文件列表:

actual_albedo_tool (0, 2015-06-22)
actual_albedo_tool\actual_albedo_hdf.o (20632, 2015-06-22)
actual_albedo_tool\actual_albedo_hdf.exe (1654366, 2015-06-22)
actual_albedo_tool\actual_albedo_bin.c (9163, 2004-05-04)
actual_albedo_tool\skyl_lut.dat (553891, 2003-01-16)
actual_albedo_tool\tell_albedo.c (3576, 2003-01-16)
actual_albedo_tool\actual_albedo_hdf.mk (2477, 2015-06-18)
actual_albedo_tool\polynomial_bsa.c (2854, 2003-01-16)
actual_albedo_tool\actual_albedo_hdf.c (18785, 2015-06-22)
actual_albedo_tool\tell_skyl.c (3030, 2003-01-16)

Readme file for actual albedo calculation SKYL LUT -------- The fraction of diffuse light (SKYL) changes with solar zenith angle, optical depth, bands and aerosol model types. In order to obtain SKYL easily and quickly, a SKYL lookup table was established with the help of the 6S code. In the lookup table, 90 solar zenith angle (0 to 89 degrees with a 1 degree step), 50 optical depths (0 to 1.0 with 0.02 step), 10 bands (7 MODIS land bands and 3 broad bands) and 2 aerosol model types (continental and maritime) were pre-calculated. The total numbers of elements in the MODIS lookup table is: 2 (aerosol model types) * 10 (bands) * 90 (szns) * 50 (optical depth) = 90,000. The LUT file generated for MODIS spectral bands is called "skyl_lut.dat". # Spectral bands for MODIS # bands: 0: 0.620-0.670 (red) # 1: 0.841-0.876 (nir) # 2: 0.459-0.479 # 3: 0.545-0.565 # 4: 1.230-1.250 # 5: 1.628-1.652 # 6: 2.105-2.155 # BB 7: 0.400-0.700 (vis) # BB 8: 0.700-4.000 (nir) # BB 9: 0.250-4.000 (sw) Calculation of WSA and BSA -------------------------- The program read the BRDF parameters from out1. Black-sky albedos are calculated according to the following polynomial albedo representation. BSA(SZN,BAND)= F_iso(BAND)*(G_0iso+G_1iso*SZN^2+G_2iso*SZN^3) + F_vol(BAND)*(G_0vol+G_1vol*SZN^2+G_2vol*SZN^3) + F_geo(BAND)*(G_0geo+G_1geo*SZN^2+G_2geo*SNZ^3) K=iso k=vol k=geo G_0k(term 1) 1.0 -0.007574 -1.284909 G_1k(term SZN^2) 0.0 -0.070***7 -0.166314 G_2k(term SZN^3) 0.0 0.307588 0.041840 WSA 1.0 0.189184 -1.377622 actual_albedo(SZN,BAND,OD,AMT) = WSA(BAND) * SKYL(SZN,BAND,OD,AMT) + BSA(SZN,BAND) * (1-SKYL(SZN,BAND,OD,AMT)) SZN: solar zenith angle BAND: band wavelength OD: optical depth AMT: aerosol model type Usage ----- * Usage: actual_albedo_hdf.exe [-par][-od][-szn][-out] This program reads the BRDF/albedo product (out1) (assuming the format of the MODIS MOD43B output -- ie MOD43B1.out1), computes the black and white sky albedos (with a simple polynomial equation, Lucht et al., 2000) and then assuming optical depth and solar zenith angle are inputs, computes the actual albedo (a linear combination of white and black-sky albedo) and writes it out in HDF format. -par input out1 result file (in HDF format) -od input optical depth (float, range: 0.0-1.0) -szn input solar zenith angle you want to compute (float, range: 0.0-89.0 degrees)\n"); -out output file to save actual albedo (in HDF format) SKYL lookup table "skyl_lut.dat" should exist in the current directory. * Usage: actual_albedo_bin.exe [-iso][-vol][-geo][-band][-od][-szn][-out] This program computes the actual albedo same as actual_albedo_hdf.exe except it accepts the binary BRDF parameters as inputs. You can convert MOD43B1 (BRDF/Albedo parameter) in HDF format to binary format using the MODIS Reprojection Tools (MRT). The MRT is a free software and can be downloaded from http://edc.usgs.gov/programs/sddm/modisdist/index.shtml -iso input MOD43B1 isotropic binary file (Parameters_01) -vol input MOD43B1 volumetric binary file (Parameters_02) -geo input MOD43B1 geometric binary file (Parameters_03) -band input band no in the MOD43B1 (1-10) -od input optical depth (float, range: 0.0-1.0) -szn input solar zenith angle you want to compute (float, range: 0.0-89.0 degrees) -out output file to save actual albedo in binary * Usage: polynomial_bsa.c (added January 2002) A simple sample program to calculate black-sky albedo at given solar zenith angle with polynomial equation (see Wolfgang Lucht et. al., IEEE TGRAS, Vol. 38, No.2, PP977-9***). It accepts binary file as inputs. * Usage: tell_skyl.exe [-od][-szn] (added July 2002) Calculate fraction of diffuse skylight through a look-up table which was pre-calculated with the 6S code for seven MODIS land spectral bands plus three broadbands (visible, NIR and shortwave) -od aerosol optical depth at 550nm [0..1] -szn solar zenith angle [0..89] * Usage: tell_albedo.exe [-par][-fd][-szn] (added July 2002) Calculate black-sky, white-sky and actual albedo for a single pixel by accepting the following command line parameters: -par parameters for three kernels They should be entered in the sequence of f_iso, f_vol and f_geo (same as in the MOD43B1) and should be the actual float number. Please note the file values in MOD43B1 are the scaled interger numbers. They should be re-scaled to the actual values by dividing by 1000. Normally, these parameters are in the range of [0..1] -fd fraction of the diffuse light You can use your own estimation or by running program "tell_skyl.exe" to get the estimation from a pre-defined lookup table. The data range should be [0..1] -szn solar zenith angle in degree data range should be between 0 and 89 degrees Files in the package -------------------- readme: this file skyl_lut.dat: SKYL lookup table. actual_albedo_bin.c: source program for binary version (compile with cc actual_albedo_bin.c -o actual_albedo_bin.exe) actual_albedo_hdf.c actual_albedo_hdf.mk: makefile. (use COMP_FLAGS = -DAVHRR for avhrr data, otherwise it generally assumes modis data as the input) actual_albedo_hdf.exe: executable SGI IRIX program for MODIS data tell_skyl.c (compile with: cc tell_skyl.c -o tell_skyl.exe) tell_albedo.c (compile with: cc tell_albedo.c -o tell_albedo.exe) polynomial_bsa.c (compile with: cc polynomial_bsa.c -o polynomial_bsa.exe) //wzs_0712 important for the input parameters data , now can only read V4 data not V5 data because the structers are different like V4 is 4 dimention and V5 is 3 dimention data

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