Cooling Effect of Paddy on Land Surface Temperature in Cold China Based on MODIS Data: A Case Study in Northern Sanjiang Plain

Abstract

Fast-growing crops have been evolved in North China, accompanied by intense paddy expansion, leading to dramatic impacts on the agricultural environment. Among these environmental issues, the impact of paddy expansion on land surface temperature is still unclear. In the present study, based on Landsat images and MODIS land surface temperature (LST) products, the crop pattern and monthly LST in the northern Sanjiang Plain are obtained. A 1 km scale grid unit is built to investigate the relationship between LST and paddy expansion. The results obtained from the study are as follows. Firstly, for crop patterns, cropland planting is given priority to paddy fields, accompanied by an aggregated pattern, while upland crops present a discrete pattern. Secondly, for LST changes during the growing season, the maximum LST occurs in June, and the lowest values occur in October across the whole region. In addition, the LST of paddy fields is lower compared with that of upland crops for the whole growing season. Thirdly, at the 1 km grid scale, the relationship between monthly LST and paddy field ratio is significantly negative, and better represented by a cubic function rather than a linear fit. Finally, LST decreases with the increased fraction of the rice paddy area more rapidly when rice paddy is aggregated and accounted for by more than 80% of each study grid. The findings of this study are important to guide agricultural production and to better understand the environmental effects of paddy expansion in cold regions.

Identification of Shift in Sowing and Harvesting Dates of Rice Crop (L. Oryza sativa) through Remote Sensing Techniques: A Case Study of Larkana District

“…The correlation coefficient we have found in the different months was stronger as compared to the reported results of Siyal et al [23] and relatively weaker as compared to Guoming et al [19]. Guoming et al [20] reported that the correlation coefficient between paddy rice and LST was stronger (greater than 95%)-except for August, as compared to our study (less than 90%). The reason for this difference in statistical correlation between Guoming's findings and our study is probably due to study area features.…”

“…The logarithmic functional relationship between these two variables has the highest correlation coefficient (R 2 = 0.7318), as compared to the linear relationship (R 2 = 0.7119). Different studies also had similar findings [20,22,23]. It shows that the more vegetative growth on the land, the lower will the LST be, and vice versa.…”

“…For example, irrigated agriculture impacted the range of diurnal air temperature [19]. Guoming et al [20] studied the relationship between LST and paddy rice expansion. They found that LST decreases with the increased fraction of the rice paddy area more rapidly when the rice paddy is aggregated and accounted for by more than 80% of each study grid.…”

Spatiotemporal variation in rice evapotranspiration under the influence of rice expansion: a case study in the Sanjiang Plain, Northeast China

“…Li et al, 2020 ;Fu et al, 2016 ;Dong et al, 2015 ). Some studies have also considered the cooling effect of rice field expansion on local surface temperature (T. Liu et al, 2018 ;Huang et al, 2022 ;G. Du et al, 2019 ).…”

Heat-Mitigation Effects of Irrigated Rice-Paddy Fields Under Changing Atmospheric Carbon Dioxide Based on a Coupled Atmosphere and Crop Energy-Balance Model

“…The heat-mitigation effect of irrigated crop fields has been recognized for a long time (Holmes 1970). In response to ongoing climate changes, an interest has emerged regarding whether and how this effect enhances or mitigates environmental changes (Dong et al 2016;Nocco et al 2019;Du et al 2019;Yang et al 2020). In particular, rice paddies comprise the typical landscapes in many parts of eastern Asia, and their role in heat mitigation may be of interest.…”