Chapter 2 - Climate Data and Monitoring

The Australian Climate Network > Oceanographic Observations

Ocean Surface Observations

Australia participates in the international Voluntary Observing Ship (VOS) scheme of the Joint (WMO/IOC) Technical Commission for Oceanography and Marine Meteorology (JCOMM), through the Australian Voluntary Observing Fleet (AVOF). The fleet currently consists of some 100 Australian and foreign-owned merchant, research, passenger and private vessels, operating mainly in the Australian region. These vessels report surface temperature (sea and air), pressure, wind and other meteorological variables up to four times per day (Figure 2.6). A number of current projects are aimed at automating the encoding and transmission of ship observations and reducing the time and effort required of crew, which will assist in keeping the fleet numbers around 100. Operation of this observing program is the responsibility of the Bureau of Meteorology.

Figure 2.6. Shows the ocean area typically covered by the Australian Voluntary Observing Fleet over the course of a year.

Australia has also committed to the international VOSClim project, which aims to provide a high-quality subset of marine meteorological data, with extensive associated metadata, in both real-time and delayed mode to support global climate studies. Six Australian vessels have been recruited to participate in VOSClim.

The Bureau of Meteorology maintains a network of about 20 drifting buoys, which provide observations of surface temperature (sea and air), pressure and ocean currents from the data sparse oceans surrounding Australia, particularly the Indian and Southern Oceans. The Bureau of Meteorology has been involved with drifting buoys since the 1970s, maintaining a modest deployment program of about six buoys per year until 1995, when this was increased to about 10-15. The majority of buoys are deployed opportunistically, subject to the availability of suitable shipping travelling near the preferred deployment area. Eleven buoys, owned and funded by the Bureau of Meteorology, were deployed in 2001-02 to the west and southwest of Australia (Figure 2.7). A similar number supplied by the US Atlantic Oceanographic Marine Laboratory of NOAA, and fitted with barometers by the Bureau of Meteorology, were also deployed.

Figure 2.7. Australian drifting buoy deployments 2001-02.

In September 2000, the AIMS deployed its first oceanographic buoy in the northern Great Barrier Reef to provide near real-time oceanographic data for its monitoring activities in this region.

A national wave-rider buoy network, in support of operational marine weather services, is coordinated and managed by the Bureau of Meteorology with the cooperation and support of other government agencies and private companies. Twentyeight wave-rider buoys are currently deployed around the Australian coastline.

The National Tidal Facility of Australia (NTFA) provides the management and operational support for an array of 16 SEAFRAME (SEA-level Fine Resolution Acoustic Measuring Equipment) stations in the Australian Baseline Sea Level Monitoring (ABSLM) network (Figure 2.8). This network is funded under the Australian Greenhouse Science Program, with assistance from the Victorian Channel Authority, to monitor sea level and climate around the coastline of Australia and nearby seas with a view to identifying long period sea level change. The NTFA, with member countries of the South Pacific Forum, also manages a network of stations recording variations in long-term sea level in 11 Pacific island countries.

The AAD, in conjunction with the NTFA and the Australian Surveying and Land Information Group (AUSLIG), operates a network of six specially designed tide gauges in Antarctica and on the sub-Antarctic islands (Figure 2.9). This network is the core of an IOC-sponsored Sea Level Pilot Project for monitoring long-term changes in the Southern Ocean.

A large number of Port Authorities around the Australian coast also maintain their own tide-gauges.

The Worldwide Recurring ASAP (Automated Shipboard Aerological Programme) Project (WRAP), which commenced in 2001, provided routine upper air soundings from ships en-route from Europe -- Cape of Good Hope -- Australia -- New Zealand -- Cape Horn -- Brazil -- Europe (Figure 2.10). Each voyage lasted around 85 days, of which about 55 days were spent in the Southern Hemisphere. In an initial contribution to the project, the Bureau of Meteorology sponsored two soundings per day between 60ºE and 160ºE and provided first-in maintenance at Australian ports.

Figure 2.10. The route of the Worldwide Recurring ASAP Project.

The AIMS operates five Automatic Weather Stations along the Great Barrier Reef (2 stations on tourist pontoons, 2 on purpose-built towers and one on land) and one on land close to Ningaloo Reef off northwest Australia. These stations record air temperature, pressure, wind speed and direction, solar radiation (and where located on a reef) sea surface temperatures. Observations are recorded at half-hourly intervals and relayed to AIMS. The longest station records extend back to 1987. The Great Barrier Reef Marine Park Authority has recently funded two additional stations which began operation in 1999 (Cleveland Bay) and 2000 (Half-Tide Rocks) and a third station at Orpheus Island in 2002 with support from James Cook University and the Australian Research Council. Near-real time data from all nine stations are posted on the AIMS web-site ( http://www.aims.gov.au/pages/facilities/weather-stations/weather-index.html) as well as summaries of the year’s weather to date. AIMS also operates a radiometer system on board a tourist vessel operating from Townsville. This provides radiometric sea surface temperature transect data twice a day, five days a week.

AIMS operates long-term current meter moorings extending back to 1987 in 200m of water near Myrmidon Reef to measure the variability of the East Australian Current. In 2000 the mooring was moved further south to position it under a JASON Altimeter track. A long-term current meter was also deployed at Tantabiddi Reef in northwest Australia in 2002 to monitor the Leeuwin and Ningaloo Currents. Longterm pressure gauges have been deployed since 1987 at Myrmidon, Flinders and Opal reefs on the outer GBR/Coral Sea. AIMS monitors water level and suspended sediment loads in monsoonal rivers of northeast Australia and continues to monitor water temperature and water quality in two regions of the Great Barrier Reef. Water temperature is also monitored at Scott Reef on the northwest shelf.

