Space-based systems have the unique advantage of obtaining global spatial coverage, particularly over the vast expanses of the oceans, sparsely populated land areas (deserts, mountains, forests, and polar regions), and the mid- and upper troposphere and stratosphere. They provide unique measurements of the Earth’s radiation budget; solar output; vegetation cover; atmospheric ozone; stratospheric water vapor and aerosols; greenhouse gas distributions; sea level and ocean state; ocean surface state, level, and winds; weather; and tropical precipitation, among others.

    But satellite observations alone are not sufficient; they require in-situ measurements for calibration and validation. In-situ observations are required for the measurement of parameters that cannot be estimated from space platforms (e.g., biodiversity, groundwater, carbon sequestration at the root zone, and subsurface ocean parameters). They also provide long time series of observations required for the detection and diagnosis of global change, such as surface temperature, precipitation and water resources, weather and other natural hazards, the emission or discharge of pollutants, and the impacts of multiple stresses on the environment due to human and natural causes.

    To meet the need for the documentation of global changes on a long-term basis, the USGCRP integrates observations from both research and operational systems, such as NOAA’s operational weather satellites and surface-based stations. The latter are essential for the USGCRP but are not included within the USGCRP programs or budget presentation.

    Following are some of the specific observation and monitoring activities that support the various program elements.

Understanding the Earth’s Climate System

Data collection from the EOS-AM satellite will provide observations of cloud structure, water vapor distribution, aerosol particles, trace gases, and terrestrial and ocean properties. These data are required for improved monitoring and modeling of air-land and air-sea interaction and of the exchanges of carbon, energy, and water.

Launch of JASON-1 will provide altimetry measurements for ocean circulation and sea-level change required for the monitoring and prediction of El Niño events.

Launch of ACRIMSAT will provide accurate data to monitor solar irradiance, and for studies of solar-terrestrial/atmosphere interaction.

Launch of the Seawinds satellite will provide more accurate measurements of ocean surface winds and wind stress required to run ocean models for El Niño prediction. The data are also required to improve weather forecasting.

Further development of a Climate Reference Network, consisting of several hundred stations from the network of 7000 sites that measure temperature and precipitation daily, will provide stable measurements of climate change with the requisite continuity over the instrumental record.

Deployment of a pilot climate monitoring array in the tropical Atlantic, including moorings, surface drifting buoys, and autonomous profiling floats, will complement similar platforms in the tropical Pacific and expand the global domain of ocean surface and subsurface observations. Similar deployments will be carried out in the North Pacific and the Indian Ocean.

A third Atmospheric Radiation Measurement Station in the western Pacific will provide data on the effects of clouds on the Earth’s radiative energy balance, a major source of uncertainty in climate models.

Figure 8. Ocean circulation profiling floats
(See Appendix E for additional information)

Biology and Biogeochemistry of Ecosystems

Launch of the Vegetation Canopy Lidar (VCL) satellite will provide detailed measurements of the vertical structure of the vegetation canopy. These data are required to improve the mapping and categorization of vegetation/biosphere, the monitoring of change, and the parameterization in models of atmosphere-land surface processes involving the exchange of heat, momentum, moisture, and gases. The data will also contribute to distinguishing between deforestation and reforestation.

Data from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument on the EOS-AM satellite will provide measurements of land and ocean surface temperatures, chlorophyll fluorescence, and land surface vegetation — key elements of land and ocean biology and ecosystems.

Ongoing data collection from the Landsat satellites will provide continued monitoring and mapping of land surface characteristics, vegetation, soils, and minerals.

The addition of several coastal sites to the existing Long-Term Ecological Research (LTER) network will provide data on the response of a broader distribution of ecosystems to short- and long-term climate changes, as well as data on the response to other stresses.

Composition and Chemistry of the Atmosphere

Continued development of the EOS Chemistry satellite, scheduled for launch in December 2002, will provide: three-dimensional profiles on a global scale of all infrared active trace gas species from the surface to the lower stratosphere and measurements of greenhouse gas concentrations, tropospheric ozone, acid rain precursors, and gas exchange leading to stratospheric ozone depletion. Data will also be obtained on water vapor, aerosols, atmospheric temperature, polar stratospheric clouds, and cloud tops.

Continued measurements of surface concentrations of ozone/UV radiation, and of CFCs and their replacement compounds, halons, and other chemicals regulated under the Montreal Protocol and its amendments, will be made by NOAA’s Climate Monitoring and Diagnostics Laboratory network (a part of the ground-based Advanced Global Atmospheric Gas Experiment).

Launch of the Total Ozone Mapping Spectrometer (TOMS) will lead to continued measurements of atmospheric ozone.

Completion of the deployment of ultraviolet radiation spectrophotometers will provide data from a UV monitoring network at 14 national parks and 8 urban sites.

