Monitoring Anthropogenic Effects on Land-surface phenologies in China from AVHRR using the Discrete Fourier Transform

Abstract

米国海洋大気庁(NOAA)による衛星搭載の改良型高分解能放射計(AVHRR)によって遠隔測定された正規化差分植生指数(NDVI)データは，地域的とある一国の規模での生物気候学的な植生について，人間による影響と自然の擾乱のレジーム／気候の両方の効果をモデル化するために使われる。特に，1982 年から2000年までのNDVI NOAA AVHRR データが，離散フーリエ変換(DFT)を使用して人間活動の影響を気候，自然の因子から識別するために使われた。

Remote sensing is increasingly used for investigating land-surface phenologies by capitalizing onthe recent availability of spaceborne optical and radar data. This paper detects temporal changes invegetation phenologies and attempts to attribute these changes in vegetation to some identifiablevegetation forcing factors, such as human activities, climate, and natural factors. Human activities, such as settlement, agricultural practices, and pollution, can significantly impact vegetative cycles. Inthe absence of human influences, vegetative growth (recurring biological cycles) is seasonally regulatedand primarily a function of temperature and precipitation. Remotely sensed Normalised DifferenceVegetation Index (NDVI) data from the National Oceanographic and Atmospheric Administration's(NOAA) Advanced Very High Resolution Radiometer (AVHRR) is used to model the impactof both anthropogenic influences and natural disturbance regimes/climate on vegetation phenologies atregional and national scales. Specifically, NDVI NOAA AVHRR data from 1982 to 2000 is used todiscriminate the influence of human activities from climatic and natural factors using the DiscreteFourier transform (DFT). Harmonic analysis of temporal NDVI in southern China shows that the firstharmonic is in-phase with atmospheric temperature, while the second and third harmonics capture thecombined influence of human activity information and climate on vegetation. But in northern Chinaand the Qingzang plateau, sandstorms and snow cover obfuscate the second and third harmonics, making correct interpretation difficult. In all, meteorological data from 560 observations are analyzedin order to detect changes to land-surface phenologies. This work can be extended by attempting to attributechanges in vegetation to specific climate forcing factors, such as greenhouse gases and humaninfluences such as deforestation.