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List of poster abstracts
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Authors H
Number 128 - Session 4
ASIA-PACIFIC DATA-RESEARCH CENTER,
A GODAE PRODUCT SERVER
P. Hacker, J. Potemra, S. DeCarlo, Y. Shen, Y. Jia, N. Maximenko, K. Lebedev
University of Hawaii IPRC, Honolulu, USA
Abstract
The Asia-Pacific Data-Research Center (APDRC) within the International Pacific Research Center (IPRC) at the University of Hawaii provides a web-based, data and product server system, which serves as a GODAE Product Server as identified in the GODAE Strategic Plan. Initiated in 2001, a primary motivation has been to provide easy access for the broad user community to the wide range of climate data and products, often underutilized due to lack of easy access. New data and products were rapidly becoming available as a result of expanding in situ and satellite observations, and the availability of increasingly realistic model-based products. Working closely with our NOAA/PMEL partners, the center has implemented a data server system using OPeNDAP protocol in order to provide easy access to a broad range of local and remote atmospheric, oceanic, and air/sea flux products, which can be directly accessed via client-based software such as GrADS, Matlab, Ferret, and FORTRAN code. The system uses a range of servers including LAS and OPeNDAP (THREDDS and GDS) for gridded products, and EPIC, DAPPER/DChart and TSANA for in situ data.
The APDRC serves a variety of GODAE and related products for research and for the initialization, boundary forcing, and downscaling of regional modeling systems. Reanalysis products include output from the ECCO consortium, GFDL, SODA, and NCEP. Near real time model products include: NLOM globally (layer 1, from 2002); and NCOM (all layers, from 2003) and Global HYCOM (all layers, from 2007) in the Hawaii region (10º-35ºN, 170ºE-140ºW). Locally produced global products available on the web-site include surface and parking depth velocity estimates from Argo floats (YoMaHa'07), and gridded 4-D products based on Argo temperature and salinity profile data, both of which are updated regularly.
In the early years the center focused on data server system and data management issues. Recently and into the future, the focus is shifting to the production of value-added products using the new observing system data sets such as Argo, and on the ongoing development of regional, data-assimilating, high-resolution models dependent on global operational models and satellite-based and in situ observations for initialization and evaluation.
Specifically, nowcast and forecasts of near-shore conditions in the Hawaii region and EEZ require representation of the open ocean eddy field (via Global HYCOM or NCOM), high-resolution bathymetry including reef structures, regional high-resolution atmospheric forcing fields and tides to capture the dominant variability. The presentation offers product examples, and identification of challenges, issues and opportunities for the future. The figure shows an example subset of APDRC Model Datasets using the data search tool on the Data page from the web. The colored buttons show LAS, OPeNDAP and DChart server access. The IPRC/APDRC server address is: http://apdrc.soest.hawaii.edu.
Number 30 - Session 3
MECHANISMS CONTROLLING SEASONAL MIXED LAYER TEMPERATURE OF
THE INDONESIAN SEAS IN AN ECCO ASSIMILATION PRODUCT
D.J. Halkides1, Tong Lee1 and Shinichiro Kida2
1Earth Sciences, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA
2International Pacific Research Center, University of Hawaii
Abstract
We use satellite ocean data assimilation products to examine seasonal mixed layer processes in the Indonesian Seas, focusing on mechanisms controlling mixed layer temperature (MLT) cooling in boreal summer. Surface heat flux dominates seasonal MLT with significant secondary reinforcing contributions by subsurface processes. Spring and fall warming occur when insolation near the equator increases, and surface heat loss and subsurface cooling decrease during monsoon transitions. Boreal summer cooling occurs when the insolation maximum is in the northern hemisphere and monsoon winds are heightened, causing increased surface heat loss and turbulent mixing. When we examine the MLT budgets in the western half (Java Sea) and eastern half (Banda and Arafura Seas) of the Indonesian Seas separately, horizontal advection is found to induce strong compensating effects in the west, but weak reinforcing effects in the east. Vertical and horizontal advective cooling are both small in the east, whereas cooling by vertical mixing is strong. Accordingly, subseasonal-to-seasonal scale winds over the Arafura Sea are relatively variable, especially on shorter timescales, effects of which can rectify into the seasonal cycle. There is negative wind curl near the New Guinea coast in boreal summer, but away from the coast wind curl is small. These factors are consistent with the weak (strong) vertical advective (vertical mixing induced) cooling. Our model resolution is too coarse to address shelfupwelling effects on cooling. However, we believe vertical mixing plays an important role in MLT variability, with a contribution that is approximately half that of the surface heat flux.
