共查询到20条相似文献，搜索用时 46 毫秒
1.
After recalibration of the temperature and conductivity sensors of three Argo profiling floats recovered after operations
for four to nine months, the results indicate that the floats basically showed no significant drift, either in temperature
or salinity, and adequately fulfilled the accuracy requirement of the Argo project (0.005°C for temperature and 0.01 psu for
salinity). Only the third float showed a significant offset in salinity of about −0.02 psu, as expected from comparison between
the float data and the shipboard conductivity-temperature-depth data. This offset was caused by the operational error of the
PROVOR-type float, in which the surface water was pumped immediately after the launch, fouling the conductivity sensor cell.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
2.
Yugo Shimizu Takanori Iwao Ichiro Yasuda Shin-Ichi Ito Tomowo Watanabe Kazuyuki Uehara Nobuyuki Shikama Toshiya Nakano 《Journal of Oceanography》2004,60(2):453-462
Six newly developed floats, which were set to drift on the 26.7 σθ isopycnal surface and to profile temperature, salinity and pressure above 1000 dbar once a week, were deployed in the Oyashio
and Kuroshio Extension (KE) in order to examine the circulation, formation site and time scale of newly formed North Pacific
Intermediate Water (NPIW). The floats were deployed in February or May 2001, and the data from their deployments to December
2002 are analyzed here. Four of the six floats were deployed near the KE axis at around the first meander crest, and they
moved eastward to 157°E–176°W at latitudes of 30°N–45°N. The other two floats deployed in the Oyashio water with low-potential
vorticity near the south coast of Hokkaido moved southward to reach the KE front and then moved eastward to the same region
as the first four floats. The temperature and salinity at 26.7 σθ measured by the profiling floats indicate that the source waters of NPIW, Oyashio and Kuroshio waters are drastically mixed
and modified in the mixed water region west of 160°E. The floats were separated into the three paths east of 160°E between
the Kuroshio Extension front and the north of Water-Mass front (nearly subarctic front). New NPIW is judged to be formed along
these three paths since the vertical profiles of temperature and salinity are quite smooth, having a salinity minimum at about
26.7σθ along each path. Kuroshio-Oyashio isopycnal mixing ratios of the new NPIW are 7:3, 6:4 and 5:5 at 26.7σθ along the southern, middle and northern paths, respectively. Potential vorticity converges to about 14–15 × 10−11 m−1s−1 along these paths. The time scale of new NPIW formation is estimated to be 1–1.5 years from the merger of Oyashio and Kuroshio
waters to the formation of the new NPIW.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
3.
利用Argo剖面浮标分析上层海洋对台风“布拉万”的响应 总被引：9，自引：2，他引：7
In situ observations from Argo profiling floats combined with satellite retrieved SST and rain rate are used to investigate an upper ocean response to Typhoon Bolaven from 20 through 29 August 2012. After the passage of Typhoon Bolaven, the deepening of mixed layer depth(MLD), and the cooling of mixed layer temperature(MLT) were observed. The changes in mixed layer salinity(MLS) showed an equivalent number of increasing and decreasing because the typhoon-induced salinity changes in the mixed layer were influenced by precipitation, evaporation, turbulent mixing and upwelling of thermocline water. The deepening of the MLD and the cooling of the MLT indicated a significant rightward bias, whereas the MLS was freshened to the left side of the typhoon track and increased on the other side. Intensive temperature and salinity profiles observed by Iridium floats make it possible to view response processes in the upper ocean after the passage of a typhoon. The cooling in the near-surface and the warming in the subsurface were observed by two Iridium floats located to the left side of the cyclonic track during the development stage of the storm, beyond the radius of maximum winds relative to the typhoon center. Water salinity increases at the base of the mixed layer and the top of the thermocline were the most obvious change observed by those two floats. On the right side of the track and near the typhoon center when the typhoon was intensified, the significant cooling from sea surface to a depth of 200×104 Pa, with the exception of the water at the top of the thermocline, was observed by the other Iridium float. Owing to the enhanced upwelling near the typhoon center, the water salinity in the near-surface increased noticeably. The heat pumping from the mixed layer into the thermocline induced by downwelling and the upwelling induced by the positive wind stress curl are the main causes for the different temperature and salinity variations on the different sides of the track. It seems that more time is required for the anomalies in the subsurface to be restored to pretyphoon conditions than for the anomalies in the mixed layer. 相似文献
4.
