The dataset of snow density measurements was obtained in the Binggou watershed foci experimental area on Dec. 6 and Dec. 10, 2007 during the pre-observation period, to survey the snow layer and acquire the snow density for retrieval and modeling from remote sensing approaches. Observation items included: (1) Snow layer density: measured by snow shovel weighing method. Each 10cm was a unit. (2) Snow density, snow depth, snow temperature, snow-soil interface temperature, and snow grain size in BG-A. Measured were carried out in BG-A on Dec. 6, 2007, and in BG-B, BG-C and BG-D on Dec. 10, 2007. The dataset includes raw data and processed data plus GPS and calibration data for the snow shovel.

The dataset of ground truth measurement synchronizing with MODIS was obtained in the Linze grassland foci experimental area on Jun. 2, 2008. Measurements were carried out twice at intervals of 125m in four quadrates (2km×2km), which were H01-H08, H09-H16, H17-H24 and H25-H32 respectively. Simultaneous ground data were mainly the canopy temperature, the half-height temperature, the land surface radiative temperature and the soil temperature (0-5cm) by the probe thermometer. For soil moisture, the soil temperature, soil moisture, the loss tangent, soil conductivity, and the real part and the imaginary part of soil complex permittivity were acquired by the POGO soil sensor, and soil gravimetric moisture, volumetric moisture, and soil bulk density after drying by the cutting ring inNo.1 quadrats (H01-H08), No.2 (H09-H16) and No.3 (H17-H24); and in No.4 quadrat 4 (H25-H32), soil moisture, soil conductivity, the soil temperature, the real part of soil complex permittivity were acquired by WET, soil gravimetric moisture, volumetric moisture, and soil bulk density after drying by the cutting ring. Complementary measurements were carried out on Jun. 3, 2008. The soil temperature, soil moisture, the loss tangent, soil conductivity, the real part and the imaginary part of soil complex permittivity were acquired by the POGO soil sensor, and soil gravimetric moisture, volumetric moisture, and soil bulk density after drying by the cutting ring in H41-H48, H49-H56 and H57-H64; and in H33-H40, soil moisture, soil conductivity, the soil temperature, and the real part of soil complex permittivity were acquired by WET, soil gravimetric moisture, volumetric moisture, and soil bulk density after drying by the cutting ring. Data were archived in Excel format. See WATER: Dataset of setting of the sampling plots and stripes in the Linze station foci experimental area for more information.

The dataset of diurnal FPAR change observations was obtained by the quantum light meter (3415 series) in the Linze station foci experimental area. Each observation lasted from 9am to 5pm at intervals of 10 minutes, in the maize field and the sunflower field on Jun. 16, and in Wulidun farmland quadrates on Jul. 1, 2008. Located 15cm above the canopy, the quantum light meter was used to measure PARci and PARcr (at 0°, 30°, 45°, 60° and 90°); located 15cm above the ground, for PARgi and PARgr. And then PAR= (PARci- PARcr)- ( PARgi- PARgr); Fpar =PAR/ PARci. Data were archived as Excel files.

The dataset of ground truth measurement synchronizing with the airborne microwave radiometers (L&K bands) mission was obtained in the Biandukou foci experimental area on Jul. 4, 2008. Observation items included: (1) the soil temperature by the handheld infrared thermometer from L1 to L8 (1km from one another) in Biandukou and soil moisture by ML2X; nine samples were collected every 200 m along each line (1.6km). (2) 5 quadrates (50cm×50cm) investigations including GPS, the vegetation cover types and the height, the actual numbering, the valve bag numbering, wet weight+the refuse bag (g), dry weight+the envelope (g), the envelope (g) and the photo numbering. The data were archived as Excel files.

