APAR Science and Engineering

The availability of APAR, in conjunction with other remote and in-situ sensors, on a single airborne platform will serve the observational needs of the broader scientific community including cloud microphysics, mesoscale meteorology, Earth Systems sciences, and climate process studies. It will not only fill the critical gap left by ELDORA in the current suite of airborne observing facilities but also provide an enhanced microphysical observational capability to the community. The on-station time of the NSF/NCAR C-130 will allow APAR to collect critical observations of weather systems such as tropical cyclones, convection over continents and oceans, orographic precipitation, and polar clouds in areas that are currently inaccessible by ground-based weather radars.

The goal of the APAR design is to optimize the important specifications and trade-offs to enable the scientific goals to be met while considering the physical limitations of a radar system (in the case of APAR, mounting on the NSF/NCAR C-130 aircraft). For example, radar beamwidth is a function of wavelength and antenna aperture. X-Band and shorter wavelengths have been preferred choices for mobile ground-based and airborne radars because the required antenna size is much smaller than for S-Band or C-Band antennas for a specified beamwidth. The size of the NSF/NCAR C-130 allows an antenna that is large enough to accommodate a C-Band radar with a 2.2 degree or smaller 3 dB beamwidth. For studying high-impact precipitation weather, C-Band offers considerable advantages over X-Band and shorter wavelength radars that have been deployed on research aircraft up to this point. The C-Band attenuation through rain is considerably less than at X-Band.

Below is the APAR Science Traceability Matrix for:

     •  Hurricanes & Tropical Cyclones

     •  Continental Convection

     •  Maritime Convection

     •  Extreme Precipitation

     •  Shallow Convection

     •  Artic Processes

     •  Aerosols, Cloud Physics and Radiation

 


HURRICANES & TROPICAL CYCLONES

 
Science Frontier Key Measurement(s) Requirements Instrument Requirements Key APAR Design
Genesis



Processes leading to rapid intensification



Determining why some land falling storms produce tornadoes and others do not



Eye wall replacement



Microphysical processes
Mesoscale vertical mass flux profiles



Vertical transport of horizontal momentum



3D wind, temperature, and humidity



Distribution and evolution of precipitation



Radiative properties
Airborne radar wind and vertical velocity in 3D



Precipitation properties and characteristics



Dropsonde measurements



Microwave profilers



In-situ observations of winds, temperature, humidity, and radiation
Measurements in remote regions and over large areas using C-130



C-Band: Lower attenuation



Sampling volume less than (0.5 km)3 at 10 km range



DR accuracy <0.2 dB; LDR limit <-22dB; pHV variance <0.005 and fDP variance <2.2 deg)



dual-Doppler 3D wind retrieval

Particle ID

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CONTINENTAL CONVECTION

 
Science Frontier Key Measurement(s) Requirements Instrument Requirements Key APAR Design
Compare observed storms coincide to conceptual models



Lower tropospheric processes that produce (or fail to produce) tornadoes and intense mesovortices



Convective organization and life cycle: from initiation to MCS formation

 
Mapping of lower troposphere outside of storms: q, T, 3D wind profile, instantaneous vertical columns, aerosols



Within storms: thermodynamic properties, microphysical properties, updraft core characteristics



Thermodynamic variables within storms

 
Dual/multi-Doppler velocity retrievals



Dual-pol radar measurements of precipitation



Fast scanning radars



Microwave radiometer combined with radar



Thermodynamic and kinematic profiles
Measurements in remote regions and over large areas using C-130



C-Band: Lower attenuation



Sampling volume less than (0.5 km)³ at 10 km range



DR accuracy <0.2 dB; LDR limit <-22dB; pHV variance <0.005 and fDP variance <2.2 deg)



dual-Doppler 3D wind retrieval

Particle ID

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MARITIME CONVECTION

 
Science Frontier Key Measurement(s) Requirements Instrument Requirements Key APAR Design
Mesoscale budgets of mass, entropy, moisture and momentum



Comparison of actual covection with cloud resolving models
Mesoscale vertical mass flux profiles



Moisture convergence



Vertical transport of horizontal momentum



Wind fields in and around convective cells



Distribution of precipitation
Airborne radar wind and vertical velocity in 3D or in transect along flight track