Long-term Sensor Drift Found in Recovered Argo Profiling Floats 总被引：5，自引：0，他引：5
We recovered three Argo profiling floats after 2 to 2.5 years of operation, and recalibrated their temperature, conductivity, and pressure sensors. The results demonstrate that these floats exhibited a significant drift in salinity of −0.0074 to −0.0125, primarily due to the conductivity sensor drift. Combined with the recalibration result for another previously recovered float, the indication is that the negative salinity drift increases nearly in proportion to the operating period of floats. The increasing rate is −0.0041 (±0.0015) year−1, which yields a salinity drift of −0.016 (±0.006) for the expected float lifetime of four years. The present result suggests that reducing the float surfacing time would improve the accuracy of the salinity measurements. 相似文献
5.
6.
《Ocean Modelling》2008,20(1):1-16
Argo is a global array of profiling floats that provides temperature (T) and salinity (S) profiles from 2000 m to the surface every ten days with a nominal spatial resolution of 3°. Here we present idealized experiments where the adjoint method is used to synthesize simulated sets of Argo profiles with a general circulation model, over a one-year period, in the North Atlantic. Using a number of drifting profilers consistent with Argo deployment objectives, the simulated array permits one to identify large-scale anomalies in the hydrography and circulation, despite the presence of a simulated eddy noise of large amplitude. Model dynamics provide an objective means to distinguish eddy noise from large-scale oceanic variability, and to infer the absolute velocity field (including abyssal velocities and sea surface height) from sets of Argo profiles of T and S. In particular, our idealized experiments suggest that volume and heat transports can be efficiently constrained by sets of Argo profiles. Increasing the number of Argo floats seems to be an adequate strategy to further reduce errors in circulation estimates. 相似文献
7.
Assimilation of satellite-derived surface datasets has been explored in the study. Three types of surface data, namely sea level anomaly, sea surface temperature and sea surface salinity, have been used in various data assimilation experiments. The emphasis has been on the extra benefit arising out of the additional sea level assimilation and hence there are two parallel runs, in one of which sea level assimilation has been withheld. The model used is a state-of-the art ocean general circulation model (OGCM) and the assimilation method is the widely used singular evolutive extended Kalman filter (SEEK). Evaluation of the assimilation skill has been carried out by comparing the simulated depth of the 20°C isotherm with the same quantity measured by buoys and Argo floats. Simulated subsurface temperature and salinity profiles have also been compared with the same profiles measured by Argo floats. Finally, surface currents in the assimilation runs have been compared with currents measured by several off-equatorial buoys. Addition of sea level has been found to substantially improve the quality of simulation. An important feature that has been effectively simulated by the addition of sea level in the assimilation scheme is the near-surface temperature inversion (2-3°C) in the northern Bay of Bengal. 相似文献
8.
Hui Chen Shuang Li Hailun He Jinbao Song Zheng Ling Anzhou Cao Zhongshui Zou Wenli Qiao 《海洋学报(英文版)》2021,40(1):70-84
The present work describes the basic features of super typhoon Meranti(2016) by multiple data sources. We mainly focus on the upper ocean response to Meranti using multiplatform satellites, in situ surface drifter and Argo floats, and compare the results with the widely used idealized wind vortex model and reanalysis datasets.The pre-existing meso-scale eddy provided a favor underlying surface boundary condition and also modulated the upper ocean response to Meranti. Results show that the maximum sea surface cooling was 2.0℃ after Meranti.The satellite surface wind failed to capture the core structure of Meranti as the idealized wind vortex model deduced. According to the observation of sea surface drifters, the near-inertial currents were significantly enhanced during the passage of Meranti. The temperature and salinity profiles from Argo floats revealed both the mixed-layer extension and subsurface upwelling induced by Meranti. The comparison results show that the sea surface temperature and surface wind in the reanalysis datasets differs from those in remote sensing system. Sea surface cooling is similar in both satellite and in situ observation, and sea surface salinity response has a lower correlation with the precipitation rate. 相似文献
9.
10.
利用Argo浮标资料分析横跨吕宋海峡20.5°N断面的水文特征 总被引：2，自引：0，他引：2
基于Argo浮标资料,分析了一条横跨南海北部、吕宋海峡和西太平洋（20.5°N,114°~130°E）断面的海水温度、盐度的分布特征.其结果表明：Argo剖面资料得到的2008年秋季20.5°N断面海水的温度、盐度分布态势与气候态秋季的分布基本一致,主要差异在于南海次表层水的盐度极大值和西太平洋次表层水的盐度极大值,2008年秋季二者均比气候态秋季的低0.1左右.通过动力计算（选取1 200 m为速度零面）表明：Argo浮标剖面资料与融合的卫星高度计产品得到的20.5°N,117.5°~124.5°E断面的表层地转流北分量的分布比较吻合;吕宋海峡中部（20°~21°N）的黑潮主轴大致位于121.5°E附近,其东边界可达123°E,而西边界仅限于121°E以西,其可能原因是该季节黑潮的左侧存在着一个气旋式环流,阻碍了黑潮西进;黑潮在20.5°N断面的体积流量为27×106m3/s左右,最大流速约为55 cm/s,出现在70 m层左右. 相似文献
11.