Number 129 - Session 5
IMPACT OF GODAE PRODUCTS ON INITIALIZING OCEAN MODELS FOR HURRICANE PREDICTION
George R. Halliwell1, Lynn K. Shay1, Jodi Brewster1, and William Teague2
1MPO/RSMAS, University of Miami, FL, USA
2U.S. Naval Research Laboratory, Stennis Space Center, MS, USA
Abstract
The impact of GODAE products on the simulated ocean response to tropical cyclones is studied using the Hybrid Coordinate Ocean Model (HYCOM), which is being developed by the U. S. National Oceanic and Atmospheric Administration (NOAA) as the next ocean component of the coupled Hurricane Weather Research and Forecasting (HWRF) tropical cyclone (TC) forecast model. The overarching goal of this project is to improve the capability of HWRF to forecast intensity change. This requires that the ocean model accurately predict the magnitude and pattern of SST cooling driven by a storm which in turn impacts the thermal energy exchange from ocean to atmosphere that fuels the storm. Simulations of the ocean response to hurricane Ivan (2004) in the northwest Caribbean and Gulf of Mexico have demonstrated that accurate initialization of thermal anomalies associated with ocean currents and eddies is the most important factor for producing an accurate ocean response, substantially exceeding the impact of other important factors such as model vertical resolution and vertical mixing parameterization. The ocean response to Ivan was evaluated against microwave satellite SST measurements and moored ocean current observations from an array of 14 Acoustic Doppler Current Profiler (ADCP) moorings that were deployed as part of the U. S. Naval Research Laboratory Slope to Shelf Energetics and Exchange Dynamics (SEED) project and that were directly hit by Ivan. The simulated magnitude and pattern of SST cooling due to Ivan was reasonably accurate because ocean features associated with large horizontal differences in ocean heat content (OHC) were initialized accurately by using fields from the U. S. Navy HYCOM-based ocean nowcast-forecast system. Initial ocean fields are evaluated against both high-quality aircraft and in-situ ocean measurements, and also against maps of OHC and key isotherm depths derived from satellite altimetry and SST. In addition to the Ivan results, an evaluation of the impact of ocean initialization by the U. S. Navy product on the simulated response to hurricanes Katrina and Rita (2005) will be presented. Also, an evaluation of the ocean initial fields that will be produced during the present (2008) hurricane season in the North Atlantic by both the U. S. Navy system and the NOAA HYCOM-based Atlantic Ocean Real-Time Ocean Forecast System (RTOFS) will be presented. The latter evaluation will provide a picture of the present capability of GODAE products to initialize ocean models for TC prediction and of the improvements that are still needed.
Number 130 - Session 4
IMPACT OF GODAE PRODUCTS ON NESTED SIMULATIONS OF THE FLORIDA AND NORTHERN GULF OF MEXICO COASTAL OCEAN
George R. Halliwell1, Vassiliki Kourafalou1, Alexander Barth2, Patrick J. Hogan3, Ole Martin Smedstad4, Robert H. Weisberg5, Lynn K. Shay1, Harley Hurlburt3, James Cummings6, Heesook Kang1, Rafael Schiller1
1MPO/RSMAS, University of Miami, FL, USA
2National Fund for Scientific Research, University of Liege, Belgium
3U.S. Naval Research Laboratory, Stennis Space Center, MS, USA
4Planning Systems, Inc., Stennis Space Center, MS, USA
5College of Marine Science, University of South Florida, St. Petersburg, FL,, USA
6U.S. Naval Research Laboratory, Monterey, CA, USA
Abstract
The impact on nested coastal simulations along the northern Gulf of Mexico (GoM), the West Florida Shelf (WFS), and the South Florida coast (SoFLA) of initial and boundary conditions provided by GODAE ocean hindcasts is documented as part of a National Ocean Partnership Program CODAE project. Coastal simulations are nested in multiple GODAE hindcast products, and also in a non-assimilative outer model that does not correctly reproduce offshore ocean synoptic-scale and mesoscale variability and thus serves as a baseline to document improvements provided by the GODAE hindcasts. The evaluated hindcast products are obtained from multiple generations of the U. S. Navy ocean nowcast-forecast system being developed at the Naval Research Laboratory. Three products have been evaluated to date, one conducted in the Atlantic Ocean using optimum interpolation to assimilate SSH with Cooper-Haines vertical projection, and two that used the NCODA (Naval Coupled Ocean Data Assimilation) system. The initial NCODA hindcast was run in a GoM