Comparison of the sensitivity of surface downward longwave radiation to changes in water vapor at two high elevation sites

Yonghua Chen, Catherine M. Naud, Imtiaz Rangwala, Christopher C. Landry, James R. Miller

Research output: Contribution to journalReview articlepeer-review

7 Scopus citations


Among the potential reasons for enhanced warming rates in many high elevation regions is the nonlinear relationship between surface downward longwave radiation (DLR) and specific humidity (q). In this study we use ground-based observations at two neighboring high elevation sites in Southwestern Colorado that have different local topography and are 1.3 km apart horizontally and 348 m vertically. We examine the spatial consistency of the sensitivities (partial derivatives) of DLR with respect to changes in q, and the sensitivities are obtained from the Jacobian matrix of a neural network analysis. Although the relationship between DLR and q is the same at both sites, the sensitivities are higher when q is smaller, which occurs more frequently at the higher elevation site. There is a distinct hourly distribution in the sensitivities at both sites especially for high sensitivity cases, although the range is greater at the lower elevation site. The hourly distribution of the sensitivities relates to that of q. Under clear skies during daytime, q is similar between the two sites, however under cloudy skies or at night, it is not. This means that the DLR-q sensitivities are similar at the two sites during daytime but not at night, and care must be exercised when using data from one site to infer the impact of water vapor feedbacks at another site, particularly at night. Our analysis suggests that care should be exercised when using the lapse rate adjustment to infill high frequency data in a complex topographical region, particularly when one of the stations is subject to cold air pooling as found here.

Original languageEnglish (US)
Article number114015
JournalEnvironmental Research Letters
Issue number11
StatePublished - Nov 1 2014

All Science Journal Classification (ASJC) codes

  • Renewable Energy, Sustainability and the Environment
  • Environmental Science(all)
  • Public Health, Environmental and Occupational Health


  • climate change
  • cold air drainage
  • downward longwave radiation
  • elevatin dependent warming
  • mountain climate
  • sensitivity
  • water vapor feedback


Dive into the research topics of 'Comparison of the sensitivity of surface downward longwave radiation to changes in water vapor at two high elevation sites'. Together they form a unique fingerprint.

Cite this