1. Evaporation in Vineyards Dennis Baldocchi and Youngryel Ryu Dept Environmental Science, Policy and Management University of California, Berkeley November 30, 2010 Fruition Sciences Symposium, St. Helena, CA

2. How Much Water Does a Vineyard Lose to Evaporation?

3. First Grand Challenges to Vintners and Viticulturalists- Regarding Water Balance of the Vineyards Know How Much Water the Vineyard Uses over the Year and During the Growing Season – Give it too much water costs $$$$$ in terms of irrigating – Give it too little water may cost $$$$ in terms of reduced yield and grape quality – Give it Optimal Levels of Water will Earn you $$$$ in terms of producing top quality Grapes and Wine

4. Know how to Evaluate Water Use across the Region as a function of: – Climate – Topography – Soil Type – Viticultural Practice, e.g. Varietal, Planting Density and Age Water Use of a Vineyard can be Measured with Micrometeorological Methods Water Use of an Appelation can be Modeled by combining Micrometeorological Theory and Remote Sensing Second Grand Challenges to Vintners and Viticulturalists Regarding Water Balance of the Vineyards

5. Third Grand, and Ultimate, Challenge What are these Optimal Levels of Water Use and How Do We Find Them? ‘Know Thy Site’ – Simplest and Cheapest Regular measurements of soil gravimetric content – Requires scale, oven, shovel and much replication and sampling – Easy with Moderate Cost Regular Measurements of Pre-Dawn Water Potential – Measures the moisture the Roots See – Invest in ‘Pressure Bomb’, few $K – Requires much sampling and replication – Most Expensive and Sophisticated Regular Measurements or Simulations with Micrometeorological Techniques – Gives you continuous and direct evaporation measurements at the field scale

6. Potential Evaporation “the evaporation from an extended surface of a short grass that is supplied with water and the canopy covers the ground completely.”

7. Potential Evaporation in California Wine Regions is Large: 4-5 mm/day (0.15-0.2 inch/day) Potential and Actual Evaporation are Decoupled in Semi-Arid System

8. The Margin for Error is Tight for Providing Optimal Water to the Vineyard ET = f(varietal, topography, planting density, soil type, climate, trellising) Enough or Too Much Water Too Little Water Volume of Water/Volume Soil Fraction of Potential EvapoTranspiration, ETactual/ETref

9. Baldocchi et al., 2004 AgForMet ET and Soil Water Deficits: Water Potential and Evaporation with Native CA Vegetation, Oaks and Grasslands Root-Weighted Soil Moisture Matches Pre-Dawn Water Potential

10. Atmospheric radiative transfer Canopy photosynthesis, Evaporation, Radiative transfer Soil evaporation Beam PAR NIR Diffuse PAR NIR Albdeo->Nitrogen -> Vcmax, Jmax LAI, Clumping-> canopy radiative transfer dePury & Farquhar two leaf Photosynthesis model Rnet Surface conductance Penman-Monteith evaporation model Radiation at understory Soil evaporation shadesunlit BESS, Breathing-Earth Science Simulator

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12. Napa County Wine Districts

13. Annual Evapotranspiration, Napa County

14. Leaf Area Grand Growth Start

15. Leaf Area Grand Growth, End + Bloom

16. Pre_Veraison Stage

17. Post Veraison Summer Water Deficits

18. Case Study 1, Sonoma County

19. Compare Carneros, Valley of the Moon, Dry Creek, Russian River, Alexander and Knights Valleys ET ~ 20 to 30 inches per year

20. Seasonal Trends in Sonoma County ET Carneros Greatest in April; Least during the Summer

21. Conclusions Actual EvapoTranspiration is Very Sensitive to Changes in Soil Moisture and Climate, so a Scientific Approach is Warranted to Manage Water Application Best. Mechanistic Theories and Satellite Information are Producing Maps of ET at 1 km scale across the Wine Growing Region of California New ET Maps can be used for Planning Vineyard Siting, Varietal Selection, Irrigation Management, Vineyard Design

23. Effects of Leaf Area and Photosynthetic Capacity on Normalized Evaporation: Well-Watered Conditions Canveg Model, Baldocchi and Meyers, 1998 AgForMet Priestley-Taylor = 1.26

