A modified surface energy balance algorithm for land (M-SEBAL) based on a trapezoidal framework

摘要: [1] The surface energy balance algorithm for land (SEBAL) has been designed and widely used (and misused) worldwide to estimate evapotranspiration across varying spatial temporal scales using satellite remote sensing over the past 15 yr. It is, however, beset by visual identification of a hot cold pixel determine temperature difference (dT) between lower atmosphere, which is assumed be linearly correlated with radiative (Trad) throughout scene. To reduce ambiguity in flux estimation SEBAL due subjectivity extreme selection, this study first demonstrates that rectangular framework contextual relationship vegetation fraction (fc) Trad, can distort distribution heat retrievals degrees. End members were replaced trapezoidal fc-Trad space modified (M-SEBAL). The warm edge determined analytically deriving temperatures bare largest water stress fully vegetated implicit both radiation budget equations. Areally averaged air (Ta) site taken framework. Coefficients linear dT Trad vary fc but are essentially invariant same or within class M-SEBAL. M-SEBAL applied soil moisture-atmosphere coupling experiment (SMACEX) central Iowa, U.S. Results show capable reproducing latent terms an overall root-mean-square 41.1 W m−2 mean absolute percentage 8.9% reference eddy covariance tower-based measurements three landsat thematic mapper/enhanced mapper plus imagery acquisition dates 2002. retrieval accuracy generally than M-SEBAL, depending largely on selected extremes. Spatial distributions from distorted certain degree its intrinsic