CCI project integration meeting, ECMWF, Reading, March 14-16, 2011 1

Michel Van Roozendael, BIRA-IASBMartin Dameris, DLR-PA

Ozone-cci

Content

• Adequacy of User Requirements

• User Requirements & Product Specifications

• Integrated perspective

• Uncertainties

• Needs for ECMWF data

CCI project integration meeting, ECMWF, Reading, March 14-16, 2011 2

Adequacy of User Requirements

- Is the URD consistent with CMUG/GCOS requirements? Yes, in the sense that it uses input from GCOS and CMUG

requirements Furthermore, these requirements are interpreted and

“translated” to requirements for the data products that will be created in the Ozone_cci project

- Sources used to determine User Requirements GCOS and climate modellers (CMUG).

Taking into account the WMO/IGACO vision of the integrated approach for ozone monitoring using satellite data, in-situ observations, and ground-based networks, in combination with model information

Responding to the GCOS requirement for FCDRs for ozone covering the period 1980-2010 to evaluate the processes controlling ozone-climate interactions and the evolution of the ozone layer

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User RequirementsInputs from GCOS (based on GCOS-107 report, 2006)

Accuracy 10 % (troposphere)20 % (stratosphere)

Horizontal resolution 5-50 km (troposphere)50-100 km (stratosphere)

Vertical resolution 0.5 km (troposphere)0.5-3 km (stratosphere)

Observation frequency 3-hourly

Stability 1 % (troposphere)0.6 % (stratosphere)

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User RequirementsInputs from GCOS (Jan 2011 draft update O3 reqs)

Variable/ Parameter

Application Horizontal Res (target)

VerticalRes (target)

Obs cycle (target)

Accuracy (target)

Stability (target)

Justification/ Source

total ozone trend, radiative forcing

20-50 km 4h 2%, 5DU <1% trends

tropospheric ozone column

trend, radiative forcing, climate chemistry interaction

20-50 km 4h 15-20% 1% radiative forcing

ozone profile troposphere

radiative forcing, climate chemistry interaction

100-200 km 1-2 km UT3-6 km

4h 10% UT20%

1% climate chemistry interaction

ozone profile stratosphere

radiative forcing, climate chemistry interaction

100-200 km 1-2 km LS3 km US

4h 3-8% 1% climate chemistry interaction

ozone profile mesosphere

Trends, climate chemistry interaction

100-200 km 3 km 4h 10-20% 1% climate chemistry interaction

User RequirementsInput on O3 requirements from CMUG

Ozone_cci User RequirementsRequirement table content/entries and scope

- Separate requirements for each of the 3 ozone products:

Total ozone column

Nadir-based ozone profiles

Limb-based ozone profiles

- User requirements include: Ozone data requirements

Data product requirements

Ancillary data requirements

- URD closely follows GCOS and CMUG requirements

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Ozone_cci User RequirementsRequirement table content/entries and scope

- The ozone data requirements consist of tables containing: Horizontal resolution Observation frequency Time period Accuracy Stability

- If applicable, distinction is made between driving research topics, geographical zone, and height range. A rationale is presented for the quantitative requirements, e.g. by reference to the contributing satellite instruments over the considered time period

- For each ozone product ancillary data requirements are defined including error characteristics, averaging kernels, a priori data, flags (e.g. detailed cloud and surface information), data format, conventions and basic visualization tools

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User RequirementsTotal ozone column requirements

Based on URD version 0.5

- Specify Achievable and Target requirements

Driving research topics, e.g.:

- Regional differences in evolution ozone layer

- Seasonal cycle and interannual profile variability

- Short-term variability

Quantity Geographical Zone

Tropics Mid-latitudes

Polar region

Horizontal resolution 20-100 km 20-50/100 km

20-50/100 km

Observation frequency 3 days 3 days 3 days

Time period 1980-2010 1980-2010 1980-2010

Accuracy ( evolution) 2% (7 DU) 2% (7 DU) 2% (7 DU)

Accuracy (variability) 3% (10 DU) 3% (10 DU) 3% (10 DU)

Stability (after corrections)

1-3% / decade

1-3% / decade

1-3% / decade

- Format: NetCDF; following CF conventions

- Error characteristics (random, systematic)

- Averaging kernels per pixel

- A priori data per pixel

- Flags (good; bad; uncertain; pixel type; snow/ice; sun glint; solar eclipse, S-Atl anomaly)

- Basic visualisation (browsable end products e.g. like temis)

- Cloud information (cloud fraction, height, albedo)

- Surface information surface albedo, (IR: emissivity)

- Level 1 not required

User RequirementsData and ancillary requirements for total ozone columns

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Based on URD version 0.5

Driving research topics e.g.

