Water and energy cycles investigating the links by liwenting


									                                             are inextricably intertwined over a
                                             large range of space- and time-scales
    Water and                                from boundary-layer turbulence to
                                             global climate change. Recognizing

    energy cycles:
                                             the pressing requirement to better
                                                                                        International GEWEX Project Office,
                                             understand and predict these complex
                                                                                        Silver Spring, Maryland, USA
                                             processes and their interactions, the
                                                                                        E-mail: gewex@gewex.org
                                             World Climate Research Programme           Web: http://www.gewex.org/igpo.html
                                             (WCRP) launched the Global Energy

    the links
                                             and Water Cycle Experiment (GEWEX)
                                             in 1990. GEWEX leads WCRP’s stud-          During Phase I, more than 1 500 scien-
                                             ies of the dynamics and thermo-            tists from over 35 countries
                                             dynamics of the atmosphere, the            participated in GEWEX activities and
                                             atmosphere’s interactions with the         more than 20 special issues of refer-
                                             Earth’s surface (especially over land),    eed papers were produced.
                                             and the global water cycle. By virtue of
                                             this central role, GEWEX connects          Understanding the role of water in the
                                             with other WCRP projects, including        climate system is a priority for WCRP
                                             the     Climate     Variability     and    and GEWEX. As vapour, water is the
                                             Predictability (CLIVAR) project, the       Earth’s strongest and most plentiful
                                             Stratospheric Processes and their Role     greenhouse gas. Clouds also have an
                                             in Climate (SPARC) project, and the        important feedback role in the climate
                                             Climate and Cryosphere (CliC) project.     system and, depending on their
                                             Furthermore, WCRP’s co-sponsors,           composition, spatial distribution and
                                             WMO), the International Council for        altitude, may enhance or diminish
                                             Science       (ICSU)      and       the    climate-change effects. Feedback
                                             Intergovernmental      Oceanographic       influences also come from land-
   By S. Sorooshian1, R.G. Lawford2,         Commission (IOC) of UNESCO,                surface states determined by soil
    P. Try2, W. Rossow3, J. Roads4,          provide GEWEX access to researchers        moisture and vegetation, which
J. Polcher5, G. Sommeria6, R. Schiffer2      in both the academic and governmen-        controls the partitioning of incoming
                                             tal sectors.                               solar radiation into radiative, sensible,
                                                                                        latent (evaporation) and ground-heat
                                                                                        fluxes and precipitation into runoff and
Introduction                                 GEWEX: Phases I and II                     infiltration. The cycle is closed by
                                                                                        evapotranspiration from the land and
The Earth’s climate fluctuates and           The first phase of GEWEX (1990-2002)       evaporation      from     the     ocean.
changes both regionally and globally.        focused on the development of analy-       Understanding, characterizing and
Inevitably, this is reflected in the vari-   sis tools and models, using operational
ability and change of Earth's water          and research satellites, regional analy-
budget and its complex and dynamic           ses of continental scale basins, and        GEWEX Phases I and II
energy balance with the Sun.                 process studies to support the devel-
Processes controlling the transports,        opment of parameterizations of
transformations and exchanges of             feedback processes (relating to clouds      GEWEX Phase II (2003-2013)
heat and water in the climate system         and land) for global climate models.        emphasizes the full exploitation of
                                                                                         the understanding and tools from
1 University of California, Irvine, USA                                                  Phase I (1990-2002), along with
2 International GEWEX Project Office, Silver Spring, USA                                 increased reliance on upgraded
3 NASA Goddard Institute for Space Studies, New York, USA                                models and assimilation systems
4 University of California, San Diego, USA
5 Laboratoire de météorologie dynamique du Centre national de la recherche scien-
                                                                                         and new environmental satellite
  tifique (CNRS), Paris, France                                                          systems to produce even greater
6 WMO/WCRP                                                                               contributions to climate science.

