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MODIS/Download/LST/NDVI  

2011-03-16 14:52:11|  分类: 空间分析 |  标签: |举报 |字号 订阅

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Data
Time series of nominal 1 km spatial resolution MODIS data from the NASA Terra satellite were downloaded from NASA's EOS data gateway (http://edcimswww.cr.usgs.gov/pub/imswelcome/) for five complete years, January 2001 to December 2005. MODIS data are produced in the sinusoidal projection (MODLAND Sinusoidal Grid) and made available as 460 tiles covering the Earth, each tile measuring 10°×10° and consisting of 1200×1200 0.859 km2 (926.63 m×926.63 m) pixels. All available images per time interval (as of 8 January 2007), called granules, were acquired for 229 tiles, including all tiles between 90°N and 60°S, except for 129 oceanic tiles and 62 tiles containing small islands, for two data sets: MODIS/Terra Land Surface Temperature/Emissivity 8-day L3 Global 1 km SIN grid (MOD11A2, version 4, [45]) and MODIS/Terra Nadir BRDF-Adjusted Reflectance 16-day L3 Global 1 km SIN grid (MOD43B4, version 4, [46]). MODIS data sets are provided in Hierarchical Data Format (HDF), and were imported to ERDAS Imagine 9.0 (Leica Geosystems, Norcross, GA) and converted to ERDAS LAN format.
The MOD11A2 data set comprises 8-day composited land surface temperature (LST) for daytime (dLST) and night-time (nLST) overpasses [45]. A complete time series for each tile of the MOD11A2 data would therefore consist of 46 granules at 8-day intervals for each of five years, or 230 granules in total.
The MOD43B4 data set provides nadir Bidirectional Reflectance Distribution Function (BRDF)-adjusted reflectances for Terra MODIS spectral bands 1–7 computed with the mean solar zenith angle of each 16-day interval over which data were composited [46]. The BRDF removes directional effects of view angle and illumination, providing reflectance values as if every pixel were viewed from nadir. Pre-processing excluded pixels with unreliable BRDF corrections, identified by quality control flags provided with the data set (QC Word 2 value >10). For each pixel a MIR channel (MODIS band 7, 2105–2155 nm) was extracted and the NDVI ([near infrared (NIR)–RED]/[NIR+RED], where NIR is MODIS band 2 and RED is band 1, 841–876 nm and 620–670 nm, respectively) and the EVI (2.5*[[NIR-RED]/[NIR+6.0*RED–7.5*BLUE+1.0]], where BLUE is MODIS band 3, 459–479 nm, [43]) were calculated. The MIR band was selected as being similar to band 3 in AVHRR, which has been shown to correlate with a number of vegetative processes including forest re-growth [47]. A complete MOD43B4 time series for each tile would consist of 23 granules at 16-day intervals for each of five years, or 115 granules in total. Although finer resolution data are available for NDVI and EVI (MODIS/Terra Vegetation Indices 16-day L3 Global 250 m resolution, MOD13Q1), MIR and LST data are only available at 1 km resolution. For consistency across products and given the much greater time involved in processing higher resolution data on a global scale, 1 km resolution data were therefore used for all products.
After temporal Fourier processing (described below), outputs for all five products were mosaicked and georeferenced (parameters in Table S1). Ocean pixels in all output layers were masked using the MODLAND Digital Elevation Model (DEM) and Land/Water Mask version 4, downloaded from ftp://landsc1.nascom.nasa.gov/pub/outgoing/dem_sin_old for all 229 tiles and processed in ERDAS Imagine 9.0 and ArcInfo 9.1 (ESRI, Redlands, CA). Since the MOD11A2 data set had been masked by the version 4 land/water mask prior to production, and this mask did not match the later version 5 mask extents based on MOD43B4 reflectance data [48], the version 4 mask was used throughout. Information on inland water and ephemeral water bodies was also extracted from the MODLAND version 4 land/water mask.

 

引:

PLoS One. 2008 Jan 9;3(1):e1408.

Global data for ecology and epidemiology: a novel algorithm for temporal Fourier processing MODIS data.

Scharlemann JP, Benz D, Hay SI, Purse BV, Tatem AJ, Wint GR, Rogers DJ.

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