Line mixing in self- and foreign-broadened water vapor at 6 μm

Line mixing has been measured for two pairs of transitions in the v(2) band of (H2O)-O-16. The rotational assignments of the four lines (in terms of the rotational quantum numbers J, K-a and K-c)are (a) two P branch lines: (1 0 1)<-(2 1 2) mixing with (2 1 2)<-(3 0 3) at 1539.061 and 1540.300 cm(-1), respectively; and (b) two R branch lines: (3 0 3)<-(2 1 2) mixing with (2 1 2)<-(1 0 1) at 1652.400 and 1653.267 cm(-1), respectively. Pressure broadening coefficients of H2O (halfwidths, pressure shifts and off-diagonal relaxation matrix elements) are reported for seven broadeners (self, H-2, He, CO2, N-2, O-2 and air) from retrievals performed by multispectrum fitting implemented with line mixing. The effect is largest for self- and H-2-broadening. (c) 2005 Elsevier B.V. All rights reserved.