Zenghong Liu Xiaogang Xing Zhaohui Chen Shaolei Lu Xiaofen Wu Hong Li Chunling Zhang Lijing Cheng Zhaoqin Li Chaohui Sun Jianping Xu Dake Chen Fei Chai 《海洋学报(英文版)》2023,42(2):1-2
The international Argo program, a global observational array of nearly 4 000 autonomous profiling floats initiated in the late 1990s, which measures the water temperature and salinity of the upper 2 000 m of the global ocean, has revolutionized oceanography. It has been recognized one of the most successful ocean observation systems in the world. Today, the proposed decade action “OneArgo” for building an integrated global, full-depth, and multidisciplinary ocean observing array for beyond 2020 ... 相似文献
12.
W. Brechner Owens Annie P.S. Wong 《Deep Sea Research Part I: Oceanographic Research Papers》2009,56(3):450-457
An improved method to estimate the time-varying drift of measured conductivity from autonomous CTD profiling floats has been developed. This procedure extends previous methods developed by Wong, Johnson and Owens [2003. Delayed-mode calibration of autonomous CTD profiling float salinity data by θ–S climatology. Journal of Atmospheric and Oceanic Technology, 20, 308–318] and Böhme and Send [2005. Objective analyses of hydrographic data for referencing profiling float salinities in highly variable environments. Deep-Sea Research Part II, 52, 651–664]. It uses climatological salinity interpolated to the float positions and observed θ surfaces and chooses 10 ‘best’ levels that are within well-mixed mode waters or deep homogeneous water masses. A piece-wise linear fit is used to estimate the temporally varying multiplicative adjustment to the float potential conductivities. An objective, statistical method is used to choose the breakpoints in the float time series where there are multiple drift trends. In the previous methods these breakpoints were chosen subjectively by manually splitting the time series into separate segments over which the fits were made. Our statistical procedure reduces the subjectivity by providing an automated way for doing the piece-wise linear fit. Uncertainties in this predicted adjustment are estimated using a Monte-Carlo simulation. Examples of this new procedure as applied to two Argo floats are presented. 相似文献
13.
Estimating the average lifetime of floats is very important for Argo, because the total cost of maintaining the monitoring
network largely depends on float lifetime. However, the actual lifetime of floats used in Argo is currently unknown. An estimate
can be made by examining past float survival, but this is complicated by floats still operating at sea and continuous improvements
in float hardware. Because APEX (Autonomous Profiling Explorer) floats are the most widely deployed type of float in the world
oceans, in this study we estimate the lifetime of the latest model of APEX powered by alkaline batteries. The expected lifetime
is estimated with a statistical method that allows for floats that are still active and that failed because of a known and
now fixed hardware fault that should not cause failure in the latest model of floats. As an example, we analyzed the APEX
fleets managed by the Japan Agency for Marine-Earth Science and Technology (JAMSTEC), because we have access to a JAMSTEC
database in which the causes of float failure have been carefully correlated to known hardware problems. Analysis of the JAMSTEC
fleet (n = 571, as of 7 May 2008) indicated that the expected lifetime of the latest model of APEX is 134.6 (127.6–141.5, considering
standard errors) cycles, equivalent to 3.7 years of 10-day cycles. We conclude that the annual deployment of 813 (773–859)
APEX floats is needed to maintain the Argo observational network of 3000 floats. Floats with different hardware configurations
(e.g., lithium batteries) or different mission programs (e.g., shallower profiling, deeper profiling every several cycles)
may be expected to have an even longer lifetime. 相似文献
14.
