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1.
北黄海QuikSCAT 卫星风速与浮标风速的对比分析 总被引：1，自引：0，他引：1
对北黄海QuikSCAT散射计矢量风资料与黄海实测浮标站风速资料进行对比分析,结果表明:北黄海QuikSCAT卫星风速和浮标观测风速的大小基本吻合,二者平均偏差是0.26 m/s,相关系数是0.74;风向偏差较大,平均偏差是117.52°。根据卫星风速和浮标风速的对比分析结果,提出了修正方案。修正后的QuikSCAT风向与实测浮标站风向的平均偏差显著提高到20.44°。该修正方案实施简单,修正效果显著,为更准确地使用卫星资料提供了保证。 相似文献
2.
基于浮标和步进频率微波辐射计(SFMR,Stepped-Frequency Microwave Radiometer)数据对NASA JPL(Jet Propulsion Laboratory)和RSS(Remote Sensing Systems)公司分别发布的已广泛应用于全球海面风场观测的ASCAT(Advanced SCATterometer)散射计风产品进行了比较和分析。结果表明,两者风速在中低风速(15 m/s)时基本一致;高风速(15 m/s)时RSS风速整体高于JPL风速。通过浮标数据对比,风速15 m/s时两者风速精度一致;风速15 m/s时两者风速RMS相当,但JPL和RSS风速分别低估和高估。利用SFMR数据检验表明RSS风速与SFMR风速一致性更好。两者风向精度在低风速(5 m/s)时较低,但随风速增加而提高并趋于稳定。该研究结果对相关科研人员的ASCAT散射计风产品选择具有重要的指导意义。 相似文献
3.
Global air-sea surface carbon-dioxide transfer velocity and flux estimated using ERS-2 data and a new parametric formula 总被引：1，自引：1，他引：0
Using data from the European remote sensing scatterometer（ERS-2） from July 1997 to August 1998,global distributions of the air-sea CO2 transfer velocity and flux are retrieved.A new model of the air-sea CO2 transfer velocity with surface wind speed and wave steepness is proposed.The wave steepness（5） is retrieved using a neural network（NN） model from ERS-2 scatterometer data,while the wind speed is directly derived by the ERS-2 scatterometer.The new model agrees well with the formulations based on the wind speed and the variation in the wind speed dependent relationships presented in many previous studies can be explained by this proposed relation with variation in wave steepness effect.Seasonally global maps of gas transfer velocity and llux are shown on the basis of the new model and the seasonal variations of the transfer velocity and llux during the 1 a period.The global mean gas transfer velocity is 30 cm/h after area-weighting and Schmidt number correction and its accuracy remains calculation with in situ data.The highest transfer velocity occurs around 60°N and 60°S,while the lowest on the equator.The total air to sea CO2 llux（calculated by carbon） in that year is 1.77 Pg.The strongest source of CO2 is in the equatorial east Pacific Ocean, while the strongest sink is in the 68°N.Full exploration of the uncertainty of this estimate awaits further data.An effectual method is provided to calculate the effect of waves on the determination of air-sea CO2 transfer velocity and fluxes with ERS-2 scatterometer data. 相似文献
4.
Kohtaro Hosoda 《Journal of Oceanography》2013,69(5):631-646
An empirical method has been developed for estimation of sea surface temperature (SST) at dawn and noon in local time from microwave observations at other times of the day. By using solar radiation, microwave sea surface wind, and SSTs, root-mean-square differences were reduced to approximately 0.75 and 0.8 °C for dawn and noon, respectively. The pseudo SST variation and spatial patterns found in daily mean SST values by simple averaging of samples were damped down by use of diurnal correction. The satellite SST with the diurnal correction shows highly significant coherent variation with in-situ measurements. 相似文献
5.
Sea ice growth and consolidation play a significant role in heat and momentum exchange between the atmosphere and the ocean. However, few in situ observations of sea ice kinematics have been reported owing to difficulties of deployment of buoys in the marginal ice zone (MIZ). To investigate the characteristics of sea ice kinematics from MIZ to packed ice zone (PIZ), eight drifting buoys designed by Taiyuan University of Technology were deployed in the open water at the ice edge of the Canadian Basin. Sea ice near the buoy constantly increased as the buoy drifted, and the kinematics of the buoy changed as the buoy was frozen into the ice. This process can be determined using sea ice concentration, sea skin temperature, and drift speed of buoy together. Sea ice concentration data showed that buoys entered the PIZ in mid-October as the ice grew and consolidated around the buoys, with high amplitude, high frequency buoy motions almost ceasing. Our results confirmed that good correlation coefficient in monthly scale between buoy drift and the wind only happened in the ice zone. The correlation coefficient between buoys and wind was below 0.3 while the buoys were in open water. As buoys entered the ice zone, the buoy speed was normally distributed at wind speeds above 6 m/s. The buoy drifted mainly to the right of the wind within 45° at wind speeds above 8 m/s. During further consolidation of the ice in MIZ, the direct forcing on the ice through winds will be lessened. The correlation coefficient value increased to 0.9 in November, and gradually decreased to 0.7 in April. 相似文献
6.
