The primary objective of this research is to support the airborne and satellite investigation of asian air quality (asia-AQ) science goals by deploying solar radiation measurement instrumentation on…

The University Corporation for Atmospheric Research (UCAR), operating as the National Center for Atmospheric Research (NCAR), received a $522,375 grant award from NASA to support the Airborne and Satellite Investigation of Asian Air Quality (ASIA-AQ) science campaign. The contract, designated 22-ASIAAQ22-0019, funds the deployment of Charge-Coupled Device Actinic Flux Spectroradiometers (CAFS) on the NASA DC-8 aircraft platform to measure spectrally resolved solar radiation and calculate photolysis frequencies for over 40 atmospherically important photodissociation reactions. These measurements are critical to understanding photochemical processes driven by actinic radiation and how they interact with complex aerosol fields and cloud dynamics over Asia, including emissions from megacities, industrial sources, biomass burning, and natural phenomena such as Gobi Desert dust and sea spray. The measurements have been identified as Priority 1 (Required) in NASA planning documentation for the campaign.

The grant, which commenced on May 1, 2023, with an ultimate completion date of April 30, 2026, is classified as a research grant with non-competitive pricing. Work will be performed at UCAR's primary facility in Boulder, Colorado. This award represents part of UCAR's substantial portfolio of federal research funding, particularly with NASA, and contributes to the broader atmospheric science research mission conducted through the organization's federally funded research and development center model sponsored by the National Science Foundation. No set-aside designation applies to this award.

The primary objective of this research is to support the airborne and satellite investigation of asian air quality (asia-AQ) science goals by deploying solar radiation measurement instrumentation on the NASA DC-8 platform for the determination of spectrally resolved actinic flux and calculation of photolysis frequencies. The charge-coupled device actinic flux spectroradiometers (cafs) measure spectrally resolved down- and up-welling in situ ultraviolet (UV) and visible actinic flux. Photolysis frequency products for over 40 atmospherically important photodissociation reactions include O3, NO2, CH2O, H2O2, hono, HNO2, HNO3, HO2NO2, N2O5, pan, CH3CH2ONO2, CH3CHO, CH3CH2CHO, chocho, CH3COCHO, CH3COCH3, CH3OOH, CH3ONO2, CH3COCH2CH2, CH3COCH2CH3, CH3CH2CH2CHO, BR2, BRO, BR2O, brcl, hobr, BRONO2, brono, BRNO2, CHBR3, CL2, CLO, CLNO2, and CLONO2. Species may be added or modified as necessary. Actinic flux radiation drives the chemistry of the atmosphere, including the evolution of ozone, biomass burning emissions, greenhouse gases, and other anthropogenic and natural trace constituents. The gases control the evolution of aerosols that, in turn, impact the actinic flux through radiative absorption and scattering. During asia-AQ the composition will consist of a mixture local and distant emissions from anthropogenic (megacities, industrial, shipping, etc.) and natural (forest, biomass burning, oceanic, mineral dust etc.) sources producing evolving intermediate chemistry as primary emissions are photo-oxidized. The radiative field will be driven by exceptionally strong and complex aerosol features (from e.g., secondary organic formation, gobi desert dust, biomass burning, sea spray, etc.) in combination with dynamical cloud fields. Thus, measurements of in situ solar radiation are critical to the photochemical research and are recognized as priority 1 (required) in the NASA planning documentation. The cafs instruments consist of separate hemispherical upward and downward facing optical sensors to remove the influence of the aircraft on the local radiation environment. UV-enhanced fiber optic cables connect the input optics to charge-coupled device detectors. The system exhibits excellent sensitivity from the UV into the visible, which allows rapid full spectral data acquisition times. The 1 HZ duty cycle will capture the rapidly changing environment expected during asia-AQ. Careful optical, sensitivity and spectroscopic calibration techniques and radiative transfer model comparisons improve the accuracy and precision of the flux. We propose extending the wavelength range to approximately 1000 NM to provide additional radiative capability while maintaining high quality UV-a and UV-b measurements. Cafs instruments have a successful heritage of radiation measurements during NASA atmospheric chemistry and satellite validation missions including AVE, pave, CR-AVE, TC-4, arctas, SEAC4RS, korusaq, atom and firex-AQ campaigns on the WB-57 and DC-8 platforms. Data from these campaigns are openly available and proven critical to NASA and community investigators in a wide range of peer reviewed publications. During asia-AQ we intend to collaborate with colleagues on chemical, aerosol and radiative analyses to publish results derived from this work.