This page's content is no longer actively maintained, but the material has been kept on-line for historical purposes.
The page may contain broken links or outdated information, and parts may not function in current web browsers.

GACP Projects

Preliminary Aerosol Climatology for the Pacific Boundary Layer and Free Troposphere

Antony D. Clarke, PI
Vladimir Kapustin, Co-PI
David Covert, Adjunct PI

Abstract: We propose to combine and interpret extensive aerosol size distribution data collected during the past decade around the Pacific Basin in order to develop a preliminary climatology of aerosol microphysics for the Pacific troposphere. This includes aircraft, ship and ground based data collected as part of our numerous field experiments supported by NASA, NOAA and NSF. Although these experiments frequently had diverse goals, most included extensive data on aerosol size distributions, optical properties (light scattering and light absorption) and chemistry. In general, only small portions of these data sets have been published with limited objectives in mind. We propose to assemble the aerosol data in order to provide spatial, temporal and regional characterization of aerosol fields over the North and South Pacific. Aircraft vertical profiles (about 100) of aerosol size distributions and light-scattering (often for both coarse and fine aerosol at 4 wavelengths) will be used to characterize vertical structure and to link it to concurrent satellite retrievals of column aerosol optical depth. Some airborne experiments (GLOBE, ACE1) also allow us to extend in-situ aerosol measurements in order to compare and interpret aerosol fields in the troposphere characterized concurrently by airborne lidar.

We propose to put our in-situ data in context and to identify links to regional meteorological regimes and processes. Size resolved aerosol types will include dust, pollution, sea-salt, sulfates and clean cloud-processed air. Characteristics will be identified that are associated with meteorological regimes in the Pacific such as the westerlies, subtropical trade-wind and equatorial regions. Interhemispheric differences will be identified as well as transitional boundaries established by the Intertropical Convergence Zones (ITCZ) and the South Pacific Convergence Zones (SPCZ). Aircraft data will extend this characterization to altitudes of 6 to 10km depending upon the specific flight missions over the Pacific (about 1 month each) that we have participated in (GLOBE1, GLOBE2, CPACE, ACE1, PEM-Tropics). Shipboard data for the marine boundary layer include more than 200 days at sea from our cruises during SAGA1, SAGA2, SAGA3, RITS88, RITS93, RITS94, ACE-1. We will focus on aerosol sizes of immediate consequence to radiative transfer (direct effect) but will also characterize smaller aerosol sizes whose behavior is often associated with the source, transport and removal of aerosol. We believe that this will help link regional aerosol characteristics to those processes that shape the size distribution as well as its optical properties. Regional aerosol size and optical parameters will be described suitable for modeling purposes and placed in a meteorological context. Thes will be made available both to NASA and/or as an accessible database on our website. Key observations and an overview paper would also be prepared.

Back to Individual Projects page