GACP Field Campaigns
Lidar IN-situ Comparison (LINC)
Objective 1 (technological):
Compare aerosol extinction and aerosol lidar ratio derived independently from horizontally-pointing lidar and calibrated in-situ measurements. Our hypothesis is that these independent methods respond to the same physical phenomena and accurately quantify those phenomena within well-understood experimental uncertainties. Our scientific methods will be capable of disproving this hypothesis if it is not correct. This experiment will constitute the first rigorous test of a hypothesis that is fundamental to the PICASSO-CENA strategy of using spaceborne lidar to better quantify direct aerosol radiative forcing.
Objective 2 (integrative):
Use the full data set acquired under objective one to address a variety of scientific issues related to aerosol radiative forcing at a polluted, regionally representative, mid-latitude site. While the data set will be limited in time, it will also be highly pedigreed in quality.
Experiment overview:
The field experiment will be conducted during late August and September of 1999 at the University of Illinois Bondville research station — the polluted, continental site within the NOAA/CMDL network of midlatitude aerosol research stations. The kernel of the experiment is a comparison of aerosol extinction coefficient and aerosol lidar ratio (ratio of extinction to 180-degree backscatter) as derived independently from (1) a horizontally pointing, ground-based, Micro-Pulsed Lidar (MPL) and (2) a suite of in-situ measurements including nephelometers (for scattering and 180-degree backscattering) and an absorption photometer. Many auxiliary measurements will be made to provide redundancy, to improve knowledge of various correction factors and their uncertainties, and to allow additional parameters relevant to aerosol direct climate forcing to be analyzed. To achieve the direct comparison between lidar and in-situ, the MPL will be sited several km from the station and pointed horizontally at the sample inlet of the BND station.
This experiment is funded under NASA Research Announcement 97-MTPE-16 in cooperation with NOAA/CMDL, the University of Washington, the University of Arizona, and the University of Illinois at Urbana-Champaign.
