Chapter 2 - Climate Data and Monitoring

The Australian Climate Network > Terrestrial Observations

Australia's contribution to international programs for terrestrial observations for climate is increasing, but is still relatively immature in comparison to its contribution to global programs for meteorological and oceanographic observation. Programs to observe various terrestrial climate variables do operate in Australia, but few operate on a national basis or with long-term climate monitoring as an objective.

A soon to be completed, four-year assessment of Australia’s soil, water and vegetation resources, the National Land and Water Resources Audit (NLWRA), aims to provide a framework for monitoring Australia's land and water resources in an ongoing and structured way. In fulfilment of this objective the Audit is likely to recommend an appropriate set of institutional arrangements and processes for ongoing monitoring, and will provide guidelines for the ongoing maintenance and updating of a range of physical and biological data sets. This process may provide a suitable starting point for a greater contribution to global terrestrial observing systems.

Hydrological Observations

In addition to the extensive rainfall networks operated by the Bureau of Meteorology, extensive networks of rainfall and streamflow stations are operated and maintained by the State and Territory-based water agencies. The water resources assessment undertaken by the National Land and Water Resources Audit (NLWRA) and published as Australian Water Resources Assessment 2000 (AWRA), used a subset of these networks to define the extent, quantity, use and quality of Australia's water resources. The processed data and results of the analyses have been brought together into a central database that is accessible through the web based Australian Natural Resource Atlas (audit.ea.gov.au/ANRA/ atlas_home.cfm). A data management infrastructure is proposed that will link the atlas with the State and Territory agencies' data archives thus enabling the NLWRA data and products to be more readily updated in the future.

The quality of the surface water and groundwater data available from the AWRA stations varies according to the primary use of each station. While the standards adopted by each of the agencies are considered to be good, the suitability of the data for use in climate analyses is yet to be assessed. A range of issues related to the availability, quantity and quality of Australian natural resources information, including water data, were identified during the NLWRA and are presented in Australian Natural Resources Information 2002.

The State and Territory water agencies identified a total of 3,200 monitoring stations as being suitable for characterizing Australia's surface water resources for AWRA. Of these stations, a total of 2,020 are currently operational. In many cases the closed stations have been included to enable pre-development and pre-regulation flow characteristics to be determined. The stations used in AWRA are available on the web from the Australian Natural Resource Atlas. A more complete list of river, rainfall and evaporation stations operated by the State and Territory water agencies and the Bureau of Meteorology are available from web based catalogues at www.bom.gov.au/hydro/ wr. Development, which is occurring at an increasing rate in many river basins, is changing the hydrological characteristics of Australia’s river basins. An increasing number of stations, therefore, will only be suitable for trend and climate analyses after considerable adjustment of the observed record to remove developmental impacts.

The network of both daily observed and continuously recording rainfall stations that make up the national climate network operated by the Bureau of Meteorology has been both expanded and modernised over recent years. On the advice of State water agencies, new stations have been opened in more remote areas where there were insufficient data for water resources assessment and planning. New technologies have been implemented to improve the efficiency of the collection and processing of the rainfall data. Data logging equipment suited to operation in remote areas is specified and installed with a tipping bucket rain gauge (TBRG) which increases data resolution and capture rates, as well as improving the efficiency of data processing over previous manual methods. Particular attention is being paid to improving the quality of the data collected through rigorous attention to the specification and monitoring of the performance of the TBRG, including much more detailed laboratory testing of gauges than in earlier years.

Land surface fluxes

The Australian ‘OzNet’ project measures fluxes of CO2 and water vapor at seven sites around Australia and is operated by CSIRO Land and Water in conjunction with several universities. The objective of the project is to provide quantitative baseline information about fluxes from representative land surfaces across the range of Australian climatic regions. OzNet is part of the developing set of international flux measuring sites in the FLUXNET component of the Global Terrestrial Network – Carbon (GTN-C). The Australian contribution is still at an early stage and most of the sites are not fully developed. In addition, the long-term viability of this network is somewhat compromised by the fact that, at present, funding for some sites derives from short-term research grants.

Surface Radiation

The Bureau of Meteorology operates a network of 15 radiation stations monitoring direct, diffuse and global solar and terrestrial exposure, direct, spectral irradiance and, at two stations, UV measurements (Figure 2.14). These sites are intended to provide long-term, stable records for both climate studies and other applications such as agrometeorology. They also provide a reference for the derivation of a nationwide satellite solar exposure product of lower quality. In addition, the Bureau of Meteorology hosts the WMO Region V Radiation Centre, which holds the Australian solar and terrestrial radiation standards.

Figure 2.14. Australia's surface radiation network.

CSIRO Atmospheric Research and the Australian Radiation Protection and Nuclear Safety Agency also operate solar UV networks for the purpose of quantifying human exposure to damaging radiation.

Cryospheric Observations

Australia reports periodically to the World Glacier Monitoring Service (WGMS) on the fluctuations of glaciers on sub-Antarctic Heard Island. In the past, the AAD has made in situ observations of these glaciers every 5-10 years, but these are expected to increase in frequency to every 3 years from 2004. Australia's 2001 report to the WGMS covers the 29 glacierized basins on Heard Island, which include 41 distinct glacier terminii.

