讲(jiang)座1：1.The BIOMASS mission: science background, mission concept and status
时间：2017 年 11 月 21日 15：00
讲座2：Measuring and correcting ionospheric effects in BIOMASS images
时间(jian)：2017 年(nian) 11 月 22日 14：00
讲(jiang)座(zuo)3.Calibration of the BIOMASS instrument
时间(jian)：2017 年(nian) 11 月 22日 15：30
1.The BIOMASS mission will launch in 2021 and will be the first P-band SAR in space, the first radar tomographic mission and the first systematic use of radar to measure forest biomass and height. This talk will present the scientific rationale for the mission and its wider societal significance. It will explain how the science requirements drive the design of the satellite and the orbit pattern and how these translate into mission phases. The role of polarimetry, polarimetric interferometry and tomography in meeting mission objectives will be explained, together with examples of these measurements from airborne campaigns. Methods of inverting the radar measurements to biomass, and how these relate to ground and airborne data will be described. Finally, BIOMASS will be placed in the context of the unprecedented range of satellites measuring forest properties that will be deployed within the next 5 years.
2.The BIOMASS mission will be strongly affected by the ionosphere through enhanced phase delays, Faraday rotation and phase scintillation, effects which are highly variable in space and time. The physical processes causing these effects and their variability will be described, and quantitative estimates of their magnitudes will be derived, based on simulated data. Methods to correct these effects will be explained, and it will be shown that these rely fundamentally on the ability to measure Faraday rotation. The accuracy of the corrections will be discussed and related to the accuracy requirements of BIOMASS. Measured examples of ionospheric effects occurring in ALOS PALSAR data will be presented and related to the analysis for BIOMASS.
3.Calibration of the BIOMASS instrument presents challenges never faced before because of the special issues associated with P-band measurements and the BIOMASS orbit pattern. A major problem for in-orbit antenna pattern measurement and calibration is identifying large scale stable distributed targets with sufficient SNR. For missions at shorter wavelengths (X-, C- and L-bands) the tropical rainforests constitute such targets but, since BIOMASS is specifically designed to measure variability in such forests, they are not suitable for this purpose. Deserts, icesheets and Permanent Point Scatterers are possibilities and an assessment of these types of targets will be presented. The special orbit pattern of BIOMASS means that the calibration transponder(s) will only be seen at intervals several months apart, so cannot be used for routine calibration and use of naturally occurring targets for polarimetric and radiometric calibration is highly desirable. Another important factor is that ionospheric effects affect radiometry and polarimetry and have to be dealt with in any calibration scheme. This affects both distributed target and transponder measurements. The special issues involved in solving the calibration equations using transponder measurements will be described.
Prof. Shaun Quegan (M’90) received the B.A. and M.Sc. degrees in mathematics from the University of Warwick, Coventry, U.K., in 1970 and 1972, respectively, and the Ph.D. degree from The University of Sheffield, Sheffield, U.K., in 1982. From 1982 to 1986, he was a Research Scientist with the Marconi Research Centre, Great Baddow, U.K., and led the Remote Sensing Applications Group from 1984 to 1986. He established the SAR Research Group at The University of Sheffield in 1986, whose success led to his professorship awarded in 1993. In the same year, he helped inaugurate the Sheffield Centre for Earth Observation Science, of which he remains the Director. In 2001, he became the Director of the Centre for Terrestrial Carbon Dynamics, U.K. National Environmental Research Council. This multi-institutional center is concerned with assimilating earth observation and other data into process models of the land component of the carbon cycle and now forms part of the U.K. National Centre for Earth Observation. His research interests include physics, systems, and data analysis aspects of radar remote sensing are now subsumed in the more general aim of exploiting many sorts of electro-optic technology to give greater quantitative understanding of the carbon cycle.