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Yanmin Shuai, Jeffrey G. Masek, Feng Gao, Crystal B. Schaaf. (2010). An Algorithm for the Retrieval of 30-m snow-free albedo from Landsat surface reflectance and MODIS BRDF , submitted to RSE under reviewing
Update Landsat Albedo
Algorithm ReviewInputs:
Landsat surface reflectance, MODIS BRDF parameters and QA
Outputs: spectral/broadband albedo, nadir view reflectance
Model: MODIS BRDF model (RossThick-LiSparse-R)
Landsat Surface Reflectance
Unsupervised classification
Reprojection and
aggregation
Landsat scene Albedo
generation
Albedo-to-Nadir Ratio
Calculation
MODIS BRDF
MODIS QA
Landsat Spectral Albedo
Landsat Broadband Albedo
A
B
C
A. Processing chainB. MODIS informationC. Landsat albedo products
Legend of modules
Validation Sites
Station NameNetwor
kStation ID#
(Lat, Long)Major Land cover type
WRS-2path/row
Scenes used
Extended facility station #15
ARM EF1536.431°N, 98.284°W
Grassland 28/35 54
Desert rock stationSURFRA
DDRA
36.62320°N, 116.01962°W
Sparse vegetation
40/35 69
Table mountainSURFRA
DTBL
40.12557°N, 105.23775°W
Sandy with exposed rocks, sparse grasses
and shrubs
34/32 27
BondvilleSURFRA
DBON
40.05155°N,88.37325°W
Agriculture 23/32 46
Goodwin creekSURFRA
DGWN
34.2547°N, 89.8729 °W
Pasture grass and sparsely distributed
deciduous trees
23/36 57
Penn state university
SURFRAD
PSU40.72033°N,77.93100 °W
AgricultureResearch field
16/32 17
0.10 0.15 0.20 0.25 0.300.10
0.15
0.20
0.25
0.30
ARM EF15 (lnd) ARM EF15 (MOD)
DRA (lnd) DRA (MOD)
TBL (lnd) TBL (MOD)
Satellite retrieval (SW-Blue Sky Albedo)
Gro
un
d m
easu
res
(Alb
edo)
MODIS Representative Sites
y = 1.5815x - 0.0821 R² = 0.7575RMSE_mod_Rep=0.02540Bias_mod_Rep=-0.01928
Landsat Representative Sites
y = 0.967x + 0.019 R² = 0.911RMSE_lnd_Rep=0.01585Bias_lnd_Rep=-0.01298
0.10 0.15 0.20 0.25 0.30 0.350.10
0.15
0.20
0.25
0.30
0.35
BON (lnd) BON (MOD)
GWN (lnd) GWN (MOD)
PSU (lnd) PSU (MOD)
Satellite retrieval (SW-Blue Sky Albedo)
Gro
un
d m
easu
res
(Alb
edo)
Landsat Non-represen-tative Sites
y=1.1097x+0.0056
R² =0.7813RMSE_lnd_nonRep=0.03894Bias_lnd_nonRep=-0.02853
MODIS Non-representa-tive Sites
y=0.0051x+0.2036 R²=4E-06RMSE_mod_nonRep=0.06302Bias_mod_nonRep=-0.04912
PSU AlbedoUpperleft: Land surface white-sky albedo composite (NIR, Red, and Green bands to RGB) Upperright: MODIS white-sky albedo composite Lowerleft: Google MapsLowerright: scattering plot between Landsat (X-axis) and MODIS (Y-axis) albedo
Area: 30km by 30kmWRS-2 path 16 and row 32(PSU site)
Site ID#Landsat MODIS
Mean bias RMSE * R2 * Slope Mean bias RMSE * R2 * Slope
A
TBL -0.01204 0.01383 0.8310 0.9474 0.00353 0.01530 0.8480 1.0019
EF15 -0.01659 0.02015 0.8289 0.8929 -0.02557 0.02900 0.7751 1.5400
DRA -0.01075 0.01316 0.5814 0.7641 -0.02503 0.02739 0.1413 0.4979
A Representative sites -0.01298 0.01585 0.911 0.967 -0.01928 0.02540 0.7575 1.5815
B
GWN -0.02054 0.02579 0.4548 0.9736 -0.03529 0.03942 0.0484 0.3750
PSU -0.02977 0.03662 0.6115 1.0361 -0.03990 0.04745 0.1701 1.2666
BON -0.02869 0.03396 0.8126 1.0719 -0.06855 0.08769 *** ***
B Non-Representative sites -0.02853 0.03894 0.7813 1.1097 -0.04912 0.06302 *** ***
All six sites -0.0189 0.0266 0.7341 0.9617 *** *** *** ***
•R2 is a determination of the correlation coefficient from the linear regression using the “least square” method; Slope is the slope of regressed line.
0 100 200 300 400 500 600 700 800 900 1000 1100 12000.1
0.2
0.3
0.4
ARM EF15 (grd) ARM EF15 (lnd)
Date (YY-DDD)
Sho
rtw
ave
albe
do
03-00 03-100 03-200 03-300 04-00 04-100 04-200 04-300 05-00 05-100 05-200 05-300
Temporal albedo over ARM EF15 site (Grassland)
0 100 200 300 400 500 600 700 800 900 1000 1100 12000.1
0.2
0.3
0.4
DRA (grd) DRA (lnd)
Date (YY-DDD)
Sho
rtw
ave
albe
do
03-00 03-100 03-200 03-300 04-00 04-100 04-200 04-300 05-00 05-100 05-200 05-300
Temporal albedo over DRA site (Desert Rock, Sparse Vegetation)
Landsat Nadir BRDF-Adjustment Reflectance (NBAR)
Landsat surface reflectance 4, 3, and 2 composite (Color enhancement:WRS-2 p012r031, 2002-07-31
Landsat NBAR (band 4,3,2 combination)(Note: no retrieval in the water region)
NIR 0-0.5;Red 0-0.06; Green 0-0.006)
Difference between surface reflectance (directional) and nadir view reflectance
Difference between directional reflectance and NBAR for NIR band
Difference between directional reflectance and NBAR for Red band
Next …Snow-covered pixels (spatial extension)Beyond MODIS-era (temporal extension)
- BRDF shapes for snow-covered surface types- BRDF shapes for typical surface types
(surface type, date, NDVI, band, etc.)- Compatible land cover classification- Narrowband to Broadband conversion