Review of 2006 GCOS Satellite Supplement

Review of 2006 GCOS Satellite supplement

Lawrence Flynn, NOAA

3.1.7. ECV Ozone

Ozone is the most important radiatively active trace gas in the stratosphere and essentially determines the vertical temperature profile in that region. The ozone layer protects the Earth's surface from harmful levels of UV radiation. Since the 1960s, stratospheric ozone has been monitored in situ by wet-chemical ozonesondes, and remotely by ground-based spectrometers. Since the late 1970s and 1980s, ozone has also been monitored by optical and microwave techniques from various satellites and ground-based stations. Atmospheric ozone amounts declined in the upper and lower stratosphere over the 1980s and 1990s, and remains at levels below those present in the 1970s and earlier, largely due to anthropogenic sources of halogens.

The following is required for this ECV:

Product A.7 Profile and total column of ozone

Benefits

Products will support monitoring and assessment of:

•the impact of the Montreal Protocol and its amendments on the anthropogenically-induced removal of stratospheric ozone

•the expected radiative influence of ozone on the climate system, and its role in the chemistry of the climate system

Target requirements

•Accuracy: 10% (troposphere), 5% (stratosphere)

•Spatial and temporal resolution: Horizontal: 5-50 km (troposphere), 50-100 km (stratosphere); Vertical: 0.5 km (troposphere), 0.5-3 km (stratosphere); 3-hourly observing cycle everywhere

•Stability: 1% (troposphere), 0.6% (stratosphere)

Requirements for satellite instruments and satellite datasets

FCDR of appropriate UV/VIS and IR/microwave radiances, for example through:

•Nadir UV/VIS instruments for total column and limited profile information

•Nadir IR sounding for profiles from lower troposphere to stratosphere

Supplemented by:

•Limb sounding in IR/UV/VIS from solar, lunar, and stellar occultation

•Limb sounding in IR/MW/UV/Vis from atmospheric emissions and scattered solar for profiles from upper troposphere to mesosphere

Fully achieving the target resolutions will require three low Earth orbit satellites, ideally in combination with five geostationary satellites.

Calibration, validation and data archiving needs

Comprehensive ground, ship-board, aircraft and balloon-borne measurements are required for calibration and validation, for example through:

•the NDACC (Network for the Detection of Atmospheric Change)

•the WMO GAW network of ground-based total column ozone measurements and profile measurements from ozonesondes

•the WMO GAW and NASA/SHADOZ ozonesonde global network

•the global networks of Dobson and Brewer instruments (and their operation in Umkehr mode) reporting to the WOUDC

•the MOZAIC/IAGOS commercial aircraft programme

Adequacy/inadequacy of current holdings

•Total column measurements provide largely adequate data record of gross change and fluctuations

•Profile information is sometimes of limited resolution and often lacking in long-term continuity

Immediate action, partnerships and international coordination

•Reprocessing of identified datasets by improved retrieval algorithms, especially with regard to instrumental biases, including effects of ageing in orbit

•TOMS and (S)BUV provide an established data record from the late 1970s onward. HIRS provides an additional possible long-term record, to be supplemented by present and future data from high spectral resolution IR sounders. IR data from operational geostationary satellites are also available. Shorter-term data records are provided by instruments such as MLS, GOME(-2), MIPAS, OMI, SCIAMACHY and TES

•Reprocessing of occultation datasets, such as from SAGE and HALOE

•In addition to the opportunity for reprocessed products from particular instruments or series of instruments, there is an emerging opportunity for provision of integrated products through data assimilation

•Continuous research and related intermittent observations are necessary to fully understand ozone chemistry in the troposphere and the stratosphere, including precursor trace gases

•Coordination by WCRP SPARC, IGBP IGAC, IGACO Ozone

Link to GCOS Implementation Plan

Activities identified here will contribute to GIP Actions 25 and 26, which call for the development and implementation of a plan for a comprehensive system for observing key atmospheric constituents, including their vertical profiles.

Other applications

•Use in NWP and air-quality forecasting

•Monitoring and assessment of UV-B exposure at the surface, with its effects on human health and the biosphere

•Monitoring and assessment of exposure to tropospheric ozone, with further effects on human health and agriculture

Ralph Ferraro, NOAA

The CMIS sensor is no longer an option, but there will be something similar forthcoming from the revamped NPOESS - DWSS; so I suggest references to CMIS be clarified or caveated somehow.
On page 21, there is a statement "...arrange for a TRMM...follow on...". This indeed is happening through the NASA/JAXA GPM (Global Precipitation Measurement) mission, which will be launched in 2013. So this statement should be updated.

