The dataset of eddy covariance observations was obtained at the A'rou freeze/thaw observation station from Jul. 14, 2008 to Dec. 31, 2010, in Wawangtan pasture (E100°28′/N38°03′, 3032.8m), Daban, A'rou. The experimental area with a flat and open terrain slightly sloping from southeast to northwest and hills and mountains stretching outwards is an ideal horizontal homogeneous underlying surface. The original observation items included the latitudinal wind speed Ux (m/s), the latitudinal wind speed Uy (m/s), the longitudinal wind speed Uz (m/s), the ultrasonic temperature Ts (°C), co2 consistency (mg/m^3), h2o consistency (g/m^3), air pressure (KPa) and the abnormal ultrasonic signal (diag_csat). The instrument height was 2.81m, the ultrasound direction was at an azimuth angle of 0°, the distance between Li7500 and CSAT3 was 30m and sampling frequency was 10HZ/s. The instrument mount was 3.15m, the ultrasound direction was at an azimuth angle of 86°, the distance between Li7500 and CSAT3 was 22cm and sampling frequency was 10HZ/s. The dataset was released at three levels: Level0 were the raw data acquired by instruments; Level1, including the sensible heat flux (Hs), the latent heat flux (LE_wpl), and co2 flux (Fc_wpl), were real-time eddy covariance output data and stored in .csv month by month; Level2 were processed data in a 30-minute cycle after outliers elimination, coordinates rotation, frequency response correction, WPL correction and initial quality control. The data were named as follows: station name +data level+data acquisition date. As for detailed information, please refer to Meteorological and Hydrological Flux Data Guide and Eddy Covariance Observation Manual.

The dataset of BRDF observations was obtained in the Linze station foci experimental area from May 25 to Jul. 11, 2008. Spectrum of the maize field quadrate and desert scrub quadrate in Wulidun farmland (May 25, 28, 30, Jun. 29 and Jul. 11), the desert transit zone strip (May 28 and 30) and Linze station quadrates (Jun. 25, 30 and Jul. 9) was measured by ASD Spectroradiometer (350～2 500 nm) from BNU, the reference board (40% before Jun. 15 and 20% hereafter), two observation platforms of BNU make and one of Institute of Remote Sensing Applications make. Raw spectral data were archived as binary files, which were recorded daily in detail, and pre-processed data on reflectance and transmittivity were archived as text files (.txt). See the metadata record “WATER: Dataset of setting of the sampling plots and stripes in the Linze station foci experimental area” for more information of the quadrate locations.

The dataset of intensive rain gauges observations was obtained in the arid region hydrology experiment area, in cooperation with dual polarized doppler radar observations. There was no single dataset for the upper stream observations for the poor quality; the middle stream dataset was collected by 29 RG3-M self-recording rain gauges: the northernmost (100.36°E, 39.16°N), the southernmost (100.34°E, 38.61°N), the easternmost (100.62°E, 38.87°N), and the westernmost (100.26°E, 38.82°N). Rain gauges R02-R09 measured from May 18 to Oct. 9, 2008, and R10-R30 from May 26 to Oct. 9, 2008. The technique criterions of these rain gauges were : (1) caliber: 165mm×254mm (2) the temperature range: 0°C —+70°C (3) resolution: 0.2mm (4) the measuring range: 0—320cm (5) the measuring accuracy: 1%

The data set include crop biomass observed at four sample regions, that is the soil moisture control experimental field at Daman county, and the EC plots, the super station, and Shiqiao sample plots at Wuxing village in Zhangye city. 1) Objective Crop biomass, a key biophysical parameter, was observed for calibration and validation of crop growth model and the retrieval of other biophysical parameters as well as the application in eco-hydrological models. 2) Measurement instrument: Electronic balance (±0.1g) and oven. 3) Measurement site a. the soil moisture control experimental field at Daman county, Twelve soil water treatments are set. The wheat biomass for each treatment is measured on 17, 23 and 29 May, and 3, 9, 14 and 24 June, and 5 and 12 July. b. the EC site Maize biomass at 14 EC site (EC-2,EC-3,EC-5,EC-6,EC-7,EC-8,EC-9, EC-10, EC-11, EC-12, EC-13, EC-14, EC-15, EC-16) are measured on 14, 21, 25 and 31 May, 7, 13, 23 and 28 June, 3, 13, 18 and 23 July, 3, 12 and 28 August. c. the super station Maize biomass at the super station is measured on 22 and 28 May, 5, 11, 18, and 25 June, and 1, 8, 15, 22 and 31 July, 9, 15 and 22 August, and 3 and 11 September. d. the Shiqiao sample site Maize biomass at the Shiqiao village is measured on 17, 22 and 28 May, 4, 11, 17 and 25 June, 1, 8, 15, 22, and 30 July, 8, 16 and 27 August, and 9 September. 4) Data processing The observational data was recorded in the sheets and reorganized in the EXCEL sheets.