    closing both the global water and                  Figure 1, GEWEX plays a critical role     mesoscales. Modelling and related
    energy budgets have been a major                   in relating WCRP prediction activities    process studies coordinated through
    focus for GEWEX research.                          to hydrology programmes, such as          the GEWEX Modelling and Prediction
                                                       those of the International Association    Panel (GMPP) addressed clouds, land-
    This agenda has placed GEWEX on the                of Hydrological Sciences (IAHS).          atmosphere interactions, and, more
    leading edge of science, which is                                                            recently, boundary-layer processes.
    directed at bringing the hydrology,                During Phase I, GEWEX activities          The radiation projects, coordinated by
    land-surface, and atmospheric science              included: (a) global dataset develop-     the GEWEX Radiation Panel (GRP),
    communities       together      through            ment; (b) process studies; and (c)        developed global data products and
    process studies in order to show the               model development support and             scientific understanding related to the
    importance of understanding soil                   modelling studies. In order to focus      global distribution and variability of
    moisture/atmosphere and cloud/ radia-              activities and to provide for better      clouds, water vapour, aerosols,
    tion     interactions     and      their           coordination, a programmatic struc-       surface radiation and precipitation.
    parameterization within prediction                 ture was adopted in 1995 that set
    models. Also, by producing or foster-              goals for GEWEX activities in three
    ing the production of global datasets to           separate areas, namely radiation,         GEWEX Hydrometeorology Panel
    validate predictive models, GEWEX is               hydrometeorology and modelling and        (GHP)
    ready to assess whether the global                 prediction. The hydrometeorology
    water cycle has been undergoing                    activities, coordinated through the       GHP efforts are directed at demon-
    significant changes in the past two                GEWEX Hydrometeorology Panel,             strating skill in predicting changes in
    decades. GEWEX has also actively                   focused on the coupling of the land       water resources and soil moisture on
    engaged and benefited the water                    and the atmosphere and hydrological       time-scales up to seasonal and annual
    resource community. As shown in                    processes at the continental and          as an integral part of the climate
                                                                                                 system. It also focuses on building
                                                                                                 upon distributed process studies in the
                                                                                                 GEWEX            Continental      Scale
                                                   Water resources                               Experiments (CSEs) as well as the
                                                   management agencies                           Coordinated Enhanced Observing
          global models                                                                          Period (CEOP) effort initiated by the
                                               Water resources                                   GHP in order to coordinate globally the
                                                                                                 CSE observations and modelling
                  models                                                                         efforts (Lawford et al., 2004). Coupling
                                                                                                 of the land-atmosphere (and the Baltic
                                                                                                 Sea) has been a central strategy for
                                                                                                 the GEWEX CSEs and five major
                           Mesoscale                                                             continental-scale field campaigns have
                                                                                                 been underway for more than a
                                                                                                 decade to provide new process under-
                                                                       Hydrological routeing
                                                                                                 standing and improved model
                                                                                                 representation in the Amazon, Baltic
                                                                                                 Sea, Mississippi and MacKenzie River
                                                                                                 Basins, and four areas in eastern Asia
                           transfers                                                             (Thailand, Tibet, Siberia and eastern
                                                                                                 China). New CSE initiatives have
                                                                                                 subsequently been developed for
                   regional models                                                               basins in Australia, the La Plata Basin
                                                                                                 of South America, and most recently
                                                                 National Hydrological Service   western Africa. The locations of the
                                                                 WMO, IAHS
                                                                                                 CSEs are shown in Figure 2.
    Figure 1 — Role of different international and national programmes and agencies in
    addressing climate prediction and water-resource management issues. (Figure:                 Through new hydrometeorological
    S. Sorooshian)
                                                                                                 data, models, and analyses, the GHP

                                            Baltic Sea Experiment                                 monsoon in the Earth’s climate
                Mackenzie GEWEX                    (BALTEX)
                 Study (MAGS)
                                                                                                  system and to improve the simulation
                                                                                                  and seasonal prediction of Asian
                                                                                                  monsoon patterns and regional water
                                                                                                  resources. The scientific strategy of
                                                                                                  GAME includes monitoring by satel-
                                                                                                  lites and in situ surface observations,
   GEWEX Americas                                                              GEWEX Asian
Prediction Project (GAPP)                                                    Monsoon Experiment   process studies based on the four
                                                                                  (GAME)          regional experiments located in
                                                                                                  distinctive climate regions (tropics,
               Large Scale                African Monsoon
          Biosphere-Atmosphere                                                                    sub-tropics, Tibetan Plateau and
         Experiment in Amazonia        Multidisciplinary Analysis
                                                (AMMA)                                            Siberia) and modelling of hydrometeo-
                                                                                                  rological processes in the climate
                                  La Plata Basin             Murray-Darling Basin (MDB)           system.

