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1.
Naoto Ebuchi 《Journal of Oceanography》2006,62(3):293-301
Marine surface winds observed by two microwave sensors, SeaWinds and Advanced Microwave Scanning Radiometer (AMSR), on the
Advanced Earth Observing Satellite-II (ADEOS-II) are evaluated by comparison with off-shore moored buoy observations. The
wind speed and direction observed by SeaWinds are in good agreement with buoy data with root-mean-squared (rms) differences
of approximately 1 m s−1 and 20°, respectively. No systematic biases depending on wind speed or cross-track wind vector cell location are discernible.
The effects of oceanographic and atmospheric environments on the scatterometry are negligible. Though the wind speed observed
by AMSR also showed agreement with buoy observations with rms difference of 1.27 m s−1, the AMSR wind speed is systematically lower than the buoy data for wind speeds lower than 5 m s−1. The AMSR wind seems to have a discontinuous trend relative to the buoy data at wind speeds of 5–6 m s−1. Similar results have been obtained in an intercomparison of wind speeds globally observed by SeaWinds and AMSR on the same
orbits. A global wind speed histogram of the AMSR wind shows skewed features in comparison with those of SeaWinds and European
Centre for Medium-range Weather Forecasts (ECMWF) analyses. 相似文献
2.
Akira Shibata 《Journal of Oceanography》2007,63(5):863-872
The effect of air-sea temperature differences on the ocean microwave brightness temperature (Tb) was investigated using the
Advanced Microwave Scanning Radiometer (AMSR) aboard the Advanced Earth Observing Satellite-II (ADEOS-II) during a period
of seven months. AMSR Tb in the global ocean was combined with wind data supplied by the scatterometer SeaWinds aboard ADEOS-II
and air temperature given by a weather forecast model. Tb was negatively correlated with air-sea temperature difference, its
ratio lying around −0.4K/°C at the SeaWinds wind speed of 14 m/s for the 6 GHz vertical polarization. Tb of AMSR-E aboard
AQUA during 3.5 years was combined with ocean buoy data, and similar results were obtained. 相似文献
3.
Kohtaro Hosoda Hiroshi Murakami Akira Shibata Futoki Sakaida Hiroshi Kawamura 《Journal of Oceanography》2006,62(3):339-350
This study compares infrared and microwave measurements of sea surface temperature (SST) obtained by a single satellite. The
simultaneous observation from the Global Imager (GLI: infrared) and the Advanced Microwave Scanning Radiometer (AMSR: microwave)
aboard the Advanced Earth Observing Satellite-II (ADEOS-II) provided an opportunity for the intercomparison. The GLI-and AMSR-derived
SSTs from April to October 2003 are analyzed with other ancillary data including surface wind speed and water vapor retrieved
by AMSR and SeaWinds on ADEOS-II. We found no measurable bias (defined as GLI minus AMSR), while the standard deviation of
difference is less than 1°C. In low water vapor conditions, the GLI SST has a positive bias less than 0.2°C, and in high water
vapor conditions, it has a negative (positive) bias during the daytime (nighttime). The low spatial resolution of AMSR is
another factor underlying the geographical distribution of the differences. The cloud detection problem in the GLI algorithm
also affects the difference. The large differences in high-latitude region during the nighttime might be due to the GLI cloud-detection
algorithm. AMSR SST has a negative bias during the daytime with low wind speed (less than 7 ms−1), which might be related to the correction for surface wind effects in the AMSR SST algorithm. 相似文献
4.
Akira Shibata 《Journal of Oceanography》2006,62(3):351-359
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. 相似文献
5.
Akira Shibata 《Journal of Oceanography》2006,62(3):321-330
Ocean microwave emissions changed by the ocean wind at 6 GHz were investigated by combining data of the Advanced Microwave
Scanning Radiometer (AMSR) and SeaWinds, both aboard the Advanced Earth Observation Satellite-II (ADEOS-II). This study was
undertaken to improve the accuracy of the sea surface temperature (SST) retrieved from the AMSR 6 GHz data. Two quantities,
6V*(H*), were defined by the brightness temperature of the AMSR at 6 GHz with two polarizations (V-pol and H-pol), adjusted
for atmospheric effects and with a calm ocean surface emission removed. These quantities represent a microwave emission change
due to the ocean wind at 6 GHz. 6V* does not change in a region where 6H* is less than around 4 K (referred to as z0). Both
6V* and 6H* increase above z0. The 6V* to 6H* ratio, sp, varies with the relative wind directions. Furthermore, the sp values
vary with the SST, between the northern and southern hemisphere, and seasonally. By specifying appropriate values for z0 and
sp, the SST error between AMSR and buoy measurement became flat against 6H*, which is related to the ocean wind. Two extreme
cases were observed: the Arabian Sea in summer and the Northwestern Atlantic Ocean in winter. The air-sea temperature difference
in the former case was largely positive, while it was largely negative in the latter. The 6V* and 6H* relations differed from
global conditions in both cases, which resulted in incorrect SSTs in both areas when global coefficients were applied. 相似文献
6.
