Transcript The important role of: continuity of observations and data products for IPCC Critical role for GCOS and WCRP Kevin Trenberth NCAR.

The important role of:
continuity of observations and
data products for IPCC
Critical role for GCOS and WCRP
Kevin Trenberth
NCAR
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Climate Observations
 Process studies: atmosphere, ocean, land,
cryosphere and their interactions
 Sustained observations: the climate record
 Enhanced monitoring
 Analysis, assimilation and data products
 Data stewardship, data access, QC
JSC 2010:
Observations white paper
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WOAP: Key climate issues
Climate data records
 Continuity, continuity, continuity;
 The need for reprocessing and reanalysis of
past data and coordination of these activities
among agencies and variables;
GRUAN,
GPS RO,or
 Includes evaluation and
assessment
CLARREO
results
 Importance of calibration, accuracy,
benchmarks,
 Space and in situ observations;
 Reanalysis to produce global gridded fields
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WOAP-1
Reprocessing: assess variables for need and readiness,
and commitments. Include in GEOSS.
5 Principles for Re-Processing Climate Data Records
For climate, the value of an observational record increases
with time, provided that the record is continuous and
homogeneous.
As datasets are used, characteristics of the data and
problems are exposed, and often solutions to problems or
algorithm improvements are proposed, especially for
satellite measurements.
Accordingly, re-processing of the record should be an
integral part of the process of creating a climate data
record.
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World Climate Research Programme
WCRP/GCOS
WOAP workshop: ESRIN, Frascati 18-20 April 2011
Evaluation of satellite climate datasets
identification of best practices in evaluating and intercomparing global climate datasets, especially where there
is more than one data set for a given parameter (e.g.,
surface temperature, sea ice concentrations, etc.).
Pentad
Daily
3 – 6 hrs
Available Global GEWEX+ Datasets
TIME
1979
1985
1990
1995
2000
Parameter
Clouds
50 km
Water Vapor
Precipitation
TOA Radiation
SRF Radiation
Evaporation
Atmospheric
Circulation
250 km
100 km
100 km
100 km
50 km
50 km
2005
2010
Large disparities among
different analyses
Daily SST (1 Jan 2007)
Reynolds and Chelton 2010 JC
Sea Level
OHC
Palmer et al 2010
OceanObs’09
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Total sea ice area, 2007 and 2008
NASA Team
NASA Team 2
SSM/I Bootstrap
AMSR Bootstrap
ASI
Cal/Val (York)
Bristol
Norsex
12
11
Area (106 square kilometers)
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Avg. of 8 algorithms
& ±1 st. dev. range
9
8
7
6
5
4
2007
2008
3
2
1/1
2/1
3/1
4/1
5/1
6/1
7/1
8/1
9/1
10/1
11/1
No single
algorithm
clearly
superior
12/1
Date
The largest factor for ice concentration/extent consistency is
intercalibration of the products through transitions through
different generations of satellite-borne sensors.
High Cloud Amount (July)
ISCCP
PATMOS-x
MODIS-ST
MODIS-CE
absolute values depend on
instrument sensitivity
& method,
but distributions similar
HCA (%)
AIRS-LMD
CALIPSO
CALIPSO
CALIPSO (t > 0.1)
AIRS_LMD
ISCCP
TOVS Path-B
(%)
Trends in LH Flux?
Reanalysis
1. Reanalysis is an essential part of climate
services, especially in monitoring, attribution
and prediction
2. Major problems remain from the changing
observing system
3. There is not a problem with lack of
reanalyses, but:
1. lack of an end to end program with adequate
vetting and evaluation of products (and the
funding for that), and
2. Reanalysis is all done in a research domain and not
sustained, so that key personnel can be lost.
3. Lack of adequate vetting and diagnosis
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Atmospheric Reanalyses
Current atmospheric reanalyses, with the horizontal resolution
(latitude; T159 is equivalent to about 0.8 ), the starting and ending
dates, the approximate vintage of the model and analysis system, and
current status.
