Estimates of biogenic emissions using satellite observations and influence of isoprene emission on O 3 formation over the eastern United States

Abstract

A biogenic emissions model for isoprene, monoterpenes, and nitric oxide has been developed with algorithms that rely on normalized difference vegetative index values derived from satellite remote sensing data to infer leaf area index. The model obtains emission factors from the Biogenic Emission Inventory System (BEIS). This biogenic emissions model, combined with a dry deposition model, was applied with environmental variable values supplied by MM5 (the fifth-generation Mesoscale Model). The modeled temporal variations and spatial distributions of the surface emissions rates of isoprene, monoterpenes, and nitric oxide the eastern US agreed well with reported simulations, measurements, and inferences. Use of the satellite data generates considerable detail in the spatial patterns, high temporal resolution, and a smooth seasonal variation in the emission rates. The new biogenic emissions model was used with a photochemistry modeling system to infer ozone (O 3) concentrations in the lower troposphere above the eastern United States for a two-day case in July 1995, which had O 3 episodes studied previously by the Ozone Transport Assessment Group. Compared to the results from the OTAG application of BEIS2, the satellite-data-derived isoprene emissions were slightly lower in the northeastern United States, which resulted in smaller values of O 3 concentration and were 3–4 times higher in southeastern mixed forests, which had little impact on O 3 except near strong NO x emission sources.