DOI: 10.25921/1t83-ag29
title: NOAA/WDS Paleoclimatology - Atlantic Tropical Cyclone Reconstructions for the Past 1500 Years

description: 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 from the reinforcing effects of La-Nina-like climate conditions and relative tropical Atlantic warmth.
description: Supplemental Information for Mann et al (2009) Nature  

Historical Tropical Cyclone (TC) counts
TC counts [Year | Annual | Decadal Smoothed| Multidecadal Smoothed]

Standard case [Mann et al '07 adjustments](1870-2006), file TC.dat
Alternative case [Landsea '07 adjustments](1870-2006), file TCLandsea.dat

 
Annual Instrumental Climate Series Used to Train Statistical Model
SST Products [Year | Blended | HadISST_ | Kaplan | NOAA ERSST] 

MDR ASO SST (1870-2006) (anomalies relative to 1870-2006 mean), file mdr.dat

Nino3  DJF (1870-2006, where year is 'D' in DJF) (anomalies relative to 
1870-2006 mean), file nino3.dat

NAO Series [Year | Index Value (CRU NAO data)] NAO DJFM (1870-2006, 
where year is 'D' in DJFM) (anomalies relative to 1951-1980 mean), file nao.dat


Decadally-Resolved Proxy Reconstructions Used in Statistical Model TC Predictions  
(anomalies relative to same base periods as above)

Proxy Reconstruction [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], file mdrrecon.dat

Nino3 (AD 850-1850) [from ref. 17 of article, reconstruction  was trained on modern 
HadCRU SST data], file ninorecon.dat

NAO (AD 1500-1850) [from ref. 18 of article, Luterbacher proxy/historical winter 
NAO reconstruction], file naorecon.dat

Corresponding Instrumental Series [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), file instrdec.dat


Statistical Model Predictions of TC Past Activity 
Proxy-Driven Predictions [Year | Predictions ]
Standard case (uses Mann et al ’07 adjustment of  historical TC series) (AD 500-1850), 
file TCStatModelRecon.dat

Alternative Case (uses Landsea ‘07 adjustment of  historical TC series) (AD 500-1850), 
file TCStatModelReconLandsea.dat

Training Interval Fit [Year | Annual | Decadal Smoothed | Multidecadal Smoothed]
Standard case (uses Mann et al ’07 adjustment of  historical TC series) (1870-2006),
file TCStatModel.dat

Alternative case (uses Landsea ‘07 adjustment of  historical TC series)  (1870-2006),
file TCStatModelLandsea.dat



Raw Individual Overwash Sediment Deposit Chronologies
Event Chronologies [ best estimate date | -1 sigma age limit | +1 sigma age limit]

Mattapoisett Marsh, MA (ref. 15 of article), file MAmatta.dat
Succotash Marsh, RI (ref. 14 of article), file RIsucc.dat
Alder Island, NY  (ref. 9 of article), file NYAlder.dat
Brigantine, NJ (ref. 13 of article), file NJBrig.dat
Whale Beach, NJ (ref. 12 of article), file NJWhale.dat
Singleton Swash, SC (ref. 8 of article; "oyster bed dates" AD 169, 652, 1283 
not used-see article), file SCSingleton.dat
Western Lake, FL (ref. 11 of article), file FLWestern.dat
Laguna Playa Grande Lake, Vieques, PR (ref.s 6,9,10 of article), file PRVieques.dat
 

Regionally Composited Sediment Chronologies
Event Chronologies [ best estimate date | -1 sigma age limit | +1 sigma age limit]

New England U.S. Coast, file NewEng.dat
Mid Atlantic U.S. Coast, file MidAtl.dat
Southeast U.S. Coast, file Southeast.dat
Gulf U.S. Coast, file Gulf.dat
Caribbean, file Caribbean.dat
 

Sediment-Based Basin-Wide Landfalling Hurricane Series and Jacknife Surrogates 
(see "Methods" for details)

Series [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), file TCoverwash.dat

Alternative case (chronologies not normalized) (AD 500-1991), 
file TCoverwashUnNorm.dat

Alternative case (uniform assumed sensitivity among sites) (AD 500-1991), 
file TCoverwashUniformPeriod.dat

Alternative case (uniform  weights on sites) (AD 500-1991), 
file TCoverwashUniformWeights.dat

 

Matlab© Codes for Performing the Analyses Described in the Article

Driver for overall analysis, file PaleoTC.m

Code to fit Poisson regression model and apply to proxy reconstructions to yield 
long-term TC reconstruction and associated standard errors, file StatModelPaleoTC.m

Code to compute ensemble of  basin-wide landfalling hurricane series from sediment 
chronologies and their estimated age model uncertainties, file MakeProxMC.m

Same as "MakeProxMC" but without New England records, file MakeProxMCNoNE.m
Same as "MakeProxMC" but without Mid-Atlantic records, file MakeProxMCNoMidAtl.m
Same as "MakeProxMC" but without Southeast U.S. record, file MakeProxMCNoSC.m
Same as "MakeProxMC" but without Gulf Coast record, file MakeProxMCNoGulf.m
Same as "MakeProxMC" but without Puerto Rico record, file MakeProxMCNoPR.m
Same as "MakeproxMC" but without Puerto record after AD 1700, file MakeProxMCNoPRRecent.m

Code to compute Gaussian random deviates used by "StatModelPaleoTC.m", file gasdev.m



Lowpass filtering codes used in various routines from Mann GRL '08 

Note that the access to ©Matlab ‘signal’ toolkit is required

Lowpass filter routine to approximately implement min norm/min slope/min roughness 
boundary constraints as described in manuscript, file lowpass.m

Lowpass filter routine to implement 'mean padded' boundary constraints 
as described in manuscript, file lowpassmeanpad.m

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), 
file lowpassadaptive.m

Lowpass filter routine used for lower boundary constraint by 'lowpassadaptive', 
file lowpassmin.m