AIMS maintains a long-term sea water temperature (SWT) monitoring program on the Great Barrier Reef (GBR) using in-situ data loggers. The program was established initially by the Great Barrier Reef Marine Park Authority in 1992 at a small number of sites in the central GBR. The program was expanded GBR-wide in 1995 with support from the CRC Reef Research Centre and expanded further to include most of Queensland’s regional shipping ports with support from the Ports Corporation Queensland. Data loggers currently deployed at ~ 50 locations on the GBR and surrounding waters record instantaneous SWTs every 30 minutes. Data loggers are downloaded every 6 to 12 months and provide detailed information about small-scale SWT variability within and between reefs and along the length of the GBR (see http://www.gbmrpa.gov.au/seatemp/index.html).

AIMS research is providing estimates of carbon removal/burial rates from coastal seas, which assists in estimation of the removal rate of fossil fuel carbon from the atmosphere and land. This work is being done on the NW shelf and slope, the NE coast of Queensland and the Gulf of Papua.

Over the past 40 years, CSIRO Marine Research has made measurements of temperature, salinity and nutrients at a large number of coastal stations around Australia. Currently only four of these stations are in operation.

Satellite-based observations of sea surface characteristics, such as temperature, sea state, colour, topography and surface wind velocity, are routinely derived by several Australian government agencies and institutions including the CSIRO, AIMS, the Bureau of Meteorology, the AAD and several universities.

Ocean Sub-surface Observations

The expendable bathythermograph (XBT) ship of opportunity program (SOOP) is a network of merchant and research ships that launch XBTs to determine the thermal structure of the upper 800m of the oceans. The network provides routine, high quality, upper-ocean thermal data for operational analysis and initialisation of climate forecast models, both nationally and internationally and in support of various operational needs including fisheries, shipping and defence. The Australian XBT SOOP program was designed and established by CSIRO Marine Research (CMR) in 1983 as an experimental network. In 1998, responsibility for the low-density component of the program was transferred to the Bureau of Meteorology to be maintained as an operational system (Figure 2.11). CMR continues to operate the high-density component of the Australian program and the Royal Australian Navy provides support through the provision of 2,500 XBTs/year, and contributes a further 1,000 XBTs to the program via broadcast sampling from its own vessels. Between 3,000 and 4,000 XBTs are deployed by the Australian XBT SOOP program per year with most profile data, including naval data, made freely available in real-time via transmission on the Global Telecommunications System. Also as part of the SOOP program, a thermosalinograph, measuring sea-surface temperature and salinity, is operated on the Antarctic supply vessel between Tasmania and Dumont D’Urville (Antarctica).

Figure 2.11. Australia's low density, operational XBT SOOP lines.

In conjunction with the Bureau of Meteorology, CMR is participating in the international Argo network, by deploying autonomous profiling floats off the coast of Australia. As an Australian contribution to Argo, 10 floats were deployed off the northwest coast of Australia, in the region of the Indonesian throughflow, during 2000. A further 19 floats were deployed in the Indian Ocean in 2002/03 as part of the joint Bureau of Meteorology/CMR Australian Argo Program. The floats are programmed for an 'Argo' mission, i.e., to drift at 2000m and profile to the surface every 10 days, delivering temperature and salinity values from 50 depths (Figure 2.12). One of the objectives of this activity is to document and describe the oceans around Australia, as a time dependent system, in order to determine the mechanisms and processes underlying their variability, and to develop and validate ocean and coupled oceanatmosphere models with the results. It is also hoped that the results will provide the scientific basis for designing an observing and data transmission system for future operational monitoring and ocean prediction. CMR and Bureau of Meteorology plan to maintain the existing array of floats off the coast of Australia and gradually extend the array further south.

Figure 2.12. Automated profiling floats are programmed for an ‘Argo’ mission – drifting at 2000m and profiling temperature and salinity to the surface every 10 days.

During 2000, CMR commenced a program to establish a set of Deep Ocean Time Series Sections around Australia, aimed at monitoring ocean inventories of heat, freshwater and carbon on decadal time-scales. The time series will build upon the highquality hydrographic sections made in the mid-1990s as part of the World Ocean Circulation Experiment (WOCE), with portions of several WOCE hydrographic lines, between Australia and 90ºE in the Indian Ocean, being re-occupied (Figure 2.13). Data from the time series will be used to validate climate model predictions and to determine whether, and how fast, climate is changing due to the enhanced greenhouse effect and/or natural decadal variability.

Figure 2.13. The hydrographic lines and stations of Australia's Deep Ocean Time Series Sections in the Indian Ocean, as marked by the cruise track of the RV Franklin from September to November 2000. Dates (day/month/) are marked at open circles at every tenth station on the line.

CMR also operates a program of ocean biogeochemical observations from a merchant vessel circumnavigating Australia, calling at all of the major ports and passing near the full length of the Great Barrier Reef. The observation equipment currently includes sensors for temperature, salinity, fluorescence, photosynthetically active radiation (PAR) and phytoplankton. Biogeochemical parameters are also measured in a separate program of monthly continental shelf transects off Perth. These repeat surveys will be used, in conjunction with physical data, to determine the relationship between climate variability and biological productivity, to facilitate the detection and attribution of climate change, and to calibrate and validate remotely sensed data, such as ocean colour.