Changes of wind waves in the North Atlantic over the last 30 years

In order to evaluate long-term climatic changes in wind wave height, visual wave estimates available from the Comprehensive Ocean–Atmosphere Data Set (GOADS) were updated for the period from 1964 to 1993. Analysis of the accuracy of visual estimates shows that observations from merchant ships can be used for the study of climate changes in storminess. Climate changes obtained in significant wave height, computed on the basis of the voluntary observed data, are quite consistent with those shown by the instrumental records at OWS L, Seven Stones Light Vessel and NDBC buoys. The linear trends in significant wave height, as well as in the wind sea and swell heights, were computed for the entire North Atlantic. Significant wave height increases of 10–30 cm/decade over the whole of the North Atlantic, except for the western and central subtropics were found. Changes in the swell height are very consistent with those seen in significant wave height. Nevertheless, wind sea indicates strong upward tendencies only in the central mid-latitudinal North Atlantic and does not show any significant trends in the Northeast Atlantic, where instrumental records of Bacon and Carter report secular changes of about 1% a year. Wind waves of smaller occurrences show significantly negative changes in the Northeast Atlantic; that is in agreement with the wind sea periods changes. Possible mechanisms driving the swell changes with no pronounced increase of the sea height and wind velocity are discussed. Changes in the intensities of intramonthly variability in different synoptic ranges are considered as the major agent of the increasing swell. The conclusion is made that the upward swell changes are driven by the intensification of high frequency synoptic processes. Copyright © 1999 Royal Meteorological Society

[1]  D.J.T. Carter,et al.  Prediction of wave height and period for a constant wind velocity using the JONSWAP results , 1982 .

[2]  H. Storch,et al.  Changing statistics of storms in the North Atlantic , 1993 .

[3]  C. E. Leith,et al.  The Standard Error of Time-Average Estimates of Climatic Means , 1973 .

[4]  L. Hasse,et al.  North Atlantic Wind Waves and Wind Stress Fields from Voluntary Observing Ship Data , 1998 .

[5]  D. Cayan.  Variability of latent and sensible heat fluxes estimated using bulk formulae , 1992 .

[6]  K. Ueno.  Inter-annual variability of surface cyclone tracks, atmospheric circulation patterns, and precipitation patterns, in winter , 1993 .

[7]  M. Earle,et al.  A study of differences between environmental reports by ships in the voluntary observing program and measurements from NOAA buoys , 1990 .

[8]  S. Bacon,et al.  A connection between mean wave height and atmospheric pressure gradient in the North Atlantic , 1993 .

[9]  L. Draper,et al.  Has the north-east Atlantic become rougher? , 1988, Nature.

[10]  J. Hurrell.  Decadal Trends in the North Atlantic Oscillation: Regional Temperatures and Precipitation , 1995, Science.

[11]  Elizabeth C. Kent,et al.  A New Global Air-Sea Heat and Momentum Flux Climatology , 1999 .

[12]  H. Mächel,et al.  Water vapour as an amplifier of the greenhouse effect: new aspects , 1992 .

[13]  B. Weare.  Uncertainties in estimates of surface heat fluxes derived from marine reports over the tropical and subtropical oceans , 1989 .

[14]  A. Carleton.  Meridional Transport of Eddy Sensible Heat in Winters Marked by Extremes of the North Atlantic Oscillation, 1948/49–1979/80 , 1988 .

[15]  F. Ayrault,et al.  North Atlantic ultra high frequency variability : an introductory survey , 1995 .

[16]  N. Hogben,et al.  Ocean Wave Statistics , 1975, Journal of Navigation.

[17]  M. Donelan,et al.  Dynamics and Modelling of Ocean Waves , 1994 .

[18]  H. Storch,et al.  German Bight storms analysed , 1993, Nature.

[19]  V. Cardone,et al.  The Recent Increase in North Atlantic Wave Heights , 1997 .

[20]  C. Duchon.  Lanczos Filtering in One and Two Dimensions , 1979 .

[21]  C. S. Ramage.  Can Shipboard Measurements Reveal Secular Changes in Tropical Air–Sea Heat Flux? , 1984 .

[22]  P. D. Cotton,et al.  Cross calibration of TOPEX, ERS‐I, and Geosat wave heights , 1994 .

[23]  Comparison of COADS Release 1a Winds with Instrumental Measurements in the Northwest Atlantic , 1999 .

[24]  J. Rogers.  The Association between the North Atlantic Oscillation and the Southern Oscillation in the Northern Hemisphere , 1984 .

[25]  Transient Eddy Forcing of the Rotational Flow during Northern Winter , 1995 .

[26]  C. G. Korevaar.  North Sea Climate , 1990 .

[27]  A. K. Laing.  An Assessment of Wave Observations from Ships in Southern Oceans , 1985 .

[28]  G. Bigg.  Comparison of coastal wind and pressure trends over the tropical atlantic: 1946 1987 , 1993 .

[29]  N. Hogben,et al.  Assessment Of A New Global Capacity For Wave Climate Synthesis , 1983, Proceedings OCEANS '83.

