Transcript 3-dimensional Animated Displays for Sifting Out Medium Range Weather

EMC
3-dimensional Animated Displays for
Sifting Out Medium Range Weather
Event Probabilities and Severe Weather
Using NCEP Model Ensembles
Jordan C. Alpert [email protected]
19th Conference on IIPS, 15.2, 83 Annual AMS Meeting, 9-13 February 2003, Long Beach, California
where the nation’s climate and weather services begin
Interactive Visualization of Animated
3-dimensional Model Data is a Reality!
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Display Three-Dimensions (D3D), Szoke, et. al., 2001 software
available for Advanced Weather Interactive Processing System
(AWIPS)...
Available for forecasters at Weather Forecast Offices (WFO)…
or
Vis5d, “visualization 5-dimensional”, meaning 3 space, time and
variable space, is an interactive visualization system created at the
University of Wisconsin (Hibbard, 1994) …
In use by the science, educational and by the atmospheric science and
NWP model research community.
The basic visualization capabilities of these systems are similar as D3D
was created from Vis5D.
3-dimensional Graphics:
Are there unique and useful views?
Forecasters
Can 3-d displays provide unique
and useful views of model
output that:
 distinguish them as an
indispensable tool,
 directly improve the ability of
forecasters,
 reduce the risk to weather
service customers and
commerce?
Researchers
Can 3-d views be used as:
tools to develop new products
that improve NWP science,
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an advantage or convenience
in model diagnostic studies to
show results not seen in 2-d
graphics?
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Here are a few examples that I think are interesting…
Visualization of Ensembles (Alpert & Brill, 1998)
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Each NCEP Ensemble contains 10 separate model
integrations with forecasts to 16 days at 6 hour intervals,
operationally displayed by thousands of 2-d images.
Consider the 3-d Vis5D (D3D) display of Ensembles, for
weather elements of height, pressure and precipitation,
Max/Min Temperature and other predicted variables.
For each weather element, arrange the ith ensemble component along
what is normally the vertical coordinate of the 3-d plane so that
moving in the vertical shows a different ensemble component.
One can then “slide” continuously through all the ensemble
components and render any weather element over any area. This is the
same as displaying each ensemble component map individually but
from a compressed data source with a quick and efficient process.
3-d can find the probability of any user
Selected Event and has the ability to “sift out”
high probability regimes when they occur.
 The ensemble components are stacked vertically and a 3-d iso-surface
may be drawn for a user selected event, e.g, >1/4” precipitation, less
than a freezing temperature or winds greater than gale force.
 The volume (of color) shown by the rendered iso-surface compared to
the total volume at a location, is the probability of a particular
forecasted event outcome at the given location and time.
 Animating the model forecasts in time will “sift out” areas and times
when the probability of an event is at a particular level (often a
forecaster will choose near 100% or 0%). This could be especially
useful in medium range forecasts.
 The probability calculation is only as good as the underlying ensemble
and model components. For height the error factor of when the
atmosphere is outside the ensemble cloud is 15-20% of the time.
A Severe Weather Proxy Unique to 3-d
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Great successes from model severe weather indicators such
as lifted index, CAPE, Helicity and other stability
measures.
A 3-d signature for severe weather is model predicted
convergence patterns in terms of their volume and depth
(vertical extent).
Qualitatively this method is competitive with stability
measures mentioned above.
Need to test the usefulness of this Hypotheses
quantitatively.
An automated verification system
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Observed ground truth is the Radar watch box text
messages (wwus60/kwns) containing the position of the
severe weather area.
Calculate the maximum height of a multiply connected
volume of convergence from the NCEP model.
When a volume outlined by 3x10-6sec-1 of convergence
extends to pressure levels greater than a critical height,
(say 500mb) severe weather is indicated.
Check the skill compared with the other skill measures for
intensity and distance (amplitude and phase errors) from
the Radar watch box.
Summary
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As NWP model resolution and physical parameterization
improves, forecasters can expect better definition of the
future state of severe weather activity.
Resource efficient animated 3-d displays of model
ensembles for probability predictions can aid in sifting out
predictable weather events and improve the ability of
forecasters.
Model predicted convergence patterns when viewed in 3-d
have the potential to be competitive with other stability
measures. Quantitative verification using observed Radar
watch box is under way.