Better-than-new LIDAR provides 24/7 atmospheric aerosol data

Dec 08, 2009
Improved data processing from this Raman lidar is helping researchers better determine how aerosols affect cloud formation and climate. The instrument, at the Southern Great Plains site in Oklahoma, sits behind a domed vestibule (front) that protects it from the elements

(PhysOrg.com) -- A team of researchers from eight institutions led by Pacific Northwest National Laboratory has solved a software and hardware problem that had perplexed scientists studying atmospheric aerosols for climate research. Not only did they fix the problem, but the instrument now performs better than it did when it was new.

Getting accurate data is the cornerstone of making predictions about how the climate will change as concentrations continue to rise in the atmosphere. Much of the uncertainty in projections of global is due to the complexity of clouds, aerosols, and cloud-aerosol interactions and to the difficulty of incorporating this information into climate models. Aerosols, tiny particles suspended in the atmosphere, absorb and scatter sunlight, which can contribute to climate change. By calibrating all measurements to consistent standards, the data can help reduce scientific uncertainties in computer models used to simulate climate change.

A lidar, similar to a radar that calculates distances by bouncing sound off of objects, measures how light bounces off aerosols in the sky. An analysis of ground-based Raman lidar data from the Atmospheric Radiation Measurement (ARM) Climate Research Facility's Southern Great Plains site in Oklahoma showed that the lidar's aerosol measurements were off by 50 percent in 2003. Built 10 years earlier, this Raman lidar was designed to take measurements continuously, night and day. To fix the problem, researchers upgraded the electronics and other hardware. By 2005, the refurbished and upgraded Raman lidar was back in business. But when researchers investigated more data in 2006, the data still looked off compared to benchmark data collected by a NASA instrument known as the Ames Airborne Tracking Sunphotometer.

In order to make the data understandable, the researchers turned to the computer program that processed the raw signals. They knew what a portion of the data-water vapor-should look like after processing based on other instrument measurements. PNNL researcher Dr. Rob Newsom adjusted the signal processing algorithm for the Raman lidar data so that for a 6 months study period it produced the known water vapor results. Then he applied the corrected algorithm to the rest of the data. The new approach of doing the signal processing resulted in a significant improvement in the quality of the science data products. Rather than being off by 50 percent, the Raman lidar was within 8 percent of the airborne sunphotometer standard. Now, improved data collection processing for the Raman lidar will provide plenty of quality data to help determine how aerosols affect cloud formation and the energy balance from the sun.

More information: B. Schmid, C.J. Flynn, R.K. Newsom, D.D. Turner, R.A. Ferrare, M.F. Clayton, E. Andrews, J.A. Ogren, R.R. Johnson, P.B. Russell, W.J. Gore and R. Dominguez. August 2009. Validation of aerosol extinction and water vapor profiles from routine Atmospheric Radiation Measurement Program Climate Research Facility measurements, J. Geophys. Res., 114, D22207, doi:10.1029/2009JD012682, Nov. 28, 2009.

Provided by Pacific Northwest National Laboratory (news : web)

Explore further: Strong quake hits east Indonesia; no tsunami threat

add to favorites email to friend print save as pdf

Related Stories

Seeing clearly despite the clouds

Apr 18, 2008

Satellites taking atmospheric measurements might now be able to see blue skies as clearly as optimists do. Researchers have found a way to reduce cloud-induced glare when satellites measure blue skies on cloudy ...

NASA Satellites Will Reveal Secrets of Clouds and Aerosols

Sep 15, 2005

Two NASA satellites, planned for launch no earlier than Oct. 26, will give us a unique view of Earth's atmosphere. CloudSat and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) are undergoing final ...

NASA's CloudSat Spacecraft Arrives at Launch Site

May 17, 2005

A NASA spacecraft designed to reveal the inner secrets of Earth's clouds has arrived at Vandenberg Air Force Base, Calif., to begin final launch preparations. The CloudSat spacecraft arrived at Vandenberg fro ...

The insides of clouds may be the key to climate change

Feb 17, 2007

As climate change scientists develop ever more sophisticated climate models to project an expected path of temperature change, it is becoming increasingly important to include the effects of aerosols on clouds, according ...

Recommended for you

Strong quake hits east Indonesia; no tsunami threat

15 hours ago

A strong earthquake struck off the coast of eastern Indonesia on Sunday evening, but there were no immediate reports of injuries or damage, and authorities said there was no threat of a tsunami.

Scientists make strides in tsunami warning since 2004

Dec 19, 2014

The 2004 tsunami led to greater global cooperation and improved techniques for detecting waves that could reach faraway shores, even though scientists still cannot predict when an earthquake will strike.

Trade winds ventilate the tropical oceans

Dec 19, 2014

Long-term observations indicate that the oxygen minimum zones in the tropical oceans have expanded in recent decades. The reason is still unknown. Now scientists at the GEOMAR Helmholtz Centre for Ocean Research ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.