02 February 2005Goddard Space Flight Center1 Goddard Role in Understanding the Global Water Budget Water Cycle Components Present Observational Capabilities and Future plans The Potential for a Global Observational System

02 February 2005Goddard Space Flight Center2 Observing the Global Water Cycle Importance to Human Health Water cycle variability: Water cycle variability: –resolve a few percent per year –Measurements stable over decades –All components measured Must evaluate: Must evaluate: –Human uses of water –Impacts on availability

02 February 2005Goddard Space Flight Center3 Observing the Global Water Cycle Importance to Human Health Human health: Human health: –Education concerning health –Environmental pollution –Availability of clean water As NASA goal: As NASA goal: –As long term vision for NASA Earth science –Supports weather & climate needs

02 February 2005Goddard Space Flight Center4 The Global Water Cycle Global water budget: Global water budget: –~ 2.5% of global water is fresh water –Of the fresh water, ~ 69% is permanent ice / snow ~ 69% is permanent ice / snow ~ 30% is ground water ~ 30% is ground water the balance is available in soil, lakes, rivers, etc. the balance is available in soil, lakes, rivers, etc. ~ 1% of the fresh water fuels life on Earth ~ 1% of the fresh water fuels life on Earth Large variability in fresh water availability due to: Large variability in fresh water availability due to: –latitude and topography –weather and climate –human influences How will the availability of fresh water change as climate changes? How will the availability of fresh water change as climate changes?

02 February 2005Goddard Space Flight Center5 The Global Water Cycle Global fresh water budget: Global fresh water budget: –Balance between evaporation, precipitation and runoff: –Small available fresh water volume, –+ large fresh water fluxes –= Short residence times: atmosphere ~ 10 days atmosphere ~ 10 days rivers ~ 10 days rivers ~ 10 days biosphere ~ 1 week biosphere ~ 1 week soil moisture ~ 2 months soil moisture ~ 2 months lakes & aquifers: variable lakes & aquifers: variable Need observations of: Need observations of: –Fresh water fluxes –Fresh water storage Observations must meet predictive requirements: Observations must meet predictive requirements: –global coverage, sampling and accuracy

02 February 2005Goddard Space Flight Center6 Water Cycle Components

02 February 2005Goddard Space Flight Center7 Measure and forecast all water cycle components Measure and forecast all water cycle components Precipitation, evaporation, atmospheric transport, runoff, storage (ice and snow, rivers and lakes, soil, ground water) Precipitation, evaporation, atmospheric transport, runoff, storage (ice and snow, rivers and lakes, soil, ground water) Related radiative issues (aerosols, effects of clouds, …) Related radiative issues (aerosols, effects of clouds, …) Measurement requirements (spatial, temporal, precision, accuracy) Measurement requirements (spatial, temporal, precision, accuracy) Water cycle variability with climate change Water cycle variability with climate change Speed up of water cycle? Speed up of water cycle? Change in intensity of events? Change in intensity of events? Sea level changes? Sea level changes? Availability of clean fresh water Availability of clean fresh water Available water resources Available water resources Effects of climate variability and change Effects of climate variability and change Ability to forecast Ability to forecast Observing the Global Water Budget the Major Issues

02 February 2005Goddard Space Flight Center8 Observing the Global Water Cycle Why Satellite Observations? Only space provides a systematic Earth view: Sea Surface Salinity 100 Years of Ship Observations One Month of Aquarius

02 February 2005Goddard Space Flight Center9 Observing the Global Water Cycle: What are we doing at Goddard? Measurement of components of the water cycle: PrecipitationEvaporation Water vapor Runoff Polar ice Snow pack Ground water Ocean salinity Soil moisture Plus data assimilation of all components into NWP Plus an active program of supporting national needs through applications

02 February 2005Goddard Space Flight Center10 Global Precipitation Measurement TRMM Global precipitation measurement with TRMM: a great leap forward!Global precipitation measurement with TRMM: a great leap forward! Quasi-operational measurement of global precipitation (with other satellites)Quasi-operational measurement of global precipitation (with other satellites) –10  85 GHz radiometers (with other satellites) –13.6 precipitation radar –Global coverage (with other satellites) –Resolution: variable –Accuracy: xyz mm/h Measure linkages: climate – weather – water cycle – ocean circulationMeasure linkages: climate – weather – water cycle – ocean circulation Needed improvements:Needed improvements: –Better accuracy –Spatial-temporal sampling –Improved vertical resolution –High latitude precipitation & snow

