Retrievals of All-Weather Daily Air Temperature Using MODIS and AMSR-E Data

Keunchang Jang,Sinkyu Kang,Suk Hong,John Kimball

doi:10.3390/rs6098387

Abstract

Satellite optical-infrared remote sensing from the Moderate Resolution Imaging Spectroradiometer (MODIS) provides effective air temperature (Ta) retrieval at a spatial resolution of 5 km. However, frequent cloud cover can result in substantial signal loss and remote sensing retrieval error in MODIS Ta. We presented a simple pixel-wise empirical regression method combining synergistic information from MODIS Ta and 37 GHz frequency brightness temperature (Tb) retrievals from the Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR-E) for estimating surface level Ta under both clear and cloudy sky conditions in the United States for 2006. The instantaneous Ta retrievals showed favorable agreement with in situ air temperature records from 40 AmeriFlux tower sites; mean R2 correspondence was 86.5 and 82.7 percent, while root mean square errors (RMSE) for the Ta retrievals were 4.58 K and 4.99 K for clear and cloudy sky conditions, respectively. Daily mean Ta was estimated using the instantaneous Ta retrievals from day/night overpasses, and showed favorable agreement with local tower measurements (R2 = 0.88; RMSE = 3.48 K). The results of this study indicate that the combination of MODIS and AMSR-E sensor data can produce Ta retrievals with reasonable accuracy and relatively fine spatial resolution (~5 km) for clear and cloudy sky conditions.

Highlights

Surface air temperature (Ta), which is defined as the measurement at the height of ~2 m above ground in the standard weather stations, is an important index of terrestrial environmental conditions [1], and plays a major role in applied meteorology and climatology [2]
We presented a simple empirical regression method combining synergistic information from Moderate Resolution Imaging Spectroradiometer (MODIS) and AMSR-E sensors for estimating Ta under both clear and cloudy sky conditions
The simple regression method developed for Ta gap filling under cloudy conditions produced generally similar accuracy relative to MODIS (MYD07_L2) Ta retrievals under clear sky conditions, and in relation to in situ temperature measurements spanning a broad range of AmeriFlux tower sites, and representing diverse climate and land cover conditions

Summary

Introduction

Surface air temperature (Ta), which is defined as the measurement at the height of ~2 m above ground in the standard weather (or meteorological) stations, is an important index of terrestrial environmental conditions [1], and plays a major role in applied meteorology and climatology [2]. Ta is major control on terrestrial biophysical processes, including plant photosynthesis, respiration, and evapotranspiration. Satellite remote sensing provides for spatially contiguous daily Ta monitoring from local to global scales. Various methods for estimating Ta from satellite optical-IR and passive microwave remote sensing have been widely implemented since the 1990s [1,2,6,7,8,9,10,11,12,13].

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