EOS Validation Program

Institution: University of Massachusetts / Lowell
                    Olney Hall - DEEAS
                    265 Riverside Street, Room 301B
                    Lowell, MA 01854
Phone: (978) 934-3904
FAX: (978) 934-3069
E-mail: Robert_Gamache@uml.edu

February 2003
April 2004

This proposed theoretical study will update the molecular line shape parameters in the HITRAN compilation for water and methane in the spectral regions important for AIRS, TES and HIRDLS. To accomplish this, complex Robert-Bonamy formalism calculations of the line shape parameters at room temperature will be made and combined with new line shape measurements (obtained through other contracts). These data will be collected and merged into HITRAN format for water transitions between 600 and 3125 cm-1 and methane transitions between 1000 and 3200 cm-1. The goal will be to incorporate accurate line shape parameters into the HITRAN database for EOS tropospheric retrievals of these two molecular species. For air-broadening of water vapor the uncertainty of the CRB calculations is a factor of 3-5 times smaller than the uncertainty of the data currently on the HITRAN database. Our study will focus on air-, and self-broadening of water vapor, and air broadening of CH4. The calculations will yield the shape parameters for strong transitions to compare with measurement and for weak transitions that cannot be accurately measured. In addition the calculations will be made at a number of temperatures between 200 K and 450 K so that we may calibrate the temperature dependence of air-broadened water and methane line shape coefficients (widths and pressure-induced shifts in positions). These calculations will be merged with measurements when possible. These data will be analyzed to form empirical lists of width and shift coefficients as a function of rotational quantum numbers and the temperature dependence. These will be merged with published room temperature results for air- and self-broadened widths, line positions and intensities to obtain complete and accurate new compilations for water and nitrogen dioxide in the spectral intervals critical to AIRS, TES and HIRDLS. The new line shape parameters will be made available to L. Brown at the Jet Propulsion Laboratory to compare the quantum mechanical theory to the new measurements to be made with the FTS at Kitt Peak. The CRB data will be delivered to L. Rothman for addition to the HITRAN database.