Spectra of surface wind speed and air temperature over the ocean in the mesoscale frequency range in JASIN-1978

1989 ◽  
Vol 47 (1-4) ◽  
pp. 71-84 ◽  
Author(s):  
Hiroshi Ishida
Keyword(s):  
Wind Speed ◽  
Air Temperature ◽  
Surface Wind ◽  
Surface Wind Speed ◽  
Frequency Range

scholarly journals Influence of SST Anomalies on Winter Turbulent Heat Fluxes in the Eastern Kuroshio–Oyashio Confluence Region

2014 ◽  
Vol 27 (24) ◽  
pp. 9349-9358 ◽  
Author(s):  
Shusaku Sugimoto
Keyword(s):  
Wind Speed ◽  
Air Temperature ◽  
Surface Wind ◽  
Surface Air Temperature ◽  
Surface Wind Speed ◽  
Heat Fluxes ◽  
Specific Humidity ◽  
Turbulent Heat ◽  
Confluence Region ◽  
Sst Anomalies

Abstract Variations in the turbulent heat flux (THF; the sum of the sensible and latent heat fluxes) in the eastern Kuroshio–Oyashio confluence region (EKOCR; 36°–40°N, 155°–160°E) were investigated over a period of 27 consecutive winters (December–February) from 1985/86 to 2011/12. The THF was calculated from a bulk formula using daily variables [surface wind speed, surface air specific humidity, surface air temperature, and sea surface temperature (SST)] of the objectively analyzed air–sea fluxes (OAFlux) dataset and bulk coefficients based on the Tropical Ocean and Global Atmosphere Coupled Ocean–Atmosphere Response Experiment (TOGA COARE) bulk flux algorithm 3.0. The winter THF over the EKOCR showed low-frequency variations, with larger THF values in the early 2000s and smaller values in the late 1990s and late 2000s. The heat release in the early 2000s was up to ~40% greater than that in the late 1990s and late 2000s. By performing experiments using combinations of daily raw data values and daily climatological data, the relative contributions of SST, surface air specific humidity, surface air temperature, and surface wind speed were quantitatively assessed in determining the THF over the EKOCR. Results showed that SST predominantly determines the THF: large amounts of heat are released during times of positive SST anomalies. By using Argo float (temperature–salinity) profiles of 2003–12 and a satellite altimetry dataset of 1992–2012, it was found that the warm–salty water transported by an occurrence of the Kuroshio bifurcation was responsible for the generation of positive SST anomalies in the EKOCR.

scholarly journals Contribution of variations in Northern Hemisphere annular mode to the near-surface wind speed changes over Eastern China for 1979-2017

2021 ◽  
Author(s):  
Jinlin Zha ◽  
Cheng Shen ◽  
Jian Wu ◽  
Deming Zhao ◽  
Cesar Azorin-Molina
Keyword(s):  
Wind Speed ◽  
Temperature Gradient ◽  
Northern Hemisphere ◽  
Air Temperature ◽  
Eastern China ◽  
Surface Wind ◽  
Surface Wind Speed ◽  
Near Surface ◽  
Annular Mode ◽  
Northern Hemisphere Annular Mode

Abstract Studies have shown that large-scale ocean-atmosphere circulations (LOACs) played the major role to the near-surface wind speed (NWS) changes over China; however, the mechanisms whereby LOACs influences NWS to have received little attention. In this study, the processes of the Northern Hemisphere annular mode (NAM) influencing the NWS changes are revealed over eastern China for 1979–2017. The results showed a slowdown in NWS, at a rate of − 0.09 ± 0.01 m s− 1 decade− 1; meanwhile, this decline could be partly driven by the weakening of the zonal wind component. When the NAM exhibits positive phases, the zonal-mean westerly weakens at the low-to-mid-latitudes (10°–40°N); meanwhile, in the troposphere descending flows prevail near 40°N and ascending flows prevail near 65°N, and in the lower troposphere there are northerly anomalies at the low-to-mid-latitudes and southerly anomalies at mid-to-high latitudes (40°–70°N). The anomalous meridional flows transport heat from lower latitudes to higher latitudes and weaken the north–south air temperature gradient. The decreased air temperature gradient over East Asia reduces the pressure-gradient near the surface in eastern China, thereby decreasing the NWS. Furthermore, the effects of NAM on NWS changes are more significant at interannual scale than decadal scale. 32.0 ± 15.8 % of the changes in the annual mean NWS are caused by the variations in NAM; meanwhile, the NAM contribution to the interannual changes in the zonal component of NWS reach 45.0 ± 12.9 %.

