1. Role of metrology in support of the long-term atmospheric composition observations Oksana Tarasova WMO, Research Department
WMO: Research Department

2. The context
Global climate change (and related ocean acidification) due to anthropogenic activity
Air Quality problem on a regional and local scale and related health impacts
Risks to food security due to air pollution
Impacts on ecosystems, soil and water pollution due to acid deposition
Stratospheric ozone depletion and related impacts
Many of these issues are addressed through environmental conventions and assessments are based on the OBSERVATIONS

3. Changing climate IPCC AR5 reinforces conclusions of AR4
Climate is changing
Greenhouse Gases are causing it
Increasing atmospheric CO2 drives ocean acidification and increase in radiative forcing
Emission reduction commitments have been made (through Intended Nationally Determined Contributions)
Key negotiation stage – COP21 in Paris in December 2015

4. Where do we go with climate (Options?)
Two or Three Degrees: CO2 Emissions and Global Temperature Impacts by Robert B. Jackson, Pierre Friedlingstein, Josep G. Canadell, and Robbie M. Andrew
“CO2 emissions are rising at a rate that could raise global temperature 2°C above preindustrial values within about 20 years and 3°C by midcentury.”
(The Bridge, 2015)

5. Risks in the urban environment
Recent estimates suggest that 7 million and 150,000 deaths, respectively, are attributable to fine PM and ozone (including indoor and outdoor air pollution)
Increasing exposure due to convergence of livelihood and properties into coastal megacities.
Urbanization and the growing needs of urban dwellers for new and improved climate, weather, water and related environmental services
The particular vulnerabilities of the urban setting
Acknowledging the wide range of urban relevant past and present initiatives within WMO and among Members
The need for an integrated approach for all weather, climate, water and related environmental components as also promoted in Doc 4.3(5) on joint research activities.
New UN Urban Agenda: UNHABITAT-III (2016)
Global map showing the location of urban agglomerations with 750,000-plus inhabitants projected for 2025 (derived from statistics in UN DESA Population Division, 2012).[IPCC AR5 WGII, Fig. 8-2]

6. Relative yields, crop production losses and economic cost losses:
Assessment of crop yield losses in Punjab and Haryana using two years of continuous in-situ ozone measurements
Relative yields, crop production losses and economic cost losses:
Relative yield losses: 21%-26%
Crop production losses: 3.2± ±1.2 million tonnes
Economic cost losses: 0.7± ±0.2 billion USD
New: RY= x AOT
Relative yield losses: 27%-41%
Crop production losses: 10.3± ±10.8 million tonnes
Economic cost losses: 2±1-4±2 billion USD
New: RY= x AOT
Enough to supply wheat and rice to million of India’s poor
Relative yield losses: 47%-58%
Crop production losses: million bales
Economic cost losses: billion USD
Research required
Relative yield losses: 3%-5%
Crop production losses: million tonnes
Economic cost losses: 3-4 million USD
New: RY= x AOT
The upper limit of the economic losses factoring in the influence of crop yields on the Nation’s GDP is 3.5%-20% of the Indian GDP
Mitigating tropospheric ozone levels would increase the income of > 54% of India’s population
B. Sinha, K. Singh Sangwan, Y. Maurya, V. Kumar, C. Sarkar, P. Chandra, and V. Sinha, Assessment of crop yield losses in Punjab and Haryana using two years of continuous in-situ ozone measurements. Atmos. Chem. Phys. Discuss., 15, , 2015 (Accepted for ACP)

7. Impacts on ecosystems 2001 ensemble-mean, 1O x 1O global S emissions
(from Global Precipitation Chemistry Assessment)

8. What is the GAW Programme?
Global Atmosphere Watch (GAW) Programme is a research programme based on a partnership involving contributors from 100 countries
GAW includes observational network, quality assurance system and expert groups to support diverse application areas through measurement and analysis activities
GAW focuses on atmospheric chemical composition and related physical parameters
GAW observations can be used to support climate studies, air quality forecasting, assimilation in NWP, ecosystem services, aeronautical services, food security and many others (different applications put different requirements to observing system).

9. GAW focal areas Stratospheric Ozone and vertical ozone distribution
Greenhouse Gases (CO2 and its isotopes , CH4 and its isotopes, N2O, SF6, CFCs)
Reactive Gases (O3, CO, VOC, NOx, SO2)
Total atmospheric deposition
Aerosols (chemical and physical properties, AOD)
UV Radiation
Different groups of variables were included in the programme during different periods, hence their understanding is in the different stage of maturity

10. Observations in GAW
GAW strives to implement “integrated” observing system including ground-based observations and satellite remote sensing integrated through models
Surface-based in situ and remote sensing observations are the backbone of the GAW network.
There are Global and Regional GAW stations and stations working within contributing networks.
Currently GAW coordinates activities and data from 30 Global stations, about 400 Regional stations, and 100 Contributing stations ( 10