卫星高度计海面风速的校准与验证 总被引：2，自引：1，他引：1
为了改善不同卫星高度计海面风速数据之间的一致性,以浮标数据为基准,对国内的HY-2A和国外的T/P、GFO、Jason-1、Envisat、Jason-2、CryoSat-2共7颗卫星高度计的海面风速数据进行了分析,给出了各个卫星高度计的海面风速校准公式,并对其校准效果进行了验证。验证结果表明:各个卫星高度计的海面风速在经过校准后,与浮标海面风速差异的均值和均方根都有所降低,其中HY-2A最为显著。经过校准后所有卫星高度计的海面风速与浮标海面风速差异的均值都在±0.2m/s以内。除了HY-2A、GFO和Jason-1,其余4颗卫星高度计校准后的海面风速与浮标海面风速差异的均方根都在1.6m/s以下。由此可以得出结论,利用本文的校准公式对各个卫星高度计(特别是HY-2A卫星高度计)的海面风速进行校准,可以有效减少其与浮标海面风速之间的差异。 相似文献
7.
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. 相似文献
8.
Monte-Carlo模拟与经验路径模型预测台风极值风速的对比 总被引：2，自引：2，他引：0
台风是我国东南沿海区域每年发生的严重自然灾害之一。本文分别采用传统的Monte-Carlo模拟方法以及较为先进的经验路径模拟方法预测中国东南沿海区域台风的极值风速(10 m高度处10 min平均值)，并对两种方法的预测结果进行了对比。本文将东南海岸线向内陆扩展约200 km的区域划分为0.25°×0.25°的网格，以每个网格点作为研究点。首先采用Monte-Carlo模拟方法产生每个研究点1 000年间的虚拟台风事件。然后采用经验路径模型方法构建了西北太平洋1 000年的热带气旋事件集，采用模拟圆方法从中提取对各个研究站点有影响的台风事件。接着采用Yan Meng风场模型计算每个研究点台风的最大风速，构成极值风速序列。最后采用极值分布模型预测每个研究点不同重现期的极值风速，并对两种不同方法预测的结果进行了对比。研究发现在研究区域的内陆侧经验路径方法预测的风速略高于Monte-Carlo模拟方法预测的结果，而在海岸沿线一带经验路径方法预测的结果略低，这主要是由两种方法构造的虚拟台风的中心压强存在差异以及模型本身的不确定性造成的。本文的研究结果可以为防灾减灾系统提供有益的参考。 相似文献
9.
灌浆连接段的疲劳性能对于海上风机单桩支撑结构至关重要。基于385种工况下的某实际5 MW单桩风机支撑结构在风、浪荷载作用下的动力响应分析,获取了灌浆连接段荷载边界条件时程。建立灌浆连接段精细化有限元子模型,将荷载边界条件转化为应力时程。对于剪力键采用"热点应力"方法进行疲劳性能评价。对于灌浆材料,选取剪力键附近灌浆材料单元积分点处的第三主应力进行疲劳性能评价。采用Palmgren-Miner线性损伤累计准则和雨流计数方法进行疲劳损伤的累计。在某实际灌浆连接段20年的设计寿命周期内,最大剪力键总疲劳损伤为1.35×10~(-10);最大灌浆材料总疲劳损伤为1.54×10~(-3)。由此可见,灌浆连接段的疲劳性能由灌浆材料控制,且损伤值远小于限值1/3,在现有的荷载条件下,灌浆连接段不会发生疲劳破坏。分析产生损伤较大的几种工况可知,风速对现有单桩结构灌浆连接段疲劳的损伤起控制作用。 相似文献
10.