The dataset of diurnal FPAR change observations was obtained in the Yingke oasis foci experimental areas. Observation items included: (1) Maize canopy reflectance spectra by ASD and 50% grey board, leaf SPAD by the chlorophyll meter and leaf photosynthesis by LI-6400 in Yingke oasis maize field on Jul. 5, 2008 (fixed point observations from 10:00-20:00 at intervals of one hour, and half an hour from 16:00) Besides, Photo: photosynthetic rate (µmol CO2 m-2 s-1), Cond: stomatal conductance (mol H2O m-2 s-1), Ci: intercellular CO2 viscosity (µmol CO2 mol-1), Trmmol: transpiration rate (mmol H2O m-2 s-1), VpdL: vapor pressure deficiency of leaves (kPa), Tleaf: leaf temperature (°C), ParIn_µm: active radiation of interior photosynthesis (µmol m-2 s-1), and ParOutµm: active radiation of outdoor photosynthesis (µmol m-2 s-1) were all archived. (2) Maize canopy reflectance spectra, leaf photosynthesis and diurnal FPAR change by ASD (Institute of Remote Sensing Applications), 50% grey board (Institute of Remote Sensing Applications), LI-6400 (Institute of Remote Sensing Applications) and SUNSCAN (Beijing academy of Agriculture and Forestry Sciences). Based on calibration lamp data (serial number: 64831), radiance spectrum on Jul. 9 by 1050 spectrometer (Beijing academy of Agriculture and Forestry Sciences) and 50% grey board and 99% white board calibration data, the spectrum data were preprocessed. Calibration was undertaken in accordance with the following precedures: a) The original DN was converted into radiance and further into readable EXCEL format by the spectrometer-matched calibration lamp data and ASD. b) Solar radiance was got by 99% white board radiance. solar radiance=the reference board radiance/the reference board reflectance. c) Spectrum from Agriculture and Forestry Sciences was sampled at an interval of 1.438nm, which was made into data at 1nm intervals by segmentation interpolation. d) Based on b=16.087a (where a is radiance before fitting and b after fitting), radiance data got by 68731 spectrograph were processed. The original maize leaf photosynthesis data (by LI-6400) were introduced into EXCEL format, diurnal changes of each leaf were archived as one single unit according to leaf classification. Maize FPAR (the fraction of photosynthetically active radiation) was got by FPAR= (canopyPAR－surface transmissionPAR－canopy reflection PAR+surface reflectionPAR) /canopy PAR; APAR= FPAR×canopy PAR. The unit for PAR was µmol m-2 s-1. The data included number (the whole leaf), observation time (hh:mm:ss), upper light (µmol m-2 s-1), upper reflectivity (µmol m-2 s-1), lower light (µmol m-2 s-1), lower reflectivity (µmol m-2 s-1) and Spread: variation coefficients of the probe optical intensity.

The dataset of ground truth measurement synchronizing with Envisat ASAR and MODIS was obtained in the arid region hydrological experimental area on May 24, 2008. The Envisat ASAR data were in AP mode and VV/VH polarization combinations, and the overpass time was approximately at 11:34 BJT. Observation items included: (1) The radiative temperature of Reaumuria soongorica and the bare soil in Huazhaizi desert No. 2 plot (HZZHMYD2)was collected using ThermaCAM SC2000 (1.2m above the ground, FOV = 24°×18°), along the diagonal (NW-SE). The data included raw data (read by ThermaCAM Researcher 2001), recorded data and the blackbody calibrated data (archived as Excel files). (2) The radiative temperature by the automatic thermometer (FOV: 10°; emissivity: 0.95), were measured at nadir with time intervals of one second. Raw data, blackbody calibrated data and processed data were all archived as Excel files. (3) The radiative temperature in Huazhaizi desert No. 2 plot by the handheld infrared thermometer (which belongs to BNU) along the diagonal (NW-SE). Raw data (.doc), blackbody calibrated data and processed data (in Excel format) were all archived. (4) Soil moisture (0-40cm) by the cutting ring and the soil temperature by the thermocouple thermometer in Yingke oasis and Huazhaizi foci experimental area. Besides, (a) roughness of No. 1 and 2 Huazhizi desert plots was also measured by self-made instruments . Sample points were selected every 30m along the diagonal of each plot. (b) soil profile moisture (0-100cm) and the temperature in the maize field of Yingke oasis. (c) soil profile moisture (0-100cm) and the temperature in one orchard of Yingke Oasis. Data were all archived as Excel files. (5) the photosynthetic rate of alfalfa and barley at Linze grass station by LI-6400. Raw data were archived in the user-defined format (by notepat.exe) and processed data were as Excel files. (6) ground object reflectance spectra of new-born rape and the bare land in Biandukou foci experimental area by ASD FieldSpec (350～2500 nm) from Institute of Remote Sensing Applications (CAS). Raw data were binary files direct from ASD (by ViewSpecPro), and pre-processed data on reflectance were in Excel format. (7) LAI by the measuring tape and the ruler in the alfalfa field of Linze grass station. The maximum length and width of alfalfa leaves and barley were measured. Data were archived as Excel files. (8) surface roughness in Huazhaizi desert No. 2 plot with the self-made roughness board (Cold and Arid Regions Environmental and Engineering Research Institute, CAS), the digital camera and the compass. Sample points were selected at equal intervals along the diagonals and marked in the photos.

The dataset of ground truth measurements synchronizing with the airborne WiDAS mission was obtained in No. 1 and No. 3 quadrates of the A'rou foci experimental area on May 31, 2008. WiDAS, composed of four CCD cameras, one mid-infrared thermal imager (AGEMA 550), and one infrared thermal imager (S60), can acquire CCD, MIR and TIR band data. The simultaneous ground data were the surface radiative temperature and surface soil moisture. The surface radiative temperature (emissivity: 1.0) was measured by the automatic thermometer at intervals of 0.05s, and the data were archived as .txt files (.dat format). The first seven rows were the header file, including acquisition date, time, and intervals; besides, Time (starting time), TObj (target temperature), Tint (the interior temperature of the probe), TBox (the temperature of the box) and Tact (the actual temperature calculated from the given emissivity) were also listed. Soil moisture (0-12cm and 0-20cm) was measured by TDR. The data including the soil temperature, soil complex permittivity and soil conductivity, were archived in Excel format.

