Identification

Title

Empirical relations between size parameters of ice hydrometeor populations and radar reflectivity

Abstract

Empirical power-law relations between the equivalent radar reflectivity factor Z(e) and the slope parameter of the gamma function Lambda (i.e., Lambda = cZ(e)(d); used to describe ice hydrometeor size distributions) are derived. The Lambda parameter can also be considered as a size parameter since it is proportional to the inverse of the hydrometeor characteristic size, which is an important geophysical parameter describing the entire distribution. Two datasets from two-dimensional microphysical probes, collected during aircraft flights in subtropical and midlatitude regions, were used to obtain Lambda by fitting measured size distributions. Reflectivity for different radar frequencies was calculated from microphysical probe data by using nonspherical-particle models. The derived relations have exponent d values that are approximately from -0.35 to -0.40, and the prefactors c are approximately between 30 and 55 (Lambda: cm(-1); Z(e): mm(6) m(-3)). There is a tendency for d and c to decrease when radar frequency increases from K-u band (similar to 14 GHz) toWband (similar to 94 GHz). Correlation coefficients between Z(e) and Lambda can be very high (similar to 0.8), especially for lower frequencies. Such correlations are similar to those for empirical relations between reflectivity and ice water content (IWC), which are used in many modeling and remote sensing applications. Close correspondences of reflectivity to both Lambda and IWC are due to a relatively high correlation between these two microphysical parameters. Expected uncertainties in estimating Lambda from reflectivity could be as high as a factor of 2, although estimates at lower radar frequencies are more robust. Stratifying retrievals by temperature could result in relatively modest improvement of Lambda estimates.

Resource type

document

Resource locator

Unique resource identifier

code

http://n2t.net/ark:/85065/d7rf5xjp

codeSpace

Dataset language

eng

Spatial reference system

code identifying the spatial reference system

Classification of spatial data and services

Topic category

geoscientificInformation

Keywords

Keyword set

keyword value

Text

originating controlled vocabulary

title

Resource Type

reference date

date type

publication

effective date

2016-01-01T00:00:00Z

Geographic location

West bounding longitude

East bounding longitude

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South bounding latitude

Temporal reference

Temporal extent

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End position

Dataset reference date

date type

publication

effective date

2017-09-01T00:00:00Z

Frequency of update

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Conformity

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version of format

Constraints related to access and use

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Use constraints

Limitations on public access

None

Responsible organisations

Responsible party

contact position

OpenSky Support

organisation name

UCAR/NCAR - Library

full postal address

PO Box 3000

Boulder

80307-3000

email address

opensky@ucar.edu

web address

http://opensky.ucar.edu/

name: homepage

responsible party role

pointOfContact

Metadata on metadata

Metadata point of contact