Mark Dowell, JRC

1) General perspective across ECVs:

a)There need for a clear statement on the difference and applicability of the requirements in the Sat. Supplement (GCOS 107) and those provided in the WMO tables (under climate). The latter has the target, minimum and goal whereas the Sat. Supplement only has the target (??). I see different agencies using one-or-other of these in defining there programme requirements.

b)sometimes there is a feeling that the ECVs requirements are specified with different levels of stringency. Some being more conservative that others. If one looks at climate modelling from a holistic point of view it seems some of the requirements are too strict.

c)some clear traceability of where the requirements come from. I recently learned that the requirements supposedly cover a range of different climate science applications (i.e. climate modelling, climate trends, other climate applications). It would be useful to learn how they combine all of these to come up with the definitive requirements and maybe in some cases subdivide these per eventual application (see OCR example below).

2) From the OCR-VC perspective:

This is sometimes a bit confusing, it is our impression that sometimes the requirements are based on Water Leaving Radiances whereas in others it is based on Chlorophyll "a" concentration. Hopefully based on the new definition for the Ocean Colour ECV in the revision of the IP we can now provide more specific requirements. This would eventually be provided to GCOS through the IOCCG as the body providing scientific recommendations. I provide, attached, a VERY early draft of what we are working on. Please don't consider the content too much at this point, this is merely to illustrate that we will divide our recommendation per application area and distinguish between water leaving radiance and Chlorophyll.

Horizontal Resolution
Parameter / Units / GCOS 107 / WMO Tables / IOCCG Climate Model / IOCCG Trends / IOCCG Regional Mod
Ocean Colour - Water Leaving Radiance / mW·cm-2·µm-1·sr-1 / 1 km / 1 , 5, 100 km / 4 km
Chlorophyll "a" / mg.m-3 / 1 km / 1 , 5, 100 km / 4 km
Observation Cycle
Parameter / Units / GCOS 107 / WMO Tables / IOCCG Climate Model / IOCCG Trends / IOCCG Regional Mod
Ocean Colour - Water Leaving Radiance / mW·cm-2·µm-1·sr-1 / 1 d / 1, 1.5, 3 d / 1 d
Chlorophyll "a" / mg.m-3 / 1 d / 1, 1.5, 3 d / 1 d
Accuracy
Parameter / Units / GCOS 107 / WMO Tables / IOCCG Climate Model / IOCCG Trends / IOCCG Regional Mod
Ocean Colour - Water Leaving Radiance / mW·cm-2·µm-1·sr-1 / 5% / 5, 8.5, 25 % / 15%
Chlorophyll "a" / mg.m-3 / 5% / 5, 8.5, 25 % / 30%
Stability /Decade
Parameter / Units / GCOS 107 / WMO Tables / IOCCG Climate Model / IOCCG Trends / IOCCG Regional Mod
Ocean Colour - Water Leaving Radiance / mW·cm-2·µm-1·sr-1 / 1% / 1% / 2%
Chlorophyll "a" / mg.m-3 / 1% / 1% / 2%
Precision?? (probably not)
Parameter / Units / GCOS 107 / WMO Tables / IOCCG Climate Model / IOCCG Trends / IOCCG Regional Mod
Ocean Colour - Water Leaving Radiance / mW·cm-2·µm-1·sr-1
Chlorophyll "a" / mg.m-3

Manfred Gottwald, DLR-IMF

General comments:

•The traceability of data is not explicitly mentioned. This is especially important for higher level products (> level 2) and might be worth adding.

•Are there references for the sources of individual requirements on ECV accuracy, stability, etc.? If they exist adding them would be an asset.

•A few statements about the consistency of data sets and external inputs could be useful.

•Is it foreseen to add something on interdependency of ECVs?

Special remarks:

•Executive summary (table 1) and table 5 on page 4: since CH4 is not explicitly listed it might be worth considering including it in the list of ECVs in future (other GCOS/CCI documents mention it)

•Chapter 1.6.1 (page 5): A link between FCDRs and 'Product' (as used here) and the associated terms 'level 1, 2 or value added' in remote sensing ground segments could be useful.