02 February 2005Goddard Space Flight Center11 Global Precipitation Measurement Present Status, Future Needs Future satellite measurement needs: Sampling & precisionSampling & precision a few percent precision for annual precipitation a few percent precision for annual precipitation dependence on ancillary measurements: dependence on ancillary measurements: surface radars & gages surface radars & gages high latitude precipitation high latitude precipitation Microwave radarsMicrowave radars Multi-frequency for cloud and precipitationMulti-frequency for cloud and precipitation Microwave radiometersMicrowave radiometers multi-frequency, V&H pol multi-frequency, V&H pol wide swath wide swath Comparison of global precipitation products Comparison of precipitation products from: TRMM satellite radar TRMM satellite radar NEXRAD ground radar NEXRAD ground radar

02 February 2005Goddard Space Flight Center12 Global Precipitation Measurement: GPM

02 February 2005Goddard Space Flight Center13 Observing the Global Water Cycle Global Evaporation, Evapotranspiration and Latent Heat Flux Calculated using bulk formula: Calculated using bulk formula: ____ ____ E L = ρL e w’q’  -ρL e K e (  q/  z) E L = ρL e w’q’  -ρL e K e (  q/  z) = -ρL e u (q a – q s ) = -ρL e u (q a – q s ) Resulting quality limited by: Resulting quality limited by: –Use of bulk formulas –Validating measurements Global Monthly Latent Heat Flux Comparison of satellite and in-situ latent heat flux (σ=20 W m -2 ) Comparison of model analyses

02 February 2005Goddard Space Flight Center14 Observing the Global Water Cycle Water Vapor Transport Global water vapor measurements: Global water vapor measurements: –Atmospheric water vapor measurement precision good (~10%) –Assimilation of water vapor in weather prediction models Improvements needed: Improvements needed: –Vertical sampling poor –Global tropospheric winds needed for transport

02 February 2005Goddard Space Flight Center15 Observing the Global Water Cycle Runoff Measurements of global runoff: Measurements of global runoff: –Highly inconsistent globally –Comparisons with models and precipitation is variable –Current proposals for ESSP runoff mission –Significant continental discharge problem

02 February 2005Goddard Space Flight Center16 Runoff / Surface Water Mission Stream Discharge and Surface Water Height from Space Interferometer Concept (JPL) Laser Altimetry Concept e.g. ICESat (GSFC) Targeted path Coincident w/ river reach Radar Altimetry Concept e.g. Topex/Poseidon over Amazon R. Motivation: critical water cycle component critical water cycle component essential for water resource planning. essential for water resource planning. stream discharge and water height data are difficult to obtain outside US stream discharge and water height data are difficult to obtain outside US find the missing continental discharge component find the missing continental discharge component Mission Concepts:

02 February 2005Goddard Space Flight Center17 ICESat Goal is to measure ice sheet mass balance: detect average ice changes of ~ 1 cm/year detect average ice changes of ~ 1 cm/year 1 cm = ~5% of annual mass input = ~ 0.001% of total ice mass 1 cm = ~5% of annual mass input = ~ 0.001% of total ice mass annual ice sheet mass changes = ~ ± 25 cm/yr = ~ ± 1 cm/yr sea level annual ice sheet mass changes = ~ ± 25 cm/yr = ~ ± 1 cm/yr sea level current sea level rise totals approximately 2 mm/year due to: current sea level rise totals approximately 2 mm/year due to: melting of small glaciers, ocean thermal expansion, and ? ? ? ? melting of small glaciers, ocean thermal expansion, and ? ? ? ? Observing the Global Water Cycle ICESat Measurements of Polar Ice

02 February 2005Goddard Space Flight Center18 Observing the Global Water Cycle ICESat Measurements of Polar Ice Science Objectives: Science Objectives: –Polar Ice Sheet Mass Balance –Cloud heights and aerosols –Land topography  surface water Instrument: Instrument: –Geoscience Laser Altimeter System (GLAS) –Weekly global update –~ 3 cm precision (over 100 km 2 ) –~ 20 cm accuracy = ~ 1 cm sea level Future Goals: Future Goals: –Improved (denser) spatial coverage –Improved precision => mass balance

