Proposal for Simultaneous Sea Surface Wind Speed and Water Vapor Observations by Spaceborne IPDA-DIAL

Water vapor data over the ocean is especially useful for numerical weather predictions of localized heavy rains and typhoons. We have proposed the spaceborne water vapor DIAL using the OPG/OPA transmitter with absorption lines in the 1350nm band and the IPDA-DIAL method to measure water vapor just above the sea surface. In this paper, we propose the IPDA-DIAL method with a smaller laser power and telescope aperture to provide flexibility in platform selection. Measurement error simulation results show that the IPDA-DIAL observes water vapor from sea level to an altitude of 600 m with an error of 7%. Furthermore, we proposed a method to simultaneously measure water vapor and wind speed over the sea surface by measuring the backscatter coefficient at the sea surface using the IPDA-DIAL. To confirm the usefulness of this method, wind speeds obtained using CALIPSO 1064nm sea surface backscatter coefficient data were validated for the ocean near a typhoon. This enables us to observe the latent and sensible heat fluxes over the ocean in a snapshot.