Related Research Areas
Atmospheric Composition

In situ solar radiation measurements are critical to NASA atmospheric composition research. Actinic flux drives the chemistry of the atmosphere, including the evolution of ozone, greenhouse gases and other trace constituents. This proposal seeks to enhance and maintain the accurate and reliable spectrally resolved actinic flux measurements provided by the Charged-coupled device Actinic Flux Spectroradiometer (CAFS) instruments. The measured flux is used to calculate photolysis frequencies and ozone columns. A collaborative proposal submitted by I. Petropavlovskikh seeks to enhance the previously developed CAFS derived ozone column algorithm, a very useful product for satellite ozone abundance validation under varying atmospheric conditions. The CAFS instruments have an excellent record of performance on the NASA AVE, PAVE, CR-AVE, TC-4 and ARCTAS missions. We propose to continue analysis of the TC4 and CR-AVE upper troposphere and tropopause region data sets. In particular, optimization of the ultraviolet data collection methods and analysis will improve the noise and accuracy of both photolysis frequency and ozone column calculations. Detailed intercomparisons with double monochromator systems and a radiative transfer model and examination of calibration sources will improve the accuracy and precision of all flux measurements. We intend to publish the conversion process from CAFS actinic flux measurements into photolysis frequencies and collaborate with colleagues on the chemical analysis and satellite validation activities. We also propose to continue development of the CAFS systems for the DC-8 and high altitude aircraft for future field campaigns, such as TC-4 Guam. Extending the wavelength range to approximately 680 nm could provide additional photolysis frequencies, while continuing to provide quality UV-B measurements. Temperature control and monitoring improvements for high altitude aircraft deployments will stabilize the spectrometer wavelength assignment. In-flight wavelength drift will be determined to confine the effects on overhead ozone and photolysis.

Project PI: Samuel Hall/NCAR

ML 019D,1850 Table Mesa Dr, Boulder, CO 80305

Phone: (303)497-1899

Fax: (303)497-1411



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Started: Aug 09, 2010

Last Activity: Dec 10, 2010


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