2018 CAN Awards

PROJECT: Remote sensing of formaldehyde at northern high latitudes: Probing the chemical impacts of Arctic greening

PI: Jingqiu Mao, Assistant Professor, UAF

The Arctic (north of 65N) and boreal regions (between 45N and 65N) have undergone dramatic temperature and ecological changes over the past century and the rate of this change has accelerated in recent decades. Satellite observations of leaf area index (LAI) and normalized difference vegetation index (NDVI) suggest that northern high latitudes shows a significant trend of greening in the past three decades as a result of vegetation growth. A major unknown is how these changes will impact biosphere-atmosphere exchange and subsequently feedback on Arctic climate and air quality.

Formaldehyde (HCHO) serves as an important indicator of biogenic volatile organic compound (VOC) emissions on regional and global scales. HCHO column abundance can now be observed from space by several satellite-based sensors including OMI on Aura (2004-), GOME-2 on MetOp-A (2006-) and MetOp-B (2012-), OMPS on SUOMI-NPP (2011-) and JPSS-1 (2017-), and TROPOMI on Sentinel-5P (2017-). But there are large uncertainties and inconsistencies among these satellite sensors, due to instrument sensitivities, retrieval algorithms, timing of observation with respect to the diurnal cycle, and other factors. In this work, we use two ground-based instruments (Pandora and MAXDOAS for total column and vertical profiling, respectively), to provide validation of HCHO columns for these satellite sensors at northern high latitudes, with a major focus on boreal forest region. In collaboration with scientists from Harvard-Smithsonian Center for Astrophysics, we will establish a long-term record of HCHO column densities in Arctic and boreal region over the past twenty years. This will improve our understanding of biosphere-atmosphere exchange at high latitudes in past and future decades. Our main scientific questions include:

  1. Do ground-based measurements of HCHO agree with satellite-based observations? If not, how can we use ground-based measurements of HCHO column densities to improve satellite-based retrievals?
  2. Can we use ground-based and satellite-based measurements, together with chemical transport models, to estimate regional emissions of biogenic VOC in boreal and Arctic regions?
  3. Is there a long-term trend of HCHO column density in boreal region as a result of Arctic greening and warming? What is the impact of Arctic greening on air quality and atmospheric composition in Arctic?

By improving our understanding on biosphere-atmosphere exchange at northern high latitudes and their impact on climate and air quality, this work aims to make significant contributions to three key science questions in the Earth science program of Science Mission Directorate (SMD). They are: (1) How is the global Earth system changing? (2) What causes these changes in the Earth system? (3) How will the Earth system change in the future?

This work aligns well with NASA Pandora project and related satellite remote sensing research at NASA Goddard Space Flight Center. The Pandora project and associated networks are priorities of the NASA Tropospheric Composition Program within the Earth Science Division (ESD) of the Science Mission Directorate (SMD). With NASA Pandora instrument, we will join NASA’s emerging Pandora Global Network (PGN) and expand PGN’s ability to integrate air quality data across a larger, more global scale for future satellite validation. This works aligns well with Alaska NASA EPSCoR’s research priority: “Monitoring of environmental change, mapping and remote sensing, and hazard prediction and mitigation.” Given the lack of long-term observations in Arctic, we also hope to develop a long-term ground-based remote sensing site at UAF and surrounding areas in Alaska. Our ultimate goal is to make UAF a primary high-latitude gas and aerosol satellite validation site for NASA, ESA, and other space agencies.

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