ISSI-BJ Forum on Exploring Greenhouse Gases, Water and Climate Changes by LEO-LEO Occultation: Main Results and Next Steps
Presenter:
Gottfried Kirchengast (1,4)
(1) Wegener Center for Climate and Global Change (WEGC) and Institute for Geophysics, Astrophysics, and Meteorology/Institute of Physics, University of Graz, Graz, Austria; (4) JOAC–Joint Laboratory on Occultations for Atmosphere and Climate by NSSC and University of Graz
(2) Institute of Atmospheric Physics (IAP), Chinese Academy of Sciences, Beijing, China; (3) National Space Science Center (NSSC), Chinese Academy of Sciences, Beijing, China; (4) JOAC–Joint Laboratory on Occultations for Atmosphere and Climate by NSSC and University of Graz; (5) ESA–Future Missions & Instrument Division, Noordwijk, Netherlands; (6) Danish Meteorological Institute, Copenhagen, Denmark; (7) Massachusetts Institute of Technology (MIT), Cambridge, MA, USA; (8) International Space Science Institute-Beijing (ISSI-BJ), Beijing, China
Talk
Occultation between Low Earth Orbit satellites (LEO-LEO sounding) is a next-generation technique advancing on GNSS radio occultation by using centimeter-wave and possibly millimetre-wave signals (LEO-LEO microwave occultation, LMO) that can exploit both the refraction and absorption of the signals to solve the temperature-humidity ambiguity in the troposphere. Cloud liquid water and rain rate profiles as well as turbulence and complementary 3D cloud information can be co-observed. Additionally, LEO-LEO infrared-laser occultation (LIO), using short-wave infrared laser signals between LEO satellites, has been designed to accurately observe key greenhouse gases (e.g., H2O, CO2, CH4, N2O), line-of-sight wind speed, and also profiles of cloud layers and aerosols as by-products.
During the last decade, ESA and NASA have investigated several proposed LMO and LIO missions for exploring the water cycle, greenhouse gases, and climate change, and done many pre-studies. In China, an Atmosphere and Climate Explorers LABoratory (ACELAB) mission has been proposed to the Strategic Priority Research Program of the Chinese Academy of Sciences (SPRPCAS): a mission for benchmark monitoring of the Earth’s atmospheric thermodynamic variables, greenhouse gases and climate change by LMO, LIO and 3D clouds imaging from low Earth orbits.
Building on this status, a Forum workshop was recently funded and held on 24-26 July 2019 at ISSI-BJ, Beijing, China, convened by the authors of this presentation. The following main topics were discussed based on latest presentations: 1) key scientific questions and challenges on forcings and feedbacks in climate change and water cycle processes as relevant for LEO-LEO; 2) the scientific objectives and observation requirements of the ACELAB mission; 3) the LMO and LIO techniques in terms of principles, algorithms and payloads.
Here we report on the main results from these discussions, and the next steps that were identified, related in particular to foster the Chinese ACELAB mission: 1) Fundamental science questions and scientific objectives of the ACELAB mission, 2) Overall design and key technologies of the ACELAB mission, 3) International collaborations and other LEO-LEO missions in preparation. Overall this ISSI-BJ Forum was a vital event in support also of the goals and recommendations of the IROWG innovative techniques subgroup, and so the valuable contribution to this group’s activities will be highlighted as well.
Presentation in PDF:
