A numerical approach for planning offshore wind farms from regional to local scales over the Mediterranean

Renewable energy resources, such as wind, are available worldwide. Locating areas with high and continual wind sources are crucial in pre-planning of wind farms. Vast offshore areas are characterized by higher and more reliable wind resources in comparison with continental areas. However, offshore wind energy production is in a quite preliminary phase. Elaborating the potential productivity of wind farms over such areas is challenging due to sparse in situ observations. The Mediterranean basin is not an exception. In this study we are proposing numerical simulations of near-surface wind fields from regional climate models (RCMs) in order to obtain and fill the gaps in observations over the Mediterranean basin. Four simulations produced with two regional climate models are examined here. Remote sensing observations (QuikSCAT satellite) are used to assess the skill of the simulated fields. A technique for estimating the potential energy from the wind fields over the region is introduced. The wind energy potential atlas and the map of a wind turbine's functional range are presented, locating the potentially interesting sub-regions for wind farms. The ability of models to reproduce the annual cycle and the probability density function of wind speed anomalies are detailed for specified sub-regions.     

Wind characteristics in the North and Baltic Seas from the QuikSCAT satellite

The QuikSCAT mission provided valuable daily information on global ocean wind speed and direction from July 1999 until November 2009 for various applications including numerical weather prediction, ocean and atmospheric modelling. One new and important application for wind vector satellite data is offshore wind energy, where accurate and frequent measurements are required for siting and operating modern wind farms. The greatest advantage of satellite observations rests in their extended spatial coverage. This paper presents analyses of the 10 year data set from QuikSCAT, for the overview of the wind characteristics observed in the North and Baltic Seas, where most of Europe's offshore wind farms operate and more will be constructed. Significant issues in data availability are identified, directly related to the flagging schemes. In situ observations from three locations in the North Sea are used for comparisons. Mean biases (in situ minus satellite) are close to zero for wind speed and ‐2.7° for wind direction with a standard deviation of 1.2 m s ^{? 1} and 15°, respectively. The impact of using QuikSCAT and in situ measurements extrapolated to 10 m for wind power density estimations is assessed, accounting for possible influences of rain‐contaminated retrievals, the sample size, the atmospheric stability effects and either fitting the Weibull distribution or obtaining the estimates from the time series of wind speed observations.Copyright © 2012 John Wiley & Sons, Ltd.     

Combining meteorological stations and satellite data to evaluate the offshore wind power resource of Southeastern Brazil

Wind is strong and steady over the ocean, but on-site marine meteorological data are sparse for evaluation of oceanic wind power. Here, we draw on meteorological station, satellite data (QuikSCAT), and both theoretical and practical measures of wind turbine performance. The meteorological stations measure directly at high time resolution but low spacial resolution, and provide validation and adjustment of the satellite data. The satellite data provide near-complete spacial coverage at lower time resolution. For the southern coast of Brazil, we use both data sets to evaluate the location, seasonal timing, and availability of the wind power resource. Then, using bathymetry and the properties of current wind-electric technology, we develop maps of wind speed, wind power density, and practical turbine output in power units (MW). In the shallower waters of south Brazil, the most favorable conditions are along the coast between 28°S and 33°S. In just this one coastal area, we find a total resource of 102 GW average electrical production, approximately equal to the electric demand of the entire country.     

A satellite-derived climatology of global ocean winds

An interactive Climatology of Global Ocean Winds (COGOW) is presented based on 5 years (August 1999-July 2004) of QuikSCAT satellite measurements of wind speed and direction 10 m above the sea surface. This climatology provides the first high spatial resolution, observationally based, online atlas of ocean winds. Users can retrieve climatological wind maps and wind statistics, both in tabular and graphical form, from the COGOW web-based atlas. The global coverage of these data provides highly accurate information about the wind statistics in regions of the world ocean that are sparsely sampled by ships and buoys. A case study of the recovery of the vessel Ehime Maru off the Hawaiian Island of Oahu is presented to demonstrate the usage and value of COGOW. Evidence of air-sea interactions, one of many wind phenomena visible within COGOW, is discussed to further familiarize users with COGOW. Finally, the utility of COGOW with regard to various operational and research communities is summarized.     

