Water Vapor Near-UV Absorption: Laboratory Spectrum, Field Evidence, and Atmospheric Impacts

Authors

Linsen Pei, Wadsworth Center, NYS Dept. of Health
Qilong Min, University at Albany, State University of New York
Yuyi Du, University at Albany, State University of New York
Zhechen Wang, Wadsworth Center, NYS Dept. of Health
Bangsheng Yin, University at Albany, State University of New YorkFollow
Kai Yang, University of MarylandFollow
Patrick Disterhoft, NOAA Earth System Research Laboratory
Thomas Pongetti, Jet Propulsion Laboratory
Lei Zhu, Wadsworth Center, NYS Dept. of Health and Dept. of Environmental Health Sciences, University at Albany, State University of New YorkFollow

Author ORCID Identifier

Lei Zhu: https://orcid.org/0000-0002-6916-1393

Document Type

Article

Publication Date

11-27-2019

Abstract

Absorption of solar radiation by water vapor in the near-UV region is a poorly-understood but important issue in atmospheric science. To better understand water vapor near-UV absorption, we constructed a cavity ring-down spectrometer with bandwidth of 5 cm^-1 (~0.05 nm) and obtained water vapor absorption cross-sections at 1 nm increments in the 290-350 nm region. Water vapor displays structured absorption over this range with maximum and minimum cross-sections of 8.4×10^-25 and 1.6×10^-25 cm²/molecule. Major water vapor absorption bands were observed at 293-295, 307-313, 319, 321-322, and 325 nm, with cross-section values higher than 4.0×10^-25 cm²/molecule. To obtain further insight into major water vapor absorption bands, we measured water vapor absorption cross-sections at 0.05 nm intervals in the 292-296, 306-314, and 317-326 nm region. Field UV residual spectra not only exhibited increased attenuation at higher atmospheric water vapor loadings but also showed structures suggested by the laboratory water vapor absorption spectrum. Spaceborne UV radiance spectra have spectral structures resembling the differential cross-section spectrum constructed from the laboratory wavelength-dependent water vapor absorption cross-sections presented here. Incorporating water vapor absorption cross-section data into a radiative transfer model yielded an estimated energy budget of 0.26 W/m² for the standard U.S. atmosphere and 0.76 W/m² for the tropics. This shows that water vapor near-UV absorption is an important contributor for climate simulation and ozone retrievals.

Comments

Publisher Acknowledgement:

This is the publisher's PDF. The version of record appears here: Pei, L., Min, Q., Du, Y., Wang, Z., Yin, B., Yang, K., et al. (2019). Water vapor near-UV absorption: Laboratory spectrum, field evidence, and atmospheric impacts. Journal of Geophysical Research: Atmospheres, 2019; 124: 14310– 14324. https://doi.org/10.1029/2019JD030724

Recommended Citation

Pei, Linsen; Min, Qilong; Du, Yuyi; Wang, Zhechen; Yin, Bangsheng; Yang, Kai; Disterhoft, Patrick; Pongetti, Thomas; and Zhu, Lei, "Water Vapor Near-UV Absorption: Laboratory Spectrum, Field Evidence, and Atmospheric Impacts" (2019). Environmental Health Sciences Faculty Scholarship. 4.
https://scholarsarchive.library.albany.edu/ehs_fac_scholar/4