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
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 |
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 |
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 |
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 |
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 |
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 |
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 |