Wednesday, 17 January 2007: 10:30 AM
When model results and observations disagree . . .
214A (Henry B. Gonzalez Convention Center)
There is stark disagreement between satellite retrieved and chemistry-transport model computed results for the seasonal variability of sea salt aerosol. In remote southern oceans (40šS to 60šS) where sea salt is by far the dominant aerosol species, chemistry-transport models predict the maximum aerosol optical depth to occur during local winter (JJA) when the surface winds are at their seasonal maximum. Meanwhile, satellite data products of aerosol optical depth from MODIS, MISR, AVRHRR, POLDER measurements all show the seasonal minimum aerosol optical depth as occurring during the June-July (winter) time period, contrary to model expectation. At issue are the basic physics of sea salt generation and unresolved problems with cloud screening, biased sampling, ocean albedo specification, and/or cloud contamination that could be common to all current retrievals of aerosol optical depth from satellite measurements.