02 February 2005Goddard Space Flight Center19 Observing the Global Water Cycle Snow Cover and Water Content Need: Need: –Major annual water resource comes from snow melt –Biosphere turns on/off at 0°C Goal: Goal: –Measure Global Snow Cover and Water Equivalent on ecological and seasonal scales MODIS global snow cover map Present and proposed measurements: Present and proposed measurements: –snow cover: color measurements –surface temperature: IR & microwave radiometry –snow water content: Ku and Ka band Radiometer –surface characteristics & vegetation: C and Ku band SAR; hyperspectral

02 February 2005Goddard Space Flight Center20 Observing the Global Water Cycle Cold Lands Mission Goals: Goals: –Vastly improved measurement precision and accuracy –Measure global snow cover and water equivalent on ecological and seasonal scales on ecological and seasonal scales account for the effects of vegetation account for the effects of vegetation

02 February 2005Goddard Space Flight Center21 Cold Land Processes Hydrology Experiment (CLPX) Colorado, NASA/JPL/GSFC, NOHRSC, CRREL, USFC, BLM, etc. Cold Land Processes Pathfinder Mission (CLPM) Synergistic dual-frequency Synthetic Aperture Radar (C- and Ku-band) and radiometers (18- and 37-GHz). Shared ~2-m antenna with 100m SAR and 5 km radiometer (25km swath). Mission concept: Active microwave (C & KU band radar) Active microwave (C & KU band radar) Passive microwave (19, 37 GHz) Passive microwave (19, 37 GHz) Capable of full global twice daily coverage (wide swath) Capable of full global twice daily coverage (wide swath) High spatial resolution (passive to 3-5km) High spatial resolution (passive to 3-5km) Address global cryospheric monitoring needs Address global cryospheric monitoring needs Observing the Global Water Cycle

02 February 2005Goddard Space Flight Center22 Observing the Global Water Cycle Aquarius Ocean Salinity Mission Ocean Salinity:Ocean Salinity: –Drives thermo-haline circulation –Investigate changes with climate variability Cool, saline water sinks, forms the ocean deep-water source Increased salinity due to mid- latitude evaporation Reduced salinity due to rainfall in inter-tropical convergence zone Increased salinity in Atlantic ocean … Why?

02 February 2005Goddard Space Flight Center23 Why measure ocean salinity?: Why measure ocean salinity?: –drives thermo-haline circulation links ocean circulation with the global water cycle links ocean circulation with the global water cycle –a measure of ocean precipitation and evaporation How to measure ocean salinity?: How to measure ocean salinity?: –Ocean emissions: L-band radiometer (GSFC) –Sea surface roughness: L-band scatterometer (JPL) –Monthly global coverage –80 km resolution –0.2 psu accuracy (0.1 K) Observing the Global Water Cycle Aquarius Ocean Salinity Mission

02 February 2005Goddard Space Flight Center24 Explain role of soil moisture & freeze/thaw in: climate and weather variability climate and weather variability global water, energy and carbon cycles global water, energy and carbon cycles soil moisture maps used to initialize weather forecast models. soil moisture maps used to initialize weather forecast models. Observing the Global Water Cycle HYDROS Soil Moisture Mission

02 February 2005Goddard Space Flight Center25 HYDROS Soil Moisture:HYDROS Soil Moisture: Global soil moisture & freeze/thaw state:Global soil moisture & freeze/thaw state: –L-band scatterometer (JPL) & radiometer (GSFC) –Global coverage in 3 days –40 km resolution –Stability: 0.5K –MIT-JPL-Goddard Mission Future improvements:Future improvements: − Daily coverage  diurnal capabilities? − 1 km resolution − Root zone penetration Observing the Global Water Cycle HYDROS Soil Moisture Mission

