Current updates of the water-vapor line list in HITRAN: A new “Diet” for air-broadened half-widths

The current edition of the HITRAN compilation employed a sophisticated algorithm for combining measurements available for the air-broadened half-widths of water-vapor absorption lines with theoretical values. Nevertheless, some of the values in the HITRAN database were found to be far from ideal, due to large dispersions that still exist in the experimental or theoretical methods. Therefore, new criteria were developed for introducing the best available air-broadened half-widths into HITRAN, based on physical principles and statistics. This update concerns the three most abundant isotopologues of water, with the values for H217O and H218O being the ones from analogous transitions of the principal isotopologues. The new parameters have been tested in different remote-sensing applications and improved constituent profiles were obtained. In total, air-broadened half-width values were updated for 11,787 transitions of water vapor in the HITRAN database (6789 for H216O, 2906 for H217O, and 2092 for H218O). Some additional updates to the water-vapor line list are also presented. The resultant file (01_hit06.par) was uploaded to the HITRAN website (http://www.cfa.harvard.edu/hitran/) in September 2006.