Shaw, J. A., J. J. Bates, H. M. Zorn, and J. H. Churnside, 1999: Observations of downwelling infrared radiance at Mauna Loa, Hawaii during the 1997-1998 ENSO event. Geophys. Res. Lett., 26, 1727-1730.


Measurements of downwelling infrared spectral radiance at Mauna Loa, Hawaii during April and May of 1998 indicate unusually high infrared atmospheric transmittance. This is linked to large-scale drying of the upper troposphere and stratosphere in the subtropical Pacific, which appears to be associated with the extreme El Niño-Southern Oscillation (ENSO) event of 1997-1998. During the driest periods, transmission windows opened in the wavenumber range of 500-600 cm-1, a water vapor rotational band that normally has high opacity. These data demonstrate the potential value of long-term mountain-top measurements for monitoring upper tropospheric water vapor and for validating satellite measurements of upper-tropospheric water vapor.