HY-2B卫星和模式风速数据随机误差及相关性分析

当利用三配准（Triple Collocation,TC）方法进行误差分析时,系统间随机误差（简称误差）不相关是一个重要前提假设,而在实际应用中不同系统误差常存在相关性,基于最小二乘法扩展配准（Extended Collocation,EC）方法能够在误差相关性存在情况进行误差分析,但对于误差弱相关性情况不能够准确估计误差的标准差。为此本文提出利用3个误差独立系统对第四个系统进行误差估计的方法,同时考虑误差相关性和表征误差,在误差弱相关情况下能更精确估计系统误差的标准差。本文根据HY-2B卫星3个载荷风速观测数据集随机误差相互独立特点,利用扩展三配准（Extended Triple Collocation,ETC）方法计算得到散射计、辐射计和高度计3个载荷风速产品误差的标准差分别为0.600 m/s、0.742 m/s和0.533 m/s;再对ECMWF再分析数据集ERA5的风速产品误差及相关性进行估计,计算出ERA5再分析风速产品随机误差的标准差为0.810 m/s,HY-2B卫星散射计风速产品和ERA5再分析风速产品误差相关性为0.231,HY-2B卫星辐射计风速产品和ERA5再分析风速产品误差相关性为0.105。本文提出利用已知3个误差独立数据集对第四个数据集误差及相关性进行估计的方法,实现了在误差弱相关情况下对系统误差的标准差更为准确的估计,有助于在同化和融合中更好地使用这些数据。     

北部湾沿海最大风速分布特征及工程设计风速推算

利用北部湾沿海7个气象站建站至2008年的年最大风速资料,采用指数律风速廓线公式和＂时次换算＂方法对年最大风速进行订正,得到长年代10m高度10min平均年最大风速序列;采用离差系数Cv分析最大风速的年际变化,应用极值Ⅰ型分布推算北部湾沿海距地10m高50a一遇和100a一遇风速的极大值.结果表明,北部湾沿海年最大风速多出现在7～9月,年最大风速离差系数Cv为0.22～0.35,与沿海城市上海、福州、广州相近;北部湾沿海50a一遇、100a一遇风速的极大值分别为22.9～42.6和24.8～46.5m/s,其空间分布特征是：越靠近海的地方多年一遇风速的极大值就越大.     

基于观测和再分析数据的LSTM深度神经网络沿海风速预报应用研究

基于海洋气象历史观测资料和再分析数据等,利用LSTM深度神经网络方法,开展在有监督学习情况下的海面风场短时预报应用研究。以中国近海5个代表站为研究区域,通过气象台站观测数据和ERA-Interim 6 h再分析数据构建数据集。选取21个变量作为预报因子,分别构建两个LSTM深度神经网络框架(OBS_LSTM和ALL_LSTM)。经与2017年WRF模式6 h预报结果对比分析,得出如下结论:构建的两个LSTM风速预报模型可以大幅降低风速预报误差,RMSE分别降低了41.3%和38.8%,MAE平均降低了43.0%和40.0%;风速误差统计和极端大风分析发现,LSTM模型能够抓住地形、短时大风和台风等敏感信息,对于大风过程预报结果明显优于WRF模式;两种LSTM模型对比发现,ALL_LSTM模型风速预报误差最小,具有很好的稳定性和鲁棒性,OBS_LSTM模型应用范围更广泛。     

基于ASCAT 散射计数据的2013 年南极周边海面风速特征分析

利用2013年1月1日~2013年12月31日的ASCAT散射计风速数据,从海面风速季平均分布特征、平均海面风速特征、海面风速大于10 m/s发生比例统计等方面,对55°S以南的南极周边海域开展了风速空间分布特性统计,得到以下结果:7月平均风速最大,为12 m/s,1月平均风速最小,为8 m/s。对于南极周边海域,区域平均风速主要在9~12 m/s,全年出现的时间大于280 d,约占全年的77%。风速大于10 m/s所占比例4~9月大于1~3月和10~12月。从全年来看,南极周边海域在4~9月风速普遍较大,且0°~60°W海域内风速明显比其他海域要小。在此基础上将2013年每日的区域平均风速与月平均风速与2012年做了对比,变化趋势与2012年基本一致。通过本项长期工作,可以了解南极风场环境基本情况,建立与更新基础资料和图件,得到南极地区风场要素时空分布、变化规律,服务于南极科学考察、全球变化等多学科研究应用。     

