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Home  Research Elements & Cross-cutting Activities
The
Global Water Cycle
Near-Term Plans |
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27 November 2007
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The
Global Water Cycle |
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The Global Water CycleNear-Term Plans Archived News Postings [June 2000 - July 2005] CCSP / USGCRP Water Cycle Working Group Members
Past Accomplishments:
Climate Change Science Program. FY 2008 Scientific Research Budget by USGCRP Research Element |
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 The GWC research element continues to pursue important, long-term priorities. For example, insights into the formation and behavior of clouds and precipitation, including better characterizations of the phase changes of water in clouds and the phases and onset of precipitation, are emerging from field campaigns and model studies and will be promoted in continuing activities. Water vapor and cloud-radiation feedback are considered a critical part of GWC studies that need to be addressed to reduce the uncertainties associated with climate change projections. The predictability of regional precipitation is another topic of vital interest: It will be assessed and better understood by ongoing diagnostic and modeling studies that identify the connections between regional- and global-scale phenomena, land surface conditions such as soil moisture and water table fluctuations, and the interface fluxes of energy and heat between the atmosphere and the land surface-vegetation-hydrology combination. Preliminary analyses from recent studies show promise of leading to earlier (and more accurate) predictions, improved ability to assess hazards and risks of extremes such as floods and droughts, and more efficient water resource management.  In FY 2008, continuing U.S. and global observations, field campaigns and experiments, improvements to data integration and analysis systems, diagnostic and predictive model development, and applications to decision support systems will be priorities under the CCSP Global Water Cycle program. A fundamental objective is to ensure that observational capability is enhanced and improved, and that the data assimilation and modeling/prediction systems are more reliable and accurate at the point of
application.  Several promising results from the past years of research will be further explored with an aim to transfer this research knowledge to operational applications that provide societal benefit. Concurrently, a cohesive research strategy will be
implemented to improve current deficiencies in understanding of all aspects of the regional and global water cycle. Several science questions remain to be answered, related to warnings of natural hazards and to the impact of global climate change, be it from natural or anthropogenic causes.  The program outlined for FY 2008 will lead to improvements in fundamental research, as well as in the planning and decisionmaking for, and management of, natural and human-made resources–a major aim of the program in addition to its fundamental research goals. A strong effort will continue to focus on major unresolved research issues that will require longer term commitments. To address both research and multi-sectoral applications needs, several initiatives will be launched in FY 2008.
Integration of Space-Based Observations and Land Surface/Hydrology Data Assimilation Systems.The GRACE satellite has demonstrated that large-scale changes in the integrated column water content of the combined atmosphere, land surface (including rivers and reservoirs), soil moisture, and groundwater system compares remarkably well with the changes documented by the Global Land Data Assimilation System (GLDAS). In FY 2008 and beyond, further research investigations will explore whether GRACE, A-Train, and other satellite and ground-based data can be assimilated by the Land Information System (LIS), and/or provide integral closure constraints (and updated process parameterizations) to improve the output products from LIS that can potentially be linked to various decision-support tools and systems involved in the management of water resources, among others. Such an activity could represent initial components of end-to-end capabilities bridging observations, research, modeling, and applications. This activity will address CCSP Goals 1 and 3 and Questions 5.1, 5.3, 5.4, and 5.5 of the CCSP Strategic Plan. Integration of Observations, Research, and Modeling.12,13The research data from CLASIC will be analyzed in FY 2008 and beyond to address significant uncertainties in climate models particularly related to their representation of clouds and aerosols. The primary goal of CLASIC is to improve understanding of the physics of the early stages of cumulus cloud convection as it relates to land surface influences, and to translate this new understanding into improved representations of coupled surface-atmosphere processes in global and regional climate models. The data from a comprehensive array of measurements from a variety of instrument platforms will be used to characterize the synoptic-scale forcing at the DOE's Atmospheric Radiation Measurement (ARM) Climate Research Facility's (ACRF) Southern Great Plains (SGP) site and to undertake modeling studies to establish the most important relationships between land surface conditions and cumulus cloud characteristics. CLASIC was designated as the core of the Global Water Cycle Interagency Working Group CCSP FY 2007 focus area. The field campaign serves as a prototype for the CCSP focus area. The campaign featured concurrent contributions by NASA, NOAA, and USDA to extend CLASIC's temporal and spatial domain to capture the seasonal time scale and regional processes. The resulting observational framework included ground- and space-based observations, measurements from six airplanes and one helicopter, surface and subsurface hydrologic components, isotopic measurements, CO2 fluxes, and associated modeling. Planning and operations for CLASIC and DOE's Atmospheric Science Program's Cumulus Humilis Aerosol Processing Study (CHAPS) were coordinated. Scientists from CLASIC and the North American Carbon Program (NACP) Mid-Continent Intensive (MCI) Campaign also coordinated measurement and modeling activities. These campaigns represent the cross-cutting activities of three CCSP science elements–the Global Water Cycle, Atmospheric Composition, and Global Carbon Cycle, respectively. This activity will address CCSP Goals 1, 2, and 3 and Questions 5.1, 5.2, and 5.3 of the CCSP Strategic Plan. Application of the ARM Mobile Facility to Study the Aerosol Indirect Effects in China.