基于Himawari-8卫星的逐时次海表温度融合 总被引：1，自引：0，他引：1
Himawari-8卫星是日本气象厅发射的新一代地球同步静止气象卫星,为获取逐时次海表温度产品提供了有力数据支持。本文以Himawari-8 AHI海表温度为基础,利用最优插值法融合GCOM-W1 AMSR2海表温度和NERA-GOOS现场观测资料,生成逐时次海表温度融合产品。为了充分利用邻近时刻的海表温度观测资料,利用Himawari-8 AHI海表温度和欧洲中期天气预报中心海面风速数据建立匹配数据集,研究建立海表温度日变化模型,实现邻近时刻海表温度的订正;为了消除多源海表温度间的系统偏差,以Himawari-8 AHI海表温度为目标数据,利用泊松方程对GCOM-W1 AMSR2海表温度进行偏差订正。实验验证结果表明,利用逐时次海表温度融合产品计算的日增温情况与海面风速具有较好的相关性,间接证实了逐时次海表温度融合产品的准确性;另外,逐时次海表温度融合产品与现场观测海表温度的偏差为0.09℃、均方根误差为0.89℃,二者具有较好的一致性,说明逐时次海表温度融合产品具有较高的精度。 相似文献
11.
Toshiro Saino Shaoling Shang Yoshihisa Mino Koji Suzuki Hideaki Nomura Sei-ichi Saitoh Hideo Miyake Toshiyuki Masuzawa Koh Harada 《Journal of Oceanography》1998,54(5):583-592
A sediment trap experiment was carried out in conjunction with an over flight of Ocean Color Temperature Scanner (OCTS) on
board Advanced Earth Observing Satellite (ADEOS) at 40°N, 143°E off Sanriku in April to May 1997. Short term variability of
particle fluxes was examined at depths of 450 m and 600 m from April 6 to May 1 with a sampling interval of two days, and
at 450 m with one day interval from 2nd to 10th May. Daily averaged mass flux at 450 m and 600 m was 815 mg m−2d−1 and 862 mg m−2d−1, respectively. A sharp increase in mass flux was observed during the period from April 26 to April 29 with the highest mass
flux of 8 g m−2d−1. About 85% of the total mass flux for the entire duration (26 days) was collected within these 4 days. Trapped material during
the peak flux period was mainly composed of diatoms dominated byThalassiosira spp. and resting spores ofChaetoceros spp. This suggested that the peak flux was the result of (a) diatom bloom(s) in the euphotic column. Current meter records
at 420 m showed that on April 26 and 27, the period when the peak flux was observed, the southwestward current had diminished
in strength and changed its direction northwestward. Low current speeds appeared to have enhanced trap efficiency to help
form the peak flux. A time series of OCTS Intensive-LAC (Local Area Coverage: Region B) images from mid-March to early May
was examined todetect phytoplankton bloom(s). In the March 26th Chl image, high concentration region was restricted to the
southwest off Cape Erimo, but spread around the warm core ring (WCR) 93A by April 10. East of the WCR93A, high Chl concentration
remained steady until May, but to the west of the WCR93A, Chl decreased rapidly before the 19th of April. From this observation
we suspect that the peak flux observed at the end of April originated from a bloom, which ceased on the 17th or 18th of April,
in the region north of 40°N and west of 143°E. Taking the current meter records into account, the source region for the trapped
material is most likely around southwest of the Cape Erimo. 相似文献
12.
E. G. Merzlyakov Yu. I. Portnyagin T. V. Solov’eva A. I. Pogoreltsev E. V. Suvorova 《Izvestiya Atmospheric and Oceanic Physics》2012,48(2):174-184
Based on empirical monthly data on the parameters of oscillations in the horizontal wind component of the diurnal migrating
tide, we calculated the altitude-latitude distributions of the parameters of oscillations in the vertical wind component of
the diurnal tide in the region of the mesosphere and lower thermosphere (80–100 km). The initial data were obtained from satellite
observations of the mesosphere and lower thermosphere at altitudes from 90 to 120 km and from data of ground-based sounding
of this region using the radio meteor method and the method of partial reflections in the altitude range from 80 to 100 km.
We compare the resulting distributions with the results of numerical modeling for the migrating diurnal tide using a global
circulation model for the middle and upper atmosphere. It is shown that, accurate to measurement errors, there is a good agreement
between the distributions of parameters of the migrating diurnal tide obtained by the models. One specific feature of the
empirical distributions of the amplitude of the vertical wind oscillations is that there are three regions of increased amplitude
values—in the vicinity of the equator and at 30° N and 30° S latitudes—which were observed for all seasons. The maximum value
of the amplitude of the vertical wind oscillations is approximately 0.1 m/s. The divergence of the Eliassen-Palm flux was
estimated to be on the order of 10 m s−1 day−1. 相似文献
13.