船测资料与智利外海QuikSCAT风场比较分析

利用大洋渔船在智利外海观测的风场资料与QuikSCAT 10 m散射风原始轨道资料L3产品进行了比较分析。两种资料的偏差统计特征显示:①智利外海船测风速总体上高于QuikSCAT风速,船测风向总体上偏于QuikSCAT风向的左侧;②智利外海船测风场资料与QuikSCAT散射风的风速偏差集中分布在-1~1 m/s之间;风向偏差主要集中分布于-60°~-10°之间,其次为10°~60° 和-10°~10°段;③智利外海白天的风速偏差特征值均小于夜晚,昼、夜风向平均偏差数值差别很大,但昼、夜风向平均绝对偏差、均方根偏差数值相差不大;④2008年智利外海船测风场资料与QuikSCAT散射风的偏差大于其他年份的整体平均值,在高风速段风速偏差尤为明显。     

Development of a water clear of sea ice detection algorithm from enhanced SeaWinds/QuikSCAT and AMSR-E measurements

We develop and evaluate water clear of sea ice (open water following ice cover) detection algorithms that make use of Scatterometer Image Reconstruction (SIR) SeaWinds/QuikSCAT (QuikSCAT) backscatter (σ°) and Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR-E) brightness temperature (T_B) measurements. Algorithm validation was performed within Canadian Arctic waters using the Canadian Ice Service Digital Archive (CISDA) ice charts, NASATeam ice concentration estimates, extended AVHRR Polar Pathfinder (APP-x) albedo data, RADARSAT-1 imagery, and MODIS imagery. Results indicate that the temporal evolution of QuikSCAT σ°, AMSR-E polarization ratio (PR18), and AMSR-E vertical spectral gradient ratio (GR3618) can detect water clear of sea ice events, however mean differences due to frequency dependent characteristics of the data (spatial resolution; sensitivity to open water) were apparent. All water clear of sea ice algorithms are in good agreement with the timing and clearing patterns given by the CISDA. The QuikSCAT algorithm provided a more representative ice edge and more details on the ice clearing process due to higher spatial resolution, however, transient clearing events were better represented by the AMSR-E PR(18) or (GR3618) algorithm. By exploiting the strengths of each sensor, we found that a QuikSCAT and AMSR-E fused algorithm provide improved open water area estimates by as much as 11%. The fusion of QuikSCAT and AMSR-E PR(18) yielded in the most spatially representative open water detection. The residual surface of the water clear of sea ice algorithms was found to provide another measure of the average September minimum pan-Arctic sea ice extent within 6% of the NASATeam algorithm estimates.     

卫星遥感反演海面风矢量数据真实性检验与质量评价

微波散射计(QuikSCAT)和微波辐射计(WindSAT)的10m风矢量数据是目前覆盖范围最大、持续时间最长的海面风场卫星数据产品。利用QuikSCAT和WindSAT运行时间重叠的风矢量原始轨道资料,分别与同步的全球海洋浮标实测风矢量资料进行比较。结果显示:QuikSCAT平均风速略大于浮标,平均绝对误差约为1m/s;风向平均绝对误差在8°以下。WindSAT平均风速略大于浮标,平均绝对误差不超过0.5m/s,均方根误差约为1m/s;风向平均绝对误差在10°以下。在全球海域,QuikSCAT和WindSAT风矢量数据质量高,可信度极好。QuikSCAT和WindSAT在同一点上空的过境时间为准同步,并且二者的风矢量数据相关性极好,可以互相替代。     

Variability in ice phenology on Great Bear Lake and Great Slave Lake, Northwest Territories, Canada, from SeaWinds/QuikSCAT: 2000-2006