domain, and the next hindcast was run in a global domain. Multiple observational programs are providing the high-quality observations required for the evaluation effort. All nowcast products and nested simulations use the HYbrid Coordinate Ocean Model (HYCOM). Flow over the inner continental shelf is dominated by the deterministic continental shelf wave response to wind forcing, so the offshore boundary conditions have little impact. Offshore boundary conditions have a substantial impact over middle and outer shelf flow variability, but only if the offshore boundary is within a few baroclinic radii of deformation of the shelfbreak. Scientific interests include the impact of the GoM Loop Current along with the anticyclonic rings that occasionally pinch off and smaller cyclonic eddies that appear along the LC and anticyclonic ring boundaries on several processes, such as: (1) transport of Mississippi River plumes; (2) flow along the WFS; (3) temperature variability over the WFS; (4) flow variability in Florida Bay; (5) formation and maintenance of the Tortugas eddy in the Florida Straits; and (5) nearshore submesoscale eddy variability in the Florida Straits. Case studies are presented that demonstrate improved representation of flow and temperature variability in the coastal simulations achieved by using GODAE ocean hindcasts to represent the offshore ocean.
Number 32 - Session 5
DEVELOPMENT OF A REGIONAL OCEAN REANALYSIS SYSTEM IN THE CHINA SEAS
Guijun Han1, Wei Li1, Xuefeng Zhang1, Dong Li1, Zhongjie He1, Xidong Wang1,
Xinrong Wu1 and Jirui Ma1
1National Marine Data and Information Service, Tianjin 300171, China
Abstract
A regional ocean reanalysis system in the China seas and the adjacent sea area has been developed recently. The regional ocean model used is a parallel version of Princeton Ocean Model with generalized coordinate system (POMgcs) with a domain covering an area extending from 10°S to 52°N in latitude and from 99°E to 150°E in longitude. A global version of the MIT general circulation model (MITgcm) is employed to provide open boundary conditions for the regional ocean model. A sequential three-dimensional variational (3DVAR) analysis scheme has been designed and implemented in both the regional and global model, using a multi-grid framework. Such sequential 3DVAR analysis scheme can be performed in three dimensional spaces which is totally different from the traditional 3DVAR which is performed on each model level with the vertical correlations ignored. This sequential 3DVAR analysis scheme can retrieve resolvable information from longer to shorter wavelengths for a given observation network and yield multi-scale, inhomogeneous analysis. The ocean model is forced by National Centers for Environmental Prediction (NCEP) reanalysis surface wind stress (combining QuikSCAT observing wind fields), heat, and water flux. By assimilating the oceanic observation data into the model, including satellite remote sensing sea surface temperature (SST), altimetry sea surface height (SSH), temperature and salinity profiles taken from Argo and World Ocean Database 2005 (WOD05) maintained by National Oceanographic Data Center (NODC), the reanalysis fields of sea surface height, temperature, salinity and current in the China seas and the adjacent sea area are produced which spans 20 years from 1986 to 2005.
Number 53 - Session 4
HYCOM DATA SERVICES FOR GODAE
S. Hankin1, A. Srinivasan2, P. Cornillon3, P. Hacker4, A. Manke1, R. Schweitzer5
1 NOAA/Pacific Marine Environmental Laboratory, Seattle, US
2Florida State University Center for Ocean-Atmospheric Prediction Studie, Tallahassee, US
3University of Rhode island Graduate School of Oceanography Narragansett,US
4University of Hawaii IPRC, Honolulu,US
5 Weathertop Consulting, LLC, College Station,US
Abstract
Ocean models running operationally at eddy-resolving resolution and on basin-scale to global domains create extraordinary data management demands. For example to support a 1/12 degree global model with 32 vertical levels the data management system must distribute 90 Gigabytes daily. The HYCOM model adds to this challenge a coordinate system which may be both curvilinear in the horizontal and time-dependent in the vertical. The users of the model outputs range in sophistication from coastal modelers, who require data of the highest possible fidelity to fisherman looking for quick guidance. There is no silver bullet that can address this range of demands ? rather a suite of management strategies and software tools, many of which were developed only recently under the umbrella of GODAE.
