acquired for the study area during three periods: before construction (January-June 2017 and 2018), under construction (July-December 2018), and after construction (2019 – 2023). The obtained images were processed through screening, cloud removal, radiometric and atmospheric correction, clipping, and mosaicking on the platform. LST was then retrieved using the statistical mono-window. Centered on the photovoltaic power fields, buffer zones were created at 100 m intervals to delineate 10 potential impact zones within a 1 km radius around the power field.

Results 1) After the completion of the photovoltaic power field, the average LST within the field was significantly lower than that of the buffer zone, resulting in a distinct "cold island" effect, with a cooling range of 0.28°C – 2.82°C. The cooling effect was notably more pronounced compared to areas outside the buffer zone. 2) Before and during the construction of the photovoltaic power field, there was little difference in LST between the buffer zones. However, after the field’s completion, the LST within the buffer zone became significantly lower than in areas unaffected by the photovoltaic power field, with a maximum decrease of 0.331°C. The closer the buffer zone was to the photovoltaic field, the more apparent the temperature difference. The influence of the photovoltaic power field on surrounding LST was primarily concentrated within a 200-meter radius of the field. 3) In winter, the "cold island" effect of the photovoltaic field was most pronounced, with a cooling range of 1.91°C, followed by summer and autumn. The effect was least noticeable in spring.

Conclusions The findings of this study hold significant theoretical and practical value for sand control, desertification prevention, and ecosystem restoration in photovoltaic power stations and their surrounding areas within desert and Gobi regions impacted by human activities.