443
19
Remote Sensing and
Modeling of Global
Evapotranspiration
Qiaozhen Mu, Maosheng Zhao,
and Steven W. Running
CONTENTS
19.1 Introduction ..................................................................................................444
19.2 Literature Review ......................................................................................... 445
19.2.1 Surface Energy Balance Models ...................................................... 445
19.2.2 Models Using the Relationship between Vegetation Index and LST .....446
19.2.3 Penman–Monteith Logic ..................................................................448
19.3 Theoretical Basis of the Global MODIS ET (RS-ET) Algorithm ................449
19.3.1 Mathematical Description ................................................................449
19.3.2 Vegetation Cover Fraction ................................................................ 450
19.3.3 Canopy Conductance Calculation .................................................... 451
19.3.4 Soil Evaporation ................................................................................ 453
19.4 Preprocessing Input MODIS and Meteorology Data .................................... 454
19.4.1 Spatially Smoothing Coarse Resolution GMAO into MODIS
Resolution ......................................................................................... 455
19.4.2 Temporally Interpolating Contaminated or Missing MODIS Data .... 455
19.5 Validations at Flux Tower Sites .................................................................... 457
19.5.1 Flux Towers ...................................................................................... 457
19.5.2 Validation Results ............................................................................. 458
19.5.3 Uncertainty in Site-Based Validations.............................................. 458
19.6 Applications of the RS-ET Algorithm at the Regional and Global Scales ........ 462
19.6.1 Regional and Global Validations ...................................................... 462
19.6.2 Seasonality and Interannual Variability ...........................................464
19.6.2.1 Seasonality .........................................................................464
19.6.2.2 Interannual Variability .......................................................464
19.6.3 Variance and Uncertainty in Regional and Global ET .....................465
19.7 Further Improvements ..................................................................................469
19.8 Conclusions ................................................................................................... 471
References .............................................................................................................. 471
19
Remote Sensing and
Modeling of Global
Evapotranspiration
Qiaozhen Mu, Maosheng Zhao,
and Steven W. Running
CONTENTS
19.1 Introduction ..................................................................................................444
19.2 Literature Review ......................................................................................... 445
19.2.1 Surface Energy Balance Models ...................................................... 445
19.2.2 Models Using the Relationship between Vegetation Index and LST .....446
19.2.3 Penman–Monteith Logic ..................................................................448
19.3 Theoretical Basis of the Global MODIS ET (RS-ET) Algorithm ................449
19.3.1 Mathematical Description ................................................................449
19.3.2 Vegetation Cover Fraction ................................................................ 450
19.3.3 Canopy Conductance Calculation .................................................... 451
19.3.4 Soil Evaporation ................................................................................ 453
19.4 Preprocessing Input MODIS and Meteorology Data .................................... 454
19.4.1 Spatially Smoothing Coarse Resolution GMAO into MODIS
Resolution ......................................................................................... 455
19.4.2 Temporally Interpolating Contaminated or Missing MODIS Data .... 455
19.5 Validations at Flux Tower Sites .................................................................... 457
19.5.1 Flux Towers ...................................................................................... 457
19.5.2 Validation Results ............................................................................. 458
19.5.3 Uncertainty in Site-Based Validations.............................................. 458
19.6 Applications of the RS-ET Algorithm at the Regional and Global Scales ........ 462
19.6.1 Regional and Global Validations ...................................................... 462
19.6.2 Seasonality and Interannual Variability ...........................................464
19.6.2.1 Seasonality .........................................................................464
19.6.2.2 Interannual Variability .......................................................464
19.6.3 Variance and Uncertainty in Regional and Global ET .....................465
19.7 Further Improvements ..................................................................................469
19.8 Conclusions ................................................................................................... 471
References .............................................................................................................. 471