Atmospheric ice particle shape estimates from polarimetric radar measurements and in situ observations

Atmospheric ice particle shape estimates from polarimetric radar measurements and in situ... AbstractA remote sensing approach to retrieve the degree of non-sphericity of ice hydrometeors using scanning polarimetric Ka-band radar measurements from a US Department of Energy Atmospheric Radiation Measurement (ARM) program cloud radar operated in an alternate transmission – simultaneous receiving mode is introduced. Non-sphericity is characterized by aspect ratios representing the ratios of particle minor-to-major dimensions. The approach is based on use of circular depolarization ratio (CDR) proxy which is reconstructed from differential reflectivity ZDR and copolar correlation coefficient ρhv linear polarization measurements. Essentially combining information contained in ZDR and ρhv, CDR-based retrievals of aspect ratios are fairly insensitive to hydrometeor orientation if measurements are performed at elevation angles of around 40°-50°. The suggested approach is applied to data collected using the third ARM mobile facility (AMF-3), deployed to Oliktok Point (Alaska). Aspect ratio retrievals were also performed using ZDR measurements, which are more strongly (compared to CDR) influenced by hydrometeor orientation. The results of radar-based retrievals are compared with in situ measurements from the tethered-balloon based Video Ice Particle Sampler and the ground-based Multi-Angle Snowflake Camera. The observed ice hydrometeors were predominantly irregular-shaped ice crystals and aggregates, with aspect ratios varying between approximately 0.3 and 0.8. The retrievals assume that particle bulk density influencing (besides the particle shape) observed polarimetric variables can be deduced from the estimates of particle characteristic size. Uncertainties of CDR based aspect ratio retrievals are estimated at about 0.1 - 0.15. Given these uncertainties, radar-based retrievals generally agreed with in situ measurements. Advantages of using the CDR proxy compared to linear depolarization ratio are discussed. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Atmospheric and Oceanic Technology American Meteorological Society

Atmospheric ice particle shape estimates from polarimetric radar measurements and in situ observations

Loading next page...
 
/lp/ams/atmospheric-ice-particle-shape-estimates-from-polarimetric-radar-BrUYdxRNuE
Publisher
American Meteorological Society
Copyright
Copyright © American Meteorological Society
ISSN
1520-0426
D.O.I.
10.1175/JTECH-D-17-0111.1
Publisher site
See Article on Publisher Site

Abstract

AbstractA remote sensing approach to retrieve the degree of non-sphericity of ice hydrometeors using scanning polarimetric Ka-band radar measurements from a US Department of Energy Atmospheric Radiation Measurement (ARM) program cloud radar operated in an alternate transmission – simultaneous receiving mode is introduced. Non-sphericity is characterized by aspect ratios representing the ratios of particle minor-to-major dimensions. The approach is based on use of circular depolarization ratio (CDR) proxy which is reconstructed from differential reflectivity ZDR and copolar correlation coefficient ρhv linear polarization measurements. Essentially combining information contained in ZDR and ρhv, CDR-based retrievals of aspect ratios are fairly insensitive to hydrometeor orientation if measurements are performed at elevation angles of around 40°-50°. The suggested approach is applied to data collected using the third ARM mobile facility (AMF-3), deployed to Oliktok Point (Alaska). Aspect ratio retrievals were also performed using ZDR measurements, which are more strongly (compared to CDR) influenced by hydrometeor orientation. The results of radar-based retrievals are compared with in situ measurements from the tethered-balloon based Video Ice Particle Sampler and the ground-based Multi-Angle Snowflake Camera. The observed ice hydrometeors were predominantly irregular-shaped ice crystals and aggregates, with aspect ratios varying between approximately 0.3 and 0.8. The retrievals assume that particle bulk density influencing (besides the particle shape) observed polarimetric variables can be deduced from the estimates of particle characteristic size. Uncertainties of CDR based aspect ratio retrievals are estimated at about 0.1 - 0.15. Given these uncertainties, radar-based retrievals generally agreed with in situ measurements. Advantages of using the CDR proxy compared to linear depolarization ratio are discussed.

Journal

Journal of Atmospheric and Oceanic TechnologyAmerican Meteorological Society

Published: Sep 29, 2017

References

You’re reading a free preview. Subscribe to read the entire article.


DeepDyve is your
personal research library

It’s your single place to instantly
discover and read the research
that matters to you.

Enjoy affordable access to
over 12 million articles from more than
10,000 peer-reviewed journals.

All for just $49/month

Explore the DeepDyve Library

Unlimited reading

Read as many articles as you need. Full articles with original layout, charts and figures. Read online, from anywhere.

Stay up to date

Keep up with your field with Personalized Recommendations and Follow Journals to get automatic updates.

Organize your research

It’s easy to organize your research with our built-in tools.

Your journals are on DeepDyve

Read from thousands of the leading scholarly journals from SpringerNature, Elsevier, Wiley-Blackwell, Oxford University Press and more.

All the latest content is available, no embargo periods.

See the journals in your area

Monthly Plan

  • Read unlimited articles
  • Personalized recommendations
  • No expiration
  • Print 20 pages per month
  • 20% off on PDF purchases
  • Organize your research
  • Get updates on your journals and topic searches

$49/month

Start Free Trial

14-day Free Trial

Best Deal — 39% off

Annual Plan

  • All the features of the Professional Plan, but for 39% off!
  • Billed annually
  • No expiration
  • For the normal price of 10 articles elsewhere, you get one full year of unlimited access to articles.

$588

$360/year

billed annually
Start Free Trial

14-day Free Trial