NASA LaRC -- Atmospheric Sciences Division (ASD)

The Lidar Applications Group (LAG) is part of the Atmospheric Sciences Division at the NASA Langley Research
Center, Hampton, Virginia. Since 1978, the LAG has been developing and applying advanced lidar systems to a 
broad range of atmospheric investigations. These activities have included the development and application of 
airborne Differential Absorption Lidar (DIAL) systems for studies of O3, H2O, aerosols, and clouds.  During 
1980, the LAG made the first remote O3 and aerosol profile measurements with a DIAL system on an aircraft, 
and this lidar system was subsequently used in a joint NASA/EPA field program to study persistent elevated
pollution episodes.  In 1981, they obtained the first water vapor profiles in the troposphere with an airborne 
DIAL system. This system was used in a Gulf Stream field experiment with the Navy in 1982.  Many investigations 
of O3 and aerosols have been conducted with the airborne DIAL system over the last 13 years as part of NASA's 
Global Tropospheric Experiments (GTE).

The first international field experiment was conducted over the tropical Atlantic from Puerto Rico during 
1982-1983, and the first cross section of a tropopause fold event was obtained over the southwestern U.S. 
in 1984 (GTE/CITE-1).Airborne lidar investigations of O3 and aerosols have been conducted by the LAG from
Barbados in 1984 (GTE/ABLE-1) and in Brazil over the Amazon rain forest in the dry season of 1985 
(GTE/ABLE-2A) and the wet season of 1987 (GTE/ABLE-2B).  They have also conducted measurements over the 
tundra and ocean regions of the Arctic in 1988 (GTE/ABLE-3A); the boreal forests and lowland regions of 
northern Canada in 1990 (GTE/ABLE-3B); the western Pacific in the summer of 1991 (PEM-West A) and the winter
of 1994 (PEM-West B); and the tropical Atlantic from Brazil and Africa in 1992 (TRACE-A).  The investigations
conducted as part of the GTE field experiments focused on the chemistry and transport of O3 and aerosols in
various tropospheric environments.  The LAG has also participated in the NASA/NOAAAirborne Antarctic Ozone 
Experiment (AAOE) in 1987; the Airborne Arctic Stratospheric Expeditions in 1989 (AASE-I) and 1991/92 
(AASE-II); and the Tropical & VortexOzone Transport Experiment in 1995/96 (TOTE/VOTE).

An airborne DIAL system was developed in 1989 using an alexandrite laser for the measurement of water vapor 
in the middle to lower troposphere.  This system was flight tested several times during field experiments in
1990-1992and again in 1994, and accurate water vapor profile measurements were made from near the surface 
into the middle troposphere during the day and night under a wide variety of meteorological conditions.  The
first flight of the Laser Atmospheric Sensing Experiment (LASE) for autonomous DIAL water vapor and aerosols
measurements from an ER-2 aircraft was conducted in 1994, and the development and testing of LASE was 
completed in an extensive validation experiment conducted in 1995.

The Lidar Applications Group also participated in the development of the Lidar In-Space Technology Experiment(LITE),
which is an aerosol and cloud lidar system that flew on the Shuttle in 1994.  Correlative measurements for LITE were
made with several airborne lidar systems, and data were analyzed to obtain global information on tropospheric aerosols.
In addition, studies are being conducted of various advanced spaceborne DIAL systems.

These Lidar Applications Group activities have led to many journal/book publications.