Identification

Title

Biases in the mesoscale prediction of ceiling and visibility in Alaska and their reduction using quantile matching

Abstract

Short-range (2 h) predictions of ceiling and visibility obtained from version 4 of the Rapid Refresh (RAPv4) model are evaluated over Alaska using surface meteorological station data. These forecasts tended to overpredict the frequency of aviation-impacting ceilings in coastal areas by as much as 50%. In winter, this overforecasting bias extends into the interior of Alaska as well. Biases in visibility predictions were more complex. In winter, visibility hazards were predicted too often throughout the interior of Alaska (+5%) and not often enough in northern and western coastal areas (-20%). This wintertime underprediction of visibility restrictions in coastal areas has been linked to the fact that the visibility diagnostic does not include a treatment for the effect of blowing snow. This, in part, results in winter IFR visibilities being detected only 37% of the time. An efficient algorithm that uses quantile matching has been implemented to remove mean biases in 2-h predictions of ceiling and visibility. Performance of the algorithm is demonstrated using two 30-day periods (January and June 2019). The calibrated forecasts obtained for the two month-long periods are found to have significantly reduced biases and enhanced skill in capturing flight rules categories for both ceiling and visibility throughout much of Alaska. This technique can be easily extended to other forecast lead times or mesoscale models.

Resource type

document

Resource locator

Unique resource identifier

code

http://n2t.net/ark:/85065/d7f76gtd

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

2020-05-01T00:00:00Z

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