Development of the Regional Oxidant Model version 2. 1. Interim report, January 1988-April 1989

This report describes improvements that were made to version 2.0 of the Regional Oxidant Model (ROM) in order to create version 2.1. The ROM is an Eulerian grid model that calculates hourly concentrations of ozone and other chemical species for episodes up to about a month long. The ROM's modeling domain, represented by a grid of cells that are approximately 19 km on a side, encompasses an area about 1000 by 1000 km. The physical processes that the ROM simulates include photochemistry, spatially- and temporally-varying wind fields, nocturnal jets and temperature inversions, terrain effects, dry deposition, and emissions of biogenic and anthropogenic ozone precursors. Major technical improvements include upgrading the Carbon Bond Mechanism to version 4.2, improving the biogenic emissions processor (which now includes a canopy model), updating the wind fields processor, and expanding the use of buoy data for determining meteorological data fields over water. Also, ROM 2.1 can be adapted more easily than version 2.0 to various modeling domains in eastern North America. In addition, the computer software was redesigned to facilitate ROM's eventual application by outside users.