Construction of surface wind stress fields with high temporal resolution using ERS-1 scatterometer data

1998 ◽  
Vol 54 (3) ◽  
pp. 247-256 ◽  
Author(s):  
Masahisa Kubota ◽  
Hidekazu Yokota
Keyword(s):  
Temporal Resolution ◽  
Wind Stress ◽  
Surface Wind ◽  
Stress Fields ◽  
High Temporal Resolution ◽  
Surface Wind Stress

Quantifying Highly Variable Air–Sea Momentum Flux Using Wavelet Analysis

2018 ◽  
Vol 35 (9) ◽  
pp. 1849-1863 ◽  
Author(s):  
Nathan J. M. Laxague ◽  
Brian K. Haus ◽  
David G. Ortiz-Suslow ◽  
Hans C. Graber
Keyword(s):  
Wind Stress ◽  
Time Windows ◽  
Surface Wind ◽  
Maximum Amplitude ◽  
High Temporal Resolution ◽  
Material Transport ◽  
Surface Wind Stress ◽  
Wave Development ◽  
A New Technique ◽  
Highly Correlated

AbstractSurface wind stress is a crucial driver of upper-ocean processes, impacting air–sea gas flux, wind-wave development, and material transport. Conventional eddy covariance (EC) processing requires imposing a fixed averaging window on the wind velocity time series in order to estimate the downward flux of momentum. While this method has become the standard means of directly measuring the wind stress, the use of a fixed averaging interval inherently constrains one’s ability to resolve transient signals that may have net effects on the air–sea interactions. Here we utilize the wavelet transform to develop a new technique for directly quantifying the wind stress magnitude from the wavelet coscalogram products. The time averages of these products evaluated at the scale of maximum amplitude are highly correlated with the EC estimates (R2 = 0.99; 5-min time windows), suggesting that stress is particularly sensitive to the dominant turbulent eddies. By taking advantage of the new method’s high temporal resolution, transient wind forcing and its dominant scales may be explicitly computed and analyzed. This technique will allow for more general investigations into air–sea dynamics under nonstationary or spatially inhomogeneous conditions, such as within the nearshore region.

FEATURES OF WIND FIELD OVER THE SEA SURFACE IN THE COASTAL AREA BASED ON SAR OBSERVATIONS

2017 ◽  
Author(s):  
Anna Monzikova ◽  
Anna Monzikova ◽  
Vladimir Kudryavtsev Vladimir ◽  
Vladimir Kudryavtsev Vladimir ◽  
Alexander Myasoedov ◽  
...  
Keyword(s):  
Wind Stress ◽  
Surface Wind ◽  
Quantitative Description ◽  
Energy Resource ◽  
Resource Assessment ◽  
Internal Boundary Layer ◽  
Offshore Wind ◽  
Internal Boundary ◽  
Sar Images ◽  
Surface Wind Stress

“Wind-shadowing” effects in the Gulf of Finland coastal zone are analyzed using high resolution Envisat Synthetic Aperture Radar (SAR) measurements and model simulations. These effects are related to the internal boundary layer (IBL) development due to abrupt change the surface roughness at the sea-land boundary. Inside the "shadow" areas the airflow accelerates and the surface wind stress increases with the fetch. Such features can be revealed in SAR images as dark areas adjacent to the coastal line. Quantitative description of these effects is important for offshore wind energy resource assessment. It is found that the surface wind stress scaled by its equilibrium value (far from the coast) is universal functions of the dimensionless fetch Xf/G. Wind stress reaches an equilibrium value at the distance Xf/G of about 0.4.

