scholarly journals A Global View on the Swell and Wind Sea Climate by the Jason-1 Mission: A Revisit

2013 ◽  
Vol 30 (8) ◽  
pp. 1833-1841 ◽  
Author(s):  
Haoyu Jiang ◽  
Ge Chen
Keyword(s):  
Wind Speed ◽  
World Ocean ◽  
Ocean Engineering ◽  
Geographical Patterns ◽  
Global View ◽  
Low Latitudes ◽  
Data Record ◽  
Wave Models ◽  
Wind Sea ◽  
Geophysical Data Record

Abstract In this study, a global climatology of swells and wind seas was investigated using near-10-yr collocated wind speed and significant wave height (SWH) measurements from the basic Geophysical Data Record (GDR) of the Jason-1 mission. A statistical method to estimate the wind sea and swell SWHs, respectively, on the basis of wave energy and wind sea/swell probability was proposed. The global distributions of swell/wind sea probability displayed the swell's dominance in the World Ocean. Their seasonal variation showed not only the regions called “swell pools” with high swell probability throughout the year at low latitudes, which have been found in previous studies, but also the regions with high swell probability only in hemispheric summer, termed “seasonal swell pools,” located at the midlatitudes of open oceans. The seasonal geographical patterns of the swell SWH were similar to those of the SWH due to the swell's dominance, and the patterns of the wind SWH were similar to those of the wind speed because of their well-coupled nature. The results could be used as a reference for related applications such as ocean engineering, seafaring, validation of wave models, and studies on climate change.

scholarly journals The Transition from Downward to Upward Air–Sea Momentum Flux in Swell-Dominated Light Wind Conditions

2018 ◽  
Vol 75 (8) ◽  
pp. 2579-2588 ◽  
Author(s):  
Ulf Högström ◽  
Erik Sahlée ◽  
Ann-Sofi Smedman ◽  
Anna Rutgersson ◽  
Erik Nilsson ◽  
...  
Keyword(s):  
Wind Speed ◽  
Momentum Flux ◽  
Water Surface ◽  
Sea Waves ◽  
Progressive Wave ◽  
Wind Speeds ◽  
Low Wind Speed ◽  
Light Wind ◽  
Wind Sea ◽  
Almost All

Abstract Fifteen hours of consecutive swell data from the experiment Flux, État de la Mer, et Télédétection en Condition de Fetch Variable (FETCH) in the Mediterranean show a distinct upward momentum flux. The characteristics are shown to vary systematically with wind speed. A hysteresis effect is found for wave energy of the wind-sea waves when represented as a function of wind speed, displaying higher energy during decaying winds compared to increasing winds. For the FETCH measurements, the upward momentum transfer regime is found to begin for wind speeds lower than about U = 4 m s−1. For the lowest observed wind speeds U < 2.4 m s−1, the water surface appears to be close to dynamically smooth. In this range almost all the upward momentum flux is accomplished by the peak in the cospectrum between the vertical and horizontal components of the wind velocity. It is demonstrated that this contribution in turn is linearly related to the swell significant wave height Hsd in the range 0.6 < Hsd < 1.4 m. For Hsd < 0.6 m, the contribution is zero in the present dataset but may depend on the swell magnitude in other situations. It is speculated that the observed upward momentum flux in the smooth regime, which is so strongly related to the cospectral peak at the dominant swell frequency, might be caused by the recirculation mechanism found by Wen and Mobbs in their numerical simulation of laminar flow of a nonlinear progressive wave at low wind speed.

Comparison of Formulations for Whitecapping in Mixed Seas

2005 ◽  
Author(s):  
Se´bastien Lacoin ◽  
David P. Hurdle ◽  
Gerbrant Ph. Van Vledder
Keyword(s):  
Sensitivity Study ◽  
Wave Models ◽  
Wind Sea

Four formulations for dissipation by whitecapping in discrete spectral wave models have been compared, and their applicability in combined swell-sea systems has been investigated. To obtain workable formulations, a sensitivity study has been carried out, followed by a simple calibration. Finally, the effect of a small background swell on the growth of a wind sea has been studied for all formulations.