Naoto Ebuchi 《Journal of Oceanography》1999,55(5):575-584
By using wind vector fields observed by the NASA Scatterometer (NSCAT) and significant wave heights observed by the TOPEX/POSEIDON and European Remote Sensing Satellite-2 (ERS-2) altimeters, one-dimensional fetch growth of wind waves has been investigated under conditions of strong wind and high waves caused by the East Asian winter monsoon in the Sea of Japan. The evolution of fetch-limited wind waves can be observed by the altimeters along their ground tracks. The fetch is estimated by using vector wind fields observed by NSCAT. The derived growth characteristics of wind waves are compared with empirical relationships between the non-dimensional fetch and significant wave height proposed by previous studies. Good agreement is discernible with Toba's fetch graph formula normalized by the friction velocity, while Wilson's well-known formula normalized by the wind speed at a height of 10 m tends to underestimate the wave height under such severe conditions of high wind and very long fetch. This discrepancy is explained by the wind-speed dependence of the drag coefficient. A simple correction to Wilson's formula for the high wind conditions is proposed and compared with the observed data. 相似文献
7.
《Oceanic Engineering, IEEE Journal of》2005,30(3):534-542
This paper describes two algorithms for the retrieval of high-resolution wind and wave fields from radar-image sequences acquired by a marine X-band radar. The wind-field retrieval algorithm consists of two parts. In the first part, wind directions are extracted from wind-induced streaks, which are approximately in line with the mean surface wind direction. The methodology is based on the retrieval of local gradients from the mean radar backscatter image and assumes the surface wind direction to be oriented normal to the local gradient. In the second part, wind speeds are derived from the mean radar cross section. Therefore, the dependence of the radar backscatter on the wind vector and imaging geometry has to be determined. Such a relationship is developed by using neural networks (NNs). For the verification of the algorithm, wind directions and speeds from nearly 3300 radar-image sequences are compared to in situ data from a colocated wind sensor. The wave retrieval algorithm is based on a methodology that, for the first time, enables the inversion of marine radar-image sequences to an elevation-map time series of the ocean surface without prior calibration of the acquisition system, and therefore, independent of external sensors. The retrieved ocean-surface elevation maps are validated by comparison of the resulting radar-derived significant wave heights, with the significant wave heights acquired from three colocated in situ sensors. It is shown that the accuracy of the radar-retrieved significant wave height is consistent with the accuracy of the in situ sensors. 相似文献
8.
9.
基于四种再分析资料的1988-2015年中国近海月均风速特征评估 总被引：1，自引：0，他引：1
This study investigates the long-term changes of monthly sea surface wind speeds over the China seas from 1988 to 2015. The 10-meter wind speeds products from four major global reanalysis datasets with high resolution are used: Cross-Calibrated Multi-Platform data set(CCMP), NCEP climate forecast system reanalysis data set(CFSR),ERA-interim reanalysis data set(ERA-int) and Japanese 55-year reanalysis data set(JRA55). The monthly sea surface wind speeds of four major reanalysis data sets have been investigated through comparisons with the longterm and homogeneous observation wind speeds data recorded at ten stations. The results reveal that(1) the wind speeds bias of CCMP, CFSR, ERA-int and JRA55 are 0.91 m/s, 1.22 m/s, 0.62 m/s and 0.22 m/s, respectively.The wind speeds RMSE of CCMP, CFSR, ERA-int and JRA55 are 1.38 m/s, 1.59 m/s, 1.01 m/s and 0.96 m/s,respectively;(2) JRA55 and ERA-int provides a realistic representation of monthly wind speeds, while CCMP and CFSR tend to overestimate observed wind speeds. And all the four data sets tend to underestimate observed wind speeds in Bohai Sea and Yellow Sea;(3) Comparing the annual wind speeds trends between observation and the four data sets at ten stations for 1988-1997, 1988–2007 and 1988–2015, the result show that ERA-int is superior to represent homogeneity monthly wind speeds over the China seaes. 相似文献
10.
