Global distribution and characteristics of diurnally varying low-level jets

AMS Citation:
Rife, D. L., J. Pinto, A. J. Monaghan, C. A. Davis, and J. R. Hannan, 2010: Global distribution and characteristics of diurnally varying low-level jets. Journal of Climate, 23, 5041-5064, doi:10.1175/2010JCLI3514.1.
Date:2010-10-26
Resource Type:article
Title:Global distribution and characteristics of diurnally varying low-level jets
Abstract: This study documents the global distribution and characteristics of diurnally varying low-level jets (LLJs), including their horizontal, vertical, and temporal structure, with a special emphasis on highlighting the underlying commonalities and unique qualities of the various nocturnal jets. Two tools are developed to accomplish this goal. The first is a 21-yr global reanalysis performed with the fifth-generation Pennsylvania State University-NCAR Mesoscale Model (MM5) using a horizontal grid spacing of 40 km. A unique characteristic of the reanalysis is the availability of hourly three-dimensional output, which permits the full diurnal cycle to be analyzed. Furthermore, the horizontal grid spacing of 40 km better resolves many physiographic features that host LLJs than other widely used global reanalyses. This makes possible a detailed examination of the systematic onset and cessation of the jets, including time-height representations of the diurnal cycle. The second tool is an index of nocturnal LLJ (NLLJ) activity based upon the vertical structure of the wind€™s temporal variation, where the temporal variation is defined in local time. The first available objectively constructed global maps of recurring NLLJs are created from this index, where the various NLLJs can be simultaneously viewed at or near their peak time. These maps not only highlight all of the locations where NLLJs are known to recur, but they also reveal a number of new jets. The authors examine the basic mechanisms that give rise to the NLLJs identified in four disparate locations, each having a profound influence on the regional climate. The first, the extensively studied Great Plains NLLJ, is used to confirm the veracity of the global analysis and the index of NLLJ activity. It also provides context for three of the many newly identified NLLJs: 1) Tarim Pendi in northwest China; 2) Ethiopia in eastern Africa; and 3) Namibia-Angola in southwest Africa. Jets in these four regions illustrate the variety of physiographic and thermal forcing mechanisms that can produce NLLJs.
Peer Review:Refereed
Copyright Information:Copyright 2010 American Meteorological Society (AMS). Permission to use figures, tables, and brief excerpts from this work in scientific and educational works is hereby granted provided that the source is acknowledged. Any use of material in this work that is determined to be "fair use" under Section 107 or that satisfies the conditions specified in Section 108 of the U.S. Copyright Law (17 USC, as revised by P.L. 94-553) does not require the Society's permission. Republication, systematic reproduction, posting in electronic form on servers, or other uses of this material, except as exempted by the above statements, requires written permission or license from the AMS. Additional details are provided in the AMS Copyright Policies, available from the AMS at 617-227-2425 or amspubs@ametsoc.org. Permission to place a copy of this work on this server has been provided by the AMS. The AMS does not guarantee that the copy provided here is an accurate copy of the published work.
OpenSky citable URL: ark:/85065/d7n87c2w
Publisher's Version: 10.1175/2010JCLI3514.1
Author(s):
  • D. Rife - NCAR/UCAR
  • James Pinto - NCAR/UCAR
  • A. Monaghan - NCAR/UCAR
  • Christopher Davis - NCAR/UCAR
  • J. Hannan
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