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Cloud Science Goals for SEAC 4 RS

Cirrus Microphysical Composition , Remote S ensing (ACE), Radiative Properties & Fluxes => Aged and fresh cirrus anvils (#3, #7, #14, ACE = #11) also, Chemical Transports by Deep Convection => TTL Cirrus (#6, #9, #14, ACE = #11 ) Effects of Aerosols on clouds and precipitation

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Cloud Science Goals for SEAC 4 RS

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  1. Cirrus • Microphysical Composition, Remote Sensing (ACE), Radiative Properties & Fluxes • => Aged and fresh cirrus anvils (#3, #7, #14, ACE = #11) • also, Chemical Transports by Deep Convection • => TTL Cirrus (#6, #9, #14, ACE = #11) • Effects of Aerosols on clouds and precipitation • Cumulus congestus & altostratus outflow (#3) • PBL clouds (#11/ACE, also #5/ships, #8/smoke, #13/biomass, #14/C&C) • Cirrus Anvils – see above (#3) • Remote Sensing of PBL clouds (#11/ACE) Cloud Science Goals for SEAC4RS

  2. Cirrus Focused Modules – Aged and Fresh Anvil Cirrus • In-situ measurements (GV & DC-8) (IWC, Ni(r), habit) • - close coordination required with ER-2 • - emphasis on profiling (via ramps/steps [2K’ deltas] or spirals) • • shorter legs than ER-2 may be desireable • GV may of necessity be primary platform in some cases • GV works upper levels, DC-8 works lower levels • Remote Sensing measurements (ER-2 & DC-8) • - 20-30 min level ER-2 legs required (very long) • DC-8 underflight strongly desired (well below cloud) => HSRL & APR-2 • • this is long level leg ~ ER-2 leg • Along the ambient wind orientation desired (toward/away from TRW), • but also some principal plane and satellite ground tracks • Coordinated with A-Train whenever possible (W-Band, CALIOPI, MODIS) • Coordination with NPP and Terra also desired SEAC4RSCirrus Focused Modules

  3. Chemistry outflow measurements (in situ, DC-8) • - emphasis on across-the-ambient-wind profiles (2K’ deltas) • => Relatively close and further away downstream • Short legs may also be desirable here • more levels, targeted on anvil core/centerline • PBL leg is necessary (before or after) – also gives us deep profile • - Coordination with ER-2? …how ? • all are 4 hour modules • Enroute measurements - porpoising maneuvers okay for in-situ (DC-8), but not for remote sensing (ER-2), i.e., give us some level pieces SEAC4RSCirrus Focused Modules

  4. Some Basic Questions & Concerns • How close can we approach convective cell? • 10 na. mi. ~ 30 min at 10 m/s => cross flow profilers • • Avoid freezing level (lightning) – 6-7 km. • • How well will we know about electrical activity? • • Do we seek isolated cells/lines, or do we venture into disturbed conditions? • • How interested are we in deep stratiform regions? • Real-time satellite support may be challenging, wx radar support is non-existent over most of the maritime areas. Horizontal visibility from in-situ aircraft may often be quite limited. SEAC4RSCirrus Focused Modules

  5. TTL Cirrus • Key questions • (1) in-cloud radiative heating profile (#6) • ER-2: level flight legs above and below cloud • DC-8: coordinated with ER-2 (up-looking lasers) • (2) remote sensing of aerosol below TTL cirrus (#12) • (3) Vertical profiling – GV (#9) • 2 hour module • Cloud free troposphere desired, some PBL okay • How do we know it is there? SEAC4RSTTL Focused Modules

  6. Aerosol effects on clouds and precipitation • Very skeptical that we can do more than what is described above for aged and fresh cirrus and stratiform anvils as regards effects on upper troposphere, e.g., smaller and more numerous ice crystals => denser anvils, smaller precipitation rate in stratiform region • Key to attribution: Acquire good MBL and lower tropospheric aerosol measurements in vicinity of deep convection. How many cases? • Strong reliance on satellite observations SEAC4RS Aerosol Effects on Clouds Modules

  7. Aerosol effects on clouds and precipitation • What can we safely do? => measure the primary aerosol-cloud interaction in young convection, i.e., before cloud top passes the freezing level (cumulus to cumulus congestus stage). • measurements in PBL (DC-8 or GV) • in-cloud measurements just above cloud base (DC-8 or GV) • in-cloud measurements a few 1000’s of feet above cloud base (GV, KA) • in-cloud measurements near cloud top before hits freezing level (GV, KA) • coordinate with multiple overpasses of DC-8 above cloud top (DC-8) • Take advantage of scanning Ku and Ka radars • Must be in-field call, i.e., organized & coordinated from DC-8 SEAC4RS Aerosol Effects on Clouds Modules

  8. Aerosol effects on clouds and precipitation • Cumulus congestus can occur near deep convection, or associated with outflow boundaries, and otherwise. • We can also profitably sample trade cumulus in the same way (much less levels required) in association with biomass burning/smoke, ship effluent or mega city plumes • 50 km racetrack orbits proposed, but can consider more windy path for in-situ platform to maximize cloud penetrations. SEAC4RS Aerosol Effects on Clouds Modules

  9. Remote Sensing of Low Clouds and/or Aerosols (ACE) • For low cloud, the biggest challenge here will be to find extended decks of relatively uniform low cloud, especially absent variable cirrus overcast • For aerosols, the biggest challenge will be to find regions without scattered to broken low clouds, and without (variable) cirrus overcast • Longer ER-2 flight legs (20-30 min), • Oriented along low level wind direction? • Flight level below overlying cirrus (maybe above and below) • DC-8 samples below cloud and in-cloud properties • GV & KA ??? Could get crowded in the vertical….. SEAC4RS Remote Sensing of Low Cloud Modules

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