June 5, 2017
Prof. Thian Yew Gan University of Alberta, Edmonton, Canada
Besides climate change impact to the hydrosphere, the cryosphere is also undergoing rapid changes during the 20th and the early 21st Century, such as significant retreat of glaciers worldwide; thinning of Arctic sea-ice extent and thickness by about 40% in late summer in recent decades; snow cover of the Northern Hemisphere decreased by about 10% in area since global observations by satellites began in the late 1960s; degradations of permafrost detected in some polar and sub-polar regions, and the total 20th Century global average sea level rise was about 0.17m. Possible implications to the future global cryosphere under the potential impact of climate change will be discussed.
Next, remote sensing is the collection of information about an object by a space platform, such as an orbiting satellite or an aircraft, without being in physical contact with the object, and the interpretation of information acquired. Given the high cost of ground measurements which are also time consuming and not practical in remote sites, there has been numerous large-scale, interdisciplinary monitoring of the environment across the world via remote observations acquired by satellites. Scientists utilize surface test sites involving land-based ship and aircraft observations to calibrate and to validate satellite sensors. The general principles behind image analysis, retrieval of certain spatial information from satellite data will be briefly discussed, and then various case studies will be presented. For example, retrieval of near surface soil moisture in central Alberta from RADARSAT-2 (microwave) and MODIS (visible bands) data using artificial intelligence techniques; Changes in snowpacks of North America detected from the Snow Water Equivalent data of SMMR and SSM/I Passive Microwave data; flood mapping of the Danube River at Romania using single and multi-date images from the ERS2-SAR sensor of European Space Agency; identifying the migration pattern, the erosion and accretion processes of the Jamuna River of Ganges Bhamaputra from Landsat-TM data; water quality monitoring (sea water turbidity) of the Ariake Sea of Japan by Landsat-TM data and field observation; developing a gross primary production model for coniferous forests of northeastern USA from MODIS data, and the gross primary production of deciduous forest of USA using remotely sensed radiation and ecosystem variables, will be presented.