Einara Zahn

Abstract Plants assimilate carbon through photosynthesis (gross primary productivity, GPP) while losing water via transpiration (Trans), with both processes responding nonlinearly to temperature. Although the air temperature optimum of GPP (\({T}_{\mathrm{opt}}^{\mathrm{GPP}}\)) is well studied, the thermal response of Trans (\({T}_{\mathrm{opt}}^{\mathrm{Trans}}\)) remains unknown.

1 Introduction Climate change has resulted in an increased frequency, intensity, and duration of heatwave events (Baldwin et al., 2019; Perkins-Kirkpatrick & Lewis, 2020), significantly altering regional hydrological cycle and energy balance (Teuling et al., 2010). Heatwave events can generate extreme surface temperatures, which can significantly disrupt ecosystem functioning (Albright et al., 2011).

2.3.1. Temperature Separation This study uses the normalized difference vegetation index (NDVI) as an indicator to separate the total surface radiometric temperature, gridded at 3.6 m resolution, into representative canopy and soil temperature grids at 3.6 m resolution. This method is based on work from prior studies [,,,,,]. In this study, we also included a framework to remove shadow effects in the temperature partitioning process (). The removal process is divided into 4 steps.