[30]  L. Hasse,et al.  Climatological fluxes at the sea surface , 1996 .

[31]  Hans von Storch,et al.  The Atmospheric Circulation and Sea Surface Temperature in the North Atlantic Area in Winter: Their Interaction and Relevance for Iberian Precipitation , 1992 .

[32]  N Hogben,et al.  Increases in wave heights over the North Atlantic: a review of the evidence and some implications for the naval architect , 1994 .

[33]  Peter G. Challenor,et al.  Joint distributions of wave height and period: A critical comparison , 1987 .

[34]  A. Hense,et al.  A reconstructed time series of the number of extreme low pressure events since 1880;Die Rekonstruktion einer Reihe über die Anzahl extrem tiefer Druckereignisse seit 1880 , 1994 .

[35]  Elizabeth C. Kent,et al.  Choice of a Beaufort Equivalent Scale , 1997 .

[36]  C. Lanczos.  Applied Analysis , 1961 .

[37]  J. Hurrell.  Influence of variations in extratropical wintertime teleconnections on northern hemisphere temperature , 1996 .

[38]  E. Agee.  Trends in Cyclone and Anticyclone Frequency and Comparison with Periods of Warming and Cooling over the Northern Hemisphere. , 1991 .

[39]  R. Reynolds,et al.  The NCEP/NCAR 40-Year Reanalysis Project , 1996, Renewable Energy.

[40]  V. J. Cardone,et al.  On Trends in Historical Marine Wind Data , 1990 .

[41]  M. Ward,et al.  Provisionally Corrected Surface Wind Data, Worldwide Ocean-Atmosphere Surface Fields, and Sahellan Rainfall Variability , 1992 .

[42]  Randy A. Peppler,et al.  North Atlantic Oscillation: Concept and an Application , 1987 .

[43]  P. D. Cotton,et al.  Fifteen years of global wave hindcasts using winds from the European Centre for Medium‐Range Weather Forecasts reanalysis: Validating the reanalyzed winds and assessing the wave climate , 1998 .

[44]  Y. Kushnir,et al.  Interdecadal Variations in North Atlantic Sea Surface Temperature and Associated Atmospheric Conditions , 1994 .

[45]  C. G. Korevaar.  North Sea Climate: Based on observations from ships and lightvessels , 1990 .

[46]  R G Quayle,et al.  Wind and Wave Summaries for Selected U.S. Coast Guard Operating Areas , 1983 .

[47]  H. Schinke.  On the occurrence of deep cyclones over Europe and the North Atlantic in the period 1930-1991 , 1993 .

[48]  E. Bouws,et al.  The Increasing Wave Height in the North Atlantic Ocean , 1996 .

[49]  Josef M. Oberhuber,et al.  An Atlas Based on the COADS Data Set: the Budgets of Heat Buoyancy and Turbulent Kinetic Energy at t , 1988 .

[50]  Elizabeth C. Kent,et al.  The Accuracy of Voluntary Observing Ships' Meteorological Observations-Results of the VSOP-NA , 1993 .

[51]  B. Hoskins,et al.  Near-Surface Wind over the Global Ocean 1949–1988 , 1996 .

[52]  S. Gulev.  Long-term variability of sea-air heat transfer in the North Atlantic Ocean , 1995 .

[53]  S. Gulev.  Climate Variability of the Intensity of Synoptic Processes in the North Atlantic Midlatitudes , 1997 .

[54]  Interannual variations and longer‐term changes in the sea state of the North Atlantic from 1970 to 1982 , 1984 .

[55]  G. Branstator.  Organization of Storm Track Anomalies by Recurring Low-Frequency Circulation Anomalies , 1995 .

[56]  L. Hasse,et al.  Did the Beaufort Scale or the Wind Climate Change , 1987 .

[57]  R. Preisendorfer,et al.  Statistical Analysis of Historical Climate Data Sets , 1985 .

[58]  F. Ayrault,et al.  North Atlantic ultra high frequency variability , 1995 .

[59]  T. P. Jardine.  The reliability of visually observed wave heights , 1979 .

[60]  B. Weare,et al.  The significance of sampling biases on calculated monthly mean oceanic surface heat fluxes , 1981 .

[61]  R. Lindau.  A New Beaufort Equivalent Scale , 1999 .

[62]  Sergey K. Gulev,et al.  Intercomparison of the North Atlantic wave climatology from voluntary observing ships, satellite data and modelling , 1998 .

[63]  J. Wallace,et al.  Horizontal structure of 500 mb height fluctuations with long, intermediate and short time scales , 1984 .

[64]  N. Hogben,et al.  Experience from compilation of global wave statistics , 1988 .

[65]  R. Knoche,et al.  Wasserdampf als ein Verstärker des Treibhauseffektes: Neue Aspekte , 1992 .

[66]  S. Gulev.  Influence of Space-Time Averaging on the Ocean-Atmosphere Exchange Estimates in the North Atlantic Midlatitudes , 1994 .