A Global Climatology of Surface Wind and Wind Stress Fields from Eight Years of QuikSCAT Scatterometer Data

2008 ◽  
Vol 38 (11) ◽  
pp. 2379-2413 ◽  
Author(s):  
Craig M. Risien ◽  
Dudley B. Chelton
Keyword(s):  
Wind Stress ◽  
Surface Wind ◽  
Stress Fields ◽  
Ocean Current ◽  
Small Scale ◽  
Seasonal Cycles ◽  
Wind Fields ◽  
Ocean Winds ◽  
Wind Measurements ◽  
Sst Gradient

Abstract Global seasonal cycles of the wind and wind stress fields estimated from the 8-yr record (September 1999–August 2007) of wind measurements by the NASA Quick Scatterometer (QuikSCAT) are presented. While this atlas, referred to here as the Scatterometer Climatology of Ocean Winds (SCOW), consists of 12 variables, the focus here is on the wind stress and wind stress derivative (curl and divergence) fields. SCOW seasonal cycles are compared with seasonal cycles estimated from NCEP–NCAR reanalysis wind fields. These comparisons show that the SCOW atlas is able to capture small-scale features that are dynamically important to both the ocean and the atmosphere but are not resolved in other observationally based wind atlases or in NCEP–NCAR reanalysis fields. This is particularly true of the wind stress derivative fields in which topographic, SST gradient, and ocean current influences on surface winds are plainly visible. Discussions of five example regions are presented to highlight these seasonally recurring small-scale features. It is expected that the SCOW atlas will prove valuable to researchers conducting hydrographic and modeling studies.

Simulating ENSO SSTAs from TAO/TRITON Winds: The Impacts of 20 Years of Buoy Observations in the Pacific Waveguide and Comparison with Reanalysis Products

2017 ◽  
Vol 30 (3) ◽  
pp. 1041-1059 ◽  
Author(s):  
Andrew M. Chiodi ◽  
D. E. Harrison
Keyword(s):  
Wind Stress ◽  
Southern Oscillation ◽  
Surface Wind ◽  
Major Elements ◽  
Ocean Model ◽  
Tropical Pacific ◽  
Wind Fields ◽  
Enso Events ◽  
The Pacific ◽  
The Impact

Abstract The fundamental importance of near-equatorial zonal wind stress in the evolution of the tropical Pacific Ocean’s seasonal cycle and El Niño–Southern Oscillation (ENSO) events is well known. It has been two decades since the TAO/TRITON buoy array was deployed, in part to provide accurate surface wind observations across the Pacific waveguide. It is timely to revisit the impact of TAO/TRITON winds on our ability to simulate and thereby understand the evolution of sea surface temperature (SST) in this region. This work shows that forced ocean model simulations of SST anomalies (SSTAs) during the periods with a reasonably high buoy data return rate can reproduce the major elements of SSTA variability during ENSO events using a wind stress field computed from TAO/TRITON observations only. This demonstrates that the buoy array usefully fulfills its waveguide-wind-measurement purpose. Comparison of several reanalysis wind fields commonly used in recent ENSO studies with the TAO/TRITON observations reveals substantial biases in the reanalyses that cause substantial errors in the variability and trends of the reanalysis-forced SST simulations. In particular, the negative trend in ERA-Interim is much larger and the NCEP–NCAR Reanalysis-1 and NCEP–DOE Reanalysis-2 variability much less than seen in the TAO/TRITON wind observations. There are also mean biases. Thus, even with the TAO/TRITON observations available for assimilation into these wind products, there remain oceanically important differences. The reanalyses would be much more useful for ENSO and tropical Pacific climate change study if they would more effectively assimilate the TAO/TRITON observations.

scholarly journals High-Resolution Satellite Measurements of the Atmospheric Boundary Layer Response to SST Variations along the Agulhas Return Current

2005 ◽  
Vol 18 (14) ◽  
pp. 2706-2723 ◽  
Author(s):  
Larry W. O’Neill ◽  
Dudley B. Chelton ◽  
Steven K. Esbensen ◽  
Frank J. Wentz
Keyword(s):  
Boundary Layer ◽  
Atmospheric Boundary Layer ◽  
Wind Stress ◽  
Large Scale ◽  
Surface Wind ◽  
Sensible Heat Flux ◽  
Wind Stress Curl ◽  
Return Current ◽  
Short Scale ◽  
Sst Gradient

