Sensitivity of isoprene emissions estimated using MEGAN to the time resolution of input climate data Lancaster Environment Centre, Lancaster University, LA1 4YQ, Lancaster, UK
Received: 02 October 2009 – Published in Atmos. Chem. Phys. Discuss.: 05 November 2009 Abstract. We evaluate the effect of varying the temporal resolution of the input
climate data on isoprene emission estimates generated by the community
emissions model MEGAN (Model of Emissions of Gases and Aerosols from Nature).
The estimated total global annual emissions of isoprene is reduced from
766 Tg y−1 when using hourly input data to 746 Tg y−1 (a reduction of
3%) for daily average input data and 711 Tg y−1 (down 7%) for
monthly average input data. The impact on a local scale can be more
significant with reductions of up to 55% at some locations when using
monthly average data compared with using hourly data. If the
daily and monthly average temperature data are
used without the imposition of a diurnal cycle the global emissions estimates
fall by 27–32%, and local annual emissions by up to 77%. A similar pattern
emerges if hourly isoprene fluxes are considered. In order to better simulate
and predict isoprene emission rates using MEGAN, we show it is necessary to
use temperature and radiation data resolved to one hour. Given the importance of
land-atmosphere interactions in the Earth system and the low computational
cost of the MEGAN algorithms, we recommend that chemistry-climate models and
the new generation of Earth system models input biogenic emissions at the
highest temporal resolution possible.
Revised: 14 January 2010 – Accepted: 25 January 2010 – Published: 03 February 2010
Citation: Ashworth, K., Wild, O., and Hewitt, C. N.: Sensitivity of isoprene emissions estimated using MEGAN to the time resolution of input climate data, Atmos. Chem. Phys., 10, 1193-1201, doi:10.5194/acp-10-1193-2010, 2010.