Reanalysis
Horiz.Res
Dates
Vintage
Status
NCEP/NCAR R1
T62
1948-present
1995
ongoing
NCEP-DOE R2
T62
1979-present
2001
ongoing
CFSR (NCEP)
T382
1979-present
2009
thru 2009, ongoing
C20r (NOAA)
T62
1875-2008
2009
Complete, in progress
ERA-40
T159
1957-2002
2004
done
ERA-Interim
T255
1989-present
2009
ongoing
JRA-25
T106
1979-present
2006
ongoing
JRA-55
T319
1958-2012
2009
underway
1979-present
2009
thru 2010, ongoing
MERRA (NASA) 0.5
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Satellite Data Streams assimilated
Dec
TOVS
Feb
Jul
TIROS-N
Apr
Sep
Nov Oct
Feb
NOAA-6
NOAA-7
NOAA-8
May Jun Jul Oct
Jan
Nov
NOAA-9
NOAA-10
Dec
Sep
Nov
Jan
Sep Sep
Sep
NOAA-11
NOAA-12
Jun
NOAA-14
Jan
Dec
NOAA-15 Sep
ATOVS
NOAA-16 Nov
NOAA-17 Jul
NOAA-18
EOS Aqua
EOS Aqua
Oct
GOES-08
GOES
Sounders
Apr
Jul
GOES-10
Apr
Jun
F08
GOES-12
Jul
SSM/I
Nov
F10
Dec
Dec
F11
Jul
Nov
Dec
Dec
F13
May
F14
May
F15 Dec
Aug
78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08
The Changing Observing System
1973
77k/6h
1987
550k
1979– 77K Obs
324k
1973
every
6hrs
2006
4,220k
1987
– 550K Obs every
6hrs
1979 – 325K Obs every 6hrs
2006 – 4.2M Obs every 6hrs
NWP Forecast skill scores continue to improve
Reanalysis
Extratropical NH and SH forecasts: 12 month means plotted at last month.
Updated from Simmons and Hollingsworth 2002
SH skill became comparable to NH after about 2002!
Global mean precipitation
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Future needs: Observations and Analysis
 Observations: in situ and from space (that
satisfy the climate observing principles);
 A performance tracking system;
 Climate Data Records (CDRs)
 The ingest, archival, stewardship of data, data
management;
 Access to data
 Data (re)processing and analysis
 The analysis and reanalysis of the observations
and derivation of products,
 Data assimilation and model initialization
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World Climate Research Programme
Future needs: Models
 Data assimilation and model initialization
 Better, more complete models
 Assessment of what has happened and why
(attribution) including likely impacts on human
and eco-systems;
 Prediction of near-term climate change over
several decades: ensembles
 Statistical models: applications
 Downscaling, regional information
 Responsiveness to decision makers and users.
Role of WCRP
• The coordinated collection, analysis and reanalysis of
climate observations is required to describe the
structure and variability of the climate system.
• Observations give the basis for evaluating and
improving models, and models providing the framework
and impetus for deciding what observations to take.
• Special efforts required to obtain, analyse and
assimilate data from the new generation of
environmental satellites.
• Enables the generation of descriptions of states of the
coupled climate system consistent with all variables and
the physical framework provided by models, both for
prediction and for documenting the climate record.
Role of WCRP
 Advocate improved observations and analysis suitable for
climate (satisfying the GCOS Climate Monitoring Principles
to ensure continuity of record). This especially includes
those from space.
 Data set development: evaluating observations and
promoting global reprocessing and reanalysis. Develop new
products and datasets, analytical and diagnostic techniques,
high level derived products: for use in understanding and
analyzing climate variability and change, and for evaluating
models.
 Mechanisms and modes of variability in climate anomalies;
operational attribution, numerical experimentation in near
real time to allow reliable statements to be made not only
about what the state of the climate is, but also why it is the
way it is and the mechanisms involved.
Role of WCRP
 Data assimilation and analysis: initializing of coupled
models for prediction.
• Provide advice on best datasets for various purposes
(climatologies and time series) and their merits and
limitations. (Error bars are greatly needed.)
• High priority needs are to have assessments of
datasets for use in evaluating climate models, and
specifically those used in the AR5 IPCC report that
will participate in the CMIP5 activity
Role of WCRP
 Help improve and promote sound data stewardship,
including data archiving, management, and access.
This includes making sure that climate-related data
variables are reaching data archives, and that
standards are set for archiving new types of data.
 Help make data accessible and available e.g., through
the internet. Promote shared efforts for data
quality control.
Climate Information System
WCRP
Trenberth, 2008
WMO Bull
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Imperative:
A climate information system
 Observations: forcings, atmosphere, ocean, land
 Analysis: comprehensive, integrated, products
 Assimilation: model based, initialization
 Attribution: understanding, causes
 Assessment: global, regions, impacts, planning
 Predictions: multiple time scales
 Decision Making: impacts, adaptation
An Integrated Earth System Information System