Abstract The marine atmospheric boundary layer (MABL) response to sea surface temperature (SST) perturbations with wavelengths shorter than 30° longitude by 10° latitude along the Agulhas Return Current (ARC) is described from the first year of SST and cloud liquid water (CLW) measurements from the Advanced Microwave Scanning Radiometer (AMSR) on the Earth Observing System (EOS) Aqua satellite and surface wind stress measurements from the QuikSCAT scatterometer. AMSR measurements of SST at a resolution of 58 km considerably improves upon a previous analysis that used the Reynolds SST analyses, which underestimate the short-scale SST gradient magnitude over the ARC region by more than a factor of 5. The AMSR SST data thus provide the first quantitatively accurate depiction of the SST-induced MABL response along the ARC. Warm (cold) SST perturbations produce positive (negative) wind stress magnitude perturbations, leading to short-scale perturbations in the wind stress curl and divergence fields that are linearly related to the crosswind and downwind components of the SST gradient, respectively. The magnitudes of the curl and divergence responses vary seasonally and spatially with a response nearly twice as strong during the winter than during the summer along a zonal band between 40° and 50°S. These seasonal variations closely correspond to seasonal and spatial variability of large-scale MABL stability and surface sensible heat flux estimated from NCEP reanalysis fields. SST-induced deepening of the MABL over warm water is evident in AMSR measurements of CLW. Typical annual mean differences in cloud thickness between cold and warm SST perturbations are estimated to be about 300 m.

scholarly journals Improved ocean wind forcing products

2020 ◽  
Author(s):  
Rianne Giesen ◽  
Ana Trindade ◽  
Marcos Portabella ◽  
Ad Stoffelen
Keyword(s):  
High Resolution ◽  
Weather Prediction ◽  
Surface Wind ◽  
Ocean Surface ◽  
Ocean Model ◽  
Wind Forcing ◽  
Small Scale ◽  
Wind Fields ◽  
Ocean Surface Wind ◽  
Ocean Wind

<p>The ocean surface wind plays an essential role in the exchange of heat, gases and momentum at the atmosphere-ocean interface. It is therefore crucial to accurately represent this wind forcing in physical ocean model simulations. Scatterometers provide high-resolution ocean surface wind observations, but have limited spatial and temporal coverage. On the other hand, numerical weather prediction (NWP) model wind fields have better coverage in time and space, but do not resolve the small-scale variability in the air-sea fluxes. In addition, Belmonte Rivas and Stoffelen (2019) documented substantial systematic error in global NWP fields on both small and large scales, using scatterometer observations as a reference.</p><p>Trindade et al. (2019) combined the strong points of scatterometer observations and atmospheric model wind fields into ERA*, a new ocean wind forcing product. ERA* uses temporally-averaged differences between geolocated scatterometer wind data and European Centre for Medium-range Weather Forecasts (ECMWF) reanalysis fields to correct for persistent local NWP wind vector biases. Verified against independent observations, ERA* reduced the variance of differences by 20% with respect to the uncorrected NWP fields. As ERA* has a high potential for improving ocean model forcing in the CMEMS Model Forecasting Centre (MFC) products, it is a candidate for a future CMEMS Level 4 (L4) wind product. We present the ongoing work to further improve the ERA* product and invite potential users to discuss their L4 product requirements.</p><p>References:</p><p>Belmonte Rivas, M. and A. Stoffelen (2019): <em>Characterizing ERA-Interim and ERA5 surface wind biases using ASCAT</em>, Ocean Sci., 15, 831–852, doi: 10.5194/os-15-831-2019.</p><p>Trindade, A., M. Portabella, A. Stoffelen, W. Lin and A. Verhoef (2019), <em>ERAstar: A High-Resolution Ocean Forcing Product</em>, IEEE Trans. Geosci. Remote Sens., 1-11, doi: 10.1109/TGRS.2019.2946019.</p>

The Impact of SST Specification on ECMWF Surface Wind Stress Fields in the Eastern Tropical Pacific