A wind speed retrieval algorithm by combining 6 and 10 GHz data from Advanced Microwave Scanning Radiometer: Wind speed inside hurricanes

A wind speed retrieval algorithm was developed using 6 and 10 GHz h-pol (6H and 10H) data of the Advanced Microwave Scanning Radiometer (AMSR) aboard the Advanced Earth Observation Satellite-II (ADEOS-II) and AMSR-E aboard AQUA, for the purpose of retrieving wind speed inside rainstorms, primarily hurricanes and typhoons. The h-pol was used rather than the v-pol, because the brightness temperature sensitivity to the ocean wind at h-pol is larger than v-pol. The microwave emission change of 6H and 10H corresponding to ocean wind was evaluated in no-rain areas by combining AMSR and SeaWinds data aboard the ADEOS-II (SeaWinds was NASA’s scatterometer), and it was found that the ratio of the two 6H to 10H increments due to ocean wind is 0.9. Assuming that this result also holds with higher wind speeds and under rainy conditions, the brightness temperatures at 6H and 10H were simulated using a microwave radiative transfer model. A parameter W6 (unit; Kelvin) was then defined, representing an increment at 6H due to ocean wind. W6 is applicable to rainy areas, and to all ranges of sea surface temperature. W6 was compared with wind speed reported by the National Hurricanes Center for several hurricanes in the Western Atlantic Ocean during three years (2002 to 2004). W6 averaged around centers of hurricanes was found to exhibit a sensitivity to wind speed, such as increasing from 22 K to 65 K as the wind speed rose from 65 to 140 knots (33 to 72 m/s), and an empirical relationship relating the averaged W6 to wind speed in hurricanes was derived.     

AEL—1型风向,风速仪

本文介绍并叙述了AEL-1型风向、风速仪的设计原理,仪器各部分的电路设计,工作过程及系统软件。该仪器适用于气象台站、工矿企业、海上浮标及科研单位等部门。     

绥中36号海上石油平台站业务化评估及其风速资料的质量检测

选取海上A平台54646为参考站,通过差值对比、趋势对比以及风向相符率对绥中36号石油平台站54553运行以来的观测资料进行了分析,以此为例来说明天津建设的环渤海海域石油平台站的业务化评估过程。采用气候学界限值、内部一致性、持续性、时间一致性及空间一致性等检查方法对该站2017年定时2 min风速和极大风速数据进行了初步质量检测,并且还通过环渤海地区2017年冬半年的较强冷空气过程,对该站观测到的风速数据进行了进一步验证。结果表明:54553站观测的各气象要素值表现合理,具有一定的局地天气气候代表性,能够投入海洋气象预报、近海风能资源评估等业务使用。同时,该站观测的风速资料质量相对较好,为环渤海海洋气象预报服务增添了新的数据保障。     

Sea surface wind speed retrieval from Sentinel-1 HH polarization data using conventional and neural network methods

Conventional retrieval and neural network methods are used simultaneously to retrieve sea surface wind speed(SSWS) from HH-polarized Sentinel-1(S1) SAR images. The Polarization Ratio(PR) models combined with the CMOD5.N Geophysical Model Function(GMF) is used for SSWS retrieval from the HH-polarized SAR data. We compared different PR models developed based on previous C-band SAR data in HH-polarization for their applications to the S1 SAR data. The recently proposed CMODH, i.e., retrieving SSWS directly from the HHpolarized S1 data is also validated. The results indicate that the CMODH model performs better than results achieved using the PR models. We proposed a neural network method based on the backward propagation(BP)neural network to retrieve SSWS from the S1 HH-polarized data. The SSWS retrieved using the BP neural network model agrees better with the buoy measurements and ASCAT dataset than the results achieved using the conventional methods. Compared to the buoy measurements, the bias, root mean square error(RMSE) and scatter index(SI) of wind speed retrieved by the BP neural network model are 0.10 m/s, 1.38 m/s and 19.85%,respectively, while compared to the ASCAT dataset the three parameters of training set are –0.01 m/s, 1.33 m/s and 15.10%, respectively. It is suggested that the BP neural network model has a potential application in retrieving SSWS from Sentinel-1 images acquired at HH-polarization.     