This activity will address CCSP Goals 1 and 2 and Questions 5.1 and 5.2 of the CCSP Strategic Plan. Advanced Ensemble Multi-Model Hydrological Prediction.
This activity will address CCSP Goals 3 and 5 and Questions 5.3 and 5.5 of the CCSP Strategic Plan. Role of Land Surface Processes in North American Hydroclimate.The feedbacks between soil moisture, vegetation, and precipitation will be investigated in observations and models with the goal of helping to understand whether land surface conditions may be a useful predictor in operational climate prediction at seasonal and sub-seasonal time scales. The behavior of snow variations and vegetation cover will be studied in order to improve land surface representations in regional climate models. The hydrologic and climatic effects of crop irrigation are not well quantified and not accurately represented in model initialization. Improvements in our understanding of the role of irrigated croplands in North American hydroclimatic regimes and their representation in models will be pursued. This activity will address CCSP Goals 3 and 4 and Questions 5.3 and 5.4 of the CCSP Strategic Plan. Continued Development of Tools for the Assimilation of Remote-Sensing Data into Water Quality and Sediment Transport and Erosion Models.
This activity will address CCSP Goals 3 and 5 and Questions 5.3 and 5.5 of the CCSP Strategic Plan. Establishing New Portals Dedicated to Specific Applications of Remote-Sensing Data with On-Line Analysis Capabilities.14"Giovanni," the Goddard Earth Sciences Data and Information Services Center (GES-DISC) Interactive Online Visualization and Analysis Infrastructure, was developed to provide researchers with advanced capabilities to perform data exploration and analysis with observational data from the Earth Observing System (EOS) research satellite system. Over the past decade, the central problem with data use has been the multi-step process required to search for the appropriate data files, request the files from a central archive, transfer the files to the scientist's own computing system, extract the relevant data from unfamiliar data formats, and then (finally) analyze the data to investigate the vital research question. Giovanni eliminates all of the above tedious steps that precede data analysis. The result is a data exploration and analysis environment that facilitates scientific investigation with actual data, allowing rapid comprehension of regional events and increased understanding of interconnected global environmental processes. The Giovanni precursor, the TRMM Online Visualization and Analysis System (TOVAS), successfully demonstrated the basic elements of a system used entirely on the Web. The simplicity of Giovanni enables the creation of portals dedicated to specific applications of remote sensing. The first of such portals will be devoted to "precipitation data for agriculture." Release is expected in FY 2008. An A-Train Data Depot Portal and the Northern Eurasia Earth Science Partnership Initiative portal are also planned for release in the same time frame. The former is expected to be particularly useful because the A-Train, which is a formation of several NASA atmospheric observational missions in the same orbit, allows for nearly simultaneous observations. In the dedicated Giovanni interface, data from these missions will be readily available for multi-parameter comparison and analysis. In FY 2008, a specific effort under the NASA Energy and Water Cycle Study will build a portal in collaboration with the Global Change Master Directory (GCMD) for hydrological networking. This activity will address CCSP Goals 1, 2, and 3 and Questions 5.1, 5.2, and 5.3 of the CCSP Strategic Plan.
