date: Sun, 1 May 2005 21:23:55 +0200
from: Eystein Jansen <Eystein.Jansen@geo.uib.no>
subject: [Wg1-ar4-ch06] Fwd: Papers of potential interest to the AR4
to: wg1-ar4-ch06@joss.ucar.edu

<x-flowed>
>Envelope-to: eystein.jansen@geo.uib.no
>Date: Sun, 01 May 2005 01:10:03 -0500
>Subject: Papers of potential interest to the AR4
>From: Noah Diffenbaugh <diffenbaugh@purdue.edu>
>To: <jto@u.arizona.edu>, <eystein.jansen@geo.uib.no>
>CC: <ipcc-wg1@al.noaa.gov>
>
>Dear Drs Overpeck and Jansen:
>
>I have attached pdfs of 4 papers that may be of interest to the Paleoclimate
>chapter of the AR4.
>
>Thank you!
>Noah
>
>--------------------
>
>The papers are:
>
>Diffenbaugh, Noah S. and L.C. Sloan, Mid-Holocene orbital forcing of
>regional-scale climate: a case study of western North America using a
>high-resolution RCM, Journal of Climate, 17(15), 2927-2937, 2004.
>
>This study used a regional climate model to test the response of
>regional-scale climate processes to mid-Holocene orbital forcing. We found
>summer warming of 1 to 2.5 C over most of the western United States,
>suggesting that observed regional mid-Holocene temperature change can be
>explained by direct orbital forcing alone, independent of climate system
>feedbacks. In contrast, positive anomalies in mean annual P-E were in
>disagreement with proxy reconstructions from the Pacific coast, suggesting
>that direct orbital forcing of regional-scale atmospheric processes was not
>the sole influence shaping the mid-Holocene moisture record of the Pacific
>coast.
>
>
>Diffenbaugh, Noah S., J.L. Bell and L.C. Sloan, Simulated changes in extreme
>temperature and precipitation events at 6 ka, Palaeogeography,
>Palaeoclimatology, Palaeoecology, preliminarily accepted to special issue,
>December 2004.
>
>This study used a regional climate model to test the response of extreme
>climate events to mid-Holocence orbital forcing, using the western North
>America as a case study. We found that anomalies in annual extreme
>precipitation event frequency were mostly positive throughout the region, as
>were differences in extreme event contribution to total annual
>precipitation. We also found large positive anomalies in extreme hot events,
>with days in which the maximum daily temperature exceeded 32 C 24 % more
>frequent in the 6 ka integration and heat waves lasting up to 12 days
>longer. We propose that such changes in the frequency and duration of
>extreme climate events could have played a substantial role in shaping
>paleoclimate records from a variety of regions.
>
>
>Diffenbaugh, Noah S., L.C. Sloan and M.A. Snyder, Orbital suppression of
>wind driven upwelling in the California Current at 6 ka, Paleoceanography,
>18(2), 1051, 10.1019/2002PA000865, 2003.
>
>This study used a regional climate model to test the response of wind driven
>upwelling in the California Current to Mid Holocene orbital forcing. The
>seasonality of modern California Current wind driven coastal upwelling
>simulated by the RCM is in strong agreement with observational data.
>Further, we show that changes in the seasonality of solar insolation induced
>by mid-Holocene Milankovitch forcing decrease early and peak season coastal
>upwelling in the California Current, along with increasing late season
>coastal upwelling.  These results are in agreement with several marine and
>terrestrial proxies, suggesting that, relative to present, California
>Current activity during the mid-Holocene was characterized by a longer and
>less vigorous upwelling season, with decreased seasonal contrast.
>
>
>Diffenbaugh, Noah S. and L.C. Sloan, Global climate sensitivity to land
>surface change: The Mid Holocene revisited, Geophysical Research Letters,
>29(10), 1476, 10.1029/2002GL014880, 2002.
>
>This study tests the response of large-scale atmospheric processes to a
>global mid-Holocene vegetation distribution reconstructed from the fossil
>record.  Large areas of the globe showed statistically significant
>temperature sensitivity to these land surface changes, with the magnitude of
>the vegetation forcing equal to the magnitude of 6 ka orbital forcing,
>emphasizing the importance of accurate land surface distribution for both
>model validation and future climate prediction.
>
>--
>Dr. Noah S. Diffenbaugh
>Assistant Professor
>Department of Earth and Atmospheric Sciences
>550 Stadium Mall Drive
>Purdue University
>West Lafayette, IN, 47907-2051
>
>(765) 494-0754 (office)
>(765) 494-2434 (lab)
>(765) 496-1210 (fax)
>
>diffenbaugh@purdue.edu
>http://web.ics.purdue.edu/~ndiffenb
>
>
>
>
>


-- 
______________________________________________________________
Eystein Jansen
Professor/Director
Bjerknes Centre for Climate Research and
Dep. of Earth Science, Univ. of Bergen
Allgaten 55
N-5007 Bergen
NORWAY
e-mail: eystein.jansen@geo.uib.no  
Phone:	+47-55-583491  -  Home: +47-55-910661
Fax: 	+47-55-584330
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