Recurrence Characteristics Analysis of Near-Surface Wind Speed Signal with Different Sampling Frequencies

2014 ◽  
Vol 599-601 ◽  
pp. 1605-1609 ◽  
Author(s):  
Ming Zeng ◽  
Zhan Xie Wu ◽  
Qing Hao Meng ◽  
Jing Hai Li ◽  
Shu Gen Ma
Keyword(s):  
Wind Speed ◽  
Surface Wind ◽  
Surface Wind Speed ◽  
Recurrence Plot ◽  
Sampling Frequency ◽  
Near Surface ◽  
Gas Leakage ◽  
Time Period ◽  
Characteristics Analysis ◽  
Quantification Analysis

The wind is the main factor to influence the propagation of gas in the atmosphere. Therefore, the wind signal obtained by anemometer will provide us valuable clues for searching gas leakage sources. In this paper, the Recurrence Plot (RP) and Recurrence Quantification Analysis (RQA) are applied to analyze the influence of recurrence characteristics of the wind speed time series under the condition of the same place, the same time period and with the sampling frequency of 1hz, 2hz, 4.2hz, 5hz, 8.3hz, 12.5hz and 16.7hz respectively. Research results show that when the sampling frequency is higher than 5hz, the trends of recurrence nature of different groups are basically unchanged. However, when the sampling frequency is set below 5hz, the original trend of recurrence nature is destroyed, because the recurrence characteristic curves obtained using different sampling frequencies appear cross or overlapping phenomena. The above results indicate that the anemometer will not be able to fully capture the detailed information in wind field when its sampling frequency is lower than 5hz. The recurrence characteristics analysis of the wind speed signals provides an important basis for the optimal selection of anemometer.

Ocean surface wind speed retrieval from C-band quad-polarized SAR measurements at optimal spatial resolution

2020 ◽  
Vol 12 (2) ◽  
pp. 155-164
Author(s):  
He Fang ◽  
William Perrie ◽  
Gaofeng Fan ◽  
Tao Xie ◽  
Jingsong Yang
Keyword(s):  
Wind Speed ◽  
Spatial Resolution ◽  
Surface Wind ◽  
Ocean Surface ◽  
Surface Wind Speed ◽  
Ocean Surface Wind

scholarly journals A Composite View of Surface Signatures and Interior Properties of Nonlinear Internal Waves: Observations and Applications

2008 ◽  
Vol 25 (7) ◽  
pp. 1218-1227 ◽  
Author(s):  
Ming-Huei Chang ◽  
Ren-Chieh Lien ◽  
Yiing Jang Yang ◽  
Tswen Yung Tang ◽  
Joe Wang
Keyword(s):  
Wind Speed ◽  
Surface Waves ◽  
Surface Wind ◽  
Surface Wind Speed ◽  
Horizontal Velocity ◽  
Surface Scattering ◽  
Full Width ◽  
Empirical Formulas ◽  
Marine Radar ◽  
Scattering Strength

Abstract Surface signatures and interior properties of large-amplitude nonlinear internal waves (NLIWs) in the South China Sea (SCS) were measured during a period of weak northeast wind (∼2 m s−1) using shipboard marine radar, an acoustic Doppler current profiler (ADCP), a conductivity–temperature–depth (CTD) profiler, and an echo sounder. In the northern SCS, large-amplitude NLIWs propagating principally westward appear at the tidal periodicity, and their magnitudes are modulated at the spring–neap tidal cycle. The surface scattering strength measured by the marine radar is positively correlated with the local wind speed when NLIWs are absent. When NLIWs approach, the surface scattering strength within the convergence zone is enhanced. The sea surface scattering induced by NLIWs is equivalent to that of a ∼6 m s−1 surface wind speed (i.e., 3 times greater than the actual surface wind speed). The horizontal spatial structure of the enhanced sea surface scattering strength predicts the horizontal spatial structure of the NLIW. The observed average half-amplitude full width of NLIWs λη/2 is 1.09 ± 0.2 km; the average half-amplitude full width of the enhanced scattering strength λI/2 is ∼0.57 λη/2. The average half-amplitude full width of the enhanced horizontal velocity convergence of NLIWs λ∂xu/2 is approximately equal to λI/2. The peak of the enhanced surface scattering leads the center of NLIWs by ∼0.46 λη/2. NLIW horizontal velocity convergence is positively correlated with the enhancement of the surface scattering strength. NLIW amplitude is positively correlated with the spatial integration of the enhancement of the surface scattering strength within the convergence zone of NLIWs. Empirical formulas are obtained for estimating the horizontal velocity convergence and the amplitude of NLIWs using radar measurements of surface scattering strength. The enhancement of the scattering strength exhibits strong asymmetry; the scattering strength observed from behind the propagating NLIW is 24% less than that observed ahead, presumably caused by the skewness and the breaking of surface waves induced by NLIWs. Above the center of NLIWs, the surface scattering strength is enhanced slightly, associated with isotropic surface waves presumably induced or modified by NLIWs. This analysis concludes that in low-wind conditions remote sensing measurements may provide useful predictions of horizontal velocity convergences, amplitudes, and spatial structures of NLIWs. Further applications and modification of the presented empirical formulas in different conditions of wind speed, surface waves, and NLIWs or with other remote sensing methods are encouraged.

GPS Reflections for Sea Surface Wind Speed Measurement

2008 ◽  
Vol 5 (4) ◽  
pp. 569-572 ◽  
Author(s):  
D. K. Yang ◽  
Y. Q. Zhang ◽  
Y. Lu ◽  
Q. S. Zhang
Keyword(s):  
Wind Speed ◽  
Surface Wind ◽  
Surface Wind Speed ◽  
Sea Surface ◽  
Sea Surface Wind Speed ◽  
Sea Surface Wind ◽  
Speed Measurement ◽  
Wind Speed Measurement
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