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Atlantic hurricanes and climate over the past 1,500 years


Hurricane Hugo, 1989. Charleston radar image courtesy of NOAA Hurricane Research Division
Hurricane Hugo, 1989. Charleston radar image courtesy of NOAA Hurricane Research Division
Atlantic hurricanes and climate over the past 1,500 years

Nature
Vol. 460, pp. 880-885, 13 August 2009
doi:10.1038/nature08219

Michael E. Mann1, Jonathan D. Woodruff2, Jeffrey P. Donnelly3, and Zhihua Zhang1
1 Department of Meteorology and Earth and Environmental Systems Institute, Pennsylvania State University, University Park, Pennsylvania 16802, USA
2 Department of Geosciences, University of Massachusetts, Amherst, Massachusetts 01003, USA
3 Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, USA.
ABSTRACT:
Atlantic tropical cyclone activity, as measured by annual storm counts, reached anomalous levels over the past decade. The short nature of the historical record and potential issues with its reliability in earlier decades, however, has prompted an ongoing debate regarding the reality and significance of the recent rise. Here we place recent activity in a longer-term context by comparing two independent estimates of tropical cyclone activity over the past 1,500 years. The first estimate is based on a composite of regional sedimentary evidence of landfalling hurricanes, while the second estimate uses a previously published statistical model of Atlantic tropical cyclone activity driven by proxy reconstructions of past climate changes. Both approaches yield consistent evidence of a peak in Atlantic tropical cyclone activity during medieval times (around AD 1000) followed by a subsequent lull in activity. The statistical model indicates that the medieval peak, which rivals or even exceeds (within uncertainties) recent levels of activity, results fromthe reinforcing effects of La-Niña-like climate conditions and relative tropical Atlantic warmth.
Download data from the WDC Paleo archive:
Description of Data Files and Matlab Code

Historical Tropical Cyclone (TC) counts:
TC counts. Columns [Year ] [Annual TC count] [Decadal Smoothed] [Multidecadal Smoothed]
Standard case [Mann et al '07 adjustments](1870-2006)
Alternative case [Landsea '07 adjustments](1870-2006)

Annual Instrumental Climate Series Used to Train Statistical Model:
SST Products. Columns [Year] [Blended SST] [HadISST_] [Kaplan] [NOAA ERSST]
MDR ASO SST (1870-2006) (anomalies relative to 1870-2006 mean)
Nino3 DJF (1870-2006, where year is 'D' in DJF) (anomalies relative to 1870-2006 mean)
NAO Series. Columns [Year] [Index Value (CRU NAO data)]
NAO DJFM (1870-2006, where year is 'D' in DJFM) (anomalies relative to 1951-1980 mean)

Decadally-Resolved Proxy Reconstructions Used in Statistical Model TC Predictions:
(anomalies relative to same base periods as above)
Proxy Reconstruction. Columns [Year] [Reconstructed Value] [-2 sigma limit] [+2 sigma limit]
MDR (AD 850-1850) [from ref. 17 of article, reconstruction was trained on modern HadCRU SST data]
Nino3 (AD 850-1850) [from ref. 17 of article, reconstruction was trained on modern HadCRU SST data]
NAO (AD 1500-1850) [from ref. 18 of article, Luterbacher proxy/historical winter NAO reconstruction]
Corresponding Instrumental Series. Columns [Year] [HadCRU MDR] [HadCRU Nino3] [Luterbacher+CRU NAO]
Decadal Instrumental Series shown in Fig 3 of paper [from ref.s 17 and 18 of article] (1851-2006)

Statistical Model Predictions of TC Past Activity:
Proxy-Driven Predictions. Columns [Year] [Predictions]
Standard case (uses Mann et al '07 adjustment of historical TC series) (AD 500-1850)
Alternative Case (uses Landsea '07 adjustment of historical TC series) (AD 500-1850)
Training Interval Fit. Columns [Year] [Annual] [Decadal Smoothed] [Multidecadal Smoothed]
Standard case (uses Mann et al '07 adjustment of historical TC series) (1870-2006)
Alternative case (uses Landsea '07 adjustment of historical TC series) (1870-2006)

Raw Individual Overwash Sediment Deposit Chronologies:
Event Chronologies. Columns [best estimate date] [-1 sigma age limit] [+1 sigma age limit]
Mattapoisett Marsh, MA (ref. 15 of article)
Succotash Marsh, RI (ref. 14 of article)
Alder Island, NY (ref. 9 of article)
Brigantine, NJ (ref. 13 of article)
Whale Beach, NJ (ref. 12 of article)
Singleton Swash, SC (ref. 8 of article; "oyster bed dates" AD 169, 652, 1283 not used - see article)
Western Lake, FL (ref. 11 of article)
Laguna Playa Grande Lake, Vieques, PR (ref.s 6,9,10 of article)

Regionally Composited Sediment Chronologies:
Event Chronologies. Columns [best estimate date] [-1 sigma age limit] [+1 sigma age limit]
New England U.S. Coast
Mid Atlantic U.S. Coast
Southeast U.S. Coast
Gulf U.S. Coast
Caribbean

Sediment-Based Basin-Wide Landfalling Hurricane Series and Jacknife Surrogates (see "Methods" for details):
Columns [Year] [Value] [Value w/out post 1700 Vieques] [j.k. surr1] [j.k. surr2] [j.k. surr3] [j.k.surr4] [j.k. surr5] Standard case (chronologies normalized, variable sensitivity assumed among sites)(AD 500-1991)
Alternative case (chronologies not normalized) (AD 500-1991)
Alternative case (uniform assumed sensitivity among sites) (AD 500-1991)
Alternative case (uniform weights on sites) (AD 500-1991)

Matlab Codes for Performing the Analyses Described in the Article:
Driver for overall analysis
Code to fit Poisson regression model and apply to proxy reconstructions to yield long-term TC reconstruction and associated standard errors
Code to compute ensemble of basin-wide landfalling hurricane series from sediment chronologies and their estimated age model uncertainties
Same as "MakeProxMC" but without New England records
Same as "MakeProxMC" but without Mid-Atlantic records
Same as "MakeProxMC" but without Southeast U.S. record
Same as "MakeProxMC" but without Gulf Coast record
Same as "MakeProxMC" but without Puerto Rico record
Same as "MakeProxMC" but without Puerto record after AD 1700
Code to compute Gaussian random deviates used by "StatModelPaleoTC.m"

Lowpass filtering codes used in various routines (based on Mann GRL '08):
Lowpass filter routine to approximately implement min norm/min slope/min roughness boundary constraints as described in manuscript
Lowpass filter routine to implement 'mean padded' boundary constraints as described in manuscript
Lowpass filter routine to implement 'adaptive' boundary constraints as described in manuscript
(minor errors fixed 9/2/08: (i) upper limit error bound too low; (ii) w3 could be chosen such that weights don't add to unity; under most circumstances-including the analyses in the manuscript--these errors do not influence results obtained, but they could under some circumstances)
Lowpass filter routine used for lower boundary constraint by 'lowpassadaptive'

To read or view the full study, please visit the Nature website.
It was published in Nature, Vol. 460, pp. 880-885, 13 August 2009
doi:10.1038/nature08219
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