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Characterization of the effects of climate variation on land surface temperature and soil moisture through stochastic analysis of long term SSM/I observations over the Tibetan plateau

Ofwono, Matthew (2010) Characterization of the effects of climate variation on land surface temperature and soil moisture through stochastic analysis of long term SSM/I observations over the Tibetan plateau.

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Abstract:This study evaluates the temporal and spatial variability in land surface temperature (LST) and soil moisture over the Tibetan Plateau (TP) in the past 2 decades (1988-2008). The LST and soil moisture time series were derived from brightness temperatures (TB) measured by the Special Sensor Microwave Imager (SSM/I). The retrieval is based on the �-� model, whereby the horizontally (H) and vertically (V) polarized 19 GHz TB are utilized for the simultaneous inversion of soil moisture and the transmissivity. Within this retrieval approach, the temperature of the emitting layer is estimated using the V-polarized 37 GHz channel. The comparison of the retrievals against a time series of LST and soil moisture measured over a period of 4-years gives an error of ±2.87 k and ±0.040 m3m-3 respectively. The western part of the TP is significantly colder than the eastern part due to a large elevation difference. The temporal variation of soil moisture over the TP follows the monsoon sequence. From November to March the soil moisture is almost zero. However as the monsoon season arrives in April the moisture content begin to rise reaching its maximum value by July and dissipates by October. Spatially, soil moisture is highest in the south and eastern parts of the TP. Image trend analysis revealed that, the entire TP experienced significant warming over the last two decades except the water bodies. However, the central TP experienced more significant positive trend in LST anomalies. A similar trend is observed over scattered areas in the east and northern part of TP, while the south and south eastern part of the TP experienced the least changes in temperature anomalies. The magnitude of warming over the TP is in the range of 0.2oC to 1.1oC/decade. Warming was more paramount at elevations over 3000m above sea level compared to areas with elevation below 3000m above sea level. The western and northern part of the TP experienced an increasing significant trend in mean annual soil moisture anomalies. While the eastern and south eastern part of the TP showed no trend in soil moisture anomalies. The soil moisture anomalies over the TP increased at the rate of 0.03 to 0.13% (volume/volume) per year. The annual trend was highest during the summer monsoon season than during the winter season.
Item Type:Essay (Master)
Faculty:ITC: Faculty of Geo-information Science and Earth Observation
Programme:Geoinformation Science and Earth Observation MSc (75014)
Link to this item:https://purl.utwente.nl/essays/92336
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