10.25392/leicester.data.10298225.v1 Sadie E. Holmes Sadie E. Holmes Mapping of spatiotemporal changes across the East African Rift System to identify geothermal anomalies using MODIS land surface temperatures University of Leicester 2019 Thesis 2019-11-13 11:07:03 Thesis https://figshare.le.ac.uk/articles/thesis/Mapping_of_spatiotemporal_changes_across_the_East_African_Rift_System_to_identify_geothermal_anomalies_using_MODIS_land_surface_temperatures/10298225 <div>A range of satellite datasets, including MODIS land surface temperature (LST), are</div><div>used to identify geothermal anomalies associated with rift basins across the East African</div><div>Rift System. Monthly and yearly absolute LST means are generated from January 2003</div><div>to December 2013 and show regions of warmer LSTs in relevant basins. However,</div><div>without auxiliary data it is not possible to show that these are related to geothermal</div><div>anomalies. Two approaches are applied to delineate the LST more clearly - principal</div><div>component analysis (PCA) and normalisation of the LST with respect to elevation. The</div><div>first technique uses PCA to delineate the known physical parameters influencing LST</div><div>and reveals elevation to be dominant. Consequently, steps have been taken to minimise</div><div>the effects on LST. This has been achieved via normalisation, whereby absolute LST is</div><div>recalculated, using linear regression analysis, to equivalent normalised LST at an</div><div>elevation of 0 m. Several previously masked areas, including the Ethiopian Dome, have</div><div>since been revealed as warmer and with an increased likelihood of relationship to</div><div>geothermal heat flux since they correspond to emissivity and tectonic patterns. Note the</div><div>impressive manner in which volcanoes including Mount Elgon, cold in absolute LST</div><div>because of elevation, are also identified as warmer post normalisation. Caution must</div><div>still be exercised with respect to the warm anomalies in normalised LST, as these can</div><div>still not be conclusively confirmed as geothermal anomalies. A restricted PCA of the</div><div>normalised LST shows that these are still sensitive to emissivity as expected but</div><div>particularly in a well-defined region around Lake Turkana. In conclusion, the likelihood</div><div>of identifying a geothermal anomaly is best associated with the normalised LST and</div><div>where high frequency spatial structure is observed. Identified regions should be checked</div><div>against the restricted PCA. Future work should incorporate the use of other indicators of</div><div>geothermal activity or heat flux to better identify the LST variance that corresponds to</div><div>geothermal anomalies.</div>