Surface soil temperatures of various land cover types within the Chianan Plain, southern Taiwan

Abstract

Surface Soil Temperature (SST) is defined as the near-surface temperature of the ground that consists of the upper boundary of the subsurface temperature-depth curve. SST is an important parameter for understanding subsurface heat transfer and effects of climate change. However, to date, no studies have focused on SST, land use surrounding monitoring wells, and temperature-depth profiles within the Chianan Plain, southern Taiwan. Values for Measured Surface Soil Temperature (MSST) were in a range of 23.8 to 28.3°C, higher than average annual air temperatures that ranged from 23.9 to 25.2°C within the Chianan Plain. Values of Present Surface Soil Temperature (PSST), which represent a long-term average, were 24.2 to 28.1°C, as determined from temperature-depth profiles. Temperature of various land cover types were 24.9, 25.6, 25.6, 26.5, and 28.8°C for crops, trees, buildings, fish ponds, and bare soils, respectively. Temperatures for trees were lower than average while temperatures for bare soil without shielding were higher. Values of SST change displayed a warming trend with a maximum value of 4.11°C and 82% of sites fell into the range from 0 to 3°C. The change in annual average air temperature due to global warming was 1 to 2°C from 1901 to 2015. Causes for SST changes larger than 2°C should be attributed to land cover change in addition to global warming. This study provides the first basic dataset for MSST and temperature-depth profiles within the Chianan Plain. The data provided can be used as a base line for future studies of climate change, groundwater and subsurface temperature changes.