The Global Energy and Water Exchanges Project (abbreviated GEWEX, formerly named the Global Energy and Water Cycle Experiment from 1990 to 2012) is an international research project and a core project of the World Climate Research Programme (WCRP).
In the beginning, the project intended to observe, comprehend and model the Earth's water cycle. The experiment also observes how much energy the Earth receives, and studies how much of that energy reaches the surfaces of the Earth and how that energy is transformed. Sunlight's energy evaporates water to produce clouds and rain and dries out land masses after rain. Rain that falls on land becomes the water budget which can be used by people for agricultural and other processes.
GEWEX is a collaboration of researchers worldwide to find better ways of studying the water cycle and how it transforms energy through the atmosphere.About GEWEX , Global Energy and Water Cycle Experiment, World Climate Research Programme, Access date 06-22-2008 If the Earth's climates were identical from year to year, then people could predict when, where and what crops to plant. However, the instability created by solar variation, weather trends, and chaotic events creates weather that is unpredictable on seasonal scales. Through weather patterns such as droughts and higher rainfall these cycles impact ecosystems and human activities. GEWEX is designed to collect a much greater amount of data, and see if better models of that data can forecast weather and climate change into the future.
Project structures GEWEX is organized into several structures. As GEWEX was conceived projects were organized by participating factions, this task is now done by the International GEWEX Project Office (IGPO). IGPO oversees major initiatives and coordinates between national projects in an effort to bring about communication between researchers.NASA is the primary sponsor of IGPO IGPO claims to support communication exchange between 2000 scientist and is the instrument for publication of major reports.International GEWEX Project Office (IGPO) GEWEX WCRP
The Scientific Steering Group organizes the projects and assigns them to panels, which oversee progress and provide critique. The Coordinated Energy and Water Cycle Observations Project (CEOP) the 'Hydrology Project' is a major instrument in GEWEX. This panel includes geographic study areas such as the Climate Prediction Program for the Americas operated by NOAA,(CPPA integrates what was formally GEWEX American Prediction Project - GAPP and Climate Variability and Predictability, U.S. CLIVAR.) Climate Program Office , National Oceanic and Atmospheric Administration but also examines several types of climate zones (e.g. high altitude and semi-arid). Another panel, the GEWEX Radiation Panel oversees the coordinated use of satellites and ground-based observation to better estimate energy and water fluxes. One recent result GEWEX's Radiation panel has assessed data on rainfall for the last 25 years and determined that global rainfall is 2.61 mm/day with a small statistical variation. While the study period is short, after 25 years of measurement regional trends are beginning to appear.Gruber A and Levizzani V. Assessment of Global Precipitation Products A project of the World Climate Research Programme Global Energy and Water Cycle Experiment (GEWEX) Radiation Panel, WCRP-128 WMO/TD-No. 1430, May 2008 The GEWEX Modeling and Prediction Panel takes current models and analyzes the models when climate forcing phenomena occur (global warming as an example of a 'climate forcing' event). GEWEX is now the core project of WCRP.
Goals and design
Predicting weather change requires accurate data that is collected over many years, and the application of models. GEWEX was conceived to respond to the need for observations of the Earth's radiation budget and clouds. Many preexisting techniques were limited to observations taken from land and populated areas. This ignored the large amount of weather that occurs over the oceans and unpopulated regions, with key data missing from these areas. Since satellites orbiting the Earth cover large areas in small time frames, they can better estimate climate where measurements are infrequently taken. GEWEX was initiated by World Climate Research Programme (WCRP) to take advantage of environmental satellites such as TRMM, but now uses information from newer satellites as well as collections land-based instruments, such as BSRN. These land-based instruments can be used to verify information interpreted from satellite. GEWEX studies the long-term and regional changes in climate with a goal of predicting important seasonal weather patterns and climate changes that occurs over a few years.
Radiation, humidity, and aerosols Sunlight and rain The Earth is made of matter, including water, which absorbs and emits energy into space. Should the Earth not orbit a star, the water would freeze solid and little precipitation would occur because the rate of evaporation would be very low. If the Earth were devoid of water, it would heat to great temperatures in the daytime and cool off more quickly at night. Therefore, water modulates heat energy by transitioning between ice, water, and steam. When heat is applied, ice becomes water and water becomes vapor-steam, absorbing heat energy. When cooling is applied, vapor condenses into water and water freezes into ice, releasing heat. While these are simple examples, rainfall results from a complex set of processes. When sunlight hits the oceans it forces liquid water into the vapor state at a rate dependent on surface temperatures, humidity, winds and pressure. At equilibration, water reaches 100% humidity, and during the day, the temperature rises, allowing more moisture to accumulate in the air. At night the temperature falls and water tends to form clouds, often resulting in ground fog in coastal areas.
