Evaluation of MODIS land surface temperature data to estimate air temperature in different ecosystems over Africa
Evaluation of MODIS land surface temperature data to estimate air temperature in different ecosystems over Africa
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DOI：
10.1016/j.rse.2009.10.002
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发表时间：
2010-02-15
影响因子：
13.5
通讯作者：
Connor, Stephen J.
中科院分区：
文献类型：
--
作者：
Vancutsem, Christelle;Ceccato, Pietro;Connor, Stephen J.
近地面气温（Ta）的估算在农业、气候相关疾病和气候变化研究等方面有着广泛的应用。气温通常是由气象站的天气测量数据获得的。在非洲，气象站的空间分布往往有限，温度数据的传播也不稳定，因此限制了它们的实时应用。可以通过使用卫星方法来弥补这种信息的缺乏。然而，从卫星获得的地表温度（Ts）推导近地表气温（Ta）远非直接。一些研究试图通过回归分析从卫星中得出最大Ta，但根据研究结果，所获得的准确度差异很大。本研究的主要目的是探讨在非洲不同生态系统的中分辨率成像光谱仪（MODIS）Ts产品检索高分辨率Ta数据的可能性。首先，夜间MODIS Ts数据与最小Ta之间的比较表明，MODIS夜间产品提供了对不同生态系统的最小Ta的良好估计（（Δ Ts - Ta）以0 ℃为中心，平均绝对误差（MAE）= 1.73 ℃，标准差= 2.4 ℃）。其次，白天的MODIS Ts数据与最大Ta之间的比较表明，（Δ Ts - Ta）强烈变化，根据季节性，生态系统，太阳辐射和云量。分析了文献中提出的从Ts中提取最大Ta的两个因素，即归一化差异植被指数（NDVI）和太阳天顶角（SZA）。（Δ Ts - Ta）与（i）NDVI和（ii）SZA之间没有很强的关系，因此需要进一步研究稳健的方法来检索最大Ta。(C)2009 Elsevier Inc. All rights reserved.
The estimation of near surface air temperature (Ta) is useful for a wide range of applications such as agriculture, climate related diseases and climate change studies. Air temperature is commonly obtained from synoptic measurements in weather stations. In Africa, the spatial distribution of weather stations is often limited and the dissemination of temperature data is variable, therefore limiting their use for real-time applications. Compensation for this paucity of information may be obtained by using satellite-based methods. However, the derivation of near surface air temperature (Ta), from the land surface temperature (Ts) derived from satellite is far from straight forward. Some studies have tried to derive maximum Ta from satellites through regression analysis but the accuracy obtained is quite variable according to the study. The main objective of this study was to explore the possibility of retrieving high-resolution Ta data from the Moderate Resolution Imaging Spectroradiometer (MODIS) Ts products over different ecosystems in Africa. First, comparisons between night MODIS Ts data with minimum Ta showed that MODIS nighttime products provide a good estimation of minimum Ta over different ecosystems (with (Delta Ts - Ta) centered at 0 degrees C, a mean absolute error (MAE) = 1.73 degrees C and a standard deviation = 2.4 degrees C). Secondly, comparisons between day MODIS Ts data with maximum Ta showed that (Delta Ts - Ta) strongly varies according to the seasonality, the ecosystems, the solar radiation, and cloud-cover. Two factors proposed in the literature to retrieve maximum Ta from Ts, i.e. the Normalized Difference Vegetation Index (NDVI) and the Solar Zenith Angle (SZA), were analyzed. No strong relationship between (Delta Ts - Ta) and (i) NDVI and (ii) SZA was observed, therefore requiring further research on robust methods to retrieve maximum Ta. (C) 2009 Elsevier Inc. All rights reserved.