•C.1 b (page 8): Requires on-ground measurements with better accuracy than spaceborne measurements. They also must provide better or equal spectral resolution than the instrument under investigation.

•Page 27 (immediate actions .....): Perhaps it's worth mentioning the possibility of data gaps, e.g. after ENVISAT and how to overcome this situation.

•Atmospheric Reanalysis (page 29): Consistency and interdependency of the data are critical, i.e.

-Are the data to be combined dependent on each other?

-Is it ensured that additional data add information?

-Are the auxiliary data (e.g. climatologies) consistent and independently derived from the data to be analyzed?

Dave Young, NASA

CLARREO related comments on Systematic Observation Requirements for Satellite-based Products for Climate – Supplemental Details to the GCOS Implementation Plan

General Comments:

The CLARREO mission is not focused on a single ECV, but will provide benefits across many of the areas identified in this document. There are several reasons for this:

1)The CLARREO suite of measurements is designed to provide an integrated view of the entire climate system. In particular, the CLARREO measurements are designed to provide information on the most critical but least understood climate forcings, responses and feedbacks associated with the vertical distribution of atmospheric temperature and water vapor, broadband reflected and emitted radiative fluxes, cloud properties, and surface albedo, temperature, and emissivity.

2)This approach deviates from the traditional deconstructionist method of understanding the parts to build the whole and takes an integrative approach that measures Earth system-level indicators and uses them to draw conclusions. CLARREO is not focused on instantaneous retrievals in the classic ECV sense. But it is focused on the goals of the creation of FCDRs of the ECVs that will be used to detect decadal scale trends in these variables.

3) Finally, CLARREO will be a significant cross-cutting component of the climate observing system due to the capability of providing a reference intercalibration standard in space. This with enable the ability to achieve the accuracy and stability goals of a wide range of ECVs that use the vis, NIR, and IR spectrum. In fact, CLARREO will provide a means to achieve accuracies sufficient to break the current reliance of the climate system on stability and overlap.

The CLARREO measurements address the following elements listed in section 1.2. (Basis provided by the GCOS Implementation Plan):

Characterize the state of the global climate system and its variability;
Monitor the forcing of the climate system, including both natural and anthropogenic contributions;
Support the attribution of the causes of climate change;
Support the prediction of global climate change;

Specific areas where CLARREO fits in the document:

Section 3.1.2 ECV Upper Air Temperature

Measurements from CLARREO

High-spectral resolution IR radiances for use in reanalysis and
GPS radio occultation;

Benefits related to CLARREO

“Monitoring and detection of temperature trends and variability in the troposphere and lower stratosphere”.
“Validation of climate models”
CLARREO will provide direct information on lapse rate and water vapor feedback

Accuracy

CLARREO’s goals is to produce accuracies of 0.1 K (k=3) for the IR radiances. This will enable trend detection through both the CLARREO data record as well as through providing a reference intercalibration of the IR sounders.

Section 3.1.3 ECV Water Vapor

Measurements from CLARREO

High-spectral resolution IR radiances for use in reanalysis and
GPS radio occultation;

Benefits related to CLARREO

“Determine radiative forcing due to water vapour and the nature of the water vapour feedback as greenhouse gases increase”
CLARREO will provide direct information on water vapor and lapse rate feedback on global, decadal scales
CLARREO will help address the stated accuracy and stability goals

Section 3.14 ECV Cloud Properties

Measurements from CLARREO

High-spectral resolution IR radiances for use in reanalysis
High-spectral resolution NIR/VIS radiances and reflectance

Benefits related to CLARREO

“Cloud feedback is considered to be one of the most uncertain aspects of projections of future climate, and is responsible for much of the wide range of estimates of climate sensitivity in climate models”
CLARREO will provide direct information of cloud feedback on global, decadal scales

The text states that the this ECV requires, “Long-term products: exploiting the operational meteorological satellites, combining at least two stable- low Earth orbit satellites, carrying VIS/IR imagers and infrared and microwave sounders, and five geostationary satellites, carrying VIS/IR imagers and some infrared sounding capability” and “Validation against active ground-based and space-based observations is needed”
CLARREO will provide the reference intercalibration for the VIS/IR imagers and IR sounders in order to achieve the accuracies needed for decadal scale FCDRs.

