Concept of Uncertainty - Resources and NRC’s report Yuejian Zhu Ensemble Team Leader...
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Concept of Uncertainty - Resources and NRC’s report Yuejian Zhu Ensemble Team Leader EMC/NCEP/NWS/NOAA Presents for NWP Forecast Training Class March 30,
Concept of Uncertainty - Resources and NRCs report Yuejian Zhu
Ensemble Team Leader EMC/NCEP/NWS/NOAA Presents for NWP Forecast
Training Class March 30, 2015, Fuzhou, Fujian, China
Slide 2
Concept of Uncertainty Resources and NRCs Report Definition of
uncertainty Uncertainty is kind of natural Uncertainty is kind of
error Errors are from: Observation instruments Reading/recording
observations Initial analysis data assimilation Model physics and
parameterizations Computations Model developer: Using ensemble to
simulate the uncertainty maximally/accurately Find out analysis
uncertainty Find out model uncertainty (dynamic and physic)
Forecasters: Using ensemble information to make uncertainty
forecast Example 1: probability forecast Example 2: deterministic
forecast with uncertainty level Example 3: uncertainty forecast
Completing forecast US NRCs report fundamental education
material
Slide 3
X-Z PlaneX-Y Plane Power Spectrum Lorenz Equation ( Chaos in
ODE) The Lorenz model is defined by three differential equations
given the time evolution of variables X(t), Y(t), Z(t)
http://crossgroup.caltech.edu/Chaos_Course/Lesson1/Demos.html
Slide 4
Errors ?
Slide 5
Ensemble Forecast System Describe Forecast Uncertainty Arising
Due To Chaos Buizza 2002
Slide 6
Concept of Uncertainty Resources and NRCs Report Definition of
uncertainty Uncertainty is kind of natural Uncertainty is kind of
error Errors are from: Observation instruments Reading/recording
observations Initial analysis data assimilation Model physics and
parameterizations Computations Model developer: Using ensemble to
simulate the uncertainty maximally/accurately Find out analysis
uncertainty Find out model uncertainty (dynamic and physic)
Forecasters: Using ensemble information to make uncertainty
forecast Example 1: probability forecast Example 2: deterministic
forecast with uncertainty level Example 3: uncertainty forecast
Completing forecast US NRCs report fundamental education
material
Due to model imperfection One day advantage Earlier Ensemble
Forecast System
Slide 9
Concept of Uncertainty Resources and NRCs Report Definition of
uncertainty Uncertainty is kind of natural Uncertainty is kind of
error Errors are from: Observation instruments Reading/recording
observations Initial analysis data assimilation Model physics and
parameterizations Computations Model developer: Using ensemble to
simulate the uncertainty maximally/accurately Find out analysis
uncertainty Find out model uncertainty (dynamic and physic)
Forecasters: Using ensemble information to make uncertainty
forecast Example 1: probability forecast Example 2: deterministic
forecast with uncertainty level Example 3: uncertainty forecast
Completing forecast US NRCs report fundamental education
material
Slide 10
Ensemble Forecasts Deterministic forecast Initial uncertainty
Verified analysis Forecast probability
Slide 11
Real example for bimodality
Slide 12
12 2-m temp 10/90 probability forecast verification Northern
Hem, period of Dec. 2007 Feb. 2008 3-month verifications Top: 2-m
temperature probabilistic forecast (10% and 90%) verification red:
perfect, blue: raw, green: NAEFS Left: example of probabilistic
forecasts (meteogram) for Washington DC, every 6-hr out to 16 days
from 2008042300 90% 10%
Slide 13
Concept of Uncertainty Resources and NRCs Report Definition of
uncertainty Uncertainty is kind of natural Uncertainty is kind of
error Errors are from: Observation instruments Reading/recording
observations Initial analysis data assimilation Model physics and
parameterizations Computations Model developer: Using ensemble to
simulate the uncertainty maximally/accurately Find out analysis
uncertainty Find out model uncertainty (dynamic and physic)
Forecasters: Using ensemble information to make uncertainty
forecast Example 1: probability forecast Example 2: deterministic
forecast with uncertainty level Example 3: uncertainty forecast
Completing forecast US NRCs report fundamental education
material
Slide 14
Uncertainties & disagreements Ensemble forecast is widely
used in daily weather forecast
Slide 15
Map of PQPF and Precipitation Types: every 6 hours, 4 different
thresholds
Slide 16
16 Example of forecast precipitation (next 24 hours) (assume
all forecasts are bias free after bias correction or calibration)
MM/24hrs 25 0 50 75 100 Fcst 1Fcst 2 Fcst 3 50 deterministic 80%
mean Which forecast is relatively easier? Or more confident! Can we
identify all these information? probabilistic mean
Slide 17
17 Resolution makes difference for Typhoon Morakot Ini:
2009080600 T126 ensemble T190 ensemble Ini: 2009080700 T126
ensemble T190 ensemble Most models do not make right forecasts Is
this a good example for uncertainty forecast???