2005 ◽  
Vol 18 (4) ◽  
pp. 530-550 ◽  
Author(s):  
Dudley B. Chelton
Keyword(s):  
Wind Stress ◽  
Weather Prediction ◽  
Surface Wind ◽  
Cold Season ◽  
Numerical Weather Prediction Model ◽  
Tropical Pacific ◽  
Stress Fields ◽  
Eastern Tropical Pacific ◽  
Ocean Atmosphere ◽  
The Impact

Abstract The impact of SST specification on low-level winds in the operational ECMWF numerical weather prediction model is investigated in the eastern tropical Pacific from comparisons of ECMWF wind stress fields with QuikSCAT satellite scatterometer observations of wind stress during the August–December cold seasons of 2000 and 2001. These two time periods bracket the 9 May 2001 change from the Reynolds SST analyses to the Real-Time Global SST (RTG_SST) analyses as the ocean boundary condition in the ECMWF model. The ocean–atmosphere interaction in the eastern tropical Pacific that is clearly evident in QuikSCAT wind stress divergence and curl fields is also evident in the ECMWF winds, but is more than twice as strong in the 2001 cold season as in the 2000 cold season, due primarily to the improved spatial and temporal resolution of the RTG_SST analyses compared with the Reynolds SST analyses. While a significant improvement compared with 2000, the response of the 2001 ECMWF wind stress field to SST is only about half as strong as the coupling inferred from QuikSCAT data and satellite observations of SST from the Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI). It is concluded that the underrepresentation of the ocean–atmosphere coupling is attributable partly to underrepresentation of SST gradients in the RTG_SST fields and partly to inadequacies of the ECWMF model. The latter may be due to errors in the parameterization of boundary layer processes or to insufficient horizontal or vertical resolution in the model.

scholarly journals Effects of spatial scale modification on the responses of surface wind stress to the thermal front in the northern South China Sea

2021 ◽  
pp. 1-44
Author(s):  
Rui Shi ◽  
Xinyu Guo ◽  
Ju Chen ◽  
LiLi Zeng ◽  
Bo Wu ◽  
...  
Keyword(s):  
South China Sea ◽  
Wind Stress ◽  
South China ◽  
Northern South China Sea ◽  
Surface Wind ◽  
Reanalysis Data ◽  
Satellite Observations ◽  
Surface Wind Stress ◽  
Linear Relationships ◽  
Sst Gradient

AbstractThe responses of surface wind stress to the mesoscale sea surface temperature (SST) anomalies associated with the SST front in the northern South China Sea (NSCS) are studied using satellite observations and reanalysis data. Both satellite and reanalysis data explicitly show the linear relationships between the spatial-high-pass filtered wind stress perturbation derivatives and the underlying SST gradient field. However, the noise in the linear relationships is much smaller in the reanalysis data than in the satellite observations. This result is rarely reported in other frontal areas.The wavelet analysis shows that the satellite scatterometer observed numerous high wavenumber perturbations within 100 km in the NSCS, but these perturbations were absent in the reanalysis data. The linear relationship between the perturbation SST gradient and derivative wind stress fields is not significant at this scale, which enhances the noise in the linear relationship. The spatial bandpass-filtered perturbation between 100 km and 300 km can give reasonable estimates of the coupling coefficients between the wind stress divergence and downwind SST gradient (αd) and between the wind stress curl and crosswind SST gradient (αc) in the NSCS, with values of 1.33 × 10−2 N m−2 per °C and 0.95 × 10−2 N m−2 per °C, respectively.

scholarly journals Interhemispheric SST Gradient Trends in the Indian Ocean prior to and during the Recent Global Warming Hiatusa

2016 ◽  
Vol 29 (24) ◽  
pp. 9077-9095 ◽  
Author(s):  
Lu Dong ◽  
Michael J. McPhaden
Keyword(s):  
Global Warming ◽  
Indian Ocean ◽  
Wind Stress ◽  
Coastal Upwelling ◽  
Surface Wind ◽  
Heat Fluxes ◽  
Thermocline Depth ◽  
Upwelled Water ◽  
The Indian Ocean ◽  
Sst Gradient