Global Trends in Extreme Wind Speed and Wave Height

2013 ◽  
Author(s):  
I. R. Young ◽  
S. Zieger ◽  
J. Vinoth ◽  
A. V. Babanin
Keyword(s):  
Wind Speed ◽  
Wave Height ◽  
Global Climate ◽  
Extreme Value ◽  
Global Perspective ◽  
Ocean Engineering ◽  
Change Analysis ◽  
Data Set ◽  
Wind Speeds ◽  
Extreme Wind

Satellite observations of the ocean surface provide a powerful method for acquiring global data on wind speed and wave height. Radar altimeters have now been in operation for more than 25 years, providing a reasonably long term data set with global coverage. This paper presents data from a fully calibrated and validated altimeter dataset. The dataset provides the basis for obtaining a global perspective of a number of parameters critical to ocean engineering design, ship operations and global climate change. Analysis of the data provides ocean climatology of mean monthly values of wind speed and wave height useful for ship operations. The data set is also sufficiently long to provide extreme value (i.e. 100-year return period) estimates of wind speed and wave height. The paper presents such values and describes the approaches most appropriate to obtain statistically significant extreme value estimates from such satellite data. With a data set of this length, it is possible to investigate whether there have been statistically significant changes in the wind and wave climates over the period. Careful trend analysis of the extensive data set shows that there has been a statistically significant increasing trend in mean wind speed over the period. The corresponding increase in wave height is less clear. There is also evidence to suggest that extreme wind speeds and wave heights are increasing and the data set is analysed to investigate these trends. The paper clearly shows the value of this dataset and its application to a range of engineering problems.

Alat Ukur Kecepatan Angin Permukaan Air Laut Berbasis Mikrokontroler

2020 ◽  
Vol 2 (2) ◽  
pp. 80-88
Author(s):  
Waluyo Waluyo ◽  
Meli Ruslinar
Keyword(s):  
Wind Speed ◽  
Surface Wind ◽  
Surface Wind Speed ◽  
Wind Data ◽  
Measuring Instrument ◽  
Ocean Engineering ◽  
Sea Surface Wind Speed ◽  
Wind Speeds ◽  
Sea Surface Wind ◽  
Engineering Modeling

The microcontroller is one technology that is developing so rapidly with various types and functions, one of which is Arduino Uno which can be used as a microcontroller for various functions in the field of electronics technology. This research was conducted at the Laboratory of Ocean Engineering Modeling, Marine and Fisheries Polytechnic of Karawang in March-June 2020. The purpose of this study was to create a microcontroller-based sea surface wind speed measuring instrument. Based on the results of the acquisition of wind data using a fan simulation and natural wind gusts with different wind speeds in the field show a significant tool response. The results of the comparison of data recording between the results of research with the existing wind speed measuring instrument show that there is an average tool error of 3.24%, a relative error of 3.78%, and an instrument accuracy rate of 96.76%. Thus it can be said that the ability of the tool is able to record wind data with high accuracy.

Effect of Swell on Wind Stress for Light to Moderate Winds

2020 ◽  
Vol 77 (11) ◽  
pp. 3759-3768
Author(s):  
Charles L. Vincent ◽  
Hans C. Graber ◽  
Clarence O. Collins
Keyword(s):  
Wind Speed ◽  
Gulf Of Mexico ◽  
Inflection Point ◽  
Friction Velocity ◽  
Flow Transition ◽  
Wind Speeds ◽  
Impact Stress ◽  
Low Wind Speed ◽  
Wind Sea ◽  
Low Wind Speeds

