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AeroCom wiki discussion entry

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AeroCom working group Air-Quality and HTAP coorperation

Participants for analysis

AeroCom model experiments for HTAP

As discussed during the 5th AeroCom workshop in Virginia Beach, October 2006, one of the activities in the second phase of AeroCom is to participate in the internationally coordinated multi-model studies of the Hemispheric Transport of Atmospheric Pollutants (HTAP). For background information, overview, and comprehensive description of the initial model experiments please go to http://aqm.jrc.it/HTAP. Here we focus on the sub-sets of experiments that are particularly relevant to the AeroCom models in addressing the issues of long-range transport of particulate matters (PM) and their impact on regional air quality. 1. Planned model experiments FIRST SET OF HTAP EXPERIMENTS: The initial HTAP experiments, set up in coordination with AeroCom, consist of two source-receptor experiments, SR1 (base run) and SR6 (perturbation run with 20% anthropogenic emissions in defined regions), and, as recommended addition one tracer experiment, TP1 (CO tracer). These experiments are described at the HTAP website. Registration is urgent and the experiments SR6 are expected for mid January. See for requirements http://aqm.jrc.it/HTAP. AeroCom suggests that biomass burning and wild fire emissions are not considered as anthropogenic for the purpose of setting up experiment SR6.

ADDITIONAL SET OF HTAP-AEROCOM EXPERIMENTS: In addition to the HTAP defined runs, AeroCom recommends three more perturbation runs. The first one is SR6z, in which anthropogenic emissions in specified pollution regions are turned off, put to zero, in order to assess the maximum impact of hemispheric transport of aerosols on regional air quality. (Note: a 20% reduction of anthropogenic emission specified in HTAP is most appropriate for ozone runs since the highly non-linear chemistry in ozone production would make the results from zeroing-out emission runs difficult to interpret.) AeroCom again suggests that biomass burning and wild fire emissions are not considered as anthropogenic for the purpose of setting up experiment SR6z.

The second one is SR6d, in which the dust emissions from major dust source region are turned off in order to estimate the impact of long-range transport of dust from a particular source region on air quality over land and on eco- system. Given the fact that long-range transport of dust is the most important mechanism for aerosol transport and the most visible from satellite data, this experiment is particularly relevant to HTAP even though most dust is from natural sources.

The third experiment is SR6b, in which emissions due to wild fires and biomass burning in the Northern Hemisphere are set to zero in three regions. The purpose of this experiment is to establish the contribution to background aerosol levels from natural and anthropogenic wild fires. Fire produced aerosols have particular potential of being long range transported.

We suggest as a deadline for submitting the additional experiments the 15th of April. Table 1 summarizes all experiments (high-lighted are the additional experiments). For the purpose of HTAP study, anthropogenic emissions are defined as all fossil and biofuel combustion, industrial, residential/commercial activities (including aircraft and shipping emissions), and agriculture activities. Wild fire and biomass burning emissions should at best correspond to the actual fire situation in the year of simulation. Note that modelers are encouraged to use the emissions of their choice.