Upper Tropospheric Water Vapor, Jet Contrails, and Implications for Climate.15,16
This activity will address CCSP Goals 1,2,3, and 4 and Questions 5.1, 5.2, 5.3, and 5.4 of the CCSP Strategic Plan.
References1) Ovtchinnikov, M., T. Ackerman, R. Marchand, and M. Khairoutdinov, 2006: Evaluation of the Multiscale Modeling Framework using data from the Atmospheric Radiation Measurement Program. Journal of Climate, 19(9), 1716-1729, doi:10.1175/JCLI3699.1.2) Dirmeyer, P.A. and K.L. Brubaker, 2006: Trends in the Northern Hemisphere water cycle. Geophysical Research Letters, 33, L14712, doi:10.1029/2006GL026359. 3) Rignot, E. and P. Kanagaratnam, 2006: Changes in the velocity structure of the Greenland Ice Sheet. Science, 311, 986-990, doi:10.1126/science.1121381. 4) Peterson, B.J., J. McClelland, R. Curry, R.M. Holmes, J.E. Welsh, and K. Aagaard, 2006: Trajectory shifts in the Arctic and sub-Arctic freshwater cycle. Science, 313, 1061-1066. 5) NRC, 2007: Colorado River Basin Water Management: Evaluating and Adjusting to Hydroclimatic Variability. National Academy Press, Washington, DC, USA, 159 pp. 6) Mote, P.W., 2006: Climate-driven variability and trends in mountain snowpack in Western North America. Journal of Climate, 19, 6209-6220. 7) Hamlet, A., P.W. Mote, M.P. Clark, and D.P. Lettenmaier, 2005: Effects of temperature and precipitation variability on snowpack trends in the western United States. Journal of Climate, 18, 4545-4561. 8) Jayawickreme, D.H. and D.W. Hyndman, 2007: Evaluating the influence of land cover on seasonal water budgets using NEXRAD rainfall and streamflow data. Water Resources Research, 43, W02408, doi:10.1029/2005WR004460. 9) Miguez-Macho, G., Y. Fan, C. Weaver, R. Walko, and A. Robock, 2007: Incorporating water table dynamics in climate modeling, Part II: Formulation, validation, and soil moisture simulation. Journal of Geophysical Research, 112, D13108, doi:10.1029/2006JD008112. 10) Mildrexler, D.J., M. Zhao, and S.W. Running, 2006: Where are the hottest spots on Earth? EOS, Transactions, American Geophysical Union, 87(43), 461-467. 11) Sheffield, J., G. Goteti, and E.F. Wood, 2006: Development of a 50-year high-resolution data set of meteorological forcings for land surface modeling. Journal of Climate, 19, 3088-3111. 12) See science.arm.gov/clasic/ 13) See asp.labworks.org/ 14) Acker, J.G. and G. Leptoukh, 2007: Online analysis enhances use of NASA earth science data. EOS, Transactions, American Geophysical Union, 88, 14-17. 15) Gettelman, A., W.D. Collins, E.J. Fetzer, A. Eldering, F.W. Irion, P.B. Duffy, and G. Bala, 2006: Climatology of upper tropospheric relative humidity from the Atmospheric Infrared Sounder and implications for climate. Journal of Climate, 19, 6104-6121. 16) Gettleman, A., E.J. Fetzer, A. Eldering, and F.W. Irion, 2006: The global distribution of supersaturation in the upper troposphere from the Atmospheric Infrared Sounder. Journal of Climate, 19, 6089-6103.
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China has exceptionally high aerosol loading with diverse properties whose influence has been detected across the Pacific Rim. The rapid pace of changes in the atmospheric
environment over China provides a natural test bed for identifying and quantifying the climatic effects of aerosols. Preliminary analyses of multiple satellite data sets [the Moderate Resolution Imaging Spectroradiometer (MODIS) and the TRMM Tropical Microwave Imager] indicate more complex and unique aerosol indirect effects than are found in relatively cleaner environments. Unfortunately, China is one of the least observed regions, especially in terms of aerosol and cloud properties. To this end, DOE's ARM Mobile Facility (AMF) will be deployed from 1 January to 31 December 2008 to investigate (1) the mechanisms of the aerosol indirect effects in the region and the roles of aerosols in affecting regional climate and atmospheric circulation with a special focus on the impact of the East Asian monsoon system, and (2) effects of long-range transport of aerosols to the Pacific Rim and the western United States. 