Figure 2 — Continental scale areas included in the GEWEX Hydrometeorology Programme.              Baltic Sea Experiment (BALTEX)

                                                                                                  BALTEX, which includes the Baltic Sea
has demonstrated the critical impor-               ect of its size to bring together the          and its drainage basin, has explored
tance of land-surface interactions,                hydrological    and    meteorological          and modelled the mechanisms deter-
soil-moisture measurements and the                 science communities for a common               mining the space and time variability of
application of regional and global high-           research goal. GCIP was launched in            energy and water budgets over the
resolution       precipitation     data.           1995 to take advantage of the exten-           BALTEX region, which covers roughly
Furthermore, major new land-surface                sive meteorological and hydrological           20 per cent of the European continent.
scheme upgrades have resulted in                   networks that existed and were being           The experiment has analysed large
improved regional to global prediction             upgraded there. The motivation for             seasonal, interannual and regional vari-
capability. The development of this                GCIP came from the recognition of the          ations in climate and episodic
new interdisciplinary relationship of              need to close regional water and               hydrometeorological events in the
the hydrological and atmospheric                   energy budgets and to improve para-            basin that have produced flooding in
sciences with a focus on coupled land              meterization of land-atmosphere                densely populated areas and have led
surface-atmosphere interactions led to             interactions and land-surface hydrol-          to important ecological changes in the
a large number of new research                     ogy in climate models. Other basins            Baltic Sea.
papers and helped to initiate the                  were soon established as CSEs after
American Meteorological Society’s                  the adoption of the GCIP in order to
Journal of Hydrometeorology. In brief,             study coupled hydrometeorology over            Mackenzie GEWEX Study (MAGS)
regional data and modelling have                   diverse climatic and political regions.
proved to be very effective in improv-             The success of the GCIP subsequently           MAGS is a multidisciplinary project
ing the understanding of local                     resulted in an expansion of activities         that is undertaking research to under-
processes and led to suggested                     as part of the GEWEX Americas                  stand and model the response of the
approaches to improve current                      Prediction Project (GAPP). Studies of          energy and water cycle in northern
regional and global models, which                  the North American Monsoon System              Canada to climate variability and
have difficulties simulating diurnal and           in GAPP have promoted closer link-             change; to define the impacts of its
surface-subsurface          hydrological           ages between GEWEX and CLIVAR in               atmospheric and hydrologic processes
processes.                                         monsoon research.                              and feedbacks on the regional and
                                                                                                  global climatic systems; and to apply
                                                                                                  these predictive capabilities to climate,
GEWEX Continental-scale                            GEWEX Asian Monsoon                            water resources, and environmental
International Project (GCIP)                       Experiment (GAME)                              issues in the cold regions. MAGS iden-
                                                                                                  tified sublimation in blowing snow as
The GCIP in the Mississippi River                  GAME research has been directed at             one of the main causes for the “miss-
Basin was the first international proj-            understanding the role of the Asian            ing     surface     water      storage.”

