Regional Mapping and Monitoring Rice Production and Greenhouse Gas Emissions in Asia with PALSAR
William Salas(1), Nathan Torbick(1), Changsheng Li(2) and Xiangming Xiao(2)
(1) Applied Geosolutions, LLC, 87 Packers Falls Rd, Durham, NH 03824, United States
(2) University of New Hampshire, Morse Hall, Durham, NH 03824, United States
Rice paddy ecosystems are an important economic and environmental resource and thus it is important to build inventories of wetland extent and type. The role of rice paddies in regional biogeochemical cycling is poorly understood due to the lack of accurate estimates of rice paddy extent and characteristics such as the vegetation biomass, hydroperiod and redox state that drive the biogeochemical cycling and trace gas emissions. Remote sensing is a critical tool for building regionally consistent and spatially explicit rice paddy inventories, especially when spatially consistent datasets are frequently available and cover large areas.
While many studies have indicated that SAR is an ideal remote sensing technology for mapping rice paddy extent and biophysical characteristics (LAI, biomass), regional SAR applications have been hampered due to the lack of routine, extensive and well-timed acquisitions of SAR imagery. However, with the launch of JAXA’s ALOS platform with the Phased Array type L-band Synthetic Aperture Radar (PALSAR) regional acquisitions are not only possible, but part of the ALOS mission plan. As part of JAXA’s Kyoto and Carbon Initiative (K&CI), an acquisition strategy has been developed for Southeast Asia which includes ScanSAR data acquisitions every 46-days for regional mapping and characterization of wetlands, including rice cultivation. Adjacent acquisitions overlap 50%, so there will be 2 acquisitions every 46 days. Regional coverage of PALSAR data will be used to (a) map rice paddy extent, (b) map rice cropping intensity, (c) monitor rice biophysical attributes (e.g. aboveground biomass) and (d) monitor hydro-period of rice paddies. These PALSAR products will in turn be used with regional climate and soils databases to run the DNDC biogeochemical model to estimate methane and nitrous oxide emissions from rice paddies at national and continental scales. This paper will present results from site level work in China and Indonesia and future plans of this effort.