Trends in mid-latitude cyclone frequency and occurrence during fire season in the Northern Rockies: 1900-2004

UNCG Author/Contributor (non-UNCG co-authors, if there are any, appear on document)
Paul A. Knapp, Professor (Creator)
Institution
The University of North Carolina at Greensboro (UNCG )
Web Site: http://library.uncg.edu/

Abstract: We examined changes in the timing and frequency of major midlatitude cyclones (MLCs) during August through October for eight climate stations in the Northern Rockies from 1900-2004. As MLCs can effectively diminish fire activity through both cooler temperatures and higher humidity/precipitation, we also determined if area burned by wildfires from 1940-2004 was correlated with the timing and frequency of these events. Our results indicate that: (1) significant long-term trends in MLCs exist, as the timing of the first MLC has occurred later in the year during the past century, with a marked upward shift post-mid-1980s; (2) MLC frequency has significantly declined since 1900, with a pronounced decrease also beginning in the mid-1980s; (3) the relationships between the timing of the first MLC and frequency of MLCs with forest area burned are significant; and (4) mid-tropospheric ridging upstream from the Northern Rockies that blocks MLCs has become more pronounced. Copyright 2007 by the American Geophysical Union.

Additional Information

Publication
Geophysical Research Letters
Language: English
Date: 2007
Keywords
midlatitude cyclone frequency, Geography, Northern Rockies