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Aerosol Indirect Effect Experiments on the J-31

Aerosol Indirect Effect Experiments on the J-31. In coordination with the R/V Ron Brown (Radar data: Pavlos Kollias). Science Objectives. Study effect of aerosol on cloud microphysics Compare different drop size retrieval methods Remote sensing from surface (radar/ m wave on RHB)

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Aerosol Indirect Effect Experiments on the J-31

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  1. Aerosol Indirect Effect Experiments on the J-31 In coordination with the R/V Ron Brown (Radar data: Pavlos Kollias)

  2. Science Objectives • Study effect of aerosol on cloud microphysics • Compare different drop size retrieval methods • Remote sensing from surface (radar/mwave on RHB) • Remote sensing from J-31(SSFR) • Remote sensing from P-3 (MIDAS, SSFR) • In-situ from P-3 (FSSP)

  3. J31: Aerosol and cloud radiative properties; AOT, aerosol extinction profiles, cloud optical depth, drop size, LWP Instrumentation: AATS-14, SSFR P-3: Emphasis on gasphase chemistry, aerosol size distribution / composition and cloud radiative properties; longer range, chasing pollution plumes Relevant Instrumentation: SSFR, MIDAS, FSSP

  4. Satellite effective radius, re (z) LWP Lidar: backscatter profiles Sunphotometer Radar microwave radiometer Surface aerosol R/V Brown

  5. Satellite AATS-14 + SSFR: re ,td , r , LWP a(z) J31 Cloud free AOT, a(z) Aerosol: n(a), b, a, s, chem Cloud: re , w, LWP

  6. Example from ARM/SGP Effective radius aerosol Method for Indirect Effect Studies • Use Lidar backscatter or extinction aas proxy for CCN • Various re retrievals • Requires non-precipitating warm clouds (single layers) with high enough bases for lidar to sample aerosol (identified 5 possible candidates) IE= - dlnre/dlna

  7. Stratocumulus observations after another front passage (14-15 July). The MWR measurements show good correspondence with the reflectivity structure and the ceilometer data along with the reflectivity data can be used to infer the cloud thickness

  8. Cloud Fraction during NEAQS from RHB A ceilometer-based distribution of hourly averaged cloud fraction during NEAQS. More than 30% of the time, clear skies were observed, while overcast cloud and precipitation conditions occurred 25% of the time.

  9. NEAQS Leg-averaged cloud fraction. Note: During leg 2, More middle and upper clouds were observed and less BL clouds

  10. Ceilometer cloud base time series Height, km Ceilometer Hourly mean cloud base. Note: During the second leg very few boundary layer clouds were observed. Furthermore as the lower panel shows, many of the low level bases in leg one were associated with fog and frontal precipitation Fractional Coverage Precipitation hourly fractional coverage as observed by the ceilometer. High fractional coverage (close to 1) may mean continuous precipitating conditions

  11. Clear Skies LWP Overcast BL clouds LWP LWP time series: Red shows periods with stratus clouds

  12. Components of aerosol-cloud interactions • Cloud properties: re , td , reflectance,r • Aerosol properties: size distr., composition, f(RH), mass loading, extinction, scattering, CCN • LWP Verification/intercomparison of independent components through redundant measurements Changes in cloud parameters as a function of changes in aerosol parameters

  13. _ d ln re d ln t _ d ln r d ln a _ d ln td d ln a Detecting and Quantifying AIE Cloud Aerosol (re , td , r) (aerosol size distr., extinction, etc) At constant LWP Changes in cloud parameters (re , td , r) as a function of changes in aerosol parameters CCN proxies

  14. July 10th Precipitation scavenging by Altocumulus Radar Reflectivity Cloud base ~ 3km Scattering (R, G, B) 14:00 UTC 20:00 UTC

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