Water Cycle

1. Water Cycle

2. Importance of the Water Cycle • “The vitality of all life on Earth and our economic prosperity depend on water.” – Call for Proposals NSF Water Cycle Research • “The cycling of water among the three phases is overwhelming important for Earth, driving not just the atmospheric general circulation but also the very existence of life as we know it”-- A Plan for a New Science Initiative on the Global Water Cycle, USGCRP • “Deficiencies in our understanding of the global water cycle severely handicap efforts to improve climate prediction and guide water resource management.” – Robert Corell A Plan for a New Science Initiative on the Global Water Cycle, USGCRP

3. Impacts of Water Cycle Variations • In the U.S., flood damage is typically of order of ~$10-20 billions per year • Flood damage varies from year to year : $200 billion in 1991-1995 and 40% of economic damage from disasters in that period • 1998 Carolina drought -- $6 – 9 billion • 1988 Midwest drought -- $40 billion • Recently the largest number of weather fatalities are due to flooding (not really true) • Advanced knowledge of local events and year-to-year variations beneficial to society

4. Water Cycle Research • GEWEX – Global Energy and Water Cycle Experiment • US Global Change Research Program’s (USGCRP) – Global Water Cycle Initiative • NSF – Water Cycle Research • NOAA – Water Cycle Program  NAME • NASA – Water and Energy Cycle

5. Water Cycle Research • NCAR has a Strategic Initiative called “Water Cycle Across Scales” http://www.rap.ucar.edu/projects/watercycles/ • The across the scales aspect is partly motivated by the societal impacts of water cycle (floods, droughts, water pollution) are local or regional, while many key aspects of the water cycle toward global scales (climate change, El Nino.) Also, many of the uncertainties in global modeling are due to problems treating subgrid scale processes.

6. My Reading Homework • Earliest work on the water cycle appears in Book 21 of the Iliad, Homer (~810 B.C.): Oceanus source of all rivers, sea, springs and wells • Thales (~600 B.C.) and Plato (~400 B.C.): Water eventually returns to the sea by various routes • Perrault and Mariotte (1600s): 1st Water budget: Seine runoff approximately balanced by rainfall and snowmelt in the Basin • Modern planning documents (Hornberger report, NCAR water cycle, papers in the literature, NASA documents, etc.)

7. 1st Possible Research Themes and Corresponding Measurement Needs • Water vapor, which is a key aspects of the water cycle is not measured accurately enough for research needs

8. From J. Nash, ATD seminar H Sensor A sensor

9. NCAR Atmospheric Technology Division Motivations 1. Individual errors and biases 2. Temporal and spatial inhomogeneity 3. Temporal and spatial sampling – Satellite (calibrated by radiosonde)

10. 1ST Possible Theme • Attempt to contribute to the measurement and research gap of accurate water vapor measurements for climate purposes • Evaluate impact of NWS sonde “upgrades” • One effort: Reference radiosonde with technology transfer and asssistance in long-term monitoring • General effort to better measure water vapor and water vapor fluxes in surface, sounding, remote sensing and from aircraft (weather, climate, carbon cycle, etc.)

11. The reference radiosonde for IHOP_2002 • S/W chilled-mirror DP hygrometer • – reference humidity sensor • Carbon hygristor • Copper-constantan thermocouple • Hypsometer Vaisala RS80 NWS VIZ B-2 Reference radiosonde 400MHz transmitter GPS receiver

12. Cirrus clouds detected by SnowWhite – thick cirrus Surface Report: Cirrus anvil (moon visible through cirrus) * Satellite image from UW-Madison CIMSS web page

13. 2nd Research Theme and Corresponding Measurement Needs • Predictive models have widely varying degrees of sensitivity to surface properties • This variation is often not reasonable and may be traced to the need for a greater understanding of the details of surface characteristics and surface exchanges in complex environments.

14. Ωp (S - W) Koster et al. 2003 GLACE website June-August run

15. IHOP Surface Tracks From Lemone et al.

16. From Lemone et al.

17. 2nd Theme and Measurement Need • Improved attack on surface exchanges and impact on boundary layer • Surface in-situ measurements • Fluxes and means, vegetation (NDVI, LAI, PAR, stomal conductance, etc.), soil measurements (soil composition, conductivity, shallow and deep soil moisture), long-term capability, do we need to go into the canopy

18. 2nd Theme and Measurement Need • Ground-based remote sensing to look at response of atmosphere (Radar refractivity, water vapor lidar, better observations of early clouds) • HIAPER remote sensing to complement surface obs (better areal coverage, satellite “calibration”)

19. Refractivity: One Day After Heavy Rainfall Aircraft In-situ data Northern edge of aircraft track Ts=45, Theta60=307, q60 = 8.5 Southern edge of aircraft track Ts=32, Theta60=306.2, q60 = 11 Weckwerth and LeMone also Fabry

20. 3rd Measurement and Observing Theme • Models have poor triggering of convection • Diurnal cycle of precipitation and clouds wrong over the central US but getting (slightly) better • Remote sensing and surface mentioned previously plus sounding/profiling supporting obs sufficient • Current focus of water cycle but still likely to be the focus

21. 4th Measurement and Observing Theme • Regional water cycle experiments that include hydrology (NAME, esp AMMA, etc.) • Need precipitation radar and current technologies, • Hydrology (can we build it?), • HIAPER as a water cycle platform • Ability to profile water vapor, clouds, surface properties • HIAPER as a satellite evaluation, platform for prototype satellite sensors and platform for understanding of and from these measurements (TRMM, GPM, EOS-Aura, EOS-Terra, EOS-Aqua, CloudSAT, CALIPSO, GRACE, AMSR, GIFTS, NAST etc) – allows us to scale up to global obs

22. Water Cycle