Takanori Iwao Masahiro Endoh Nobuyuki Shikama Toshiya Nakano 《Journal of Oceanography》2003,59(6):893-904
In order to examine the formation, distribution and synoptic scale circulation structure of North Pacific Intermediate Water
(NPIW), 21 subsurface floats were deployed in the sea east of Japan. A Eulerian image of the intermediate layer (density range:
26.6–27.0σθ) circulation in the northwestern North Pacific was obtained by the combined analysis of the movements of the subsurface floats
in the period from May 1998 to November 2002 and historical hydrographic observations. The intermediate flow field derived
from the floats showed stronger flow speeds in general than that of geostrophic flow field calculated from historical hydrographic
observations. In the intermediate layer, 8 Sv (1 Sv ≡ 106 m3s−1) Oyashio and Kuroshio waters are found flowing into the sea east of Japan. Three strong eastward flows are seen in the region
from 150°E to 170°E, the first two flows are considered as the Subarctic Current and the Kuroshio Extension or the North Pacific
Current. Both volume transports are estimated as 5.5 Sv. The third one flows along the Subarctic Boundary with a volume transport
of 5 Sv. Water mass analysis indicates that the intermediate flow of the Subarctic Current consists of 4 Sv Oyashio water
and 1.5 Sv Kuroshio water. The intermediate North Pacific Current consists of 2 Sv Oyashio water and 3.5 Sv Kuroshio water.
The intermediate flow along the Subarctic Boundary contains 2 Sv Oyashio water and 3 Sv Kuroshio water.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
15.
Direct measurements of surface and mid-depth circulationin the Shikoku Basin by Argo profiling floats 总被引：1，自引：0，他引：1
The circulation in the Shikoku Basin plays a very important role in the pathway of the Kuroshio and the water exchange in the subtropical gyre in the North Pacific Ocean. The Argo profiling floats deployed in the Shikoku Basin are used to study the circulations and water masses in the basin. The trajectories and parking depth velocity fields derived from all Argo floats show an anticyclonic circulation at 2 000 m in the Shikoku Basin. There are inhanced eddy activities in the Shikoku Basin, which have large influence on the Shikoku Basin circulation patterns. The characteristics of temperature-salinity curves indicate that there are North Pacific Ocean tropical water (NPTW), North Pacific Ocean subtropical mode water (NPSTMW) and North Pacific Ocean intermediate water (NPIW) in the Shikoku Basin. The NPTW is only exists south of 32°N. In the middle part of the basin, which is 28°~31°N,133°~135°E, there is a confluence region. Water masses coming from the Kuroshio mix with the water in the Shikoku Basin. 相似文献
16.
Newly formed North Pacific Tropical Water (NPTW) is carried to the Philippine Sea (PS) by the North Equatorial Current (NEC) as a subsurface salinity maximum. In this study its spreading and salinity change processes are explored using existing hydrographic data of the World Ocean Database 2009 and Argo floats. Spreading of NPTW is closely associated with the transports of the NEC, Mindanao Current (MC), and Kuroshio. Estimated for subsurface water with salinity S greater than 34.8?psu, the southward (northward) geostrophic transport of NPTW by the MC (Kuroshio) at 8°N (18°N) is about 4.4 (5.7)?Sv (1?Sv?=?106?m3?s?1), which is not sensitive to reference level choice. Fields of salinity maximum, geostrophic current, sea level variation, and potential vorticity suggest that the equatorward spreading of NPTW to the tropics is primarily afforded by the MC, whereas its poleward spreading is achieved by both the Kuroshio transport along the coast and open-ocean mesoscale eddy fluxes in the northern PS. The NPTW also undergoes a prominent freshening in the PS. Lying beneath fresh surface water, salinity decreases quicker in the upper part of the NPTW, which gradually lowers the salinity maximum of NPTW to denser isopycnals. Salinity decrease is especially fast in the MC, with along-path decreasing rate reaching O (10?7?psu?s?1). Both diapycnal and isopycnal mixing effects are shown to be elevated in the MC owing to enhanced salinity gradient near the Mindanao Eddy. These results suggest intensive dispersion of thermal anomalies along the subtropical-to-tropical thermocline water pathway near the western boundary. 相似文献
17.
Josia Jacob Prosenjit Ghosh A. P. Dineshbabu P. Sabu K. Srinivas Bindu Sulochanan 《Journal of Oceanography》2014,70(3):251-266
Coastal marine environments are important links between the continents and the open ocean. The coast off Mangalore forms part of the upwelling zone along the southeastern Arabian Sea. The temperature, salinity, density, dissolved oxygen and stable oxygen isotope ratio (δ18O) of surface waters as well as those of bottom waters off coastal Mangalore were studied every month from October 2010 to May 2011. The coastal waters were stratified in October and November due to precipitation and runoff. The region was characterised by upwelled bottom waters in October, whereas the region exhibited a temperature inversion in November. The surface and bottom waters presented almost uniform properties from December until April. The coastal waters were observed to be most dense in January and May. Comparatively cold and poorly oxygenated bottom waters during the May sampling indicated the onset of upwelling along the region. δ18O of the coastal waters successfully documented the observed variations in the hydrographical characteristics of the Mangalore coast during the monthly sampling period. We also noted that the monthly variability in the properties of the coastal waters of Mangalore was related to the hydrographical characteristics of the adjacent open ocean inferred from satellite-derived surface winds, sea surface height anomaly data and sea surface temperatures. 相似文献
18.