The dataset of ground truth measurements for snow synchronizing with MODIS was obtained in the Binggou watershed foci experimental area on Mar. 14, 2008. Those provide reliable data for snow-cover extent mapping and the retrieval of the snow surface temperature from MODIS remote sensing approaches. Observation items included: (1) Snow parameters including the snow surface temperature, the snow-soil interface temperature, the land surface (ground surface) temperature by the handheld infrared thermometer, the snow layer temperature by the probe thermometer, snow depth by the ruler, snow density by the snow shovel, the snow grain size by the handheld microscope and the snow surface temperature synchronizing with MODIS. (2) Snow albedo by the total radiometer in BG-A from 11:10-13:24 on Mar. 14, 2008. (3) The snow spectrum by the portable ASD (Xinjiang Meteorological Administration) synchronizing with MODIS in BG-A and BG-I. Two files including raw data and the preprocessed data were archived.

The dataset of canopy structure and biophysical parameter measurements was obtained in the Linze grassland foci experimental area. Detailed information was as follows: {| !Observation item !observation time !plot |- | The leaf angle || 2008-06-24 || E |- | The leaf angle || 2008-06-29 || A E |- | Vegetation biomass || 2008-06-18 || A D E |- | Vegetation biomass || 2008-06-24 || A E |- | Vegetation biomass || 2008-06-29 || A E |- | Plant height || 2008-05-26 || A D E |- | Plant height || 2008-06-14 || B |- | LAI || 2008-05-28 || E |- | LAI || 2008-06-05 || E |- | LAI || 2008-06-06 || A |- | LAI || 2008-06-11 || A |- | LAI || 2008-06-18 || D E |- | Coverage || 2008-5-27 || subplots (30m) in A, D and E |- | Coverage || 2008-5-26、27 || plots (360m) in D and E |- | Coverage || 2008-6-14 || plots (360m) in B |- |} Data were archived in Excel and txt file. See WATER: Dataset of setting of the sampling plots and stripes in the foci experimental area of Linze station for more information.

The dataset of airborne Polarimetric L-band Multibeam Radiometers (PLMR) was acquired on 10 July, 2012, located in the middle reaches of the Heihe River Basin. The aircraft took off at 10:30 am (UTC+8) from Zhangye airport and landed at 15:30 pm, with the flight time of 5 hours. The flight was performed in the altitude of about 2500 m and at the speed of about 220-250 km during the observation, corresponding to an expected ground resolution of about 750 m. The PLMR instrument flown on a small aircraft operates at 1.413 GHz (L-band), with both H- and V-polarizations at incidence angles of ±7.5°, ±21.5° and ±38.5°. PLMR ‘warm’ and ‘cold’ calibrations were performed before and after each flight. The processed PLMR data include 2 DAT files (v-pol and h-pol separately) and 1 KMZ file for each flying day. The DAT file contains all the TB values together with their corresponding beam ID, incidence angle, location, time stamp (in UTC) and other flight attitude information as per headings. The KMZ file shows the gridded 1-km TB values corrected to 38.5 degrees together with flight lines. Cautions should be taken when using these data, as the RFI contaminations are often higher than expected at v-polarization.

The dataset of ground truth measurement synchronizing with the airborne microwave radiometers (L&K bands) was obtained in the Biandukou foci experimental area from 11:20 to 12:30BJT on Mar. 19, 2008. Observation items included: (1) the frost depth by the chopstick and the ruler. The soil was considered frozen when it was hard and with ice crystal. The data can be opened by Microsoft Office Word. (2) the surface radiative temperature by the handheld infrared thermometer and the physical temperature by the thermocouple. The data can be opened by Microsoft Office Word. (3) the soil moisture (soil samples from 0-1cm, 1-3cm and 3-5cm) by the microwave drying method. The data can be opened by Microsoft Office Word. (4) photos of each sampling point in .jpg for further reference. Six data files were included, the ground-based K-band microwave radiometer, the ground-based L-band microwave radiometer, the frost depth, soil moisture, the surface temperature and the surface conditions.

