Understanding the Effect of Drought on Biogenic Isoprene and the Biosphere-Atmosphere-Chemistry Relationship with NASA GISS ModelE+MEGAN Simulations

Abstract:

Drought is a hydroclimatic extreme that causes perturbations to the terrestrial biosphere. As a stressor for vegetation, drought can induce changes to vegetative emissions known as BVOCs (Biogenic Volatile Organic Compounds). Biogenic isoprene represents about half of total BVOC emissions and is a precursor to ozone (O₃) and secondary organic aerosol (SOA), both of which are climate forcing species. In order to simulate isoprene during drought and the feedbacks associated with these complex BVOC-chemistry-climate interactions, we implemented the MEGAN3 (Model of Emissions of Gases and Aerosols from Nature) isoprene drought stress parameterization in NASA GISS (Goddard Institute of Space Studies) ModelE, a leading Earth System Model. New diagnostics are programmed into ModelE to allow for the evaluation of the algorithm’s performance and comparisons to limited isoprene flux measurements and satellite derived HCHO (formaldehyde) column. Offline and online drought stress simulations will be used to demonstrate the effect of the parameterization. With the improved isoprene emissions incorporated into ModelE, drought stress feedbacks onto O₃ and SOA will be explored.