| Message: |
We recently completed a modeling study using ISCST3 for urban air toxics applications. It appears to handle near ground level area sources reasonably well, compared with monitoring data we have. ADMS and AERMOD are very limited for these types of applications, as ISCST3 contains numerous updates and advantages over AERMODs underlying ISC2 architecture. Keep in kind, I'm talking about 500-1000 area sources with nearly 1000 receptors. ADMS can't handle that many sources/receptors. I think AERMOD can BUT, ISCST3 has the SCIM option that allows the model to sample one hour of met data per day, then at user specified intervals thereafter (our case every 25 hours). This is meant for apps that use 5 years of met data. Urban air toxics applications would be darn near impossible on a "normal" computer if this option werent available (run times in the hundreds of hours). Using this option with 5 years of met data means that each hour of the day is sampled about 1800 times, which should pick up diurnal patterns.
This is important when accounting for wet and dry deposition.
When AERMOD gets final approval, I'm sure a lot of the algorithms in later versions of ISC3 will be updated in AERMOD. For point source type applications, I'd probably go with a different model, but for area source type (mobile source) emissions, I am impressed with the current version of ISCST3. Back to work..... |