- Regional differences in evolution ozone layer

- Height dependence of evolution ozone layer

- Seasonal cycle and interannual profile variability

- Short-term variability

Quantity Height Range

Lower Stratosphere Middle Atmosphere

Horizontal resolution

100-300 km 100-300 km

Vertical resolution 1-3 km 3-5 km

Accuracy in height attribution

0.5 km 0.5 km

Observation frequency

3 days 3 days

Time period (1980-2010) – (2003-2010)

(1980-2010) – (2003-2010)

Accuracy ( evolution)

8 % 8 %

Accuracy ( variability)

15 % 15 %

Stability ..% / decade  ..% / decade

User RequirementsLimb-based ozone profiles

The lower stratosphere (LS) extends from the tropopause (defined as ozone > 150 ppbv) to about 25 km, and the middle atmosphere extends from about 25 to 60 km altitude.

- Format: NetCDF; following CF conventions

- Error characteristics (noise; smoothing; pointing acc.; a priori)

- Number of layers (optimized for accuracy)

- Averaging kernels per pixel

- Full covariance matrix per pixel

- A priori data per pixel

- Flags (good; bad; uncertain; cloud contamination; solar eclipse, S-Atl anomaly)

- Basic visualisation (browsable end products e.g. like temis)

- Cloud information per profile (cloud fraction, height)

- Temperature profile

- Level 1 not required

User RequirementsData and ancillary requirements for limb ozone profiles

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Do the PSD meet the needs of the CRG?

• Yes, it should: the PSD is being written under the leadership and explicit guidance of the Ozone_cci CRG

• The PSD builds upon the URD. It translates the demands listed in the URD into generic specifications for the 3 main ozone ECV products. Detailed specs for each instrument will be documented in the IODD.

• Ozone_cci products will be used by the CRG and examples of such applications are given in the PSD

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Integrated perspective

• How do we address the integrated perspective for consistency between ECVs?

• Take consideration of CCI guidelines for data format, error characterisation, RR, etc

• PSD specifications/requirements are given for ozone data products which are needed together with data products derived from global model systems, including CCMs and CTMs. Other ECVs (e.g. aerosol, water vapour) should naturally fulfil very similar requirements, e.g. with regard to spatial and temporal resolution. For the PSD of the Ozone_cci project we have defined those specifications on the basement of the currently available model systems.

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Uncertainties in products

• Specification of data characterization and error analysis is ongoing questionnaire distributed among EOST teams (KIT lead)

• Issues under review:• sampling, vertical/horizontal resolution, systematic & random

errors (terminology), instrument specific errors, precision estimate

• definition of a common error budget (terminology)

• error evolution, e.g. degradation, long-term behaviour/stability, quality flags

• averaging kernel data/covariance matrix

• horizontal averaging kernels (to be decided)

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Example: SCIAMACHY

Uncertainties in knowledge of stratospheric aerosols

Tangent height errors

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ECMWF data usage

Source of PT data

Product

retrieved climatology ECMWF

Operational ERA40 ERA-Interim

Total ozone X(1) X

Nadir ozone profile X(2) X(3)

SCIAMACHY limb ozone profile

X

MIPAS ozone profile X X(4)

GOMOS ozone profile

X

Assimilated ozone products

X(5) X(6) (X)

(1) the total ozone algorithm retrieves an effective ozone-weighted mean temperature. A priori T° profiles are taken from the TOMS v8 climatology.(2) default in KNMI algorithm(3) default in RAL algorithm(4) ECMWF data are used as a-priori in the inversion process(5) from year 2000 onward(6) ERA40 used for assimilation of data before year 2000. Switch to ERA-Interim is planned.

Current status of ECMWF data usage for Ozone_cci data product generation:

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Need for ECMWF reanalysis data

• ECMWF data are used in Ozone_cci for:• Retrieval algorithms, either as a-priori information or as ancillary

information (model parameters)

• Data assimilation tools

• Global chemistry/climate modeling

• Operational data are mostly used, but reanalysis data are planned to be used for assimilation of historical data sets

• There is “no pressing need” to incorporate reanalysis data into retrieval schemes (in some cases it is even out of scope of the project)

• Current baseline:• RR selection and prototyping based on current input data• confirm in the RR that ECMWF data are used consistently• use the "best", consistent reanalysis in the actual ECV production

phase

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