Current Browsing: Galactic System

MODIS Snow cover product dataset in China (2000-2004)

The data set is from February 24, 2000 to December 31, 2004, with a resolution of 0.05 degrees, MODIS data, and the data format is .hdf. It can be opened with HDFView. The data quality is good. The missing dates are as follows: 2000 1 -54 132 219-230 303 2001 111 167-182 2002 079-086 099 105 2003 123 324 351-358 2004 219 349 The number after the year is the nth day of the year Pixel values ​​are as follows: 0: Snow-free land 1-100: Percent snow in cell 111: Night 252: Antarctica 253: Data not mapped 254: Open water (ocean) 255: Fill An example of file naming is as follows: Example: "MOD10C1.A2003121.004.2003142152431.hdf" Where: MOD = MODIS / Terra 2003 = Year of data acquisition 121 = Julian date of data acquisition (day 121) 004 = Version of data type (Version 4) 2003 = Year of production (2003) 142 = Julian date of production (day 142) 152431 = Hour / minute / second of production in GMT (15:24:31) The corner coordinates are: Corner Coordinates: Upper Left (70.0000000, 54.0000000) Lower Left (70.0000000, 3.0000000) Upper Right (138.0000000, 54.0000000) Lower Right (138.0000000, 3.0000000) Among them, Upper Left is the upper left corner, Lower Left is the lower left corner, Upper Right is the upper right corner, and Lower Right is the lower right corner. The number of data rows and columns is 1360, 1020 Geographical latitude and longitude coordinates, the specific information is as follows: Coordinate System is: GEOGCS ["Unknown datum based upon the Clarke 1866 ellipsoid",     DATUM ["Not specified (based on Clarke 1866 spheroid)",         SPHEROID ["Clarke 1866", 6378206.4,294.9786982139006,             AUTHORITY ["EPSG", "7008"]]],     PRIMEM ["Greenwich", 0],     UNIT ["degree", 0.0174532925199433]] Origin = (70.000000000000000, 54.000000000000000)


China 1km resolution digital elevation model dataset

DEM is the English abbreviation of Digital Elevation Model, which is an important source of data for river basin terrain and feature recognition. The principle of DEM is to divide the watershed into m rows and n columns of quadrilaterals (CELLs), calculate the average elevation of each quadrilateral, and then store the elevations in a two-dimensional matrix. Because DEM data can reflect local terrain features with a certain resolution, a large amount of surface morphological information can be extracted through DEM. These information include the slope, aspect, and relationship between cells in a watershed grid cell. At the same time, a certain algorithm can be used to determine the surface water flow path, the river network and the boundary of the watershed. Therefore, to extract watershed characteristics from DEM, a good watershed structure model is the premise and key of designing algorithms. The data includes: 1. 1: 1KM basic DEM Data based on China's 1: 250,000 contours and elevation points, including DEM, mountain shadows, slopes, and aspect maps 2. SRTM 1km DEM Cut from SRTM data of 1KM worldwide, including DEM, mountain shadow, slope, aspect map 3. ASTER GDEM According to the 30-meter ASTER GDEM, stitching, cutting, and resampling into 1KM The file formats are: geotiff Data set projection: Projection = Albers Conical Equal Area ", GEOGCS ["Krasovsky", DATUM ["Krasovsky", SPHEROID ["Krasovsky", 6378245,298.3000003760163]], PRIMEM ["Greenwich", 0], UNIT ["degree", 0.0174532925199433]], PROJECTION ["Albers_Conic_Equal_Area"], PARAMETER ["standard_parallel_1", 25], PARAMETER ["standard_parallel_2", 47], PARAMETER ["latitude_of_center", 0], PARAMETER ["longitude_of_center", 105], PARAMETER ["false_easting", 0], PARAMETER ["false_northing", 0], UNIT ["metre", 1,] Data range: Corner Coordinates: Upper Left (-3656885.097, 6579746.944) (51d 4'21.50 "E, 51d19'19.71" N) Lower Left (-3656885.097, 1560746.944) (73d20'22.18 "E, 9d42'56.35" N) Upper Right (3405114.903, 6579746.944) (155d50'50.17 "E, 52d29'29.44" N) Lower Right (3405114.903, 1560746.944) (134d36'43.08 "E, 10d27'15.15" N) Center (-125885.097, 4070246.944) (103d32'28.11 "E, 37d57'32.64" N)


SRTM DEM dataset in China (2000)

The SRTM sensor has two bands, namely C-band and X-band. The SRTM we are using now comes from the C-band. The publicly released SRTM digital elevation products include DEM data at three different resolutions:     * SRTM1 covers only the continental United States, with a spatial resolution of 1s;     * SRTM3 data covers the world with a spatial resolution of 3s. This is the most widely used dataset. The elevation reference of SRTM3 is the geoid of EGM96 and the horizontal reference is WGS84. The nominal absolute elevation accuracy is ± 16m, and the absolute plane accuracy is ± 20m.     * SRTM30 data also covers the world, with a resolution of 30s. There are multiple versions of SRTM data. The early SRTM data was completed by NASA's "JPL" (Jet Propulsion Laboratory) ground data processing system (GDPS). The data is called SRTM3- 1. The National Geospatial Intelligence Agency has further processed the data, and the lack of data has been significantly improved. The data is called SRTM3-2. This dataset is mainly the fourth version of SRTM terrain data obtained by CIAT (International Center for Tropical Agriculture) using a new interpolation algorithm. This method better fills the SRTM 90 data hole. The interpolation algorithm comes from Reuter et al. (2007). The data of SRTM is organized as follows: every 5 latitude and longitude grids is divided into a file, which are divided into 24 rows (-60 to 60 degrees) and 72 columns (-180 to 180 degrees). The file naming rule is, where XX indicates the number of columns (01-72), and YY indicates the number of rows (01-24). The resolution of the data is 90 m. Data use: SRTM data uses a 16-bit value to represent the elevation value (-/ + / 32767 meters), the maximum positive elevation is 9000 meters, and the negative elevation (12,000 meters below sea level). -32767 standard for empty data.


1:100000 topographic index of the Heihe River Basin

The “Eco-Hydro Integrated Atlas of Heihe River Basin” is supported by the Synthetic Research on the Eco-hydrological Process of the Heihe River Basin– a key project to provide data collation and service for the Heihe River Basin eco-hydrological process integration study. This atlas will provide researchers with a comprehensive and detailed introduction to the Heihe River Basin background and basic data sets. The 1:100,000 topographic framing index of the Heihe River Basin is one of the basic geographs of the atlas, with a scale of 1:2500000, Lambert conformal conic projection, and a standard latitude: north latitude 25 47 . Data source: 1:100000 topographic map index data, Heihe River boundary.


Aerial Drone photos of Hoh Xil plot (2018)

On August 22, 2018, in the Lancang River Source Park, a camera was carried on DJI Elf 4 UAV to take aerial photographs of the sample area. A total of 20 routes (5 missing routes) were set up, flying at a height of 100 m, and the overlap degree of adjacent photos was not less than 70%. A total of 1160 aerial photographs were obtained and stored in two folders of "100 MEDIA" and "101 MEDIA".