    Furthermore, MAGS scientists quanti-        x 1° observational datasets covered a       changes in external forcing factors
    fied evaporative losses from large          two-year period and have been used          (Chahine, 1997).
    northern lakes and improved under-          widely in research and education. The
    standing and model representation of        second data collection initiative
    runoff processes in the northern            (ISLSCP II) produced datasets at            Phase I components
    regions. Along with GAME-Siberia,           spatial resolution of 1° to 0.5° and
    MAGS has strengthened the links             0.25° for the period 1986-1995.             The principal Phase I components of
    between GEWEX and CliC.                                                                 GMPP include the GEWEX Cloud
                                                GHP has mounted several global proj-        Study System and Global Land-
                                                ects that integrate studies and             Atmosphere System Study with its
    Large Scale Biosphere-Atmosphere            activities in all of the CSEs. These        primary subprojects: the Project for
    Experiment in Amazonia (LBA)                activities include the Water and            Intercomparison of Land-Surface
                                                Energy Budget Sudies (WEBS) and the         Parameterization Schemes and the
    The hydrometeorological aspects of          Waer Resources Applications Project         Global Soil Wetness Project. GMPP
    LBA have been directed at under-            (WRAP). GHP also coordinates                studies have reduced uncertainties in
    standing the role of tropical forests       GEWEX-related research with global          the understanding and simulation of
    and the consequences of deforesta-          projects, including the Coordinated         key water-cycle variables through the
    tion for regional energy and water          Enhanced Observing Period (CEOP)            application of Phase I observations and
    budgets. Phase I field experiments,         and the International Association of        land-surface and cloud-process para-
    modelling, and analyses showed a 44         Hydrologic Sciences Project for             meterizations derived through regional
    per cent imbalance of the water cycle       Ungauged Basins, global data centres,       studies and model intercomparisons.
    in the Amazon basin. Amongst the            including the Global Precipitation
    many important findings, LBA studies        Climatology Centre and the Global           The GEWEX Atmospheric Boundary
    determined the transport of moisture        Runoff Data Centre, and international       Layer Study was formed in 1999 to
    from Amazonia to southern Brazil via        agencies, including the International       study how the interactions of the land
    the low-level jet east of the Andes and     Atomic Energy Agency. Its activities        surface and the boundary cloud layer
    quantified the interannual variability of   help to coordinate and disseminate          are mediated through the atmospheric
    the Amazon Basin as a source/sink of        hydrological results to the international   boundary layer.
    carbon dioxide and moisture based on        hydrological community.
    an assessment of carbon sequestra-
    tion in tropical forest environments                                                    GEWEX Cloud Study System
    during ENSO events.                         GEWEX Modelling and Prediction              (GCSS)
                                                Panel (GMPP)
                                                                                            The GCSS has carried out studies that
    International Satellite Land Surface        GMPP contributes to the global model-       support the development of new phys-
    Climatology Project (ISLSCP)                ling of the processes that control the      ically-based cloud parameterizations
                                                global energy and water budget and          using cloud-resolving models of differ-
    The ISLSCP initially focused on field       demonstrates the value of predicting        ent cloud system types for numerical
    experiments but more recently has           the variability of this cycle and its       weather prediction and climate
    undertaken the development of inter-        response to climate forcing with a          models: marine boundary-layer clouds,
    disciplinary data sets. These field         particular emphasis on cloud and land-      Cirrus, extra-tropical layer clouds, tropi-
    experiments included the First ISLSCP       surface process representation. The         cal deep convection and polar clouds.
    Field Experiment (FIFE) and the Boreal      goal of GMPP research is to demon-          GCSS investigates these cloud types
    Ecosystems-Atmosphere            Study      strate the capability to predict water      with a combined analysis of a wide
    (BOREAS). Subsequently, ISLSCP              storage and runoff over continental         range of models: from turbulent-eddy-
    launched two interdisciplinary data         regions, as an element of seasonal-to-      resolving models to cloud-resolving
    collections to develop co-registered        interannual climate predictability, and     and regional-scale models to single-
    interdisciplinary Earth science land        to demonstrate the capability to            column and general circulation models
    datasets for variables needed by            predict the radiation budget and fluxes     used for weather forecasting and
    modellers for coupled land atmos-           as an element of decadal-to-centennial      climate in addition to a wide range of in
    phere modelling. The first co-located 1     climate variability and response to