Efforts will continue to focus on the calibration and validation of research-mode ensemble (multi-model) forecasting techniques for surface and
subsurface hydrological parameters, especially on longer seasonal time scales. The objective is to transfer improved hydrological prediction techniques for operational application on the seasonal to interannual time scale. This activity will expand on the recently developed Advanced Hydrological Prediction Service (AHPS) of NOAA's
hydrological forecasting system that includes new model calibration strategies, distributed modeling approaches, ensemble forecasting, data assimilation techniques, enhanced data analysis procedures, flood forecast inundation maps, hydrological routing models and multi-
sensor precipitation estimates. Data will also be ingested from USGS streamflow observations, gridded multi-sensor precipitation and SWE estimates, and others. New approaches for the remote sensing of
precipitation, snow, and other inputs will be integrated into the hydrological forecast operation. AHPS is slated to be fully implemented nationwide in 2013. In parallel, CCSP researchers plan to participate in the further development of the international Hydrological Ensemble Prediction Experiment (HAPEX), which will bring the international hydrological community together with the meteorological community and demonstrate how to produce reliable hydrological ensemble forecasts that can be used with confidence by emergency management and water resources sectors to make decisions that have important consequences for the economy, and for public health and safety.
Agricultural research activities in the area of land data assimilation systems and model analysis are focused on the
efficient integration of ground-based and remote-sensing data into critical resource and conservation practice assessment models. Existing agency research projects are aimed at the sequential assimilation of surface soil moisture retrievals and vegetation indices from microwave and visible remote sensors to constrain crop growth and root-zone water balance models. In FY 2008 and beyond, this work will expand with an emphasis that includes the assimilation of remote-sensing data into distributed water quality and sediment transport and erosion models. Particular attention will be paid to development of data assimilation and modeling capabilities to quantify benefits
arising from the adoption of conservation practices within agricultural watersheds. 
Water vapor in the upper troposphere, while insignificant in the total mass of column water vapor, can have significant effects on climate through the formation of clouds
(longwave forcing) or direct absorption of radiation. One study using a radiative transfer model estimated that a 10% increase in upper-tropospheric humidity (UTH) could contribute as much as 1.4 Wm-2 of direct radiative forcing. Supersaturation in the upper troposphere can be inferred from the presence of persistent
contrails behind jet aircraft, which require humidity above that of ice saturation to form. Supersaturation is critical for understanding the process of ice cloud formation. This process, which is also affected by the presence or absence of aerosols, has implications for the radiative balance of the climate system through its effect on clouds and water vapor. Most global models of the climate
system do not permit supersaturation but instead dictate full
condensation of all water vapor to maintain a vapor pressure less than 100% over ice at temperatures where only ice exists (typically below -20 to -40°C). Using relative humidity (RH) data from the Atmospheric Infrared Sounder (AIRS) on the Aqua satellite, the annual mean frequency of supersaturation maximizes below the extratropical tropopause ranges between 10 and 30% of the time. 
This value is similar to the annual mean potential contrail coverage frequency (which implies RH over ice greater than 100%) reported from European Centre for Medium-Range Weather Forecasts' reanalyses. While these comparisons are good, AIRS RH is not a point-wise measurement and observed supersaturation may not quantitatively define what an air parcel or a cloud/ice nucleus experiences. Further studies of supersaturated conditions from AIRS are being considered that may be able to shed some light on cloud
nucleation processes when combined with other satellite sensors. In the future, an updated AIRS retrieval and cloud properties from a suite of sensors flying in formation on NASA's A-Train (such as MODIS on the EOS Aqua satellite and the Cloud Profiling Radar on CloudSat) may be useful to answer important questions about ice nucleation and its global impact, as well as to improve global models in order to examine perturbations to the Earth system. Such studies could also be useful in
evaluating the potential implications of aviation on climate. 
