Pre-Aura Validation Campaign in Costa Rica Produces Key Results

Will climate change affect the tropical atmosphere? How will water vapor levels change in our atmosphere? Will rain rates increase? Will the upper atmosphere get wetter and cloud frequencies increase? These questions require both computer modeling of the atmosphere, and global measurements to test the accuracy of the models. Water vapor and ozone in the atmosphere are extremely important "greenhouse gases, but few measurements are actually available in the tropics. Researchers need high quality measurements around the equator to answer these key questions.

The NASA Pre-Aura Validation Experiment (AVE) recently flown in Costa Rica in January and February, 2004, has produced some key data about water and clouds in the tropics. New instruments (including a new balloon borne instrument) provided extremely high quality water observations in the tropics, and new insights into cloud formation in the tropical upper troposphere. Co-project scientists Dr. Paul A. Newman of NASA Goddard, and Dr. David Fahey of the NOAA Aeronomy Laboratory led the campaign.

The Pre-AVE campaign is a prelude to the future Aura Validation Experiment (AVE) that will be flown on NASA aircraft for validation of Aura instrument data. The Earth Observing System (EOS) Aura satellite is a NASA mission for studying the Earth's ozone layer, air quality and climate. NASA sponsors ground and aircraft campaigns to measure the same atmospheric gases that Aura will measure from space. These campaigns provide a ground-truthing or validation of the satellite observations and give researchers a higher degree of confidence in using Aura observations for science studies.

This field campaign showed that NASAs WB-57F aircraft is an excellent platform for the tropical upper troposphere and lower stratosphere, and that San Jose, Costa Rica is an ideal tropical site for observations," said Dr. Newman.

The Pre-AVE campaign enabled scientists to test fly aircraft instruments to make sure that their measurements are adequate for Aura validation. The campaign was designed to exercise the aircraft instruments and to test flight strategies for underflights of Aura after it is launched. Underflights happen when the aircraft flies directly below the path of the satellite. Dr. Leslie R. Lait of NASA GSFC used meteorological forecasts of air motions at altitudes from 20,000 to 65,000 feet to design flight tracks for the NASA WB-57F. These designer flight tracks provided a bigger bang for the buck, by directing the aircraft into air that was either extremely cold or possibly influenced by descent from the stratosphere into the troposphere.

There were three main goals at the outset of the Pre-AVE campaign. First, the researchers wanted to test Aura satellite validation concepts and show that they could provide high quality in-situ and remote data for gases and particles for the Aura satellite instruments. The team also wanted to characterize air in the upper troposphere that is transported to the lower stratosphere and is intimately involved in ozone depletion. Finally, they wanted to examine water vapor, particles and other gases in the tropics to gain insight into their relationships to climate change.

The campaign began on January 12, 2004 with the integration of 20 instruments onto the NASA WB-57F aircraft at NASA Johnson Space Centers Ellington Field. The first test flight of the full payload was flown on January 15, and two additional flights were flown on January 19 and 21 near the jet stream over the United States. The WB-57F reached altitudes over 60,000 feet on these flights, and made a number of measurements in the lower stratospheric ozone layer. On January 24, the WB-57F flew to San Jose, Costa Rica at 10N. The complement of 60 scientists accompanied the WB-57F in a U. S. Air Force C-5a cargo plane flown by members of the Texas Air National Guard. Following the arrival, 3 science flights were flown over the equator from San Jose on January 27, 29, and 30. The WB-57F and the C-5a concluded the campaign with their return to the United States on Monday, February 2.

Now that the Pre-Ave campaign has been completed, scientists are gearing up for the Aura Validation Experiment (AVE), a multi-year experiment that will be flown on NASA aircraft for validation after the Aura satellite is launched, currently scheduled for June 2004.

During the upcoming AVE campaign, a set of aircraft instruments will be flown approximately twice a year to provide a direct test of the Aura observations. These twice per year campaigns will be selectively flown on the NASA WB-57F, the NASA DC-8, and unpiloted robotic aircraft, and will be about 3 weeks in duration. The measurements from the aircraft will include common observations such as temperature, water vapor, and ozone, but will also include other more exotic observations such as nitric acid, methane, and sulfur hexafluoride. These atmospheric measurements will be used to validate Aura instrument measurements and will also be used to study the Earth's ozone layer, air quality and climate.

Key collaborations have been set-up between satellite instrument investigators and aircraft instrument teams. Furthermore, key collaborations have also been established with Costa Rican scientists for future tropical missions.

Contacts:

Cyntia M O'Carroll

Links:

For more information about the mission, please visit:

http://earthobservatory.nasa.gov/Newsroom/Campaigns/AVE_Mission.html

For information about Aura:

http://aura.gsfc.nasa.gov/