24. Stomatal Conductance Scales with Photosynthesis Wilson et al. 2001, Tree Physiology Schulze et al 1994. Annual Rev Ecology Photosynthetic Capacity Scales with Nitrogen Stomatal Conductance scales with Nitrogen Stomatal Conductance Scales with N, via Photosynthesis

25. MOD04 MOD05 MOD06 MOD07 aerosol Precipitable water cloud Temperature, ozone MCD43albedo MOD11Skin temperature Atmospheric radiative transfer Net radiation MOD15LAI POLDER Foliage clumping Canopy radiative transfer Challenge for a Computationally-Challenged Biometeorology Lab: Extracting Data Drivers from Global Remote Sensing to Run the Model Youngryel was lonely with 1 PC

26. Residual Energy Balance Net Radiometer, NR-Lite: $1600 Soil Heat flux, Hukseflux: $500 Sonic anemometer: RM Young, 81000VRE: $3200 Data logger: Campbell CR-1000: $1500

27. as far as topic This 2010 vintage has been really puzzling for all vineyard managers and winemakers in the sense that phenological stages were reached either later than usual or in some cases, never (some varietals had berries that never turned red). Everyone "feels" that it is climate related, without really understanding what parameters of the climate are driving those changes. I think that using ET as a way to characterize climate variations is a first step in that direction. Thus, it would be ideal if a cross vintage comparison could be shown so that people understand to which extend 2010 was different from 2009 and 2008 for instance. Based on your suggestions, here is what I think would be interesting: 1. From simple to fancy evaporation estimates measurement methods (it would be best if you could keep it very simple, without complex equations if possible !) 2. Effect of evaporation on soil water balance 3. Surface renewal and eddy covariance : I would not spend too much time on those for fear of losing the attention; but I think it is good to mention that this is the newest and most promising method with one "punch slide". 4. Relationship between normalized Evaporation and soil moisture : this is the central piece! This would be really useful to illustrate how/why different years have different effects on soil moisture. In that part a multi- year comparison would be really relevant (if available). 5. Spatial variations of normalized Evaporation : Great! I would highlight within a small geographical area (like Napa valley and Sonoma valley) what is the magnitude of the differences to be expected within a year. 6. I would conclude - if possible- with a comparison of the effect that different years vs. different locations within Napa can have on evaporative demand...I think this should be a really interesting way to compare the effect of vintage vs. terroir on plant.

28. Actual Evaporation Aerodynamic Approach Energy Balance (Bowen Ratio) Approach Eddy Covariance Lysimeter Evaporation Pan Soil Water Budget Combination Method – Penman Equation – Penman-Monteith Equation – Modified Priestly-Taylor Method Climatological Methods – Thornthwaite Equation

29. Bowen Ratio Method, measured with temperature and humidity gradients

30. ESPM 228 Adv Topic Micromet & Biomet Energy Balance Method R n, net radiation flux density, W m-2 H, sensible heat flux density E, latent heat flux density G, soil heat flux density Cp, specific heat of air http://pages.unibas.ch/geo/mcr/Projects/EBEX/img_profile/profile02.jpg

31. Eddy Covariance, Flux Density: mol m -2 s -1 or J m -2 s -1

32. ESPM 228 Adv Topic Micromet & Biomet Surface Renewal Paw U et al., 1989

33. ESPM 228 Adv Topic Micromet & Biomet Validation at Vaira Ranch

34. ESPM 228 Adv Topic Micromet & Biomet Sfc Renewal Relatively Cheap and Simple Needs Calibration for your Site or Class

35. Baldocchi et al., 2004 AgForMet ET and Soil Water Deficits: Water Potential and Evaporation with Native CA Vegetation, Oaks and Grasslands Root-Weighted Soil Moisture Matches Pre-Dawn Water Potential ET of Annual Grass responds to water deficits differently than Trees

36. ET and Soil Water Deficits: Root-Weighted Soil Moisture Baldocchi et al., 2004 AgForMet

37. Pellegrino et al 2004, Plant and Soil Southern France, Syrah Grapes are Much More Sensitive to Soil Water Deficits than Native Oaks and Grasses

38. Williams et al. 2003 Irrigation Sci ET Thompson Seedless, Fresno