situ, surface, and satellite remote-         Project for Land-Surface                        simulate climate predictability. GLASS
sensing observations.                        Parameterization Schemes and                    also developed a critical set of standards
                                             Global Soil Wetness Project                     for the exchange of forcing data to facil-
Tools for conducting these studies                                                           itate    modelling      studies      using
have been gathered on a linked set of        Initially through the Project for               land-surface models.
Websites, the main one being the             Intercomparison of Land-Surface
GCSS Data Integration for Model              Parameterization Schemes (PILPS) and            The GMPP facilitates the transfer of
Evaluation (DIME) site at http://gcss-       now through GLASS, the development              knowledge about models and modelling
dime.giss.nasa.gov. These activities         of improved land-surface models has             techniques to operations through an
are leading not only to improved cloud       been coordinated at the process level.          annual joint meeting with the WMO
parameterizations but also to the            Subsequently, the Global Soil Wetness           Commission       for    Atmospheric
implementation of more focused new           Project (GSWP) carried out intercom-            Science/Joint Scientific Committee
field experiments and advances in the        parisons of land-surface models on the          Working     Group    on   Numerical
use of combined sets of surface and          global scale. More generally, GLASS             Experimentation (WGNE).
satellite-based active sensors.              initiated within the community the tran-
                                             sition for land-surface parameterizations
GCSS study results have supported            bound to an atmospheric model to land-          GEWEX Radiation Panel (GRP)
improved understanding of the effects        surface models. PILPS and GLASS have
of the three-dimensional structure of        led to the accelerated development of           Efforts of the GRP are directed
clouds on radiative fluxes, the interac-     LSMs by model and data intercompar-             towards determining the diabatic heat-
tion of clouds with the marine surface       isons for different climate regimes.            ing of the atmosphere and surface by
and atmospheric boundary layer, the                                                          radiative, sensible and latent energy
organization and distribution of precip-     The evaluation of simulated soil wetness        exchanges with accuracy sufficient to
itation    in    tropical   convective       and precipitation predictions in ensem-         diagnose the processes influencing
complexes, and the character and             bles of models within GSWP and the              variations of the surface and atmos-
evolution of Cirrus and polar clouds.        Global Land Atmosphere Coupling                 phere from weather to decadal climate
                                             Experiment (GLACE) has raised the               scales. GRP projects analyse long-
                                             awareness of the community to the               term, global satellite observations that
Global Land-Atmosphere System                intrinsic limitation of LSMs to produce         are supported by key, high-quality,
Study (GLASS)                                observable quantities. For example,             long-term, in situ measurements that
                                             coupled LSMs and global climate                 are used to diagnose the causes of
GLASS seeks to improve our under-            models (GCMs) have been assessed in             forced and unforced climate variations
standing of, and capability to simulate,     terms of their sensitivity to soil moisture     (Rossow et al., 2005). The GRP stud-
surface processes from the plot scale        and ocean sea-surface temperatures,             ies foster improvements in radiative
to the global scale by multi-institutional   which can greatly affect their ability to       transfer models used in weather and
experiments of both stand-alone land-                                                        climate models and in the analysis of
surface models (LSMs) and coupled                 Energy and water cycles of climate         satellite- and surface-based remote-
land-atmosphere models on both the                                                           sensing observations.
local (point, plot, and catchment) and                    Radiative fluxes
large (continental to global) scales.                                                        The GRP projects have developed 15-
Through multi-model experiments,                                                             25 year global data products
GLASS confronts the hypothesis under                                                         quantifying the variability of radiative
which the LSMs have been developed                                            Atmospheric
                                                                                             fluxes, clouds, water vapour, aerosols,
and thus advance the community’s             Clouds                                          precipitation and turbulent fluxes at
knowledge of their capabilities. The                                Water                    the ocean’s surface and are working to
goal of GLASS is to incorporate                                                              develop more advanced products. All
improved understanding of the physi-                                                         these data products are available and
cal processes at the land surface into                                                       are being used to study recent climate
global models and to identify and                           precipitation
                                                                                             variations associated with volcanic
understand the important components                                                          eruptions and El Niño-Southern
of land-atmosphere interaction.              Figure 3 — Dominant atmospheric linkages        Oscillation cycles by quantifying all the
                                             in the global energy and water budgets

