LSFM series – Surfing on the data freak wave! PART I: Knowing your turf, knowing your surf!

2020 ◽  
Author(s):  
Elisabeth Kugler
Keyword(s):  
2005 ◽  
Vol 32 (13) ◽  
pp. 1572-1589 ◽  
Author(s):  
S.H. Kwon ◽  
H.S. Lee ◽  
C.H. Kim

1997 ◽  
Vol 119 (3) ◽  
pp. 146-150 ◽  
Author(s):  
J. Skourup ◽  
N.-E. O. Hansen ◽  
K. K. Andreasen

The area of the Central North Sea is notorious for the occurrence of very high waves in certain wave trains. The short-term distribution of these wave trains includes waves which are far steeper than predicted by the Rayleigh distribution. Such waves are often termed “extreme waves” or “freak waves.” An analysis of the extreme statistical properties of these waves has been made. The analysis is based on more than 12 yr of wave records from the Mærsk Olie og Gas AS operated Gorm Field which is located in the Danish sector of the Central North Sea. From the wave recordings more than 400 freak wave candidates were found. The ratio between the extreme crest height and the significant wave height (20-min value) has been found to be about 1.8, and the ratio between extreme crest height and extreme wave height has been found to be 0.69. The latter ratio is clearly outside the range of Gaussian waves, and it is higher than the maximum value for steep nonlinear long-crested waves, thus indicating that freak waves are not of a permanent form, and probably of short-crested nature. The extreme statistical distribution is represented by a Weibull distribution with an upper bound, where the upper bound is the value for a depth-limited breaking wave. Based on the measured data, a procedure for determining the freak wave crest height with a given return period is proposed. A sensitivity analysis of the extreme value of the crest height is also made.


2009 ◽  
Vol 58 (6) ◽  
pp. 4011
Author(s):  
Xie Tao ◽  
Nan Cheng-Feng ◽  
Kuang Hai-Lan ◽  
Zou Guang-Hui ◽  
Chen Wei

Ekosistemy ◽  
2021 ◽  
pp. 5-15
Author(s):  
R. V. Gorbunov ◽  
T. Yu. Gorbunova ◽  
V. A. Tabunshchik ◽  
A. V., Drygval

The research team calculated the values of the radiation balance elements of the plain Crimea ecosystems on the bases of open databases of climate data and GIS-modeling and, moreover, analyzed their spatial and temporal differentiation. It is revealed that the spatial distribution of the radiation balance is characterized by an increase in values from the center to the coast of the peninsular. It correlates with the spatial differentiation of both total solar radiation and all other elements of the short-wave part of the radiation balance. There is a significant excess of radiation balance values of the plateau landscape level ecosystems over values of the hydromorphic landscape level ecosystems. This difference is determined by the location of selected key areas on the western coast of the Crimean Peninsula, which is characterized by the maximum values of total solar radiation supply. The elements of the long-wave part of the radiation balance change in the opposite direction, compared with the short-wave part of the radiation balance, which is associated with an increase of air temperature and climate continentality in the direction from the coast to the center of the peninsula. Two periods were identified in the interannual dynamics corresponding to the change of the circulatory periods of the Northern Hemisphere. In general, the considered ecosystems are characterized by trends of increasing radiation balance values in conditions of growth of all its elements. Such growth is provided by significant increase of values during the second period compared with the negative trends of radiation balance values for a number of ecosystems in the first one.


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