The dataset of evapotranspiration observed by the micro-lysimeter (d:25cm; h:24cm) was obtained in the Yingke oasis foci experimental area at 6:30am and 8:00pm from Jun. 14 to Jul. 13, 2008. The weather condition of the day was also recorded. Data were archived as Excel files. Observations on Jun. 25 and 26 discontinued.

The dataset of the albedo measurements was obtained by the shortwave radiometer (KippZonen CMP3, 310nm-2800nm, 1m above the ground) in the Linze station foci experimental area. Sand, psammophyte and withered annual herbs in A9 of the south-north desert strip and LY07, and flax, maize and tomatoes in Linze station were measured on May 28, Jun. 5, 6, 15, 22, 25, 30 and Jul. 4, 2008. Voltage was measured manually by the digital multimeter (UNIT) at intervals of 2 minutes for albedo from May 28 to Jun. 22; self-recording Campbell CR1000 was used at intervals of 1s from Jun. 25 to Jul. 4. TIMESTAMP (observation time), SOLAR_UP_AVG (downward shortwave radiation), SOLAR_DOWN_AVG (upward shortwave radiation), SOLAR_NET_AVG (net radiation)= SOLAR_UP_AVG - SOLAR_DOWN_AVG, albedo_Avg (albedo) = SOLAR_DOWN_AVG / SOLAR_UP_AVG, batt_volt_Min (voltage), and ptemp (CR1000 temperature) were all recorded. Manual data were archived as Excel files and the self-recording data in .dat, which were processed into Excel.

The dataset of ground truth measurements synchronizing with Envisat ASAR was obtained in No.2 quadrate of the A'rou foci experimental area on Oct. 17, 2007 during the pre-observation period. The Envisat ASAR data were in AP mode and VV/VH polarization combinations, and the overpass time was approximately at 23:04 BJT. The quadrate was divided into 3×3 subsites, with each one spanning a 30×30 m2 plot. 25 sampling points were chosen, including centers and corners of each subsites. Simultaneous with the satellite overpass, numerous ground data were collected, soil volumetric moisture by ML2X; soil volumetric moisture, soil conductivity, soil temperature, and the real part of soil complex permittivity by WET soil moisture sensor; the surface radiative temperature by the hand-held infrared thermometer; soil gravimetric moisture, volumetric moisture, and soil bulk density after drying by the cutting ring (100cm^3). Meanwhile, vegetation parameters as height, coverage and water content were also observed. Surface roughness was detailed in the "WATER: Surface roughness dataset in the A'rou foci experimental area". Those provide reliable ground data for retrieval and validation of soil moisture and freeze/thaw status from active remote sensing approaches.

The dataset of ground-based RPG-8CH-DP microwave radiometer and ground truth observations for soil freeze/thaw cycle was obtained in the A'rou foci experimental area from Mar. 10 to 11, 2008. The radiometer was set 4.5m height above a smooth land, which was covered with snow less than 10cm deep. The field of view was roughly determined and not as ideal. Frozen soil was observed clockwise 240° and snow clockwise 270° with the truck head as the 0 degree azimuth; the elevation angle was set at -40° for the former, and from -20° to -70° for the latter. Observation items included surface soil moisture (microwave drying to get the gravimetric moisture), the soil temperature by the thermal resistor and vegetation. The shallow layer of the site was covered with withered grass with exuberant roots underground due to rich organic. The soil temperature changes were reflected by the thermal resistor and recorded by the DataTaker. The brightness temperature was archived as .BRT and .txt files (the ASCII format). Data in two formats were the same. Each row in .txt format was listed by year, month, date, hour, minute, second, 6.925GHz (h), 6.925GHz (v), 10.65GHz (h), 10.65GHz (v) , 18.7GHz (h), 18.7GHz (v), 36.5GHz (h), 36.5GHz (v), the elevation angle, and the azimuth angle. Values for 6.925GHz and 10.65GHz were zero due to disfunction.

The dataset of snow spectral reflectance observations was obtained in the Binggou watershed foci experimental area from Dec. 5 to Dec. 15, 2007 during the pre-observation period. The aims of the measurements were to verify feasibility of the predetermined observation schemes and to collect data for retrieval from remote sensing approaches. All data were acquired by ASD spectrometer from Xinjiang Meteorological Administration. Observation items included: (1) Random observations on snow spectrum in the chosen snowpack at the Binggou cold region hydrometeorological station on Dec. 5, 6 and 7, 2007 (2) Snow spectrum observations in BG-A simultaneous with MODIS and Terra MISR on Dec. 10, 2007 (3) The pure and the mixed snow pixel spectrum in BG-A on Dec. 15, 2007 (4) Multi-angle snow spectrum in the chosen snowpack in BG-A on Dec. 15, 2007 Seven subfolders including raw data and pre-processed data are named after the acquisition time, Dec. 5, 2007, Dec. 6, 2007, Dec. 7, 2007, Dec. 10, 2007, Dec. 13, 2007, Dec. 15, 2007 and Dec. 15, 2007, respectively.