| PI Name: | Wynn Eberhard NOAA Environmental Technology Laboratory |
|---|---|
| Co-Investigators: | Graham Feingold Cooperative Institute for Research in Environmental Sciences |
| Proposal Title: | Aerosol Profiling and Closure Studies for ACE-Asia by Shipborne Scanning Lidar |
| Proposal Synopsis: | It is proposed to deploy the NOAA/ETL Depolarization and Backscatter Unattended Lidar (DABUL) on board the ACE-Asia research ship during the spring of 2001. DABUL is a compact, eye-safe system operating at 523 nm that has been deployed in numerous field experiments, including prior shipboard experiments (e.g. R/V Ron Brown in June-July 1999). It is housed in a weather-proof box and will include upgraded capability to point and scan at sea. DABUL will provide range-resolved backscatter and depolarization ratio at all altitudes in the troposphere when not blocked by clouds. These measurements will assist in tracking the Asian dust and pollution plumes and will provide a spatial context to the shipboard aerosol and path-integrated radiation measurements. Calibrated aerosol backscatter will be derived in post-processing, and aerosol extinction profiles will be obtained when feasible. These results and depolarization profiles will be archived for region-wide comparison with other lidars and other investigations. In-situ aerosol measurements will provide a valuable calibration point for the lidar observations. Closure experiments will be conducted by intercomparing a variety of aerosol-related measurements from different instruments. Results of these closure studies will assist in narrowing the uncertainty of aerosol radiative forcing. Closure studies will include: comparison of path-integrated aerosol optical depths from sunphotometers and radiometers with lidar derived optical depths and vertical profiles; comparison of observed lidar backscatter and extinction with that calculated from the aerosol properties measured in situ; and so forth. In addition to providing the context of the shipboard measurements and the opportunity for closure experiments, a number of other scientific objectives will be addressed: (a) DABUL's depolarization capabilities will be used to explore depolarization by Asian dust, continental pollution, and sea salt; (b) investigation of the effect of relative humidity on aerosol backscatter; (c) DABUL's ability to detect cloud occurrence and phase (water vs. ice), especially thin cirrus, will be valuable for interpreting surface radiation measurements and contribute to climatological data sets; (d) shallow scanning near the ocean surface will yield high resolution profiles of the near-surface backscatter which, together with horizontal wind measurements, will provide information on particle emissions from the sea-surface. These contextual, closure, and other scientific studies will be valuable for characterizing the aerosol properties and assessing their direct radiative forcing. |