Typhoon wind hazard model and estimation on return period of typhoon wind speed

Typhoons are one of the most serious natural disasters that occur annually on China’s southeast coast. A technique for analyzing the typhoon wind hazard was dev...     

Characterizing random wave surface elevation data

The definition and subsequent use of dimensional and dimensionless parameters to characterize various nonlinear aspects of ocean surface waves has again become a matter of great interest to the offshore community. The desire to ascertain whether laboratory simulations are adequately representing the surface waves found in the oceans and the concern over the mechanisms behind platform response phenomena, like ringing, has driven this resurgence of interest. This paper presents a depth independent characterization of single design waves, from which improved estimates of localized wave crest front and back slopes follow that are consistent with discrete time series analysis. Characterization of the nature of the entire wave data recorded requires a combination of spectral parameters and probabilistic models in addition to those used in the design wave characterization. A new expression for the direct evaluation of the kurtosis from knowledge of the spectral bandwidth, the relationship between some of the common spectral parameters, and some modified spectral parameters are presented and discussed. Three illustrative examples are presented. The first example provides a detailed examination of wave data measured from a series of random amplitude and random phase tests in a large model basin. The second presents estimates of the various parameters for the Pierson-Moskowitz and Wallops wave spectrum models. The third example investigates the use of the spectral peakedness ratio for comparing data with selected wave spectrum models. The examples illustrate how the formulae can provide a comprehensive local and global parametric characterization of surface wave elevation data.     

Characterizing random wave surface elevation data

The definition and subsequent use of dimensional and dimensionless parameters to characterize various nonlinear aspects of ocean surface waves has again become a matter of great interest to the offshore community. The desire to ascertain whether laboratory simulations are adequately representing the surface waves found in the oceans and the concern over the mechanisms behind platform response phenomena, like ringing, has driven this resurgence of interest. This paper presents a depth independent characterization of single design waves, from which improved estimates of localized wave crest front and back slopes follow that are consistent with discrete time series analysis. Characterization of the nature of the entire wave data recorded requires a combination of spectral parameters and probabilistic models in addition to those used in the design wave characterization. A new expression for the direct evaluation of the kurtosis from knowledge of the spectral bandwidth, the relationship between some of the common spectral parameters, and some modified spectral parameters are presented and discussed. Three illustrative examples are presented. The first example provides a detailed examination of wave data measured from a series of random amplitude and random phase tests in a large model basin. The second presents estimates of the various parameters for the Pierson-Moskowitz and Wallops wave spectrum models. The third example investigates the use of the spectral peakedness ratio for comparing data with selected wave spectrum models. The examples illustrate how the formulae can provide a comprehensive local and global parametric characterization of surface wave elevation data.     

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

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.     

长江口外海上风速的近似推算摸式

在分析长江口外海陆风速差的日变化、季节变化特征的基础上,考虑了海陆不同下垫面的粗糙度和温度层结对风速变化的影响,建立了一个利用沿海陆地站测风推算近岸海上风速的模式。计算结果表明,推算值与实测值有着相当好的吻合,具有一定的实用价值。     

CYGNSS卫星风速产品的精度检验

针对 CYGNSS卫星风速产品的适用性问题,以美国国家数据浮标中心(NDBC)的实测风速与美国国家飓风中心(NHC)的最佳路径风速为参照,选取美国西南部海域为研究区,通过数据匹配和对比分析,评估了CYGNSS不同模型估算风速产品的精度。结果表明,CYGNSS FDS模型估算的中、低风速产品与NDBC浮标实测风速具有较好的一致性,CYGNSS风速与浮标风速的差异在春夏季稍高、秋冬季略低;CYGNSS YSLF模型估算的高风速产品与NHC最大风速存在较大差异,CYGNSS风速低于NHC最大风速;对于CYGNSS两种模型估算的风速产品,利用遥感观测量NBRCS反演出的风速都比LES反演出的风速具有更好的精度。总体而言,本研究验证了CYGNSS风速产品的真实有效性,对提高海洋数值预报能力具有一定的意义。     