At 100% humidity, any loss of radiant energy from water causes vapor to condense into water. Circulation and convection can carry moist air upward in the air column, and this often cools moist air. The air forms water droplets, even in the heat of daytime, creating clouds. As the density of droplets in the clouds increase, the air can no longer support droplets and they fall as rain. More moist air can be drawn into clouds as energy is released, allowing the development of large thunderstorms. Prevailing winds are a factor in storm formation, particularly when changes occur. Tropical waves that develop in westerly flows around the Earth's semitropical and tropical region can organize into horizontal circles over the water, creating a cyclone.
A cyclone is a stereotype energy transfer system. It gathers steam off of warm water and quickly moves it upwards releasing the energy into space. This causes the characteristic rain bands. The energy transferred is so great it gives rise to catastrophic winds, which disturb surface waters, increasing steam release, and also increase the rate at which moisture is drawn into the center. The heat of the water under the storm drops. Cyclones demonstrate how much latent energy is stored in the world's oceans.Fluxes, radiation and aerosols The moisture for a cyclone can be defined as the warm water below the storm. As the cyclone leaves warm water its energy dissipates quickly. Less powerful, long-term rainfall generators can rely on moisture driven by warm waters far from the greatest region of rainfall. In the tropics, the energy came from, stored heat in ocean currents and moving thermoclines can provide sources far away, such as is seen in El-Nino.
Another example is the floods that hit the Midwest U.S. in 1993. The energy that drove moisture into the air occurred in the Gulf, and strong winds and lack of cooling in coastal regions permitted the moisture to travel 1000 miles until conditions were ripe for rain. As the rain fell it cooled the air and dissipated heat, and as new moisture arrived, the process continued. When the sun did come out, it heated wet ground, which created more rain.
Aerosols over the ocean can cause a lack of sufficient heat in the middle of the day to create sufficiently humid air. When the air reaches land, which may be warmer, there may be inadequate convection and other processes to create rains, and this can cause droughts. To better see these events progress, scientists need data and models to see what elements of the data are most useful in determining rainfall.
Research goals The research interest of GEWEX is to study fluxes of radiation at the Earth's surface, predict seasonal hydration levels of soils and develop accurate models of predicting energy and water budgets around the world. The project sets its goal as to improve, by an order of magnitude, the ability to model and therefore prediction hydration (rainfall and evaporation) patterns GEWEX is linked to other WCRP projects such as Stratospheric Processes and their Role in Climate (SPARC) Project, and the Climate and Cryosphere Project through WCRP.Climate and Cryosphere (CliC) World Climate Research Program and Scientific Committee on Antarctic Research and thus shares information and goals with other WCRP projects. The goal becomes more important with the newer WCRP project, the Coordinated Observation and Prediction of the Earth System.WCRP STRATEGIC FRAMEWORK 2005-2015 World Climate Research Program, WCRP Strategic Support Unit, Institut Pierre Simon Laplace (IPSL)
Complexity of the experiment Aside from fluctuations of solar radiation, the sunlight that is transformed by the Earth can vary greatly, some have concluded for instance, that ice-ages self-perpetuate once enough ice has accumulated in the polar regions to reflect enough radiation at high elevations to lower the global average temperature, whereas it takes an unusually warm period to reverse this state. Water usage by plants, herbivore activities can change albedo in the temperate and tropical zones. These trends in reflection are subject to change. Some have proposed extrapolating pre-GEWEX information using new information and measurements taken with pre-GEWEX technology. Natural fires, volcanism, and man-made aerosols can alter the amount of radiation reaching the Earth. There are oscillations in oceanic currents, such as El-Niño and North Atlantic Oscillation, which alter the parts of the Earth's ice mass and land water availability. The experiment takes a sampling of climate, with some trends lasting a million years, and as paleo-climatology shows, can abruptly change. News article in Nature Therefore, the ability to use data to predict change depends on factors that are measurable over periods of time, and factors that can affect global climate that abruptly appear can markedly alter the future.
Design GEWEX is being implemented in phases. The first phase comprises information gathering, modelling, predictions, and advancement of observation techniques and is complete. The second phase addresses several scientific questions such as prediction capacity, changes in Earth's water cycle, and the impact on water resources.
First phase (1990–2002) Phase I (1990–2002), also called the "Build-Up Phase", was designed to determine the hydrological cycle and energy fluxes by means of global measurements of atmospheric and surface properties. GEWEX was also designed to model the global hydrological cycle and its impact on the atmosphere, oceans and land surfaces. Phase I processes were to develop the ability to predict the variations of global and regional hydrological processes & water resources, and their response to environmental change. It was also to advance the development of observing techniques, data management, and assimilation systems for operational application to long-range weather forecasts, hydrology, and climate predictions.
During Phase I GEWEX projects were divided into the three overlapping sectors.