Identification

Title

Response time characteristics of the fast-2D optical array probe detector board

Abstract

Two-dimensional optical array probes are commonly used for imaging raindrops and ice particles on research aircraft. The ability of these probes to accurately measure particle concentration and size partly depends on the response characteristics of the detection system. If the response characteristics are too slow, then small particles are less likely to be detected and the associated effective sample volume decreases. In an effort to better understand the sample volumes of optical array probes at the National Center for Atmospheric Research, the temporal response of the Fast-2D optical array probe detector board from optical input on the detector to digitization was characterized. The analysis suggests that the board electronics have a response time constant consistently near 50 ns. However, there is also a slow decay term that conforms to a 1/root t decay rate. The amplitude of this slow function can impact the probe response, varying the minimum detectable pulse width between 60 and 150 ns. Also, the amplitude of the slow function is largely dictated by the illumination angle of incidence. The effects of the response time characteristics are analyzed using a simulator for a 2D cloud (2D-C) probe with 25-mu m photodiode spacing. The results show the greatest sensitivity to response time characteristics when particles are smaller than 150 mu m, where 10% uncertainty in the slow fraction is likely to produce sample volume uncertainties near 10%. Ignoring response time effects may bias sample volume estimates in the small size regime by as much as 25%.

Resource type

document

Resource locator

Unique resource identifier

code

http://n2t.net/ark:/85065/d7tf003d

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

North bounding latitude

South bounding latitude

Temporal reference

Temporal extent

Begin position

End position

Dataset reference date

date type

publication

effective date

2016-12-01T00:00:00Z

Frequency of update

Quality and validity

Lineage

Conformity

Data format

name of format

version of format

Constraints related to access and use

Constraint set

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