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SIZE DISTRIBUTION OF SEA-SALT EMISSIONS AS A FUNCTION OF RELATIVE HUMIDITY
Citation:
ZHANG, K. M., E. M. KNIPPING, A. S. WEXLER, P. BHAVE, AND G. S. TONNESEN. SIZE DISTRIBUTION OF SEA-SALT EMISSIONS AS A FUNCTION OF RELATIVE HUMIDITY. ATMOSPHERIC ENVIRONMENT. Elsevier Science Ltd, New York, NY, 39(18):3373-3379, (2005).
Impact/Purpose:
The objectives of this task are to continue development and improvement of EPA's mesoscale (regional through urban scale) air quality modeling systems, such as the Community Multiscale Air Quality (CMAQ) model, as air quality management and NAAQS implementation tools. This task focuses on needed research and development of air quality models targeted for a major CMAQ model release in FY08. Model development for a broad scope of application is envisioned. For example, CMAQ will need to be able to simulate air quality feedbacks to meteorology and climate as well as intercontinental transport. The 2008 release of CMAQ is timed to coincide with EPA/OAR's and the states' needs for an improved model for assessments of progress (mid-course corrections) in the post-SIP submittal timeframe.
Description:
This note presents a straightforward method to correct sea-salt-emission particle-size distributions according to local relative humidity. The proposed method covers a wide range of relative humidity (0.45 to 0.99) and its derivation incorporates recent laboratory results on sea-salt properties. The formulas are given as functions of relative humidity and compared with growth factors derived from earlier theoretical work. Application of this method to several common open-ocean and surf-zone sea-salt-particle source functions is described. The resulting sea-salt-emission aerosol distributions can be used directly in atmospheric model simulations without further correction.