NASA SBIR 01-II Solicitation


PROPOSAL NUMBER: E1.03-8641 (For NASA Use Only - Chron: 013358 )
PROPOSAL TITLE: In Situ Lidar for Cloud and Aerosol Radiation Sciences

The largest error source in validation of NASA's EOS satellite cloud products is the mismatch in sampling volumes between the remote sensors and the in situ cloud probes. The sampling error from the extrapolation of the in situ cloud probe measurement of a few cm3 to the remote sensing measurement of millions of m3 is very large because of the extreme variability of cloud density. The new in situ lidar built in Phase I and tested in cloud on a mountaintop measures the volumetric extinction coefficient in cloud volumes ranging from millions to billions of m3. The in situ lidar differs from a regular lidar in that inside an optically thick cloud the laser pulse is multiply scattered by cloud droplets and the signal measured by the detector is the number of photons returned as a function of time. The amplitude and shape of the returned pulse contain information about the cloud volumetric extinction coefficient at different spatial scales around the instrument and the distance to the cloud boundaries.

Phase I proof-of-concept tests conducted in cloud on a mountaintop demonstrated that the time-varying signal measured by the in situ lidar fit exactly the shape of the signal predicted by a physical model. The volumetric extinction coefficients measured over a period of several hours by the in situ lidar agreed in magnitude with local measurements using a cloud droplet probe, although as expected, there was considerable variability in the measurements. In Phase II we will build an airborne in situ lidar and install it on a Learjet research aircraft. The in situ lidar will be compared with microphysical measurements of cloud properties and cloud boundaries collected by the Learjet in various types of clouds.

The in situ lidar will play a critical role in validating remote measurements from both ground-based and spaceborne remote sensing instruments. It will be sought for several government field projects and international programs. The military can use the in situ lidar to measure visibility and cloud boundaries around aircraft carriers and in dense aerosol clouds on the battlefield. The ability of an in situ lidar to measure cloud boundaries will generate an application at uncontrolled airports that will increase aviation safety and provide a substantial commercial market. When the aircraft enters a low-lying fog on approach to landing, the visibility, which previously looked good from aloft, rapidly drops to a few hundred feet in the horizontal, often causing disorientation and disaster. An unattended in situ lidar will warn pilots through the automated weather observing system (AWOS).

NAME AND ADDRESS OF PRINCIPAL INVESTIGATOR (Name, Organization Name, Mail Address, City/State/Zip)
Paul Lawson
SPEC, Inc.
3022 Sterling Circle, Suite 200
Boulder , CO   80301 - 2388

NAME AND ADDRESS OF OFFEROR (Firm Name, Mail Address, City/State/Zip)
SPEC, Inc.
3022 Sterling Circle, Suite 200
Boulder , CO   80301 - 2388

Form Printed on 05-09-02 16:37