Slide 18
Typhoon Megi 2010101512 2010101612 20101017122010101812 1.NCEP
2.CMC 3.ECMWF 4.3-ENS Is this a good example to discuss forecast
consistency and accuracy?
Slide 19
00UTC 20121022 (8 days) Opr: T254L42 (55km) Opr: T254L42 (55km)
Para: T574L64 (33km) Para: T574L64 (33km) 06UTC Thick blue:
ensemble mean Bimodality? Red arrow means good forecast
Slide 20
Concept of Uncertainty Resources and NRCs Report Definition of
uncertainty Uncertainty is kind of natural Uncertainty is kind of
error Errors are from: Observation instruments Reading/recording
observations Initial analysis data assimilation Model physics and
parameterizations Computations Model developer: Using ensemble to
simulate the uncertainty maximally/accurately Find out analysis
uncertainty Find out model uncertainty (dynamic and physic)
Forecasters: Using ensemble information to make uncertainty
forecast Example 1: probability forecast Example 2: deterministic
forecast with uncertainty level Example 3: uncertainty forecast
Completing forecast US NRCs report fundamental education
material
Slide 21
Completing the Forecast Characterizing and Communicating
Uncertainty for Better Decisions Using Weather and Climate
Forecasts US NRC report (174 pages) The National Academic Press
2006 Coming soon in Chinese
Slide 22
Completing the Forecast Board on Atmospheric Sciences and
Climate Characterizing and Communicating Uncertainty for Better
Decisions Using Weather and Climate Forecasts
Slide 23
Task Provide guidance on how to identify and characterize needs
for uncertainty information among various users of forecasts.
Support this with examples of needs. Identify limitations in
current methods for estimating and validating forecast uncertainty,
relating these limitations to users needs and recommend
improvements or new methods and approaches. Identify sources of
misunderstanding in communicating forecast uncertainty, including
vulnerabilities dependent on the means of communication used, and
recommend improvements in the ways used to communicate forecast
uncertainty. Recognizing the breadth and depth of this task, NWS
advised the committee at its opening meeting to "teach us how to
fish as opposed to giving us a fish."
Slide 24
Report Contents Summary Introduction Uncertainty in Decision
Making Estimating and Validating Uncertainty Communicating Forecast
Uncertainty Overarching Recommendations
Slide 25
Recommendations The entire Enterprise should take
responsibility for providing products that effectively communicate
forecast uncertainty information. NWS should take a leadership role
in this effort. NWS should improve its product development process
by collaborating with users and partners in the Enterprise from the
outset and engaging and using social and behavioral science
expertise. All sectors and professional organizations of the
Enterprise should cooperate in educational initiatives that will
improve communication and use of uncertainty information. NWS
should develop and maintain the ability to produce objective
uncertainty information from the global to the regional scale.
Slide 26
Recommendations To ensure widespread use of uncertainty
information, NWS should make all raw and post-processed
probabilistic products easily accessible to the enterprise at full
spatial and temporal resolution. Sufficient computer and
communications resources should be acquired to ensure effective
access by external users and NWS personnel. NWS should expand
verification of its uncertainty products and make this information
easily available to all users in near real time. A variety of
verification measures and approaches (measuring multiple aspects of
forecast quality that are relevant for users) should be used to
appropriately represent the complexity and dimensionality of the
verification problem. Verification statistics should be computed
for meaningful subsets of the forecasts (e.g., by season, region)
and should be presented in formats that are understandable by
forecast users. Archival verification information on probabilistic
forecasts, including model-generated and objectively generated
forecasts and verifying observations, should be accessible so users
can produce their own evaluation of the forecasts.
Slide 27
Recommendations To enhance development of new methods in
estimation, communication, and use of forecast uncertainty
information throughout the Enterprise, and to foster and maintain
collaboration, confidence, and goodwill with Enterprise partners,
NWS should more effectively use testbeds by involving all sectors
of the Enterprise. The committee endorses the recommendation by the
NRC Fair Weather report to establish an independent advisory
committee and encourages NOAA to bring its evaluation of the
recommendation to a speedy and positive conclusion. NWS should
dedicate executive attention to coordinating the estimation and
communication of uncertainty information within NWS and with
Enterprise partners.
Slide 28
Key points not to forget Broad applicability within NOAA and
other agencies This will take time (turn the aircraft carrier) Lets
get started now NWS evolution - time is right to incorporate
uncertainty information into process Uncertainty is another
component of improving the forecast its not detached from the
primary mission of forecast improvement Uncertainty is not an
add-on it is in the nature of the product