جستجوی مقالات مرتبط با کلیدواژه "تجزیه وتحلیل هارمونیک" در نشریات گروه "جغرافیا"

Phenology is the study of the occurrence of repeatable plant life events in relation to living and non-living factors. The phenology reflects the response and adaptability of ecosystems to climate change. Phonological study can be used to regulate livestock grazing management programs at rangeland, various agricultural activities, and etc. In order to study the effect of height and temperature on plant phenological processes, harmonic analysis of time series satellite observations was used. In this study, the 8-day products of the NDVI indices of MODIS sensor (namely MOD09Q1) with a spatial resolution of 250 m was used. First, the HANTS algorithm was used to decompose the one-year NDVI MODIS products time series to thier Fourier Series components (the amplitude and phase images). Then, the correlation of each of these components with respect to height and temperature were investigated in Shirkoh area of Yazd province. According to the results, with 1 centigrade decrease in the average spring temperature, which occurs with elevation, there were a delay of 6.6 days in annual cycles and 3.9 days in the 6-month cycles of the NDVI time series, respectively. These results indicate that a delay of 6.3 days was observed in phenological processes and plant starting growth time in plant with annual growth periods and a delay of 3.9 days in plants with seasonal and six-month growth stages. Accordingly, the results of the HANTS algorithm and the Fourier series analysis can be very effective in understanding the effects of climatic factors on phenological processes and the onset of plant growth.