           60˚   90
                 90˚       120
                           120˚     150˚
                                    150      180˚
                                             180    210
                                                    210˚    240˚
                                                            240     270
                                                                    270˚     300˚
                                                                             300       330˚
                                                                                       330         0      30
                                                                                                          30˚   60˚
     90˚                                                                                                              urement uncertainties of more than a
                                                                                                                      factor of two. The Global Precipitation
     60                                                                                                               Climatology Centre (GPCC), a data
                                                                                                                      centre that is linked with GRP precipi-
     30˚                                                                                                              tation studies, has compiled an
                                                                                                                      extensive collection of surface precipi-
                                                                                                                      tation gauge data and analyses. Both
                                                                                                                      these initiatives are key elements of the
                                                                                                                      Global Climate Observing System

    -60˚                                                                                                              In preparation for Phase II of GEWEX,
                                                                                                                      the GRP has an ongoing project,
    -90                                                                                                               known as the Intercomparison of
                                                                                                                      Radiation Codes in Climate Models, to
                       0          500      1 000    1 500   2 000    2 500     3 000          3 500 (mm/year)         foster significant development of
                                                                                                                      radiative transfer codes in all atmos-
    Figure 4 — Annual average precipitation 1988-1997: the Coordinated Enhanced Observing
                                                                                                                      pheric general circulation models and a
    Period (CEOP) aims at developing a global network of pilot joint meteorological-hydrological
                                                                                                                      working group to develop a coordi-
    stations and makes use of the huge amounts of Earth observing satellite data available
    today. (Source: GEWEX Continental-Scale International Project)
                                                                                                                      nated approach for the reduction and
                                                                                                                      analysis of combinations of atmos-
                                                                                                                      pheric profiling instruments (radars,
    interactions illustrated in Figure 3. A                  pilot study that pioneered the merger                    lidars and sodars) from a worldwide
    reconstruction by the Surface                            of water-vapour measurements from                        network of long-term monitoring sites.
    Radiation Budget project (SRB) of the                    the international constellation of                       In addition, the GRP is working with
    global radiation budget using GRP and                    weather satellites and in situ atmos-                    other GEWEX activities to develop an
    other global data products has                           pheric soundings to produce a detailed                   advanced, comprehensive analysis of
    achieved a more accurate quantifica-                     description of the global distribution of                the fluxes of energy and water
    tion of the role of clouds in partitioning               atmospheric water-vapour profiles                        between the land and atmosphere.
    the planetary radiation budget among                     resolving daily-to-decadal variations.
    the atmosphere, ocean, land, and                         The Global Aerosol Climatology                           Challenges
    cryosphere.                                              Project recently completed a system-
                                                             atic analysis of year-to-year variations                 To achieve its objectives in Phase II
    The International Satellite Cloud                        of aerosols that is now being merged                     (see box •••), GEWEX will develop and
    Climatology Project (ISCCP) has                          with an analysis of the associated vari-                 apply a wide range of modelling tools
    pioneered the cross-calibration, analy-                  ations     of   cloud    microphysical                   ranging from global climate models to
    sis and merger of measurements from                      properties. In addition, the first                       regional and mesoscale models, and
    the international constellation of                       comprehensive compilation of in situ                     will evaluate downscaling methods
    weather satellites to produce the first                  ocean surface flux measurements was                      suitable for the smaller spatial and
    global quantitative description of the                   produced by the SeaFlux project.                         temporal scales generally associated
    physical properties of clouds resolving                  These efforts have fostered improve-                     with hydrological models used in local
    diurnal-to-decadal variations. The Global                ments in global satellite-based                          water-resource management.
    Precipitation Climatology Project has                    products, providing turbulent fluxes of
    produced the first globally complete                     heat, water, and momentum resolving                      Another primary element of Phase II is
    determination of precipitation resolv-                   daily-to-decadal variations. The global                  the Coordinated Enhanced Observing
    ing five-day-to-decadal variations by                    satellite observation analysis projects                  Period (CEOP). The first phase of this
    the analysis and merger of measure-                      are supported by reference networks                      experiment (CEOP I) is described in
    ments       from    the     international                established by GRP and data centres.                     Koike (2004). CEOP II will focus on the
    constellation of weather satellites and                  For example, the development of the                      development of a two-year data set of
    in situ measurements. The Global                         Baseline Surface Radiation Network                       in situ, satellite and model data for the
    Water Vapour Project conducted a                         BSRN) has led to reductions in meas-                     period of 2003-2004 to support