The atmosphere-ocean exchange of climatically important gases is determined by the transfer velocity (k) and concentration gradient across the interface. Based on observations in the northwestern subarctic Pacific and Sagami
Bay, we report here the results of the first ever application of the natural abundance of triple isotopes of dissolved oxygen
(16O, 17O and 18O) for direct estimation of k and propose a new relationship with wind speed. The k values estimated from nighttime variations in oxygen isotopes are found to be higher than the direct estimations at low wind
speed (<5 m s−1) and lower at high wind speeds (>13 m s−1) and showed significant spatial variability. The method presented here can be used to derive seasonal and spatial variations
in k and the influence of surface conditions on the value, leading to improved estimates of biogenic/anthropogenic gas exchange
at the air-sea interface. 相似文献
14.
Algorithm and validation of sea surface temperature observation using MODIS sensors aboard terra and aqua in the western North Pacific 总被引：4，自引：0，他引：4
Kohtaro Hosoda Hiroshi Murakami Futoki Sakaida Hiroshi Kawamura 《Journal of Oceanography》2007,63(2):267-280
A regional algorithm to estimate SST fields in the western North Pacific, where small oceanographic disturbance are often
found, has been developed using Moderate Resolution Imaging Spectroradiometers (MODIS) aboard Terra and Aqua. Its associated
algorithm, which includes cloud screening and SST estimation, is based on an algorithm for the Global Imager (GLI) aboard
Advanced Earth Observing Satellite-II (ADEOS-II) and is tuned for MODIS sensors. For atmospheric correction, we compare Multi-Channel
SST (MCSST), Nonlinear SST (NLSST), Water Vapor SST (WVSST) and Quadratic SST (QDSST) techniques. For NLSST, four first-guess
SSTs are investigated, including the values for MCSST, climatology with two different spatial resolutions, and near-real-time
objective analysis. The results show that the NLSST method using high-resolution climatological SST as a first-guess has both
good quality and high efficiency. The differences of root-mean-square error (RMSE) between the NLSST models using low-resolution
climatology and those using high-resolution climatology are up to 0.25 K. RMSEs of the new algorithm are 0.70 K/0.65 K for
daytime (Aqua/Terra) and 0.65 K/0.66 K for nighttime, respectively. Diurnal warming and the stratification of the ocean surface
layer under low wind are discussed. 相似文献
15.
Kunio Kutsuwada 《Journal of Oceanography》1998,54(5):443-456
Data sets of surface wind and wind-stress fields in the North Pacific from September 1996 to June 1997 have been constructed
using NASA Scatterometer (NSCAT) data on-board ADEOS to investigate their variability and implications for the wind-driven
oceanic circulation. Using a weighting function decreasing with the distance between each grid and data points, and of Gaussian
type for time, daily, 10-day and monthly averages are calculated for each 1°×1° grid. Products are validated by comparison
with those calculated from in-situ measurement data at oceanic buoys around Japan (JMA) and in the equatorial area (TAO).
The RMS differences for wind direction and speed never exceed 20° and 2 ms−1, respectively, for the TAO buyos. This does not hold for data taken by JMA buoys, suggesting that the reliability in the
mid-latitudes is not good for time averages shorter than several days. Zonal integration of the Sverdrup transport in a zone
of 28°–30°N calculated from the monthly-mean products ranges between 25 and 60×106 m3s−1 (Sv) around its mean of 38 Sv. These are not so different from the Kuroshio transport values calculated from oceanic measurements. 相似文献
16.
Recent investigation suggests that volume transport through the Tsushima/Korea Strait often has double peaks during the summer
to autumn period with decreasing transport in September. The satellite-observed wind changes from weak northwestward (across-strait)
in summer to strong southwestward (along-strait) in early autumn (September) in the strait. Such a strong along-strait wind
is related to tropical cyclones, which frequently pass through the East China Sea in September. The effect of the along-strait
wind component on the transport variation is examined using a three-dimensional numerical model. The simulated volume transport
through the Tsushima/Korea Strait shows realistic seasonal and intra-seasonal variations. According to sensitivity experiments
on local winds, the transport variations in September are mainly generated by strong along-strait (southwestward) wind rather
than weak across-strait wind. The strait transport responds to the along-strait wind (southeastward), which produces a sea
level increase along the Korean coast, resulting in the geostrophic balance across the strait. The transport minimum through
the Tsushima/Korea Strait in September can be determined by the combination of the across-strait geostrophic and along-strait
ageostrophic balances.