Wind Stress Over Waves: Effects of Sea Roughness and Atmospheric Stability

2002 ◽  
Vol 124 (3) ◽  
pp. 169-172 ◽  
Author(s):  
Dag Myrhaug ◽  
Olav H. Slaattelid
Keyword(s):  
Boundary Layer ◽  
Wind Stress ◽  
Local Equilibrium ◽  
Surface Wind ◽  
Atmospheric Stability ◽  
Sea Surface ◽  
Stability Function ◽  
Sea Surface Wind ◽  
Surface Wind Stress ◽  
Sea Surface Roughness

The paper considers the effects of sea roughness and atmospheric stability on the sea surface wind stress over waves, which are in local equilibrium with the wind, by using the logarithmic boundary layer profile including a stability function, as well as adopting some commonly used sea surface roughness formulations. The engineering relevance of the results is also discussed.

Uncertainties in reanalysis surface wind stress and their relationship with observing systems

2018 ◽  
Vol 52 (5-6) ◽  
pp. 3061-3078 ◽  
Author(s):  
Caihong Wen ◽  
Arun Kumar ◽  
Yan Xue
Keyword(s):  
Wind Stress ◽  
Surface Wind ◽  
Surface Wind Stress ◽  
Observing Systems

scholarly journals Southern Ocean Wind Stress in CMIP5 Models: Role of Wind Fluctuations

2020 ◽  
Vol 33 (4) ◽  
pp. 1209-1226 ◽  
Author(s):  
Xia Lin ◽  
Xiaoming Zhai ◽  
Zhaomin Wang ◽  
David R. Munday
Keyword(s):  
Southern Ocean ◽  
Time Scales ◽  
Wind Stress ◽  
Surface Wind ◽  
Coupled Model ◽  
Cmip5 Models ◽  
Coupled Models ◽  
Surface Wind Stress ◽  
Stress Changes ◽  
The Mean

AbstractThe Southern Ocean (SO) surface wind stress is a major atmospheric forcing for driving the Antarctic Circumpolar Current and the global overturning circulation. Here the effects of wind fluctuations at different time scales on SO wind stress in 18 models from phase 5 of the Coupled Model Intercomparison Project (CMIP5) are investigated. It is found that including wind fluctuations, especially on time scales associated with synoptic storms, in the stress calculation strongly enhances the mean strength, modulates the seasonal cycle, and significantly amplifies the trends of SO wind stress. In 11 out of the 18 CMIP5 models, the SO wind stress has strengthened significantly over the period of 1960–2005. Among them, the strengthening trend of SO wind stress in one CMIP5 model is due to the increase in the intensity of wind fluctuations, while in all the other 10 models the strengthening trend is due to the increasing strength of the mean westerly wind. These discrepancies in SO wind stress trend in CMIP5 models may explain some of the diverging behaviors in the model-simulated SO circulation. Our results suggest that to reduce the uncertainty in SO responses to wind stress changes in the coupled models, both the mean wind and wind fluctuations need to be better simulated.

scholarly journals Retrieval of Sea Surface Wind Fields Using Multi-Source Remote Sensing Data

2020 ◽  
Vol 12 (9) ◽  
pp. 1482 ◽  
Author(s):  
Tangao Hu ◽  
Yue Li ◽  
Yao Li ◽  
Yiyue Wu ◽  
Dengrong Zhang
Keyword(s):  
Linear Model ◽  
Temporal Resolution ◽  
Science Studies ◽  
Piecewise Linear ◽  
Surface Wind ◽  
Sea Surface ◽  
Mean Bias Error ◽  
High Temporal Resolution ◽  
Sea Surface Wind ◽  
Piecewise Linear Model

Timely and accurate sea surface wind field (SSWF) information plays an important role in marine environmental monitoring, weather forecasting, and other atmospheric science studies. In this study, a piecewise linear model is proposed to retrieve SSWF information based on the combination of two different satellite sensors (a microwave scatterometer and an infrared scanning radiometer). First, the time series wind speed dataset, extracted from the HY-2A satellite, and the brightness temperature dataset, extracted from the FY-2E satellite, were matched. The piecewise linear regression model with the highest R2 was then selected as the best model to retrieve SSWF information. Finally, experiments were conducted with the Usagi, Fitow, and Nari typhoons in 2013 to evaluate accuracy. The results show that: (1) the piecewise linear model is successfully established for all typhoons with high R2 (greater than 0.61); (2) for all three cases, the root mean square error () and mean bias error (MBE) are smaller than 2.2 m/s and 1.82 m/s, which indicates that it is suitable and reliable for SSWF information retrieval; and (3) it solves the problem of the low temporal resolution of HY-2A data (12 h), and inherits the high temporal resolution of the FY-2E data (0.5 h). It can provide reliable and high temporal SSWF products.

