论文部分内容阅读
This paper presents the long-term climate changes of significant wave height(Hs) in 1958–2001 over the entire global ocean using the 45-year European Centre for Medium-Range Weather Forecasts(ECMWF) Reanalysis(ERA-40) wave data. The linear trends in Hs and regional and seasonal differences of the linear trends for Hs were calculated. Results show that the Hs exhibits a significant increasing trend of about 4.6 cm decade-1 in the global ocean as a whole over the last 44 years. The Hs changes slowly during the periods 1958–1974 and 1980–1991, while it increases consistently during the periods 1975–1980 and 1995–1998. The Hs reaches its lowest magnitude in 1975, with annual average wave height about 2 m. In 1992, the Hs has the maximum value of nearly 2.60 m. The Hs in most ocean waters has a significant increasing trend of 2–14 cm decade-1 over the last 44 years. The linear trend exhibits great regional differences. Areas with strong increasing trend of Hs are mainly distributed in the westerlies of the southern Hemisphere and the northern Hemisphere. Only some small areas show obvious decreasing in Hs. The long-term trend of Hs in DJF(December, January, February) and MAM(March, April, May) is much more stronger than that in JJA(June, July, August) and SON(September, October, November). The linear trends of the Hs in different areas are different in different seasons; for instance, the increasing trend of Hs in the westerlies of the Pacific Ocean mainly appears in MAM and DJF.
This paper presents the long-term climate changes of significant wave height (Hs) in 1958-2001 over the entire global ocean using the 45-year European Center for Medium-Range Weather Forecasts (ECMWF) Reanalysis (ERA-40) wave data. The linear trends in Hs and regional and seasonal differences of the linear trends for Hs were calculated. Results show that Hs exhibits a significant trend trend of about 4.6 cm decade-1 in the global ocean as a whole over the last 44 years. The Hs changes slowly during the periods 1958-1974 and 1980-1991 while it increases consistently during the 1975-1980 and 1995-1998. The Hs reaches its lowest magnitude in 1975, with an average average wave height about 2 m. In 1992, the Hs has the maximum value of nearly 2.60 m. The Hs in most ocean waters has a significant increasing trend of 2-14 cm decade-1 over the last 44 years. Areas with strong increasing trend of of Hs are mainly distribu ted in the westerlies of the southern Hemisphere and the northern Hemisphere. Only some small areas show obvious decreasing in Hs. The long-term trend of Hs in DJF (December, January, February) and MAM (March, April, May) is much more stronger than that in JJA (June, July, August) and SON (September, October, November). The linear trends of the Hs in different areas are different in different seasons; for instance, the increasing trend of Hs in the westerlies of the Pacific Ocean mainly appears in MAM and DJF.