The HYCOM model is run operationally by Naval Research Lab, at Stennis Space Center, Mississippi. It is distributed to the public (http://hycom.rsmas.miami.edu/dataserver/) through a collaboration that includes the FSU/COAPS managing the data with NOAA/PMEL and OPeNDAP, Inc. (http://opendap.org/) developing tools for data services. At present a prototype global forecast system produces approximately 90 Gig of data daily which consists of an analysis and a five day forecast daily. The data produced daily is first downloaded to FSU/COAPS. Here it is converted into CF complaint NetCDF for distribution. Currents, temperature, salinity, sea surface elevation, boundary layer depth are some of the variables that are available.
To minimize the data volumes that must be distributed several techniques are used. On-demand subsetting of the data ? delivering only the specific variables needed over a specified space/time region ? is performed both by the OPeNDAP server and by the Live Access Server (http://ferret.pmel.noaa.gov/LAS/), for binary data streams and netCDF subsets, respectively. On-demand visualizations of model fields eliminate the need for data downloads in many cases. Server-side data reduction, (e.g. averaging in Z or T), which has the potential to greatly reduce the volume of data that must be downloaded, is currently being deployed in an experimental mode utilizing a specially-enhanced version of the Unidata THREDDS Data Server (TDS). Modelers, who require HYCOM outputs for model initialization or for boundary conditions are provided with either HYCOM format output for use with the HYCOM model or NetCDF data for use with other models. Users of HYCOM data who are not modelers generally prefer to avoid the complexities of hybrid vertical coordinates, so all HYCOM data is also provided on a fixed-Z grid (Levitus) grid.
HYCOM data management is a partnership that includes regional data services such as the Asia-Pacific Data-Research Center (http://apdrc.soest.hawaii.edu). The APDRC supports a research community engaged in the development of nowcast and forecast products of near-shore conditions in the Hawaiian Islands chain and EEZ. Several higher resolution nested models (HYCOM, POM, ROMS) are forced and initialized by the Global HYCOM at four lateral boundaries.
There is a steadily growing international user community including public, private and educational end-users. These users cover a wide range of applications including ocean research, oil and gas exploration, search and rescue, ship and small boat routing, ocean racing, ecologists, fisheries etc.
Number 54 - Session 4
CLIMATE AND FORECAST (CF) CONVENTIONS FOR NETCDF -- THE FOUNDATION OF GODAE DATA INTEROPERABILITY
S. Hankin1, J.D. Blower2, T. Carval3, K. Casey4, C. Donlon5, O. Lauret6, T. Loubrieu3, L. Petit de la Villeon3, J. Piollé3, S. Smith7, A. Srinivasan7, J. Trinanes8
1NOAA/Pacific Marine Environmental Laboratory, Seattle, US
2University of Reading Environmental Systems Science Centre, Reading, UK
3Ifremer , Brest, France
4NOAA/National Ocean Data Center,Washington D.C., US
5Met Office Hadley Centre International Group for High Resolution SST Project Office, Exeter, UK
6 CLS Space Oceanography Division, Cedex, France
7Center for Ocean-Atmospheric Prediction Studies, The Florida State University, Talahassee, US
8NOAA/AOML (Miami,US) and University of Santiago de Compostela, Santiago de Compostela, Spain
Abstract
A key element in the success of GODAE has been the ability to share and intercompare data ? ocean model outputs, remote sensed observations and in-situ measurements. This fusion of data types has been possible because the GODAE data management strategy utilizes the Climate and Forecast (CF) conventions and netCDF files. With this poster we document the role of CF in GODAE through illustrations of the data that are made inter-operable by CF: model outputs from HYCOM, FOAM, etc.; GHRSST, AVHRR and satellite altimetry products; and in-situ ocean observations such as Argo profiles (http://www-argo.ucsd.edu/) and OceanSites time series (http://www.oceansites.org/). Recently GOSUD (http://www.ifremer.fr/gosud/) and SAMOS (http://samos.coaps.fsu.edu/html/) are working to develop CF-compliant representations for underway ship observations as well.
Files that utilize CF conventions are said to be "self-describing"; they include those elements of metadata that are essential to the utilization of the data. CF files describe the coordinate structure of the data without requiring references to external tables and documentation. CF contains "use metadata", such as array dimensions, machine-interpretable (standardized) variable names and standardized units. Coordinate systems may be any number of dimensions -- 1 through 4 in space-time and higher. Coordinate concepts include rectilinear and curvilinear horizontal coordinate systems; and fixed-Z, sigma, and hybrid vertical coordinate systems. One-dimensional CF coordinate systems describe time series, vertical profiles, and trajectories (e.g. a surface drifter or ship track). When used in conjunction with the OPeNDAP protocol (http://www.opendap.org/), CF becomes much more than a convention for formatted files; it provides a complete specification for network access to remote data.
