dennis d. mccarthy elements of prediction. why are we here? iers working group on predictions iers...
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Why are we here?Why are we here?
IERS Working Group on PredictionsIERS Working Group on Predictions Definitive user requirementsDefinitive user requirements Comprehensive look at prediction methodsComprehensive look at prediction methods Comprehensive look at new data setsComprehensive look at new data sets IERS Technical Note describing current state-IERS Technical Note describing current state-
of-the-art EOP prediction including of-the-art EOP prediction including requirements, methods, and data set requirements, methods, and data set information contentinformation content
Workshop Goal: Workshop Goal: Provide specific recommendations to Provide specific recommendations to
improve current techniques/IERS Products improve current techniques/IERS Products
History of Earth Orientation History of Earth Orientation PredictionPrediction
USNO began USNO began publishing predictions publishing predictions weekly in April, 1979weekly in April, 1979
Originally designed to Originally designed to improve Doppler improve Doppler satellite geodesysatellite geodesy
Original goal was 0.03” Original goal was 0.03” thirty days in advancethirty days in advance
Accuracy
Predictions 10 day 20 day 40 dayPolar Coordinates 0.0029" 0.005 0.0090"UT1-UTC 0.00072s 0.00208s 0.00563sCelestial Pole 0.0002" 0.0002" 0.0002"
Accuracy in 2009
In the next 30 years…?
Predictions 10 day 20 day 40 dayPolar Coordinates 0.012" 0.016" 0.027"UT1-UTC 0.0017s 0.0032s 0.0065s
Accuracy in 1979
30 Years Later
Input Data
Combination of Observations AstronomicalAstronomical
VLBIVLBI GPSGPS SLR/LLRSLR/LLR DORISDORIS
MeteorologicalMeteorological Oceanographic?Oceanographic? Geophysical?Geophysical?
Forecasts MeteorologicalMeteorological OceanographicOceanographic??
Information
Astronomical
Meteorological
Oceanographic
Geophysical
Accuracy
Polar Coordinates 0.00008"UT1-UTC 0.000057sCelestial Pole 0.0001"
Accuracy in 2009
In the next 30 years…?
Polar Coordinates 0.0020"UT1-UTC 0.00022s
Accuracy in 1979
30 Years Later
Limiting FactorsLimiting Factors
Systematic ErrorsSystematic Errors System stabilitySystem stability
Data availabilityData availability LatencyLatency
Constraints built into the input dataConstraints built into the input data
FormatsFormats
The Quest for the Holy Grail
"The High Mysterious Call" from: Rolleston, T. W. Parsifal, or the Legend of the Holy Grail retold from Ancient Sources
The Future?The Future? Develop robust software to
Combine data at the observation level
Adapt to changing systems Accept new contributions Accept streaming input
observations Use geophysical data? Provide sub-daily EOPs Provide real time analysis Be interactive Maintain reference system
stability
The Beginning of the Quest McCarthy, D. D., 1981, “On the adoption of a terrestrial
reference frame,” Reference coordinate systems for earth dynamics; Proceedings of the Fifty-sixth IAU Colloquium, Warsaw, Poland, September 8-12, 1980.
McCarthy, D. D. and Babcock, A. K., 1985, “The U.S. Naval Observatory C.O.R.E. (Combined solution for the orientation of the Earth) solution during project MERIT,” in Earth rotation and the terrestrial reference frame, I. I. Mueller (ed.) .
What should IERS provide to users?
Develop Model
Algorithm
Information
As tronomical
Meteorolog ical
Oceanographic
Geophys ical
?Test
Implement Model• Plots• Daily values• Sub-daily values• Mathematical Formulas
• Annual Values
Collect Information• User needs• Research
• Available Knowledge• Collect and analyze new observations
Disseminate ProductsE-mail Bulletins
Stored data
What Should IERS Provide to What Should IERS Provide to Users?Users?