The dataset of ground-based microwave scatterometer and ground truth observations for soil freeze/thaw cycle was obtained in No. 3 quadrate of the A'rou foci experimental area from 22:33 on Mar. 16 to 15:00 on 17, 2008. Observation items included the mean soil temperature from 0-5cm by the probe thermometer, the soil temperature at 5cm and 10cm by the glass geothermometer, the soil temperature, soil volumetric moisture, the loss tangent, soil conductivity, and the real part and the imaginary part of soil complex permittivity by the POGO soil sensor, and soil gravimetric moisture, volumetric moisture, and soil bulk density after drying by the cutting ring (100cm^3). Those provide reliable ground data for retrieval and validation of soil moisture and freeze/thaw status from active remote sensing approaches. Two files were included, the microwave scatterometer and ground truth observations; both were archived in Excel format.

The dataset of ground truth measurements synchronizing with Envisat ASAR was obtained in No. 1, 2 and 3 quadrates of the A'rou foci experimental area on Jul. 14, 2008. The Envisat ASAR data were in AP mode and VV/VH polarization combinations, and the overpass time was approximately at 11:31 BJT. The quadrates were divided into 4×4 subsites, with each one spanning a 30×30 m2 plot. Those provide reliable ground data for retrieval and validation of soil moisture from active remote sensing approaches. Observation items included: (1) soil moisture by POGO soil sensor in No. 1, 2 and 3 quadrates; 25 corner points of each subsite were chosen for the soil temperature, soil volumetric moisture, the loss tangent, soil conductivity, and the real part and the imaginary part of soil complex permittivity; (2) the soil temperature by the handheld infrared thermometer 3# and 5# from BNU in No. 1 quadrate, 1# and 4# in No. 2 quadrate, and 2# and 6# in No. 3 quadrate; 25 corner points of each subsite were measured twice by two groups, and time, the maximum, the minimum and the mean value, and the land cover types were all recorded. (3) spectrum of the grassland, the bare land and the stellera by the thermal infrared spectrometer, 102F. The dataset includes ASAR images, preprocessed data of the thermal infrared spectrometer, 102F, the surface temperature and soil moisture synchronizing with Envisat ASAR.

The dataset of surface roughness measurements was obtained in No. 1 and 2 quadrates of the Biandukou foci experimental area during the pre-observation period. Both the quadrates were divided into 3×3 subsites, with each one spanning a 30×30 m2 plot. The original photos of each sampling point, surface height standard deviation (cm) and correlation length (cm) were included. With the roughness grid board 110cm long and the measuring intervals of 1cm, the samples were collected along the soil surface from south to north and from east to west, respectively. The coordinates of sample points would be got with the help of ArcView; and after geometric correction, surface height standard deviation (cm) and correlation length (cm) could be acquired based on the formula listed on pages 234-236, Microwave Remote Sensing, Vol. II. The roughness data files were initialized by the sample name, which was followed by the serial number, the name of the file, standard deviation and correlation length. Each .txt file is matched with one sample photo and standard deviation and correlation length represent the roughness. In addition, the length of 101 needles is also included for further checking. Those provide reliable ground data for improving and verifying the microwave remote sensing algorithms.

The dataset of ground truth measurement synchronizing with MODIS was obtained in C1, G1 and B2 of the Biandukou foci experimental area on Mar. 12, 2008. Observation items included: (1) the surface temperature by the handheld infrared thermometer in C1, G1 and B2 from 11:30 to 12:15. The underlying surface was the deep plowed land, the rape stubble and the grassland. (2) the gravimetric soil moisture (soil samples from 0-1cm, 1-3cm, 3-5cm, 5-10cm and 10-20cm) by the microwave drying method. (3) the frost depth by the chopstick and the ruler. The soil was considered frozen when it was hard and with ice crystal. The land cover type photos were archived. Four data files were archived, MODIS data, C1 (the land cover type, the surface temperature and the vegetation parameters), G1 ( the surface temperature, the frost depth and the soil moisture) and B2 (the surface temperature, the frost depth and the soil moisture) data.