Paleoenvironment/Paleoclimate

Improved technology to delineate more accurately the timing of pre-historical climatic events will provide data on the temporal and spatial character of natural climate variability and abrupt climate changes during the period prior to significant anthropogenic impact.

Establishment of a global network of centuries-long paleoclimatic time series will help create links to sedimentological, paleobiological, and geochemical data.

Continued extraction of paleoenvironmental data from North America will provide a clearer evaluation of climate-induced vegetation and ecosystem change over the last 20,000 years.

Human Dimensions of Climate Change

Data from the ongoing Landsat program will provide monitoring and categorization data on land cover and land use, urban expansion, and agricultural practices.

Integration of climate data with human health statistics will provide information on the occurrence and spread of vector-borne diseases, heat-related mortality, and vulnerabilities of social systems to climate variability and global change processes.

Measures of the health effects of CFC replacement chemicals (HCFCs and halogenated hydrocarbons) and UV radiation will provide information to decisionmakers.

LTER sites, which continue to provide information on the response of ecosystems to changes due to climate and other multiple stresses, will assist in distinguishing between direct and indirect human-induced impacts.

The Global Water Cycle

Continued measurements from rainfall radar on board the Tropical Rainfall Measuring Mission (TRMM) satellite, together with surface radars and rainfall stations, will provide a benchmark for rainfall in the tropics. The data will be used to develop a rainfall climatology, validate climate models, and demonstrate the impact of rainfall in assimilation and weather forecast schemes. These data will provide key information for the improved understanding, monitoring, and modeling of the global water cycle, and assessment of water resources.

The North American Rain Gauge Network will provide detailed information on the regional and local impact of El Niño and climate change on rainfall, water supply, and water resources.

Data collection from the EOS-AM satellite will provide data on clouds and on the exchanges of water and energy between the atmosphere, land, and oceans. These data will also contribute to improved parameterizations in models of water/moisture transports and budgets, improved weather forecasting, and the prediction of the impacts of climate change on water resources.

Carbon Cycle Science

The operation of 25 AmeriFlux sites, representing major ecosystem types in North and Central America (including forests, croplands, grasslands, rangelands, and tundra), will provide data for comparative (across ecosystem types) assessments of atmosphere/terrestrial-biosphere exchanges of energy and water, net sequestration of carbon dioxide, and the effects of environmental factors (including climate variations) on the net exchange of carbon and the role of biophysical processes controlling this exchange.

Landsat, MODIS, and VCL, along with the Advanced Very High-Resolution Radiometer (AVHRR) will provide improved global measurements of vegetation cover and changes, key components in the carbon budget and carbon cycle of the Earth system. Ocean color data from MODIS will include global ocean productivity maps at weekly time intervals for assimilation into carbon cycle models.

Continued data collection from SeaWifs will provide global and more accurate measures of ocean biology and land surface vegetation, which are key elements in the global carbon cycle.

Data and information management from these activities are critical to the success of the USGCRP, supporting not only scientists but also a broader range of users including teachers and educators, land use managers, and the public at large. Information on the availability of data sets will be widely disseminated through the Global Change Data and Information System (GCDIS). In FY 2000, the system will provide the following data products to the broad range of users:

Integrated global data sets from both research and operational space- and ground-based platforms supporting all the research programs of the USGCRP.

El Niño monitoring and prediction information.

Warning of natural hazards.

The analysis and assessment of:

ozone depletion and associated chemistry;

greenhouse gas concentrations;

global and regional land and ocean surface temperature;

global tropical precipitation;

global vegetation cover;

global ocean productivity;

global and regional carbon sources and sinks;

global and regional ecosystems;

natural climate changes of the past;

global and regional water resources;

solar-climate relations; and

global change and vector borne diseases.

    Over the longer term, USGCRP agencies are exploring ways to maintain the long-term data records necessary for documenting and understanding global change. NASA, NOAA, and DOD, the partners in the National Polar-orbiting Operational Environmental Satellite System (NPOESS), are exploring ways to extend the long-term measurements of key global change parameters beyond the EOS AM-1 and PM-1 time frame to provide a bridge into the post-2008 NPOESS era. Internationally, the United States participates with other nations in the Committee on Earth Observation Satellites, which has called for developing an Integrated Global Observing Strategy (IGOS) to link space and in-situ observations in a common strategic framework. The United States also participates in the international coordination of the Global Climate Observing System (GCOS), the Global Ocean Observing System (GOOS), and the Global Terrestrial Observing System (GTOS). The broader objective of IGOS is to develop a comprehensive strategy for integrated space-based and in-situ observations to monitor the interactive Earth system holistically, addressing the needs of scientific research and those of the broad community of users involved in operational resource management, international assessments, and policy development.