From: J. E. Dye (dye at ucar.edu)
Organization: NCAR/MMM

Research Area: CLOUD MICROPHYSICS AND RADIATION

Mission Scenario: Kinematics, Chemistry, Radiation, Electricity, Aerosols, and Microphysics of Deep Convection -- The KCREAM Experiment

Thunderstorms play a significant role in many aspects of atmospheric science. They transport and potentially modify chemical constituents from the PBL to the upper troposphere. Aerosols acting as cloud forming nuclei are activated to form cloud droplets or ice particles and those not activated can be modified by in-cloud and chemical processes with the net results of modifying the cloud active and non-active aerosol properties. Aqueous chemical reactions occurring on particles can modify both the aerosols and the chemical composition. Lightning in the storms produce NOx. Ice particles produced by the convection and blown off into the anvil can persist for long periods of time altering the radiation balance locally and collectively globally. Overshooting tops can cause stratospheric/tropospheric exchange of constituents, water vapor and momentum and excite gravity waves. Some lightning flashes induce electrical changes above the storm causing sprites, elves and blue jets. All of the above are processes and areas in which further understanding is needed and which can be investigated utilizing appropriate instruments on HIAPER. Several other investigators have suggested some of these topics separately, but many of the goals could potentially be combined because somewhat similar flight patterns are needed. There are needs for these kinds of studies at mid-latitudes, but particularly in the tropics.

HIAPER Mission: The following types of patterns would apply if taking off locally for continental mid-latitude studies or from another base for tropical studies. The experiment is best done in conjunction with another aircraft making measurements similar to HIAPER in the boundary layer and at mid-levels and with a fore-aft scanning Doppler radar to characterize the chemical, aerosol, electrical, thermodynamic and wind conditions as was successfully done in the STERAO-Deep Convection Experiment. Surface multi-parameter Doppler radars, sounding and lightning mapping systems would also be used. A high altitude aircraft flying above HIAPER would also be desirable.

The HIAPER payload would include new and hopefully reduced size instruments for reactive chemical species and tracer measurements, microphysical, aerosol and cloud forming nuclei probes, wind measurement systems, radiometers (perhaps frequency scanning as well as fixed), electric field and field change measurements, absorption spectrometers such as Susan Solomon has used, and other instruments better defined by others.

HIAPER would take off and proceed to the experimEntal area before deep convection developed. Large diameter spiral soundings would be made upwind of where convection is anticipated from near the surface to above the tropopause or as high as operationally realistic. When possible penetrations of clouds in the developing stage would be made to document the microphysical structure of that region. After the storm matured the anvil outflow would be investigated using a combination of spirals and repeated, stepped penetrations at constant altitude. The spirals and penetrations would extent from below the anvil to above the visible anvil with some near the storm core and others are larger distances from the core. HIAPER would continue to follow the storm anvil with spirals, repeated penetrations and sometimes long legs away from the anvil throughout the active stage of the storm and for a few hours after the decay of active convection. Depending upon specific goals determined for that flight, passes could also be made above the tops of shallower storms to examine the radiative properties of the core and anvil. Some flights might be extended past nightfall to investigate altered chemistry at night and also electrical conditons above the storm during periods when sprites and blue jets were occurring. Flights would be 8 to 10 hours duration depending upon the lifetime of the convection.

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