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Climate-chemistry interactions observed from space

A major feedback between climate and atmospheric chemistry lies in the dependence of the biogenic emission fluxes into the atmosphere to the meteorology. Although the short-term response of biogenic fluxes to meteorological drivers is relatively well established, their long-term response is not yet assessed due to the lack of long-term observations of biogenic fluxes. In this study, and for the first time, the variability of hydrocarbon emission fluxes is assessed by using 11 years of spaceborne
formaldehyde data in combination with multi-year model simulations.
Biogenic volatile organic compounds (BVOCs) play a crucial role in the atmosphere as precursors of tropospheric ozone and aerosols in polluted environments. BVOCs play, therefore, a key role for air quality concerns and in our understanding of the climate system. Their emissions are strongly dependent on temperature, and are therefore expected to increase in response of climate change. This study addresses two fundamental questions: (i) Can we assess the long‐term response of biogenic fluxes to meteorology? (ii) Does a widely used biogenic emission model (MEGAN) provide reliable predictions of how those fluxes might respond to climate change? Analysis of a unique observation record of spaceborne formaldehyde data over 2005-2015 backed by multiyear simulations with the IMAGES atmospheric model reveals clear evidence that (i) the observed interannual variability is primarily driven by climate, (ii) the formaldehyde data record validates the long‐term response of biogenic emissions to climate variability predicted by the MEGAN state‐of‐science emission model, and (iii) the predicted biogenic emission trends appear consistent with the formaldehyde data record.

Trend

Fig. 1. Trends over 2005-2015 of (a) observed by the OMI satellite sensor and (b) modeled formaldehyde columns, (c, d) isoprene and monoterpenes, (e) temperature, and (f) solar radiation, from Stavrakou et al. Impact of short‐term climate variability on volatile organic compounds emissions assessed using OMI satellite formaldehyde observations, Geophys. Res. Lett., https://doi.org/10.1029/2018GL078676, 2018.