# Comprehensive Effects of Atmosphere and Soil Drying on
## 2 Materials and Methods  
### Data  
The FLUXNET2015 dataset ([[http://fluxnet.fluxdata.org/data/Fluxnet2015](http://fluxnet.fluxdata.org/data/Fluxnet2015) dataset/]([http://fluxnet.fluxdata.org/data/Fluxnet2015](http://fluxnet.fluxdata.org/data/Fluxnet2015) dataset/), accessed on 16 June 2020) is a global dataset of eddy covariance flux measurements, which are used to estimate the exchange of carbon dioxide, water vapor, and energy between the terrestrial ecosystem and the atmosphere. Hourly and half-hourly eddy covariance measure-related fluxes and meteorological data were selected for the study. The FLUXNET2015 dataset categorizes plant functional types (PFTs) into broad groups based on their growth form and ecological characteristics, such as forests, grasslands, croplands, wetlands etc.  
The selected data from all the stations of fluxnet2015 Tier1 meet the requirement that they have continuously available data for at least three years, and the meteorological indicators include temperature (ta), precipitation (P), vapor pressure difference (VPD), soil water content (SWC), wind speed (WS), friction velocity (USTAR), soil heat flux (G), latent heat flux (LE), sensible heat flux (H), net radiation (Rn), gross primary productivity (GPP), and ecosystem respiration (RECO) [33; 34]. The location and information of the stations are shown in Figure 1 and Table S1. FLUXNET data are observed and quality-controlled according to unified standards, including friction velocity filtering and missing measured value filling. Finally, 36 sites from around the world were selected, which cover five plant functional types (PFTs), namely crops (CRO, station 9), deciduous broad-leaved forest (DBF, station 5), evergreen coniferous forest (ENF, station 6), grassland (GRA, station 10), and savanna (SAV, station 6).  
CRO typically refers to agricultural lands that are managed for crop production, such as row crops including corn, wheat, soybeans, and other cultivated lands. These areas are characterized by annual or seasonal vegetation that is typically managed through planting, harvesting, and other agricultural practices. DBF represents forests dominated by deciduous broad-leaved tree species, which are known for their seasonal leaf turnover. ENF represents forests dominated by evergreen coniferous tree species, such as pine, spruce, and fir. Evergreen coniferous forests are characterized by trees that retain their needles throughout the year, allowing them to photosynthesize and maintain their green color. GRA typically refers to ecosystems dominated by grasses as the main vegetation type, with little or no tree cover. They have important ecological roles, such as supporting grazing animals, carbon storage, and fire regimes. SAV typically refers to ecosystems that are characterized by a mix of grasses and trees, with an open canopy structure. Savannasplay important roles in biodiversity conservation, carbon storage, and the livelihoods of local communities.  
To ensure there are enough stations for each type, a number of stations with limited observation time spans did not pass the quality check. Thus, plant functional types including evergreen broad-leaved forest (EBF), mixed forest (MF), and shrub (CSH) are not considered in this study, while wetland (WET) is also excluded due to the lack of measurement of soil heat flux.