Land surface temperature data are rarely available at high-temporal and high-spatial resolutions at the same locations. To fill this gap, the low-spatial-resolution data can be disaggregated at high-temporal frequency using empirical relationships between remotely sensed temperature and fractional green (photosynthetically active) and senescent vegetation cover. In this study, a new disaggregation methodology is developed by physically linking remotely sensed surface temperature to fractional green and senescent vegetation cover using a radiative transfer equation. Moreover, the methodology is implemented with two additional factors related to the energy budget of irrigated areas, being the fraction of open water and soil evaporative efficiency (ratio of actual to potential soil evaporation). The approach is tested over a 5 km by 32 km irrigated agricultural area in Australia using airborne PLMR (Polarimetric L-band Multi-beam Radiometer) brightness temperature and spaceborne ASTER (Advanced Scanning Thermal Emission and Reflection radiometer) multi-spectral data. Fractional green vegetation cover, fractional senescent vegetation cover, fractional open water and soil evaporative efficiency are derived from red, near-infrared, shortwave-infrared and microwave-L band data. Low-resolution land surface temperature is simulated by aggregating ASTER land surface temperature to 1 km resolution, and the disaggregated temperature verified against the high-resolution ASTER temperature data initially used in the aggregation process. The error in disaggregated temperature is successively reduced from 1.65 to 1.16◦C by including each of the four parameters. The correlation coefficient and slope between disaggregated and ASTER temperature is improved from 0.79 to 0.89 and from 0.63 to 0.88, respectively. Moreover, the radiative transfer equation allows quantification of the impact on disaggregation of the temperature at high-resolution for each parameter: fractional green vegetation cover is responsible for 42% of the variability in disaggregated temperature, fractional senescent vegetation cover for 11%, fractional open water for 20% and soil evaporative efficiency for 27%.