The mixed layer depths over the Arabian Sea were computed for the three successive years 2004-2006 using ARGO floats data. The large availability of ARGO floats for the above period resulted in better estimation of mixed layer depth (MLD) over the Arabian Sea. The results were compared with World Ocean Atlas 1994 MLD Climatology. Marked variability in MLD on a monthly time scale is observed and it was in accordance with the wind stress and/or net heat gain variability, which are the principal factors influencing mixed layer over Arabian Sea. With the availability of large number of ARGO profile data, an attempt is made to study the monthly variability of Mixed Layer. 相似文献
11.
针对中国南海ERS-2／SAR三维对流涡旋图像,分别利用Young的协方差方法和惯性子域方法,反演了对流海洋大气边界层高度、海洋大气边界层垂直对流尺度速度、表面浮力通量、Obukhov长度、稳定性校正后的海面风速和海面风速稳定性校正因子。结果表明,2种反演方法的结果符合较好,在一定程度上说明利用协方差方法和惯性子域方法从卫星SAR图像反演海洋大气边界层参数的有效性。 相似文献
12.
南海混合层近惯性能通量的时空变化 总被引：1，自引：1，他引：0
On the basis of the QSCAT/NCEP blended wind data and simple ocean data assimilation(SODA), the wind-induced near-inertial energy flux(NIEF) in the mixed layer of the South China Sea(SCS) is estimated by a slab model, and the model results are verified by observational data near the Xisha Islands in the SCS. Then, the spatial and temporal variations of the NIEF in the SCS are analyzed. It is found that, the monthly mean NIEF exhibits obvious spatial and temporal variabilities, i.e., it is large west of Luzon Island all the year, east of the Indo-China Peninsula all the year except in spring, and in the northern SCS from May to September. The large monthly mean NIEF in the first two zones may be affected by the large local wind stress curl whilst that in the last zone is probably due to the shallow mixed layer depth. Moreover, the monthly mean NIEF is relatively large in summer and autumn due to the passage of typhoons. The spatial mean NIEF in the mixed layer of the SCS is estimated to be about 1.25 m W/m2 and the total wind energy input from wind is approximately 4.4 GW. Furthermore, the interannual variability of the spatial monthly mean NIEF and the Ni?o3.4 index are negatively correlated. 相似文献
13.
《Ocean Modelling》2001,3(1-2):21-31
A 1/6° model simulation of the Atlantic ocean forced with daily fluxes from ECMWF (re-analysis 1979–1993 and analysis 1994–1999) has been carried out within the Clipper project. A storage strategy which filters out inertial oscillations is defined: five-day mean fields are continuously stored at five-day intervals. It is shown that aliasing errors on the monthly mean meridional heat transport (MHT, a second-order moment) are negligible in that case. These errors are of the order of 0.8 PW in the tropics in the case of a sampling strategy based on instantaneous fields stored every five days, even in the case where step-like variations in the forcing are avoided by an interpolation of the daily wind stress to the model time step. It is also shown that aliasing errors on the annual mean MHT can be as large as 0.2 PW in the tropics in the case of sub-sampling with instantaneous fields. 相似文献
14.
The geophysical model function (GMF) describes the relationship between a backscattering and a sea surface wind, and enables a wind vector retrieval from backscattering measurements. It is clear that t... 相似文献
15.
《African Journal of Marine Science》2013,35(1):195-203
Principal components analysis was used to examine monthly data on sea level obtained from tide-gauge records from the west coast of southern Africa over the period 1957—1975. After a simple correction had removed the effect of local atmospheric pressure, this statistical analysis revealed the structure of nearshore ocean variability over time periods of months to years. The first principal component, accounting for over 55 per cent of the variability in monthly mean sea level, was a near uniform rise and fall everywhere along the west coast of southern Africa. The spectrum of this large-scale structure showed a strong interannual trend, which correlated well with long-term trends of temperature anomaly over the entire South-East Atlantic, and a high-frequency term, which could not be resolved at a time period of one month. The second principal component showed the contrasting response of the northern and southern sites on a seasonal scale, and it could be correlated with seasonal wind data. These results compared well with similar analysis carried out in the North Pacific Ocean. 相似文献
16.