CF today is an open, volunteer-driven standard. The scope of the standard is continually increasing ? a boon to data interoperability, but creating ever greater needs for careful coordination of the growing technical content. Lawrence Livermore National Laboratories generously provides support for the CF Web site (http://cf-pcmdi.llnl.gov/) and the British Atmospheric Data Center (BADC) generously provides a ½ time individual to coordinate the development of the CF Standard Names list. Community discussions of technical enhancements on the CF Web site are organized by topic using the "trac" software (http://trac.edgewall.org/). The volunteer CF Governance Committee (http://cf-pcmdi.llnl.gov/governance), that provides strategic guidance for CF, recognizes the need for a ½ time funded technical coordinator as well, and is actively seeking additional funding to support this position.
Number 133 - Session 3
Seasonal to decadal variability of the global overturning circulation inferred from the ECCO-GODAE ocean state estimate
P. Heimbach1, R.M. Ponte2, C. Wunsch1, G. Forget1, J.M. Campin1 and C. Hill1
1 MIT, EAPS, Cambridge, MA, USA
2 AER, Lexington, MA, USA
Abstract
With its provision of the first continuous oceanographic data set of quasi-global coverage, satellite altimetry was the main driver for embarking on the Estimating the Circulation and Climate of the Ocean (ECCO) project. The goal was, and remains, to combine as many satellite and in-situ observations as practical with a state-of-the-art general circulation model (GCM) to produce a best estimate of the time-evolving three-dimensional state of the ocean, being the dynamically consistent solution to a free-running GCM. Since its start, the adjoint-based branch of ECCO has gone through several product versions. The latest of these, version 3, is currently being produced as part of what is formally ECCOGODAE. Improvements lie with the underlying model, the inclusion of new and novel types of observations, and the refinement of (still poorly known) prior uncertainty estimates in every observational element whose magnitude determines the least-squares solution.
In terms of scientific analysis the focus is on global three-dimensional aspects of oceanic changes, in particular the global meridional overturning circulation (MOC). This recognizes the fact that the Atlantic MOC which has been the subject of much debate is merely a component of the larger general circulation, and attempts to detect secular changes ought to be directed at the global problem. Changes in any region propagate through the global ocean over long time scales, with (multi-decadal) adjustment through baroclinic Rossby waves providing a lower bound of such adjustments. Analysis of the 15-year solution which spans the recent period of unprecedented sampling reveals most of the variability in the annual and semi-annual cycles and contained mainly in the vast bodies of the tropical Pacific and the Southern Ocean water masses. However, robust trend estimates remain elusive, with only some weak spatially complex signatures, and the poor data sampling before the 1990s render problematic reliable trend estimates over longer periods.
All of these inferences have strong implications for long-running circulation observation strategies, including the need to avoid aliasing of the strong seasonal cycles, distinguishing purely local effects from larger-scale ones, and the long duration of the observations that will be required for documentation and understanding.
Work on a next-generation estimation system is in progress to address some remaining gap in the current product. This includes a fully global grid representing the Arctic, and with an extended control space to account for model parameter uncertainties. Technical hurdles include the extension of the adjoint infrastructure to generalized grid topologies, and the provision of stable adjoint sea ice sensitivities. Another focus is the continued extension of the observational backbone, such as the use of time-varying satellite gravity measurements from GRACE.
Number 91 - Session 6
DATA ASSIMILATION RESEARCH OF THE EAST ASIAN
MARINE SYSTEM: PRELIMINARY RESULTS
Naoki Hirose1, Jae-Hong Moon2, Hideyuki Kawamura3, Noriyuki Okei4
1Center for East Asian Ocean-Atmosphere Research, Research Institute for Applied Mechanics,
Kyushu University, Kasuga, Japan
2Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Kasuga, Japan
3Division of Environment and Radiation Sciences, Japan Atomic Energy Agency, Tokai, Japan
4Ishikawa Prefecture Fisheries Research Center, Noto, Japan
Abstract
Ocean current carries not only active tracers of heat and salt but various passive tracers such as biological resources or marine litters. To study comprehensively the marine system in the East Asian region, we are currently extending the prediction model of the Japan/East Sea (Hirose et al., J. Oceanogr., 2007) to the broader northwestern Pacific area. The model resolves mesoscale variability with the grid spacing of 1/12?. The major rivers (Changjang, Huanghe, and Amur) give freshwater flux directly, and the other minor rivers are accounted by the coastal precipitation resulting in an accurate representation of the surface salinity variation. The dense SST and SSH data are assimilated to the first and second versions of the system (DREAMS1.0? and ?), respectively. The system will start online operations officially in 2009 (http://oops.riam.kyushu-u.ac.jp).