11. Attributes of the GAW observations
Multi-national and multi-agency
Global in nature
Diverse in measurement approach (flask sampling, continuous, remote sensing techniques)
BUT:
Have to be comparable between countries
Have to be compared with and assimilated into the global models
Have to be compared with the satellite observations (one instrument per globe)

12. GAW’s Foundation - “Collecting adequate information on the chemical composition of the atmosphere and on the consequences of the anthropogenic impact on a global scale is valuable and possible only IF all the relevant measurements are expressed in the same units or on the same scale and IF data from the countries and at different sites are comparable”

13. QMF principles
Full support of the GCOS Climate Monitoring Principles
Network-wide use of only one reference standard or scale (primary standard). In consequence, there is only one institution that is responsible for this standard.
Full traceability to the primary standard of all measurements made by Global, Regional and Contributing GAW stations.
The definition of data quality objectives (DQOs).
Establishment of guidelines on how to meet these quality targets, i.e., harmonized measurement techniques based on Measurement Guidelines (MGs) and Standard Operating Procedures (SOPs).
Establishment of MGs or SOPs for these measurements.
Use of detailed log books for each parameter containing comprehensive meta information related to the measurements, maintenance, and 'internal' calibrations.
Regular independent assessments (system and performance audits).
Timely submission of data and associated metadata to the responsible World Data Centre as a means of permitting independent review of data by a wider community.

14. Complexity of the GAW approach
GAW has six groups of variables with completely different properties (long-lived gases, short-lived gases, total column, physical properties of aerosols, chemical properties of aerosols, chemical composition of aerosols and rain water)
Different variables allow for different traceability chain
Different groups express requirements in a different way
Within GAW Central Calibration Laboratories are responsible for long-term support of the network reference (standard or scale)

15. Role of NMIs in support of the GAW Central Calibration Laboratories (CCLs)
Variable
WMO/GAW CCL (non NMI)
WMO/GAW CCL
(supported by NMIs)
CO2
NOAA/ESRL
Included in MoU
carbon isotopes
MPI-BGC
CH4
N2O
CFCs, HCFCs, HFCs
Total Ozone
NOAA/ESRL(Dobson),
Environment Canada (Brewer)
Ozone Sondes
FZ-Jülich
Surface Ozone
NIST
Precipitation Chemistry
Illinois State Water Survey, Champaign IL, USA (ISWS) CO
VOC
NPL, NIST
SO2
NOx
CCQM
Aerosol
Optical Depth
Physikalisch-Meteorologisches Observatorium Davos/World Radiation Centre, Davos, Switzerland (PMOD/WRC)
UV Radiation
Solar Radiation
Physikalisch-Meteorologisches Observatorium Davos/World Radiation Centre, Davos, Switzerland(PMOD/WRC) H2
Is it enough to support the applications? Not completely…

16. An Integrated, Global, Greenhouse Gas Information System (IG3IS)
Over the next few years, governments will likely become more involved in efforts to limit atmospheric concentrations of greenhouse gases.
Changes in emissions will vary by location and type
Strategies will vary by nation, region, and economic sector
Many nations are already pursuing such activities and some are coordinating efforts.
Any large-scale emission reduction effort requires independent information to succeed.
A suitable information system would include
ground-based and space-based observations,
improvements in transport and carbon-cycle modeling,
fossil fuel-use, terrestrial trends, and oceanic processes,
information about sources and sinks of greenhouse gases at sub-continental, policy-relevant scales.
Despite some efforts to reduce emissions, greenhouse gases in the atmosphere continue to rise.
Focus on two main bullets here
GEO Carbon – Tarasova and Butler

17. Complexity of carbon cycle: complexity of measurements
Identification of sinks needs dedicated measurements
Knowledge of terrestrial and ocean sinks is essential for definition of anthropogenic contribution
Insufficient measurements of isotopes and co-emitted gases for source attribution

18. Ocean acidification
(Included in the 10th WMO Greenhouse Gas Bulletin, 2014)
Incompatible observations on different scales (e.g. global and local observations) and in different media (e.g. atmospheric observations vs. pCO2 observations)

19. Metrological challenges in support of climate application
Traceability of the GHG observations on different scales (regional and global measurements are traceable to WMO scale, urban observations not always)
Traceability of the isotopic measurements (current CO2 isotopic reference is based on artefacts, need for traceability of methane isotopes)
Traceability of the measurements made by different instruments and from different platforms (in situ, ground based remote sensing, satellite)
Observations in different media (ocean CO2)
Complex observations (e.g. flux measurements or O2/N2)
To properly address impact of atmospheric composition on climate one has to consider aerosols and short-lived climate pollutants

20. Importance of Aerosols
WMO
Atmospheric aerosols are critical in determining the absorption or reflection of heat by the Earth’s surface, clouds and atmosphere, as well as the formation of clouds and precipitation.
Aerosol studies have become a major research area and will be a principal component of next-generation climate- and weather-prediction models.
Aerosols are impacting climate and regional weather patterns, human health, state of ecosystems and agriculture, ocean productivity, transport security and many other important areas.