结合经验的台风风场模型和NCEP再分析资料构造了南海台风风场,并以此作为一个第三代海浪模式的输入模拟了1999年约克(York)台风经过南海时所产生的台风浪场.模拟结果显示,尽管文中构造的南海台风风场比较接近真实的风场,但模拟出的台风浪场相对于TOPEX/Poseidon高度计的观测波高仍有一定差异,因此进而采用了一种简单的最优插值同化方法,开展了波高资料的初步同化试验.试验结果显示,资料同化显著地改进了海浪模式的(后)预报精度,而这种改进在涌浪区更加显著,同化有效维持时间大约是43h. 相似文献
17.
In this study, we used the National Centers for Environmental Prediction monthly sea surface temperature (SST) and surface
air temperature (SAT) data during 1982–1994 and the National Center for Atmospheric Research surface wind stress curl data
during 1982–1989 to investigate the Japan Sea SST temporal and spatial variabilities and their relations to atmospheric forcing.
First, we found an asymmetry in the correlation coefficients between SST and wind stress curl, which implies that the SST
variability at the scales of the order of one month is largely due to atmospheric forcing. Second, we performed three analyses
on the data fields: annual mean, composite analysis to obtain the monthly anomaly relative to the annual mean, and empirical
orthogonal function (EOF) analysis on the residue data relative to the summation of the annual mean and the monthly anomaly.
The first EOF mode of SST accounts for 59.9% of the variance and represents the Subpolar Front. The temporal variation of
the first EOF mode implies that the deep Japan Sea could be cooler in cold seasons (November–April) of 1984–1987. Third, we
computed cross-correlation coefficients among various principal components and found that the atmospheric warming/cooling
is the key factor causing intra-seasonal and interannual SST variabilities. 相似文献
18.
Motivated by an analysis of a satellite sea surface temperature image suggesting that a train of extra-tropical cyclones induces amplification of the Kuroshio meander, a regional Kuroshio/Oyashio general circulation model was used to investigate the impact of high-frequency wind on the Kuroshio path variations. Near Japan, the standard deviation of the wind stress curl can be 10 times larger than the monthly mean, so the synoptic variations of the wind stress curl cannot be neglected. With the bimodal Kuroshio case realized in the model, sensitivity tests were conducted using monthly and daily mean QuikSCAT-derived wind stress forcings. The comparison showed that the high-frequency local wind perturbed the Shikoku recirculation gyre (SRG) and caused a transition of the path from straight to meander. The strong anticyclonic eddy within the SRG triggered the meander in the latter case. The high-frequency wind perturbed the motion of the eddy that would have otherwise detached from the Kuroshio, migrated south and terminated the meandering state. The result reinforces the suggestion from previous studies that the anticyclonic eddy within the SRG plays an active role in controlling the Kuroshio path variations. 相似文献
19.
根据TOGA—COARE强化观测期间的资料,分析热带西太平洋西风爆发(WWB)的天气型特征。提出引发和维持WWB过程的低层流场基本有三:1.北半球南下冷源与SE信风结合型;2.北半球南下冷气流与SPCZ上的热带气旋结合型;3.南北取向由双气旋构成的偶极子型流场。指出该偶极子相对稳定在更日线附近,并解释了这一事实存在的原因。还讨论了WWB的多时间尺度性,以及WWB过程中气象要素场变化特征等问题。 相似文献
20.
A preliminary assessment of the sea surface wind speed production of HY-2 scanning microwave radiometer 总被引：3，自引：3，他引：0
HUANG Xiaoqi ZHU Jianhu LIN Mingsen ZHAO Yili WANG He CHEN Chuntao PENG Hailong ZHANG Youguang 《海洋学报(英文版)》2014,33(1):114-119
A scanning microwave radiometer（RM） was launched on August 16,2011,on board HY-2 satellite.The six-month long global sea surface wind speeds observed by the HY-2 scanning microwave radiometer are preliminarily validated using in-situ measurements and WindSat observations,respectively,from January to June 2012.The wind speed root-mean-square（RMS） difference of the comparisons with in-situ data is 1.89 m/s for the measurements of NDBC and 1.72 m/s for the recent four-month data measured by PY30-1 oil platform,respectively.On a global scale,the wind speeds of HY-2 RM are compared with the sea surface wind speeds derived from WindSat,the RMS difference of 1.85 m/s for HY-2 RM collocated observations data set is calculated in the same period as above.With analyzing the global map of a mean difference between HY-2 RM and WindSat,it appears that the bias of the sea surface wind speed is obviously higher in the inshore regions.In the open sea,there is a relatively higher positive bias in the mid-latitude regions due to the overestimation of wind speed observations,while the wind speeds are underestimated in the Southern Ocean by HY-2 RM relative to WindSat observations. 相似文献