The forward simulation (first guess) already shows good agreement with the measured transport through the Tsushima/Korea Straits (r~0.8). The assimilation of ship-mounted ADCP data will further improve the model's performance. Sensitivity experiments suggest that the local wind essentially controls the intraseasonal magnitude of the throughflow.
Energetic mesoscale variability is modeled and observed in regions of the subtropical countercurrent, the Kuroshio extension, the Kuroshio/Oyashio mixed water, and the southern Japan/East Sea. Realistic mesoscale changes should be represented by the ? version through the assimilation of satellite SSH data using approximate Kalman filter. As we find that in-situ tide gauge data assimilation improves the modeled coastal current significantly, new gauge is installed at Hegura Island (~38?N, 137?E) in this summer for better estimation and understanding of the coastal changes around Noto Peninsula. Strong sea level variability is also found in coastal region of the East China Sea associated with the local wind variation and the river discharge.
Number 52 - Session 4
Results from a real-time nowcast/forecast system in the Gulf of Mexico
Patrick Hogan
NRL, USA
Abstract
A numerical model of the Gulf of Mexico has been configured with the Hybrid Coordinate Ocean Model (HYCOM) with 1/25 degree horizontal resolution and 20 layers in the vertical. Lateral boundary conditions are taken from a 1/12 degree HYCOM Atlantic model. The Gulf of Mexico system assimilates satellite SSH and SST observations and runs in near real-time. The Navy Coupled Ocean Data Assimilation (NCODA) system is used for quality control and data assimilation, which includes in situ profile assimilation in addition to the surface observations. Surface wind and heat flux forcing are provided by the 0.5 degree NOGAPS product. The model was initialized on 02 September 2003 and continues to the present day. A 8-year reanalysis has also been performed, spanning the years 2000-2007.
Model analyses and forecasts from both the reanalysis and real-time run are compared to independent (non-assimilated) IR frontal positions and drifter trajectories. The system shows substantial skill in the ability to simulate the major circulation features of the Gulf of Mexico, including the Loop Current Extension and associated Loop Current Eddy shedding. Cyclonic "shingle" eddies are also accurately simulated. The system produces a 7-day forecast once per day.
Number 87 - Session 4
RECENT ENHANCEMENT OF GLOBAL HYDROLOGICAL CYCLE FROM
SURFACE LAYER SALINITY DATA DETECTED BY ARGO FLOATS
S. Hosoda1, T. Suga2, N. Shikama1, K. Mizuno1
1JAMSTEC/IORGC, Yokosuka, Japan
2Tohoku University, Sendai, Japan
Abstract
We investigated surface layer salinity distributions and characteristics of those spatial and temporal variations in the World Ocean. Surface layer salinity is one of the most important measures indicating the condition of an ocean. However, due to a lack of temporally and spatially homogeneous salinity data, previous observational studies did not detail global changes in surface layer salinity. Since the start of the
Argo Project in 2000, the development of the Argo float is increasing and the Argo float array has allowed us to document changes in global salinity. In the climatology calculated using historical data in 1970-1989, the surface layer salinity is generally lower in the subpolar and tropical regions and higher in the subtropics. We compared the annual averaged surface layer salinity distribution in 2003-2006 with the climatology and found a general enhancement of lower and higher surface layer salinity, except in the North Atlantic Ocean.
Since direct estimation of evaporation and precipitation (E-P flux) by observations is difficult at the sea surface, estimating the E-P flux from oceanic salinity is an effective alternative. We estimated the changes of basin-scale E-P flux associated with the enhancement of the global hydrological cycle from the surface layer salinity in 2006. The result shows that the strength of the global hydrological cycle is enhanced by approximately 3.1% compared to that 25 years ago. Our results, based on changes in 2006 global surface layer salinity, may provide an evidence of an enhanced global hydrological cycle probably caused by global warming.
(Last Updated: 30-10-2008)