Seasonal dynamics in colored dissolved organic matter in the Mediterranean Sea: Patterns and drivers
Two autonomous profiling “Bio-Argo” floats were deployed in the northwestern and eastern sub-basins of the Mediterranean Sea in 2008. They recorded at high vertical (1 m) and temporal (5 day) resolution, the vertical distribution and seasonal variation of colored dissolved organic matter (CDOM), as well as of chlorophyll-a concentration and hydrological variables. The CDOM standing stock presented a clear seasonal dynamics with the progressive summer formation and winter destruction of subsurface CDOM maxima (YSM, for Yellow Substance Maximum). It was argued that subsurface CDOM is a by-product of phytoplankton, based on two main characteristics, (1) the YSM was located at the same depth than the deep chlorophyll maximum (DCM) and (2) the CDOM increased in summer parallels the decline in chlorophyll-a. These observations suggested an indirect but tight coupling between subsurface CDOM and phytoplankton via microbial activity or planktonic foodweb interactions. Moreover, the surface CDOM variations observed both by floats and MODIS displayed different seasonal dynamics from what recorded at subsurface one. This implies that CDOM standing stock can be hardly detected by satellite. It is worthnoting that surface CDOM was found to be more related to the sea surface temperature (SST) than chlorophyll-a concentration, suggesting its physical origin, in contrast to the biological origin of YSM and subsurface standing stocks. 相似文献
19.
Direct measurements of mid-depth circulation in the Shikoku basin by tracking SOFAR floats 总被引：1，自引：0，他引：1
Keisuke Taira Shoji Kitagawa Katsuto Uehara Hiroshi Ichikawa Hiroyuki Hachiya Toshihiko Teramoto 《Journal of Oceanography》1990,46(6):296-306
Mid-depth circulation of the Shikoku Basin was measured by tracking four SOFAR floats drifting at the 1,500 m layer. Two floats were released on 17 April 1988 at 30°N, 135°59E and tracked for 433 days. Another two were released on 3 November 1988 at 29°52N and 133°25E, and tracked for 234 days. Two floats flowed clockwise around the Shikoku Warm Water Mass with a diameter of 400 km centered at 31°N and 136°E and a mean drift speed of 4.5 cm sec–1. One of the floats showed about ten counterclockwise rotations with a period of about 8 days and a maximum speed of 80 cm sec–1 in the sea area west to the Izu Ridge. In the east to Kyushu, a southward flow was observed under the northward flowing Kuroshio. The southward flow of 4 cm sec–1 drift speed was considered to be a part of the counterclockwise circulation at deep layers along the perimeter of the Shikoku Basin. One float remained for 234 days in a limited area of 100 km by 150 km in the western part of the basin. 相似文献
20.
ROMS with horizontal grid spacing of 3.5 km for the region off Central California was compared to RAFOS float observations and satellite altimetry on meso/submesoscales. The approach introduced and used two new metrics for model-data comparison, as well as suggested how to calculate these metrics for different spatio-temporal scales. The first metric consisted of the first two moments of exit time and was used to compare ROMS against RAFOS float observations at mid-depths (between 300 m and 350 m). Exit time is the time a float launched at a point takes to leave a domain for the first time. The second metric was spectral entropy and was used to estimate how well ROMS reproduced variability of the sea surface height (SSH) anomaly field extracted from an AVISO data set (1992–2007) for specified temporal and spatial scales. Calculations showed that ROMS reproduced the mid-depth mesoscale/submesoscale currents next to the coast in a very accurate manner (low-order exit time statistics of floats were reproduced by ROMS with an accuracy better than 95%); but ROMS overestimated the speed of westward drift of floats by as much as 20–30% at distances greater than 350 km from the coastline. ROMS predicted the variability of the mesoscale (100–400 km) SSH anomaly field for temporal scales of 1–12 months with a reasonable accuracy. A wavelet transform modulus maxima technique applied to the spectral entropy of SSH anomaly also demonstrated good agreement between ROMS and satellite altimetry for mesoscales characterized by singular exponents and multi-fractal spectra for 1–12 month time scales. 相似文献