Statistical modeling for forecasting land surface temperature increase in Taiwan from 2000 to 2023 using three knots cubic spline

Taiwan is highly mountainous, making it the world's fourth-highest island. The main island is distinguished by the contrast between its eastern two-thirds, which consist primarily of rough forest-covered mountains. Taiwan's climate is influenced by the east Asian monsoon, whereas regions of central and southern Taiwan have a tropical monsoon climate. Climate change is causing the monsoon to become increasingly irregular, unreliable, and even deadly, with more severe rainfall and worsening dry spells. Land surface temperature (LST) is an essential parameter because the warmth rising off Earth’s landscapes influences our world’s weather and climate patterns. Therefore, the objectives of this study are: (i) to investigate the daytime LST annual seasonal patterns and trends, and (ii) to forecast LST increase in sub-regions and regions in Taiwan. The data used in this study was time series data of daytime LST from 2000 to 2023 from the moderate resolution imaging spectroradiometer (MODIS) website. The natural cubic spline method with eight knots was used to investigate the annual seasonal patterns of daytime LST. The linear regression model was applied to model the LST trends, and a cubic spline with 2, 3, and 4 knots was then applied to forecast LST trends over 23 years. Moreover, the multivariate regression model was used to adjust the spatial correlation and to evaluate the increase in daytime LST. The results demonstrate that daytime LST in Taiwan has increased on average by 0.151 °C per decade. Most of the daytime LST by sub-regions had a consistent increase. Furthermore, daytime LST in all regions had increasing trends. Using three knots of cubic spline to forecast daytime LST trends illustrates the significant increase trends compared with other spline knots. In conclusion, daytime LST in Taiwan is gradually increasing and the reasons for these trends toward daytime LST need to be explored in future studies.