Dual-polarization radar observations of heavy precipitation



Dropsondes
Measurements in remote regions and over large areas using C-130



C-Band: Lower attenuation



Sampling volume less than (0.5 km)³ at 10 km range



Dual-polarimetric (ZDR accuracy <0.2 dB; LDR limit <-22dB; pHV variance <0.005 and fDP variance <2.2 deg)



dual-Doppler 3D wind retrieval



Sensitivity of -11 dBZ at 10 km



Particle ID

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EXTREME PRECIPITATION

 
Science Frontier Key Measurement(s) Requirements Instrument Requirements Key APAR Design
Atmospheric rivers



Role of topography in extreme events
Kinematics within precipitation



Microphysical parameters



Large scale wind and thermodynamic environment including upstream conditions
Airborne radar 3D wind



Dual-polarization radar observations of heavy precipitation



Dropsondes, profiling radars and lidars
Measurements in remote regions and over large areas using C-130



C-Band: Lower attenuation



Sampling volume less than (0.5 km)³ at 10 km range



Dual-polarimetric (ZDR accuracy <0.2 dB; LDR limit <-22dB; pHV variance <0.005 and fDP variance <2.2 deg)



dual-Doppler 3D wind retrieval



Sensitivity of -11 dBZ at 10 km



Particle ID

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SHALLOW CONVECTION

 
Science Frontier Key Measurement(s) Requirements Instrument Requirements Key APAR Design
Interactions between shallow convection and turbulent scale and feed back to environment



Maritime high-latitude cloudy boundary layer structure and interactions with sea/ice/open water/land boundaries



Mesoscale organization (over both ocean and land)
Wind Shear



Doppler radar



High resolution water vapor, temperature and 3D winds



Mass fluxes



Spatial distribution



Cloud macrophysics
Polarimetric radars



Aircraft in-situ microphysical probes and state measurements



Scanning radars at different frequencies



Dropsondes
Measurements in remote regions and over large areas using C-130



C-Band: Lower attenuation



Sampling volume less than (0.5 km)³ at 10 km range



Dual-polarimetric (ZDR accuracy <0.2 dB; LDR limit <-22dB; pHV variance <0.005 and fDP variance <2.2 deg)



dual-Doppler 3D wind retrieval



Sensitivity of -11 dBZ at 10 km

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ARTIC PROCESSES

 
Science Frontier Key Measurement(s) Requirements Instrument Requirements Key APAR Design
Arctic cyclone genesis and evolution



Arctic cyclone impact on sea ice and coast lines
Meso-scale 3D winds



Precipitation characteristics and distribution



Thermodynamic profiles



In-cloud and clear-air chemistry
Polarimetric radars



dual-Doppler 3D wind analysis



Dropsondes



Microphysical probes and state measurements



Trace gases
Measurements in remote regions and over large areas using C-130



C-Band: Lower attenuation



Sampling volume less than (0.5 km)³ at 10 km range



Dual-polarimetric (ZDR accuracy <0.2 dB; LDR limit <-22dB; pHV variance <0.005 and fDP variance <2.2 deg)



dual-Doppler 3D wind retrieval



Sensitivity of -11 dBZ at 10 km

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AEROSOLS, CLOUD PHYSICS and RADIATION

 
Science Frontier Key Measurement(s) Requirements Instrument Requirements Key APAR Design
Feedbacks between vertical motion and aerosol and microphysical processes



Hydrometeor size distributions
Full in-situ microphysical measurements for both liquid and ice



Updraft / downdraft vertical velocity



Base state variables within the updrafts / downdrafts



Microphysical processes



Aerosol size distributions



Liquid wiater path



Lightning and electrification



Fire weather
Remote sensing particle size profiles (ice and water): multi-wavelength radar, lidar



In-situ microphysical measurements



Condensate mixing ratios using suite of in-situ probes to cover entire particle size distribution: 0.01 g/kg



Electric field mills



Trace gases
Measurements in remote regions and over large areas using C-130



Sampling volume less than (0.5 km)³ at 10 km range



Dual-polarimetric (ZDR accuracy <0.2 dB; LDR limit <-22dB; pHV variance <0.005 and fDP variance <2.2 deg)



dual-Doppler 3D wind retrieval



Sensitivity of -11 dBZ at 10 km



Particle ID

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