A comprehensive emission inventory of biogenic volatile organic compounds in Europe: Improved seasonality and land-cover

by D. C. Oderbolz, S. Aksoyoglu, J. Keller, I. Barmpadimos, R. Steinbrecher, C. A. Skj??th, C. Pla??-D??lmer, A. S H Pr??v??t
Atmospheric Chemistry and Physics ()
Get full text at journal

Abstract

Biogenic volatile organic compounds (BVOC) emitted from vegetation are\nimportant for the formation of secondary pollutants such as ozone and\nsecondary organic aerosols (SOA) in the atmosphere. Therefore, BVOC\nemission are an important input for air quality models. To model these\nemissions with high spatial resolution, the accuracy of the underlying\nvegetation inventory is crucial. We present a BVOC emission model that\naccommodates different vegetation inventories and uses satellite-based\nmeasurements of greenness instead of pre-defined vegetation periods.\nThis approach to seasonality implicitly treats effects caused by water\nor nutrient availability, altitude and latitude on a plant stand.\nAdditionally, we test the influence of proposed seasonal variability in\nenzyme activity on BVOC emissions. In its present setup, the emission\nmodel calculates hourly emissions of isoprene, monoterpenes,\nsesquiterpenes and the oxygenated volatile organic compounds (OVOC)\nmethanol, formaldehyde, formic acid, ethanol, acetaldehyde, acetone and\nacetic acid. In this study, emissions based on three different\nvegetation inventories are compared with each other and diurnal and\nseasonal variations in Europe are investigated for the year 2006. Two of\nthese vegetation inventories require information on tree-cover as an\ninput. We compare three different land-cover inventories (USGS GLCC,\nGLC2000 and Globcover 2.2) with respect to tree-cover. The often-used\nUSGS GLCC land-cover inventory leads to a severe reduction of BVOC\nemissions due to a potential miss-attribution of broad-leaved trees and\nreduced tree-cover compared to the two other land-cover inventories. To\naccount for uncertainties in the land-cover classification, we introduce\nland-cover correction factors for each relevant land-use category to\nadjust the tree-cover. The results are very sensitive to these factors\nwithin the plausible range. For June 2006, total monthly BVOC emissions\ndecreased up to -27% with minimal and increased up to +71% with\nmaximal factors, while in January 2006, the changes in monthly BVOC\nemissions were -54 and +56% with minimal and maximal factors,\nrespectively. The new seasonality approach leads to a reduction in the\nannual emissions compared with non-adjusted data. The strongest\nreduction occurs in OVOC (up to -32%), the weakest in isoprene (as\nlittle as -19%). If also enzyme seasonality is taken into account,\nhowever, isoprene reacts with the steepest decrease of annual emissions,\nwhich are reduced by -44% to -49%, annual emissions of monoterpenes\nreduce between -30 and -35%. The sensitivity of the model to changes in\ntemperature depends on the climatic zone but not on the vegetation\ninventory. The sensitivity is higher for temperature increases of 3K\n(+31% to +64%) than decreases by the same amount (-20 to -35%). The\nclimatic zones ``Cold except summer{''} and ``arid{''} are most\nsensitive to temperature changes in January for isoprene and\nmonoterpenes, respectively, while in June, ``polar{''} is most sensitive\nto temperature for both isoprene and monoterpenes. Our model predicts\nthe oxygenated volatile organic compounds to be the most abundant\nfraction of the annual European emissions (3571-5328 Gg yr(-1)),\nfollowed by monoterpenes (2964-4124 Gg yr(-1)), isoprene (1450-2650 Gg\nyr(-1)) and sesquiterpenes (150-257 Gg yr(-1)).\nWe find regions with high isoprene emissions (most notably the Iberian\nPeninsula), but overall, oxygenated VOC dominate with 43-45% (depending\non the vegetation inventory) contribution to the total annual BVOC\nemissions in Europe. Isoprene contributes between 18-21 %, monoterpenes\n33-36% and sesquiterpenes contribute 1-2%. We compare the\nconcentrations of biogenic species simulated by an air quality model\nwith measurements of isoprene and monoterpenes in Hohenpeissenberg\n(Germany) for both summer and winter. The agreement between observed and\nmodelled concentrations is better in summer than in winter. This can\npartly be explained with the difficulty to model weather conditions in\nwinter accurately, but also with the increased anthropogenic influence\non the concentrations of BVOC compounds in winter. Our results suggest\nthat land-cover inventories used to derive tree-cover must be chosen\nwith care. Also, uncertainties in the classification of land-cover\npixels must be taken into account and remain high. This problem must be\naddressed together with the remote sensing community. Our new approach\nusing a greenness index for addressing seasonality of vegetation can be\nimplemented easily in existing models. The importance of OVOC for air\nquality should be more deeply addressed by future studies, especially in\nsmog chambers. Also, the fate of BVOC from the dominant region of the\nIberian Peninsula should be studied more in detail.

Cite this document (BETA)

Readership Statistics

17 Readers on Mendeley
by Discipline
 
47% Environmental Sciences
 
24% Earth Sciences
 
12% Biological Sciences
by Academic Status
 
41% Ph.D. Student
 
18% Post Doc
 
12% Student (Master)
by Country
 
6% United Kingdom

Tags

Sign up today - FREE

Mendeley saves you time finding and organizing research. Learn more

  • All your research in one place
  • Add and import papers easily
  • Access it anywhere, anytime

Start using Mendeley in seconds!

Sign up & Download

Already have an account? Sign in