5.1 Results
The anomalies in precipitation for year 2001-06 were computed from 30-years point-based rainfall records. Negative anomaly from year 2001 to 2006 was found. As well, there were downward trends in 6-year EVI temporal profiles with negative anomalies in rice, crops, and deciduous forest (Figure 2). This suggested that the impact of drought on vegetation can be seen in MODIS EVI observation. The seasonal dynamics across the major land cover types, rice, sugar cane, cassava, deciduous, and evergreen forest sites were plotted and analyzed with MODIS, 1km resolution 16-day composite VI profiles for years 2001-06. Overall, temporal profiles of rice, sugar cane, cassava, and deciduous forest depicted dry-wet seasonal contrast strongly coupled with rainfall with a pronounced dry season and wet seasons (Figure 2). During the rainy season, May through October, high vegetation activity can be seen. For the dry-down phase of the dry season, November through April, EVI values decreased. However, differences in EVI seasonal profiles were apparent among evergreen forest and other land cover types (Figure 3). The evergreen forest showed the lowest seasonal contrast with high EVI values throughout the year. The green up occurred during the dry season (~ February) and reached the “green” peak of growing season in June-July. metrics were utilized to further filter and reduce cloud contaminated pixels. Vegetation seasonality was analyzed with 6-years (2001-06) of 16-day composite EVI time series at 1km
resolution (MOD13A2) over local sites, encompassing the rice fields, the sugar cane and cassava fields, and the deciduous and evergreen forests. Point-based long-term rainfall data over the region were collected from the Thai Meteorological
Department (http://www.tmd.go.th/). Monthly precipitation values for anomaly analyses were computed from 30-year stationary records. Satellite and rainfall data anomalies were analyzed using long-term point-based monthly and
annual rainfall records and year 2000-06 MODIS EVI data. Correlations of rainfall and EVI were analyzed using simple regression method.
5.1 Results
The anomalies in precipitation for year 2001-06 were computed from 30-years point-based rainfall records. Negative anomaly from year 2001 to 2006 was found. As well, there were downward trends in 6-year EVI temporal profiles with negative anomalies in rice, crops, and deciduous forest (Figure 2). This suggested that the impact of drought on vegetation can be seen in MODIS EVI observation. The seasonal dynamics across the major land cover types, rice, sugar cane, cassava, deciduous, and evergreen forest sites were plotted and analyzed with MODIS, 1km resolution 16-day composite VI profiles for years 2001-06. Overall, temporal profiles of rice, sugar cane, cassava, and deciduous forest depicted dry-wet seasonal contrast strongly coupled with rainfall with a pronounced dry season and wet seasons (Figure 2). During the rainy season, May through October, high vegetation activity can be seen. For the dry-down phase of the dry season, November through April, EVI values decreased. However, differences in EVI seasonal profiles were apparent among evergreen forest and other land cover types (Figure 3). The evergreen forest showed the lowest seasonal contrast with high EVI values throughout the year. The green up occurred during the dry season (~ February) and reached the “green” peak of growing season in June-July. metrics were utilized to further filter and reduce cloud contaminated pixels. Vegetation seasonality was analyzed with 6-years (2001-06) of 16-day composite EVI time series at 1km
resolution (MOD13A2) over local sites, encompassing the rice fields, the sugar cane and cassava fields, and the deciduous and evergreen forests. Point-based long-term rainfall data over the region were collected from the Thai Meteorological
Department (http://www.tmd.go.th/). Monthly precipitation values for anomaly analyses were computed from 30-year stationary records. Satellite and rainfall data anomalies were analyzed using long-term point-based monthly and
annual rainfall records and year 2000-06 MODIS EVI data. Correlations of rainfall and EVI were analyzed using simple regression method.
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