02 February 2005Goddard Space Flight Center26 Observing the Global Water Cycle GRACE: groundwater, soil moisture, snow, surface water GRACE senses water storage changes as variations in the Earth’s gravity field Terrestrial Water Storage Anomalies in the Mississippi River Basin, April 2002 – December 2003 Bars = GRACE terrestrial water storage (800km smoothing) Dots = Atmospheric-terrestrial water balance Red line = GLDAS/Noah modeled soil moisture + snow Blue line = Well observations of groundwater Green line = Red line + Blue line (Total Water Storage) GRACE team: U. of Texas U. of Texas JPL JPL GSFC GSFC

02 February 2005Goddard Space Flight Center27 FORCING DATA & PARAMETERS Land Data Assimilation System (LDAS) Land Data Assimilation System (LDAS) Provides land surface states (snow depth, soil moisture, temperature, etc.) and fluxes (evaporation, etc.) for water resource applications. Provides land surface states (snow depth, soil moisture, temperature, etc.) and fluxes (evaporation, etc.) for water resource applications. Results used to initialize of weather and climate prediction models and surface water resource applications. APPROACH: Force land surface models with data from space- based and ground observing systems. Root zone soil water content [%] LDAS North American LDAS Global LDAS Land Information System Precipitation, Temperature, Radiation, etc. Vegetation Types, Soil Classes, Elevation, etc. Output Soil Moisture, Evaporation, Energy Fluxes, River Runoff, Snowpack Characteristics, etc. Application DSS Floods/Drought, Agriculture Management, Water Quality with USDA, Bureau Reclamation, EPA Assimilation Land Surface Model

02 February 2005Goddard Space Flight Center28 Measurement approaches must consider the requirements for: frequency of observation spatial sampling measurement precision As set by the characteristic scales of the phenomena. Observing the Global Water Cycle

02 February 2005Goddard Space Flight Center29 Observing the Global Water Cycle: As a 20 year goal, the global water cycle can be measured with sufficient As a 20 year goal, the global water cycle can be measured with sufficient temporal and spatial resolution, temporal and spatial resolution, measurement precision, measurement precision, to provide needed understandings of natural variability in availability of water, natural variability in availability of water, short term climatic effects, and short term climatic effects, and changes in cycling of water due to long term climate change. changes in cycling of water due to long term climate change. But: But: –Could this be done operationally?

02 February 2005Goddard Space Flight Center30 Select instruments based on measurement requirements and observational capabilities: sampling & precision Observing the Global Water Cycle: Select orbits based on instrument measurement capabilities and orbital sampling characteristics

02 February 2005Goddard Space Flight Center31 Observing the Global Water Cycle: Satellites and Data Access Is it reasonable to consider observing Earth’s complete water cycle with >20 satellites?

02 February 2005Goddard Space Flight Center32 Geostationary Orbits: 6-8 satellites provide: hourly  diurnal scales hourly  diurnal scales short wavelength instruments short wavelength instruments LEO orbits: 8-10 satellites provide: multi-hour to multi-day scales multi-hour to multi-day scales longer wavelength instruments longer wavelength instruments Special LEO: ~10 satellites ~10 satellites multi-day to weekly sampling multi-day to weekly sampling longer wavelength instruments longer wavelength instruments Observing the Global Water Cycle: Satellites and Data Access

02 February 2005Goddard Space Flight Center33 Observing the Global Water Cycle: Satellites and Data Access Sensor WebSensor Web –links data to computational nodes –synthesizes information in data assimilation model Develop a network of specialized satellites all working together Data are accessed by end users.

02 February 2005Goddard Space Flight Center34 Future Operational Water Cycle Observations & Predictions Water Table 3-D Cloud & Water Vapor Global Precipitation Ocean Salinity Soil Moisture Earth Systems Model Ice and Snow

02 February 2005Goddard Space Flight Center35 Observing the Global Water Cycle: What are we doing at Goddard? Measurement of components of the water cycle: PrecipitationEvaporation Water vapor Runoff Polar ice Snow pack Ground water Ocean salinity Soil moisture Plus data assimilation of all components into NWP Plus an active program of supporting national needs through applications

02 February 2005Goddard Space Flight Center36 Observing the Global Water Cycle Importance to Human Health Human health: Human health: –Education concerning health –Environmental pollution –Availability of clean water As NASA goal: As NASA goal: –As long term vision for NASA Earth science –Supports weather & climate needs