一种改进的高度计风速反演模式函数研究

本文利用角动量模式计算获得高风速资料,并通过气象观测站实测资料验证了风速资料的准确性,并将所得风速应用于Jason-1高度计风速反演模式函数研究,得到了一个新的风速反演模式函数。研究结果表明,本文提出的模式函数能更好地反映台风经过时海表面风速情况,实现了高度计对高风速(10~40 m/s)的反演,可作为Jason-1高度计风速反演业务化算法在高风速情况下的补充,以提高高度计风速反演精度。     

Estimation of wind speed and wave height during cyclones

Wave and wind characteristics based on the cyclones, in the vicinity of the Nagapattinam coastline (east coast of India) were estimated. In all, 11 cyclones have crossed near the study region during 1960–1996. For the four severe cyclones, the isobaric charts were collected at three hourly intervals from the India Meteorological Department. The storm variables such as central pressure, radius of maximum wind, speed of forward motion and direction of storm movement were extracted and the method based on standard Hydromet pressure profile, were used for the hindcast of storm wind fields. For all the cyclones the maximum significant wave height within the storm and its associated spectral peak period was estimated using the Young’s model considering the moving wind field and the results are compared with the hurricane wave prediction techniques provided in the shore protection manual published by the US Army Corps of Engineers in 1984. The study shows that the estimated wind speed and the data reported by ships were comparable. Empirical expressions relating wind speed, wave height and wave period to storm parameters were derived. The design wave height for different return periods was obtained by fitting a two-parameter Weibull distribution to the estimated significant wave heights. The design wave height was 9.39 m for 1 in 100 year return period for a direct hit of cyclone.     

Improving extreme wind speed prediction for North Sea offshore oil and gas fields

The paper adresses accuracy improving of statistical prediction, extracted from a shorter stochastic process, using the information provided by another synchronous highly correlated stochastic process that has been measured for a longer time. As an example, the specific issue of improving extreme wind speed prediction has been addressed. For this purpose, an efficient transfer of information is necessary between two synchronous, highly correlated stochastic processes. To illustrate the efficiency of the proposed technique, two time series of measured wind speed data from North sea oil and gas fields were used.     

CTD资料质量控制浅析

物理海洋学调查自上世纪70年代开始以来,至今已有100余年的历史.调查方法和观测仪器也已有了根本性的变化.就海水温盐度测量而言,由当时的颠倒温度表、南森采水器和BT(深度温度仪)等机械式观测仪器发展到XBT(抛弃式温深计)、AXBT(机载抛弃式深度温度计)和CTD(温盐深仪)等电子仪器设备.     

基于微波散射计观测的气候态海面风场和风应力场

收集了星载微波散射计NSCAT,QuikSCAT和SeaWinds on ADOES-II的全球海面风速和方向L2B数据,数据涉及的时间序列长度为11.5 a。通过对所收集数据的质量控制、Loess低通空间滤波和统计处理,构建了气候态的逐月全球海面风场、风应力场和风应力旋度场(简称为SCAT),其空间网格间距为0.25°×0.25°。SCAT资料与其他有关资料相比,包含了更丰富的海面风场中小尺度空间变化的信息,可广泛应用于海洋、气候、海气相互作用等方面的研究,特别适合应用于海洋中小尺度过程的研究。作为我国"海洋二号"("HY-2")卫星预研项目的成果之一,SCAT资料将由国家海洋局国家卫星海洋应用中心提供给有关用户。     

上海沿海站点极大风速预报方程的细化和完善

利用上海沿海14个站点2012-2019年的观测资料,分析了2 min平均风速和极大风速的关系,对沿海站点极大风速预报方程进行了细化和完善.结果 表明:2 min平均风速与极大风速具有近似线性的关系;2 min平均风速和极大风速的关系不是均一分布,各站点极大风速回归方程的回归系数从沿岸到近海基本呈递减趋势;对4级以上的...