Intra-event trends in stable isotopes: Exploring midlatitude precipitation using a vertically pointing micro rain radar

Research output: Contribution to journalArticle

Authors

External organisations

  • University of New South Wales (UNSW) Australia
  • NASA Goddard Space Flight Center

Abstract

Annual, monthly, and daily analyses of stable isotopes in precipitation are commonlymade worldwide, yet only a few studies have explored the variations occurring on short time scales within individual precipitation events, particularly at midlatitude locations. This study examines hydrogen isotope data from sequential, intra-event samples from 16 precipitation events during different seasons and a range of synoptic conditions over an 18-month period in Birmingham, United Kingdom. Precipitation events were observed simultaneously using a vertically pointing micro rain radar (MRR), which, for the first time at a midlatitude location, allowed high-resolution examination of themicrophysical characteristics (e.g., rain rate, fall velocity, and drop size distributions) thatmay influence the local isotopic composition of rainwater. The range in the hydrogen isotope ratio (δD, where Drefers to deuterium) in 242 samples during 16 eventswas from -87.0% to 19.2%, while the largest variation observed in a single event was 55.4%. In contrast to previous work, the results indicate that some midlatitude precipitation events do indeed show significant intra-event trends that are strongly influenced by precipitation processes and parameters such as rain rate, melting-level height, and droplet sizes. Inverse relationships between rain rate and isotopic composition are observed, representing an example of a local type of "amount effect," a still poorly understood process occurring at different scales. For these particular events, the mean d value may therefore not provide all the relevant information. This work has significance for the testing and development of isotopeenabled cloud-resolving models and land surface models at higher resolutions, and it provides improved insights into a range of environmental processes that are influenced by subsampled precipitation events.

Details

Original languageEnglish
Pages (from-to)194-213
Number of pages20
JournalJournal of Hydrometeorology
Volume16
Issue number1
Publication statusPublished - Feb 2015

Keywords

  • Hydrometeorology, Isotopic analysis, Radars/Radar observations

ASJC Scopus subject areas