What do users want?What do users want? Survey questionnairesSurvey questionnaires Product usageProduct usage Interactive feedbackInteractive feedback
What will users want in the future?What will users want in the future? Prediction of UT1-UTC will be more Prediction of UT1-UTC will be more
important if leap second disappears in 2019important if leap second disappears in 2019 Who will be the users of the future?Who will be the users of the future? What systems will be developed that What systems will be developed that
require predictions?require predictions? Dissemination processes in the futureDissemination processes in the future
General Requirements
One unique set of IERS prediction products
Easily accessible User friendly Reliable Meets users’ needs for
Accuracy Update frequency Spacing Prediction interval Metadata
Collect InformationCollect Information
Prograde Annual Wobble
Prograde Semi-annual Wobble
Atmospheric Tides
Precession
NutationsFree Core Nutation
1 2-2 -1Frequency in the Terrestrial Reference Frame (cycles per day)
2 3-1 0 1
0
Frequency in the Celestial Reference Frame (cycles per day)
POLAR MOTIONPOLAR MOTION
NUTATIONNUTATION
Po
wer
Ch
an
dle
r W
ob
ble
Frequency
Pow
er
annual
semi -annualsouthern oscillation
quasi-biennial oscillation
40-50 -day oscillations
monthly
fortnightly
atmospheric tidesdecade fluctuations
(from core?)
atmospheric modes
solid Earth and ocean tides
0.1 year-1
0.2 year-1
1 year-1
0.1 month-1
Observational Information
Survey of suitable Survey of suitable observational dataobservational data AstronomicalAstronomical MeteorologicalMeteorological OceanographicOceanographic HydrologicalHydrological GeophysicalGeophysical
Assessments of Assessments of likely future likely future observational data observational data
Develop ModelDevelop Model
Depends on prediction Depends on prediction interval and nature of interval and nature of prediction productprediction product Prediction for next 5 days? 30 Prediction for next 5 days? 30
days? decade?days? decade? Product provided hourly? Product provided hourly?
daily? annually?daily? annually? Statistical / physical ?Statistical / physical ? QualitiesQualities
AccuracyAccuracy Stability over timeStability over time Compatible with data likely to Compatible with data likely to
be availablebe available
Implement ModelImplement Model
Tables of dataTables of data Daily?Daily? Sub-daily?Sub-daily? Quarterly?Quarterly? Annually?Annually?
Mathematical models/formulas?Mathematical models/formulas? Rotation matrix elementsRotation matrix elements UpdatedUpdated
As data become available?As data become available? Hourly?Hourly? Daily?Daily?
Disseminate ProductsDisseminate Products
On-demandOn-demand E-mailE-mail Web siteWeb site BulletinsBulletins
The Future: Predictions about Predictions
Increasing demand for near real-time information
Improved observational data
Improved Earth Orientation Observations
Densified geodetic networks Improved analysis models Improved celestial reference
frameCIP
TIO
CIO
Earth Rotation Angle
The Future: Predictions about Predictions
Increasing demand for near real-time information
Improved observational data Increased geophysical input
Increased Geophysical Input
• Improved meteorological forecast datao Densified observational
networkso Longer forecast intervals
• Oceanographic data• Hydrological data• Additional geophysical
data?
The Future: Predictions about Predictions
Increasing demand for near real-time information
Improved observational data Increased geophysical input Near real-time observations
The Future: Predictions about Predictions
Increasing demand for near real-time information
Improved observational data Increased geophysical input Near real-time observations Changes to forecast model(s)
Changes to Forecast Model(s)
Adapt toAdapt to User needsUser needs Data accuracyData accuracy Data latencyData latency
Multiple models may be requiredMultiple models may be required
The Future: Predictions about Predictions
Increasing demand for near real-time information
Improved observational data Increased geophysical input Near real-time observations Changes to forecast model(s) Near real-time product updates Sub-daily spacing New Products
New Products
High quality with prediction intervals < few days Lesser quality for prediction intervals < 2 weeks Low quality quarterly predictions for special users Interactive NTP UT1
Next StepsNext Steps Establish user needsEstablish user needs Support oceanographic dataSupport oceanographic data Develop models to meet user needs, data Develop models to meet user needs, data
accuracy and latencyaccuracy and latency
Let’s Get Started
Workshop Goal: Provide specific
recommendations to improve current techniques/IERS Products