This data set including:
1) Gap-filled daily data of CH4 flux of HW, LW and CK in 2019−2020;
2) Gap-filled daily data of soil temperature and moisture at all depths for HW, LW and CK treatments;
3) Annual data of soil properties at 0−10 cm soil depth and CH4 uptake for HW, LW and CK treatments ;
4) Gap-filled daily soil temprature at 5 cm depth from 2016 to 2021 for HW, LW and CK treatments.


Ecosystem methane flux, and soil moisture and soil temperature at 5 cm, 15 cm, 30 cm soil depths were observed for an entire F-T cycle from June 2019 to June 2020 in a typical alpine meadow on the Qinghai- Tibetan Plateau (QTP), where a long-term warming experiment was established in 2014. Soil temperature and VWC at all three depths from June 2019 to June 2020 were analysed and used in this study, and soil temperature at 5 cm depth from June 2016 to June 2021 was included in the supplemental materials to support the results. Precipitation was recorded at 30-min intervals by the Hongyuan county weather station. The warming experiment included three treatments: ambient temperature (CK), low-level warming (LW, +2.4℃ at 5 cm soil depth), and high-level warming (HW, +4.5℃ at 5 cm soil depth). The measurement intervals between treatments were 5−20 mins and all data were daily averaged for data analysis in the paper. Methane uptake was gap-filled by using a random forest algorithm in R. 

Soil F-T cycle for each plot of all treatments were divided into the following stages: thawed, freezing, frozen, and thawing (Figure 1d) according to the definitions used in previous studies (Zona et al., 2016; Taylor et al., 2018; Arndt et al., 2019, Bao et al., 2021). Specifically, the thawed stage was when daily mean soil temperature at 5 cm depth (daily mean T_soil at 5 cm) was > 0.75℃ for at least five consecutive days. The frozen stage was when daily mean T_soil at 5 cm was < −0.75℃ for at least five consecutive days. The freezing and thawing stages were defined as freezing-frozen and frozen-thawing transition periods, respectively, when daily mean T_soil at 5 cm was between −0.75℃ and 0.75℃ (Figures 1b, d and Table S1). According to these F-T stages, all of which occurred in the control plots, we divided our measurements into four seasons: autumn freeze (Saf), frozen winter (Sfw), spring thaw (Sst), and warm season (WS). The cold season (CS) included autumn freeze, frozen winter, and spring thaw.

Mineral soil samples were obtained from depths of 0−10 cm, 10−20 cm, and 20−40 cm from each plot in August 2020 for soil chemical and microbial analyses including soil pH, available phosphorus (AP), soil total carbon (TC) and nitrogen (TN) contents, soil microbial biomass carbon (MBC) and nitrogen (MBN) and methanotrophs abundance.
