9/26/20121ESPM 129 Biometeorology 1Lecture 13, Temperature and Thermodynamics, part III:• Temperature and the Canopy Microclimate– Diurnal and Annual Patterns– Vertical Profiles• Thermal Indices• Agriculture and MicroclimatesESPM 129 Biometeorology 2wheat, Boardman, ORTime0 500 1000 1500 2000Air Temperature81012141618202224Summer Diurnal Pattern, Air Temperature over Wheat9/26/20122ESPM 129 Biometeorology 3Hour0 4 8 12162024Tair, C81012141618202224oak savannaannual grasslandMean Annual Diurnal Pattern at Two Contrasting SitesESPM 129 Biometeorology 4Winter (NDJ)Hour0 4 8 12162024Tair, C9.69.810.010.210.410.610.8grasslandsavannaSummer (JJA)Hour0 4 8 12162024Tair, C101520253035grasslandsavannaMean Diurnal Patterns by Season9/26/20123ESPM 129 Biometeorology 5GrasslandSoil Moisture (cm3 cm-3)0.05 0.10 0.15 0.20 0.25 0.30 0.35Tmax-Tmin (C)051015202530Temperature Amplitude and Soil Moisture DeficitsESPM 129 Biometeorology 6Day0 50 100 150 200 250 300 350daily-averaged Potential Temperature, C051015202530grasslandSavannaEffects of Land Use on TemperatureBaldocchi and Ma, unpublished9/26/20124ESPM 129 Biometeorology 7potential temperature differenceDay0 50 100 150 200 250 300 350Oak Savanna-Annual Grassland, C-2-10123Baldocchi and Ma, unpublishedWho is Warmer/Cooler, Depends on Season, Roughness, Energy Balance andPhysiological StatusESPM 129 Biometeorology 8Lee et al 2011 NatureDifferences in MeanAnnual Air TemperatureOpen Land minus ForestForests can be Darker, AbsorbMore Energy and thereby beWarmer than Nearby Grasslands9/26/20125ESPM 129 BiometeorologyJune 1, 1999, 1800 UTOak Ridge, TN280 290 300 310 320Pressure, mb7007508008509009501000Virtual Potential TemperatureDry Bulb TemperatureunstableneutralStableProfiles of Air and Potential TemperatureESPM 129 Biometeorology 10Aspendata of TA Black et al.Temperature (C)11 12 13 14 15 16 17 18 19Height (m)01020304050midday (D210)midnight9/26/20126ESPM 129 Biometeorology 11Temperature (C)22.5 25.0 27.5 30.0051015202530u= 3 m s-1shaded leavessunlit leavesairZ (m)Theoretical Temperatures in a ForestESPM 129 Biometeorology 12Helliker and Richter 2008 NatureIs Mean Leaf Temperature Invariant?9/26/20127Tleaf0 10203040pdf0.000.020.040.060.080.100.121993198119821984199419971995Temperate Broadleaved ForestDays 100 to 273Leaf Temperature and Isotopes?Helliker and Richter 2008 NaturePonderosa Pine, Metolius, ORTleaf (C)-20-15-10-5 0 5 101520253035pdf0.000.020.040.060.080.100.120.14TleafTairTranspiration-weigthed Tleaf = 23.6 CFlux-Weighted Temperature pdf9/26/20128sunlit leaves, daytimeOak Ridge, TN 1997Tleaf0 10203040Probability0.000.020.040.060.08ambient, 100 mm leaves CO2=1500 ppm, 100 mm leaves small leaves, 10 mm100 mm leaves, ea times 0.5Role of Leaf Size and CO2 on Leaf TemperatureEnergy Balance Feedbacks seem to Seek a Common OptimumEvolutionary Adaptations Attempt to Avoid Extreme StressesESPM 129 Biometeorology 16Mean Annual Air Temperature9/26/20129ESPM 129 Biometeorology 17-124 -122 -120 -118 -116 -1143234363840420123456789101112131415161718192021222324California Average Temperature, 1971-2000“Spatial Climate Analysis Service, Oregon State University, http://www.ocs.oregonstate.edu/prism/,ESPM 129 Biometeorology 189/26/201210ESPM 129 Biometeorology 19Summary• Inside dense forests at night, the thermal stratification will be stable in the upper portion of the canopy, but can be unstable near the forest floor causing the layers to become decoupled.• Simple trigonometric principles can be used to compute summed heat and chill hours based solely on maximum and minimum temperature measurements.ESPM 129 Biometeorology 209/26/201211ESPM 129 Biometeorology 21Feng and Hu, 2004, J Theor Appl ClimTrends in Growing Season Length and Last Frost DateUnited StatesESPM 129 Biometeorology 22Christy et al., 2006 J ClimateCentral Valley Trends in Minimum Temperature:Partially Attributed to Land Use Change9/26/201212ESPM 129 Biometeorology 23Peng et al PNAS, 2003Role of Temperature Extremes on RiceGrain YieldBiomassSpikeletsESPM 129 Biometeorology 24Almond Yield (ton acre-1) Almond Yield AnomalyD. Lobell, Unpublished, Data source: CIMIS, NASSRole of Seasonal Statistics9/26/201213ESPM 129 Biometeorology 25TminTmaxTrefadbcTavemidnightNoonChillhours T T tref()024tanminabhrTTave6dchillhoursTTref2tan ( )minESPM 129 Biometeorology 26slope 0.973, offset 0.738, r2 0.87 Tavg0