Australia monitors Antarctic sea ice motion, thickness and concentration, using a variety of in situ and satellite-based systems, as part of its Antarctic Science Program.

Drifting buoys, measuring meteorological and oceanographic variables, are deployed onto ice floes and drift with the Antarctic pack ice. Measurements from the buoys’ sensors are relayed back to Australia via a satellite link, and the buoys' locations are determined either by the satellite system or an onboard GPS receiver. The buoys typically remain within the Antarctic sea ice zone for only a year or less. Currently, 2-6 buoys are deployed each year.

Australia also deploys upward-looking sonar systems on oceanographic moorings at key locations around the East Antarctic coast to obtain time series of sea ice thickness (keel depth). Data are recovered only when the moorings are retrieved, typically after a year. A total of eight sonars have been deployed since 1994, and the longterm plan is to maintain three moorings along the 110ºE longitude.

In a scheme developed by Australian researchers, ship-based sea ice observations are being used to establish the seasonally varying climatology of sea ice thickness and snow cover around Antarctica. The scheme makes use of a large number of simple but standardised observations from vessels transiting the ice, including observations of floes overturned by the passage of an ice-breaking vessel, area-wide estimates of the extent and thickness of ridging and of thin ice and, where possible, direct measurement of the thickness along drillhole profiles. These different observational methods are each best for different categories of ice thickness and, although each has weaknesses, they can be combined to provide a composite picture of the pack. Observations have thus far been collected at the rate of approximately three ship cruises per year. A broad-scale ice thickness climatology has been completed from Australian data for the East Antarctic sector (60° to 150°E) for the period 1980-1997. In addition, weekly measurements (drilled holes) of land-fast sea ice thickness and snow cover thickness are made at several sites near the Australian Antarctic stations of Davis and Mawson.

Various Australian agencies have monitored Antarctic sea ice concentration by satellite-borne passive microwave radiometers since 1973. The Bureau of Meteorology routinely receives full (1km) resolution AVHRR data from its NOAA ground station at Casey, providing images of sea ice along the East Antarctic coast. The AAD is currently researching a variety of satellitebased methods of cryospheric monitoring, including tracking of ice berg drift, mapping the extent of surface melt, measuring surface ice sheet velocity and ground line location and mapping grain size.

Land Cover and Vegetation Observations

The Bureau of Meteorology routinely derives Normalised Difference Vegetation Index (NDVI) products for the Australian region using AVHRR data received at its Melbourne ground station. These products support drought monitoring and climate services to primary industry, derivation of curing index maps for fire weather services and hydrological applications such as flood monitoring on inland rivers. Monthly maps have been produced and archived by the Bureau of Meteorology since 1997 and are accessible through a browse system on the Bureau’s website (www.bom.gov.au). The CSIRO and the Environmental Resources Information Network (ERIN) are also involved in mapping NDVI using NOAA AVHRR data and the higher resolution Landsat data.

The Bureau of Rural Sciences recently released Land cover changes in Australia, a report on the results of a project on the remote sensing of agricultural land cover change from 1990 to 1995, based on Landsat data. The report details the methods used to map woody vegetation cover and to detect land cover change, quality assurance procedures, the types of vegetation cleared and estimates of above ground biomass lost through clearing. The report and information about obtaining the data sets developed by the project are available from their website (www.brs.gov.au/land&water/landcov/alcc_report.html).

The systematic observation of vegetation fires using NOAA AVHRR data is a relatively new application of satellite data to climate monitoring. In Australia, two different groups are engaged in this activity: (i) a consortium of State agencies in Western Australia, South Australia and the Northern Territory are using AVHRR to detect hotspots and to map fire scars; and (ii) the CSIRO Earth Observation Centre is hosting a regional node of the pilot World Fire Web (WFW) project of the Joint Research Centre of the European Commission. The WFW, which started in June 1998, is a system for deriving daily global maps of vegetation fires in near real time.

Indicator Species

Among the most important ecological parameters that are required to detect, predict and assess the impacts of climate change are the distribution and composition of plant and insect species. An example of such an observation program is the Global Observation Research Initiative in Alpine Environments (GLORIA), in which Australia's La Trobe University is a participant along with the National Parks and Wildlife Service of the Snowy Mountains region. Australia's mountains are low by world standards with only one to two hundred metres separating the treeline from some mountaintops. Yet, more than 250 species of alpine plants grow in this restricted habitat. Monitoring the height of alpine treelines and the species colonising them will provide direct evidence of the effects of climate change.

Australia also contributes to the International Long-Term Ecological Research network, established in 1993. The Australian network currently consists of four sites covering a range of forest types including mixed eucalypt and open forest and woodland, temperate rainforest and tropical lowland rainforest. These sites were established to facilitate the understanding of ecological processes and to integrate research and monitoring activities. This network is expected to remain in operation at least until 2010.

In conjunction with its other climate monitoring activities within the Great Barrier Reef Marine Park, the AIMS has operated a long-term monitoring program for key organisms that inhabit the reef, including corals and algae, reef fishes and the crown of thorn starfish, since 1985. Currently, 47 reefs are surveyed once annually in a sequence of five or six regional cruises over the summer period. In addition to providing information assisting with informed management of the park, the information is used in ecological studies of population changes and abundance on a large geographic scale.