Section 3.16 ECV Earth Radiation Budget

Measurements from CLARREO

High-spectral resolution IR radiances for use in reanalysis
High-spectral resolution NIR/VIS radiances and reflectance

Benefits related to CLARREO

“Insight into the response of the system to changes in its forcing and feedbacks (due to changes in greenhouse gases and other factors)”

CLARREO will provide a decadal record of the global, integrated climate system over the full reflected and emitted spectrum.
CLARREO will provide improved calibration for CERES and its follow-on missions. The combination of CLARREO and CERES will be needed to derive decadal change in cloud feedback.

Section 1.6.1 Data Records and Products

Section 1.6.2 Accuracy, Stability and Resolution

“In this document, the term ““Fundamental Climate Data Record”” (FCDR) is used to denote a long-term data record, involving a series of instruments, with potentially changing measurement approaches, but with overlaps and calibrations sufficient to allow the generation of homogeneous products providing a measure of the intended variable that is accurate and stable enough for climate monitoring. FCDRs include the ancillary data used to calibrate them”

CLARREO will provide in-orbit, continual, long-term reference intercalibration to improve the accuracy of IR, NIR and vis imagers and sounders. This impacts a wide range of ECVs in terms of instantaneous accuracy, but more importantly, for accuracy stability and intercalibration across multiple instruments for long-term climate data records. CLARREO will contribute to the calibration goals of many ECVs including:

Upper air temperature
Water vapor
Cloud properties
Earth Radiation Budget
Albedo
Ocean Color
Aerosols
Leaf area index

Section 2 Cross-cutting needs – providing calibration to SI standards per GSICS

This is a main objective of CLARREO. The CLARREO mission design is based on the principles described under “C.1 Comprehensive and routine calibration of satellite instruments.” CLARREO is coordinating with GSICS on the use of CLARREO for reference intercalibration to provide traceable calibration to other space-based sensors.

CEOS SEO Response: Brian Killough, Shelley Stover

1.)GCOS-107 target requirements in section 3 are directed at in-situ and/or space observations. There is no way to allocate a single requirement attribute to space or in-situ. Therefore, a statement to this effect is needed in each of the “Target Requirements” sections. Also, suggest that a statement be included for each ECV in section 3 on state of the art in-situ availability. Explain to the space community what exists for in-situ observations and let them derive the goals for space instruments. Also, address key technology needs for each type of space instrumentation that would enhance a measurement.

2.)Emphasize to the space community, as in page 26 of the GCOS IP, that they should focus on using gap analyses to identify other missions/instruments to coordinate with to meet requirements, if necessary. In addition they should focus on using calibration data for various instruments, especially CLARREO, to increase accuracy of the measurement.

3.)Identify/suggest metadata standards that the space community should be using temporarily until Key needs 10 and 12 of the IP are fulfilled.

4.)Continually state in the IP that the space community needs to make measurements to SI standards but no specific standards are cited. Be specific in the Supplement and suggest to them what to use.

5.)Discuss cal standards and best practices for each measurement by instrument type. This information needs to be understood by instrument teams so they are consistent in design practices.

6.)Mention SCOPE-CM and the CEOS Climate Working Group to stress the importance of long term ECV generation. Suggest that each mission have an ECV generation plan which would entail the development of ECVs, including data processing, data assimilation with other instruments including calibration data, calibration standards, data storage, data availability, and ECV data storage. Furthermore, each ECV generation plan should follow a standard format set.

7.)Stress the importance of data access and availability. Missions/instruments must make the mission data products publicly available for others to use in generating ECVs. Discuss how data for ECVs may be used to generate another ECV or multiple ECVs. The data is also important for climate models and should be made freely available to the space community. Also discuss how analysis uncertainties and algorithms must be made available.

8.)Put out a call for the space community to work together in the generation of ECVs. Call for international coordination of ECV data generation centers and suggest a coordinating body organize this work (the CEOS Climate Working Group).

9.)Stress that international space agencies need to direct missions to have requirements on instruments/missions to provide standardized data to the user community and ECV data centers. Stress the need for a coordinating body to provide matchmaking for the instruments/missions. Possibly call for this body to provide a mission liaison to educate mission teams on standards, ECV data centers, etc.