The Editor-in-Chief does not recommend the usage of the term “Japan/East Sea” in place of “Sea of Japan”. 相似文献
17.
The rain rate (RR) retrieval method for the RR estimation over ice-free areas of the ocean is presented. Measurements of the Japanese Advanced Microwave Scanning Radiometer 2 (AMSR2) on board the satellite GCOM-W1 are used. The method is based on the results of the numerical modeling of brightness temperatures of the outgoing microwave radiation of the ocean–atmosphere system and their subsequent conversion into the RR using neural networks. A simplified form of the transfer equation is used. Its errors for the considered wavelengths do not exceed 1 K at an RR of less than 20 mm/h. The method is verified by comparison with the Tropical Rainfall Measuring Mission’s (TRMM) Microwave Instrument (TMI) RR product. As a result of the comparison, the rain rate retrieval error within the range of 20 mm/h is found to be 1 mm/h. 相似文献
18.
Futoki Sakaida Masao Moriyama Hiroshi Murakami Hiromi Oaku Yasushi Mitomi Akira Mukaida Hiroshi Kawamura 《Journal of Oceanography》1998,54(5):437-442
The Ocean Color and Temperature Scanner (OCTS) aboard the Advanced Earth Observing Satellite (ADEOS) can observe ocean color
and sea surface temperature (SST) simultaneously. This paper explains the algorithm for the OCTS SST product in the NASDA
OCTS mission. In the development of the latest, third version (V3) algorithm, the OCTS match-up dataset plays an important
role, especially when the coefficients required in the MCSST equation are derived and the equation form is adjusted. As a
result of the validation using the OCTS match-up dataset, the algorithm has improved the root mean square (rms) error of the
OCTS SST up to 0.698°C although some problems remain in the match-up dataset used in the present study. 相似文献
19.
基于CCMP(cross-calibrated multi-platform)再分析风场数据,研究了9907号, 9908号和9909号3个台风对中国沿海5个风电场的影响,分别从台风的形成以及路径,对沿海风电场风速的影响,台风期间的发电情况等详细地描述了台风对风电机组的影响。发现:台风对5个海上风电场的影响可以分为3个阶段,第一阶段是1999年8月1—4日,输出功率由南向北依次降低,此时主要受9907号台风的影响;第二阶段是8月6—9日,8月6日也呈现输出功率由南向北降低,主要是9909号台风由南海途径台湾海峡即将进入东海的影响;受9908号台风影响, 8月7日最大输出功率出现在S3风机。8月8日,受9908和9909号台风的叠加影响, S4风机的输出功率达到15天的最大值38.4 MW。第三个阶段是8月12—15日,受大气锋面的影响, S1—S5输出功率呈现波动。台风过境期间提高了各站点的运营能力和部分站点的额定容量,未对风电机组产生大的破坏。研究成果可为相关部门在台风期间海洋风力发电的决策提供参考。 相似文献
20.
We have examined wind-induced circulation in the Sea of Okhotsk using a barotropic model that contains realistic topography
with a resolution of 9.25 km. The monthly wind stress field calculated from daily European Centre for Medium-Range Weather
Forecasting (ECMWF) Re-Analysis data is used as the forcing, and the integration is carried out for 20 days until the circulation
attains an almost steady state. In the case of November (a representative for the winter season from October to March), southward
currents of velocity 0.1–0.3 m s−1 occur along the bottom contours off the east of Sakhalin Island. The currents are mostly confined to the shelf (shallower
than 200 m) and extend as far south as the Hokkaido coast. In the July case (a representative for the summer season from April
to September), significant currents do not occur, even in the shallow shelves. The simulated southward current over the east
Sakhalin shelf appears to correspond to the near-shore branch of the East Sakhalin Current (ESC), which was observed with
the surface drifters. These seasonal variations simulated in our experiments are consistent with the observations of the ESC.
Dynamically, the simulated ESC is interpreted as the arrested topographic wave (ATW), which is the coastally trapped flow
driven by steady alongshore wind stress. The volume transport of the simulated ESC over the shelf reaches about 1.0 Sv (1
Sv = 106 m3s−1) in the winter season, which is determined by the integrated onshore Ekman transport in the direction from which shelf waves
propagate.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献