AbstractBuoy observations from a 1999 Gulf of Mexico field program (GOM99) are used to investigate the relationships among friction velocity u*, wind speed U, and amount of swell present. A U–u*sea parameterization is developed for the case of pure wind sea (denoted by u*sea), which is linear in U over the range of available winds (2–16 m s−1). The curve shows no sign of an inflection point near 7–8 m s−1 as suggested in a 2012 paper by Andreas et al. on the basis of a transition from smooth to rough flow. When observations containing more than minimal swell energy are included, a different U–u* equation for U < 8 m s−1 is found, which would intersect the pure wind-sea curve about 7–8 m s−1. These two relationships yield a bilinear curve similar to Andreas et al. with an apparent inflection near 7–8 m s−1. The absence of the inflection in the GOM99 experiment pure wind-sea curve and the similarity of the GOM99 swell-dominated low wind speed to Andreas et al.’s low wind speed relationship suggest that the inflection may be due to the effect of swell and not a flow transition. Swell heights in the range of only 25–50 cm may be sufficient to impact stress at low wind speeds.

scholarly journals Coastal Waveform Retracking in the Slick-Rich Sulawesi Sea of Indonesia, Based on Variable Footprint Size with Homogeneous Sea Surface Roughness

2019 ◽  
Vol 11 (11) ◽  
pp. 1274 ◽  
Author(s):  
Xifeng Wang ◽  
Kaoru Ichikawa ◽  
Dongni Wei
Keyword(s):  
Surface Roughness ◽  
Leading Edge ◽  
Sea Surface ◽  
Altimeter Data ◽  
Sea Surface Roughness ◽  
Waveform Retracking ◽  
Data Record ◽  
Along Track ◽  
Surface Dynamic ◽  
Geophysical Data Record

Waveforms of radar altimeters are often corrupted due to heterogeneous sea surface roughness within footprints, such as slicks. In past studies, subwaveform retrackers such as the adaptive leading edge subwaveform retracker (ALES) which use only a section of the waveform have been proposed. However, it is difficult to choose a reasonable estimation window from an individual waveform. In the present study, a post-processed subwaveform retracker is proposed which identifies the waveforms of surrounding along-track points. The size of the estimation window is variable and is determined to keep the sea surface roughness within the corresponding footprint homogeneous. The method was applied to seven years of 20 Hz Jason-2 altimeter data over the slick-rich Sulawesi Sea of Indonesia and compared with ALES and sensor geophysical data record (SGDR) products. The standard deviation of the sea surface dynamic heights was around 0.13 m, even without spatial smoothing or some geophysical corrections. This is only 75% and 25% of the ALES and SGDR results, respectively. Moreover, all retrievals of the range, SWH, and sigma0 include less outliers than the other products. These results indicate that the variable estimation windows determined in the present study can adapt well to the variation of sea surface roughness.

Origin of Passerine Migratory Waves: Evidence from the Blackcap at a Stopover Site

2010 ◽  
Vol 56 (2) ◽  
pp. 135-151 ◽  
Author(s):  
Ophir Shneor ◽  
Gidon Perlman ◽  
Amir Balaban ◽  
Yoram Yom-Tov
Keyword(s):  
Wind Speed ◽  
Stable Isotope ◽  
Isotope Composition ◽  
Morphological Characteristics ◽  
Weather Conditions ◽  
Wave Pattern ◽  
Stable Isotope Composition ◽  
Stopover Site ◽  
Early Season ◽  
Low Latitudes

Hundreds of millions birds migrate through Israel every spring, usually in several waves during which a large number of birds are seen flying over Israel for several days, followed by periods in which only a small number are spotted. The aims of this study were to (1) determine whether the spring migration of the blackcap demonstrates a wave pattern, (2) determine the effect of weather conditions en route on the number of blackcaps arriving and forming each wave, and (3) use morphological characteristics and stable isotope composition of the feathers to examine the hypothesis that early arriving blackcaps represent populations breeding in low latitudes while later ones represent northern populations.We found that (1) our first hypothesis was fully supported, and blackcaps arrive to Israel in "waves"; (2) weather conditions, and in particular wind speed and direction, were significantly related to the number of blackcaps captured; and (3) our morphological and δ C-13 data suggest that birds from the early season originated from more southern latitudes and/or more western longitudes within the breeding range of blackcaps.

Sign in / Sign up

Export Citation Format

Share Document