21. Aerosol characteristics
Physical Properties:              • particle number concentration (size integrated)              • particle number size distribution              • particle mass concentration (two size fractions)              • cloud condensation nuclei number concentration (at various super- saturations)        
Optical Properties:              • light scattering coefficient (various wavelengths)              • light hemispheric backscattering coefficient (various wavelengths)              • light absorption coefficient (various wavelengths)
Chemical Properties:              • mass concentration of major chemical components (two size fractions)
Column and Profile:                • aerosol optical depth (various wavelengths)                • vertical profile of aerosol backscattering coefficient                • vertical profile of aerosol extinction coefficient
Additional parameters recommended for long-term or intermittent observation:        • dependence of aerosol properties on relative humidity        • detailed, size segregated chemical composition.

22. Quality Assurance system for aerosol measurements
parameter
Central Calibration Laboratory
World Calibration Center
aerosol physical properties
missing
Institute for Tropospheric Research, Leipzig, Germany
aerosol chemical composition
aerosol optical depth (AOD)
Physikalisch-Meteorologisches Observatorium Davos/World Radiation Centre, Davos, Switzerland
In aerosols only methods comparisons and reference instruments are used. Reference materials are not used.
AOD standards is Precision Filter Radiometers (PFR)

23. GAWG Particle Workshop BIPM, 15th april 2015
Collaboration with Metrology community on aerosol reference materials
GAWG Particle Workshop BIPM, 15th april 2015
Several National Metrology Institutes (NMIs) have facilities and services that address the need for reference materials, and comparisons have recently taken place to evaluate levels of mutual agreement, and thus start the process of putting metrological traceability for aerosol measurements on the same basis as for gas analysis measurements.

24. Future Priorities for aerosol observations
Traceability of aerosol chemical composition measurements (critical for health, climate and ecosystem services applications), special emphasis on comparable black carbon/elemental carbon measurements
Establish traceability for aerosol particle size measurements, particularly coarse fraction > 500 nm
Establish connection between size distribution observations and filter methods (traceability of different measurement methods)
Lower priority for particle mass measurements. May change with future legislation in aviation and vehicle emission

25. Air quality and human health
GAW coordinates atmospheric composition observations under unpolluted conditions
New category of GAW local stations was introduced to link global atmospheric composition observations and measurements in the areas impacted by pollution sources
Major pollutants are included in GAW in the group of reactive gases
Different kind of measurement techniques (research vs cheap sensors) are used at the background stations and urban stations. Many sensors are very poorly characterized.

26. Quality Assurance for Reactive Gases
Central Calibration Laboratory
World Calibration Center
Surface Ozone
NIST
Empa CO
NOAA ESRL
VOC
NPL (NMHCs)
NIST (monoterpens)
IMK-IFU
SO2
NOx
IEK-8 (NO)
Traceability in for CO and VOCs is ensured via distribution of the gas standards by assigned CCLs and audits by WCCs at Empa and Karlsruhe Institute of Technology (IMK-IFU).
CO is part of the GHG Round-Robin campaign

27. Ecosystem services/ nitrogen cycle
Most of GAW focal areas address nitrogen species:
NO and NO2 are in Reactive Gases group
N2O is in GHG group
N containing ions in precipitations are in Total Atmospheric Deposition group
N containing ions in aerosols are in Aerosol Group
Issues:
NH3 is not a GAW parameter but it is the key element of nitrogen cycle
Traceability for aerosol chemistry and dissolved ions is not established
Some instruments measure NOy - how to establish traceability of such “lumped” measurements
Traceability of remote sensing

28. Water vapor
GAW Scientific Steering Committee decided to establish a task team to consider feasibility of the inclusion of water vapor as a chemical constituent in the GAW Programme
Stratospheric water vapor trends over Boulder (Hurst et al. JGR2011)
Lacis et al., 2013
Water vapor would require the same traceability as any other compounds included in GAW

29. General conclusions
The standards are required to ensure the traceability of measurements supporting carbon cycle (isotopic measurements, gases dissolved in water, flux measurements etc.)
Measurement compatibility between different environments (polluted vs background) has to be established
Additional standards are required for observations in the background atmosphere (stable standards at atmospheric levels) in particular for reactive gases.
There are number of the emerging measurement techniques in the area of atmospheric composition (for greenhouse and reactive gases), which need thorough checks and method uncertainty assessment. Experience of NMIs in the instruments and measurement methods characterization would be extremely valuable.
There is a substantial gap in the metrological support of aerosol observations. There are standards available only for a limited number of aerosol characteristics (e.g. AOD). The lack of international standards and proper characterization of the observational methods for the different aerosol parameters hampers the harmonization of the observational network.

30. Thank you for your attention