Slide 1Microphysical measurement needs1. Liquid HydrometeorsForward Scattering Spectrometer Probe (FSSP)FSSP Scattered EnergyPhase Doppler Particle Interferometer (PDPI)InterferometrySlide 8Larger particles D>>Comparison of FSSP and OAPs2. Ice HydrometeorsSmall ice – the perennial problemInterarrival times in ice cloudsSlide 14The Small Ice Detector (SID)Large ice crystals: OAPsLarge ice crystals: Cloud Particle Imager (CPI)Slide 18More common crystals3. CCN/IN characterizationThermal diffusion chamberThermal diffusion chambersIN characterization4. Characterization of thermodynamic environmentHumidityLiquid water contentObservational approachesto understanding cloud microphysicsMicrophysical measurement needsQuantitative characterization of….1) Size distribution of liquid hydrometeors from CCN size (0.01 m) to precipitation size (10000 m) – 6 orders of magnitude range of size (18 of mass!)2) Size/mass distributions and habits of ice-phase hydrometeors (1-10000 m)3) Efficacy of aerosols to act as CCN and IN4) Thermodynamic and dynamic environment in which hydrometeors form, exist, grow, and evaporate1. Liquid HydrometeorsForward Scattering Spectrometer Probe (FSSP)Radius range 1-25 µmNCARFSSP Scattered Energy1 10 100Diameter [microns]Scattered energy per particle [arbitrary units]1 10 100 1000Phase Doppler Particle Interferometer (PDPI)Size range 1-1000 µmInterferometryLarger particles D>>Baumgardner and Korolev, J Atmos. Ocean Tech., 1997•Optical Shadow Probes (Optical Array Probes, OAPs)Size range 10-10000 µmExamples:260-X2D-C2D-PHVPSComparisonof FSSP and OAPs•Problems in overlap zoneBaumgardner and Korolev, J Atmos. Ocean Tech., 19972. Ice HydrometeorsSmall ice – the perennial problem•FSSPs can be used, but….Interarrival times in ice cloudsField et al., J Atmos. Ocean Tech., 2003•Bursts of particles observed•Shattering of large ice giving impression of many small xtalsSmall ice – the perennial problem…andThe Small Ice Detector (SID)•Examines angular dependence of scattering•Irregular particlesUniversity of Hertfordshire, UKLarge ice crystals: OAPsField, JAS, 1999Size range 25-4000 µm•OAP images1000 microns [1 mm]Large ice crystals: Cloud Particle Imager (CPI)SPEC Inc, BoulderSize range 10-4000 µm•CCD camera takes photographs of particlesMore common crystals3. CCN/IN characterizationThermal diffusion chamberRHsupersaturatedeT•Supersaturation maximizes in center of chamber and can be controlled by T•Subject aerosols to known supersaturation and check for rapid growth using a droplet counter•Vary T and obtain a CCN spectrumThermal diffusion chambers•New designs allow for:–continuous flow in chamber–Multiple supersaturations simultaneously•Can be used at between ice and water saturation to characterize heterogeneous deposition nucleiIN characterization•Cannot measure (in-situ):–Contact freezing IN–Immersion freezing IN4. Characterization of thermodynamic environment •Temperature•Vapor content•Liquid water contentHumidity•High concentrations:–Optical (Lyman-alpha)–Tunable diode laser–Dewpoint Hygrometer•Low concentrations:–Fluorescence hygrometerLiquid water content•Hotwire probes•Nevzorov probes•Lyman-alpha, total water