MODIS LST Research Articles

The Relationship Between Inter-annual Variations of Land Surface Temperature and Climate Factors in the Yangtze River Delta

With the Yangtze River delta as the study area,this paper quantitatively analyzed the temporal responses of land surface temperature annual variability to climate factors based on MODIS LST products and meteorological observation data.First,the Harmonic Analysis of Time Series(HANTS) algorithm was employed to distill LST harmonics(periodical fluctuation characters) and reconstruct cloud-free LST time-series.The solar radiation of the study area was calculated and its impact on LST inter-annual was investigated by time lag cross-correlation analysis.The high correlation coefficient(mean coefficient is 0.991 6) indicates the sensitivity of LST seasonal variations to solar radiance,and lag days show that the peak time of LST is about 20 days later than solar radiance.The analysis between the inter-annual variations of land surface temperature and air temperature shows that air temperature has significant correlations with LST and the air temperature delays about 5 days relative to LST seasonal fluctuation.

THE LAND SURFACE TEMPERATURE AND EMISSIVITY RETRIEVED FROM THE AMSR PASSIVE MICROWAVE DATA

AMSR and MODIS are two EOS (Earth Observing System) instruments in Aqua satellite. A regression analysis between the brightness of all AMSR bands and the MODIS land surface temperature product provided by NASA indicates good correlation, and hence retrieving land surface temperature from AMSR passive data is available without ground true data (soil moisture and land surface type). The analytical results in such regions as North Africa, Northeast China, Tibet China and India indicate that the radiation mechanism of snow-covered surface is different from mechanism of other conditions. In order to retrieve land surface temperature more accurately, we can classify the land surface at least into two groups. For land surface covered with no snow, the average land surface temperature error is about 2℃ relative to the MODIS LST product. For snow-covered land surface, the average land surface temperature error is about 2~3℃ relative to the MODIS LST product. Besides, the emissivity of passive microwave is a very important parameter for retrieving soil moisture. The authors computed the emissivity through land surface temperature retrieved by the statistical regression method and made an analysis.