                                                                                       CHAHINE, M.J., 1997: GEWEX strategies
 GEWEX Phase II                        studies. GEWEX also takes the lead on             and goals are affirmed by the Joint
 objectives                            behalf of WCRP in the Integrated                  Science Committee, GEWEX
                                       Global Water Cycle Observations                   Newsletter, 7 (3), p.2.
 • Produce consistent research         theme of the Integrated Global
   quality data sets complete with     Observing Strategy Partnership. In that         KOIKE, T., 2004: The Coordinated
   error descriptions of the Earth’s   regard, CEOP has been endorsed as                  Enhanced Observing Period—an initial
   energy budget and water cycle       the first element of the new IGWCO                 step for integrated global water cycle
   and their variability and trends    theme. GEWEX also will contribute to               observation. WMO Bulletin 53 (2).
   on interannual to decadal time      the Global Water System project within
   scales, and for use in climate      the Earth System Science Partnership            LAWFORD, R.G., R. STEWART, J. ROADS,
   system analysis and model           (ESSP) framework. In addition,                    H.-J. ISEMER, M. MANTON, J. MARENGO,
   development and validation          research projects in GEWEX Phase II               T. YASUNARI, S. BENEDICT, T. KOIKE and
                                       will be supportive of WCRP’s new                  S. WILLIAMS, 2004: Advancing global
 • Enhance the understanding of        strategy, commonly known as the                   and continental scale hydrometeorol-
   how energy and water cycle          Coordinated       Observation      and            ogy: Contributions of the GEWEX
   processes function and quantify     Prediction of the Earth System                    Hydrometeorology Panel, Bulletin of
   their contribution to climate       (COPES). Readers wishing to follow                the American Meteorological
   feedbacks                           the progress of GEWEX or to access                Society, 85 (12).
                                       the wide range of data and data
 • Determine the geographical          products available through the GEWEX            ROSSOW, W.B., B.E. CARLSON,
   and seasonal characteristics of     home page (www.gewex.org).                        P.W. STACKHOUSE, B.A. WIELICKI and
   the predictability of key water                                                       Y-C ZHANG, 2005: Implications and
   and energy cycle variables over                                                       opportunities suggested by long-term
   land areas and through collabo-     Acknowledgements                                  changes of radiative fluxes at the
   rations with the wider WCRP                                                           surface and top of the atmosphere.
   community determine he              It should be noted that the successes and         (Submitted to the Bulletin of the
   predictabiity of energy and         progress reported here would not have been        American Meteorological Society in
   water cycles on a global basis      possible without the major contributions and      October 2004).
                                       data services of the US National Aeronautics
 • Develop better seasonal predic-     and Space Administration, the US National
   tions of water and energy cycle     Oceanic and Atmospheric Administration,
   variability through improved        the Japan Aerospace Exploration Agency,
   parameterisations encapsulating     the German Association of Natural
   hydrometeorological processes       Resources, the European Space Agency, the
   and feedbacks for atmospheric       European Organization for the Exploitation
   circulation models                  of Meteorological Satellites, the European
                                       Community, the Meteorological Service of
 • Undertake joint activities with     Canada, and the National Research
   operational hydrometeorologi-       Committee of Engineering. A number of
   cal services and hydrological       other national and international agencies and
   research programmes to              programmes have also contributed data and
   demonstrate the value of new        infrastructure to the project. Also, the
   GEWEX prediction capabilities,      authors would like to thank Dr Bisher Imam
   data sets and tools for assessing   and Ms Dawn Erlich and Carolyn Serey for
   the consequences of global          their help in preparing the figures and the
   change                              finalizing the text for this article.

research objectives in the climate
prediction and monsoon system


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