Abstract Sea surface temperatures (SSTs) have been rising for decades in the Indian Ocean in response to greenhouse gas forcing. However, this study shows that during the recent hiatus in global warming, a striking interhemispheric gradient in Indian Ocean SST trends developed around 2000, with relatively weak or little warming to the north of 10°S and accelerated warming to the south of 10°S. Evidence is presented from a wide variety of data sources showing that this interhemispheric gradient in SST trends is forced primarily by an increase of Indonesian Throughflow (ITF) transport from the Pacific into the Indian Ocean induced by stronger Pacific trade winds. This increased transport led to a depression of the thermocline that facilitated SST warming, presumably through a reduction in the vertical turbulent transport of heat in the southern Indian Ocean. Surface wind changes in the Indian Ocean linked to the enhanced Walker circulation also may have contributed to thermocline depth variations and associated SST changes, with downwelling-favorable wind stress curls between 10° and 20°S and upwelling-favorable wind stress curls between the equator and 10°S. In addition, the anomalous southwesterly wind stresses off the coast of Somalia favored intensified coastal upwelling and offshore advection of upwelled water, which would have led to reduced warming of the northern Indian Ocean. Although highly uncertain, lateral heat advection associated with the ITF and surface heat fluxes may also have played a role in forming the interhemispheric SST gradient change.

scholarly journals Numerical modelling of pollutant dispersion in sea breeze conditions

1996 ◽  
Vol 14 (6) ◽  
pp. 665-677 ◽  
Author(s):  
J. Camps ◽  
J. Massons ◽  
M. R. Soler
Keyword(s):  
Mesoscale Model ◽  
Numerical Study ◽  
Surface Wind ◽  
Three Dimensional ◽  
Coastal Region ◽  
Pollutant Dispersion ◽  
Sea Breeze ◽  
Wind Fields ◽  
Wind Measurements ◽  
Reactive Pollutant

Abstract. The characteristics of air pollution in Tarragona (Spain) were investigated. Tarragona has an important petrochemical industry in a coastal region with a complex terrain. The numerical study was made in sea breeze conditions with a three-dimensional mesoscale model. Temporal and spatial variations of the wind fields have been used in the Eulerian equation for a non-reactive pollutant. The results of this study reveal the complexity of the dispersion patterns due to the combined effects of the sea breeze circulation and the orography. This work presents a comparison between the model output and the observed wind data by sodar and surface wind measurements. The evaluation shows that the model is capable of providing very realistic wind fields within this domain.

Summertime Influence of SST on Surface Wind Stress off the U.S. West Coast from the U.S. Navy COAMPS Model*

2008 ◽  
Vol 38 (11) ◽  
pp. 2414-2437 ◽  
Author(s):  
Tracy Haack ◽  
Dudley Chelton ◽  
Julie Pullen ◽  
James D. Doyle ◽  
Michael Schlax
Keyword(s):  
Time Scales ◽  
Wind Stress ◽  
West Coast ◽  
Mesoscale Model ◽  
Surface Wind ◽  
Gradient Field ◽  
Wind Stress Curl ◽  
Surface Wind Stress ◽  
The U.S ◽  
Sst Gradient

Abstract High-resolution mesoscale model sea surface temperature (SST) analyses and surface wind stress forecasts off the U.S. West Coast are analyzed on monthly time scales for robust signatures of air–sea interaction as the surface winds encounter ocean surface features such as SST fronts, filaments, and eddies. This interaction is manifest by the linear relationship, or coupling coefficient, between the downwind SST gradient and wind stress divergence and between the crosswind SST gradient and wind stress curl evident from analysis of fields averaged over 29 days. This study examines fields from the Coupled Ocean–Atmosphere Mesoscale Prediction System (COAMPS) model, spanning the summer months, June–September, for four consecutive years, 2002–05. Relative to several models evaluated previously, coupling coefficients are much closer to those calculated from Quick Scatterometer (QuikSCAT) satellite measurements. In addition, the summertime correlation between the wind stress derivative field and its corresponding SST gradient field on monthly time scales agrees well with satellite-derived correlations. Sensible and latent heat flux fields are also analyzed for features indicative of pronounced air–sea exchange associated with SST influence.

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