The temporal evolution of the backscatter coefficient, sigma-nought (σ°) from QuikSCAT was evaluated for monitoring ice phenology on Great Bear Lake (66°N, 121°W) and Great Slave Lake (61°40′N, 114°W), Northwest Territories, Canada. Results indicated that σ° from QuikSCAT can be used to detect melt onset, water clear of ice and freeze onset dates on both lakes. An ice phenology algorithm was then developed to assess the spatiotemporal variability on both lakes from QuikSCAT for the period 2000-2006. Results showed that for Great Slave Lake, the average melt onset date occurred on year day (YD) 123, the average water clear of ice date was on YD164, and the average freeze onset date was on YD330. On Great Bear Lake, the average melt onset date occurred on YD139, the average water clear of ice date was YD191, and the average freeze onset date was YD321. Ice cover remained present for at least five weeks longer on Great Bear Lake than on Great Slave Lake and most of the difference can be explained by earlier ice melt on Great Slave Lake. Spatially, on Great Bear Lake, melt onset took place first in the eastern arm, water clear of ice occurred first in southeastern and western arms, and freeze onset appeared first in the northern arm and along the shorelines. On Great Slave Lake, melt onset began first in the central basin and then progressed to the northern and eastern arms later in the season. The central basin of Great Slave Lake cleared earlier than the periphery due to the discharge from the Slave River. Freeze onset on Great Slave Lake occurred first within the east arm, closely followed by the north and west arms, and then finally in the centre of the main basin.     

星载散射计再分析风场在海浪模拟中的应用研究

基于第三代海浪(谱)模式WAVEWATCHⅢ,采用NCEP/QuikSCAT混合风场作为模式输入,进行了东中国海、太平洋东岸以及太平洋中部夏威夷附近海域的海浪数值模拟。在东中国海,模拟有效波高与浮标的参考值有较高的相关系数,波高的均方根误差约为0.5 m;在太平洋东岸和夏威夷附近海域,模拟有效波高比浮标的参考值普遍偏低,不同月份波高的均方根误差在0.4~1.2m之间,但模拟波高与浮标的参考值仍有较强的相关性。结果表明利用WAVEWATCHⅢ结合NCEP/QuikSCAT混合风场模拟东中国海的波高是可行的,但要模拟太平洋中、东部开阔深水海域的波高仍需考虑如涌浪、海流等非风场因素。     

SeaWiFS sensing of hazardous algal blooms and their underlying mechanisms in shelf-slope waters of the Northwest Pacific during summer

RCA-chlorophyll (red tide index chlorophyll algorithm — RCA) estimates from the SeaWiFS, sea surface height (SSH) variations/geostrophic currents from the multi-satellite altimeters, sea surface temperature (SST) from the NOAA-AVHRR, and wind speed/direction from the QuikSCAT are used in conjugation with field observation data to first describe comprehensively the occurrences of various hazardous algal blooms (HABs) and their underlying mechanisms and link to nutrient enrichment during the summer (June-September) in shelf-slope waters off the Northwest Pacific (NWP) covering China, Korea, Japan and Russia (perhaps this is the first satellite-based study in Russia). These datasets provide a coherent view of the summertime evolution of HABs and related physical processes in the above regional segments with four common dynamic regions: coastal cold/estuary water zones, upwelling zones next to the coast, repeated meanders/eddies, and frontal regimes induced by the Kuroshio and its tributaries. Summer HABs numerically dominated by dinoflagellates and diatoms (only in few cases) were initiated in these hydrodynamically active coastal regions and subsequently transported throughout their coastal and oceanic ranges by major currents and eddy systems. As a consequence, dense and colossal blooms displayed mean RCA of > 7 mg m^− 3 and TBCA (total bloom covered area) of > 20 × 10³ km², which limits the research vessels to observe concomitantly their spatially explicit phases together with physical oceanographic features in such large regions. Less dense and spatially disbanded blooms were characterized by mean RCA of < 3 mg m^− 3 and TBCA of < 8 × 10³ km². Besides those of the nutrient-abundant zones, high blooms coincided with the coastal upwelling and cyclonic eddy regimes that followed SST minimum and large negative SSH along with favorable phase of winds. By contrast, relatively low mean RCA were consistent with the fronts and anticyclonic meanders revealing moderate-high SSH fields along with variable winds blown off the NWP coast. These anticyclonic meanders, on some occasions, when nutrient-containing coastal water setoff higher chlorophyll biomass and major currents gained force in August, straddled the continental margin, entraining high chlorophyll water from the coast and from the adjacent cyclonic eddies (and upwelling) located nearby into their outer rings that formed a conveyer-belt system of transport to inject coastal blooms into the deep-sea (e.g., East Sea) region of the NWP. The above findings based on satellite data combined with field hydrographic/bloom observation data evidently illustrated richness of the response of summer HABs to the surface circulation and nutrient enrichment processes in shelf-slope waters off the NWP coast.