scholarly journals The Effects of Surface Wind Stress and Buoyancy Flux on the Evolution of a Front in a Turbulent Thermal Wind Balance

Fluids ◽  
2020 ◽  
Vol 5 (2) ◽  
pp. 87
Author(s):  
Matthew N. Crowe ◽  
John R. Taylor
Keyword(s):  
Wind Stress ◽  
Numerical Solutions ◽  
Surface Wind ◽  
Vertical Mixing ◽  
Spreading Rate ◽  
Buoyancy Flux ◽  
Thermal Wind ◽  
Surface Wind Stress ◽  
Shear Dispersion ◽  
Surface Buoyancy

Here we consider the effects of surface buoyancy flux and wind stress on a front in turbulent thermal wind (TTW) balance using the framework of Crowe and Taylor (2018). The changes in the velocity and density profiles induced by the wind stress and buoyancy flux interact with the TTW and can qualitatively change the evolution of the front. In the absence of surface-forcing, Crowe and Taylor (2018) found that shear dispersion associated with the TTW circulation causes the frontal width to increase. In many cases, the flow induced by the surface-forcing enhances the spreading rate. However, if the wind stress drives a cross-front flow which opposes the frontal buoyancy gradient or the buoyancy flux drives an unstable stratification, it is possible to obtain an up-gradient cross-front buoyancy flux, which can act to sharpen the front. In certain conditions, an equilibrium state develops where the tendency for the TTW circulation to spread the front is balanced by the frontogenetic tendency of the surface forces. We use numerical solutions to a nonlinear diffusion equation in order to test these predictions. Finally, we describe the connection between surface-forcing and vertical mixing and discuss typical parameters for mid-ocean fronts.

scholarly journals An Idealized Model of Weddell Gyre Export Variability

2014 ◽  
Vol 44 (6) ◽  
pp. 1671-1688 ◽  
Author(s):  
Zhan Su ◽  
Andrew L. Stewart ◽  
Andrew F. Thompson
Keyword(s):  
Wind Stress ◽  
Deep Water ◽  
Surface Wind ◽  
Oscillation Amplitude ◽  
Mesoscale Eddy ◽  
Eddy Diffusivity ◽  
Weddell Sea ◽  
Alternative Mechanism ◽  
Weddell Gyre ◽  
Surface Wind Stress

Abstract Recent observations suggest that the export of Antarctic Bottom Water (AABW) from the Weddell Sea has a seasonal cycle in its temperature and salinity that is correlated with annual wind stress variations. This variability has been attributed to annual vertical excursions of the isopycnals in the Weddell Gyre, modifying the water properties at the depth of the Orkney Passage. Recent studies attribute these variations to locally wind-driven barotropic dynamics in the northern Weddell Sea boundary current. This paper explores an alternative mechanism in which the isopycnals respond directly to surface Ekman pumping, which is coupled to rapidly responding mesoscale eddy buoyancy fluxes near the gyre boundary. A conceptual model of the interface that separates Weddell Sea Deep Water from Circumpolar Deep Water is described in which the bounding isopycnal responds to a seasonal oscillation in the surface wind stress. Different parameterizations of the mesoscale eddy diffusivity are tested. The model accurately predicts the observed phases of the temperature and salinity variability in relationship to the surface wind stress. The model, despite its heavy idealization, also accounts for more than 50% of the observed oscillation amplitude, which depends on the strength of the seasonal wind variability and the parameterized eddy diffusivity. These results highlight the importance of mesoscale eddies in modulating the export of AABW in narrow boundary layers around the Antarctic margins.

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