Global Mapping of Total Atmospheric Deposition in Support of Critical Loads: Results of a WMO Workshop

Transcription

1 Global Mapping of Total Atmospheric Deposition in Support of Critical Loads: Results of a WMO Workshop Silvina Carou WMO, Research Department 33 rd TaskForce Meeting of the ICP Modelling and Mapping 4-6 April 2017, Wallingford, UK

2 World Meteorological Organization Global Atmosphere Watch Workshop on Measurement-Model Fusion for Global Total Atmospheric Deposition (MMF-GTAD) February 28 March 2, 2017 World Meteorological Organization Geneva, Switzerland An initiative of GAW s Scientific Advisory Group for Total Atmospheric Deposition (SAG-TAD)

3 Global Atmosphere Watch Programme GAW is a programmeof WMO dedicated to the coordination and provision of reliable scientific data and information on the chemical composition of the atmosphere and its natural and anthropogenic change, and to help improve the understanding of interactions between atmosphere, the oceans and the biosphere. GAW svision for the next decadeisto growthe international network of high-quality observations across the global to local scales to drive highquality and impact science while co-producing a new generation of researchenabled products and services to strengthen climate, weather and air quality predictive capabilities; contribute to scientific assessments in support of environmental policy; reduce environmental risks to society and meet the requirements of environmental conventions. New GAW IP: published in February 2017

4 GAW Scientific Advisory Group for Total Atmospheric Deposition General goal is to provide a more comprehensive understanding and quantification of total atmospheric deposition at the global and regional scales, with emphasis on the harmonization of data and methods. Task to research measurement-model fusion methodologies to obtain total deposition estimates A Global Assessment of Precipitaton Chemistry and Depositionof Sulfur, Nitrogen, Sea Salt, Base Cations, Organic Acids, Acidity and ph, and Phosphorus (Vet et al., 2014)

5 Combined measurement-model global maps of atmospheric deposition Measurement ( ) Model (2001 Ensemble Mean) Vet et al A global assessment of precipitation chemistry and deposition of sulfur, nitrogen, sea salt, base cations, organic acids, acidity and ph, and phosphorous, Atmospheric Environment, 93:

6 MMF-GTAD Workshop Objective To review the state-of-the-science on Measurement-Model Fusion for Global Total Atmospheric Deposition and establish a GAW project for the purpose of generating global maps of total atmospheric deposition, important atmospheric gases, and particles

7 What is Measurement-Model Fusion? Data Assimilation Applied Retroactively Asch, Mark; Bocquet, Marc; Node, Maëlle Data Assimilation: Methods, Algorithms, and Applications. Fundamentals of Algorithms. Society for Industrial and Applied Mathematics, DOI: The simplest view is that it is an approach/method for combining observations with model output with the objective of improving the latter. we need to rely on models. But when models are not corrected periodically by reality, they can be of little value. Thus, we need to fit the model state in an optimal way to the observations, before an analysis or prediction is made. The comparison between model output and observations is performed by some form of optimization recall that we seek an optimal match between simulations of the model and measurements taken of the system that we are trying to elucidate. This optimization takes two forms: classical [variational] and statistical [sequential]. Classical optimization involves minimization of a positive, usually quadratic cost function that expresses the quantity that we seek to optimize. In most of the cases that we will deal with, this will be a function of the error between model and measurements in this case we will speak of least-squares error minimization. The second form, statistical optimization, involves minimization of the variability or uncertainty of the model error and is based on statistical estimation theory.

8 Measurement-Model Fusion of Total Atmospheric Deposition: Sweden and U.S.A Total Deposition of Sulfur Source: Alpfjord, H. and Andersson, C., Nationell miljöövervakning med MATCH Sverige-systemet -ny metodik, utvärdering och resultat för åren , Swedish Meteorological and Hydrological Institute, Nr Source: Schwede D. and Lear G., Atmospheric Environment, Volume 92, August 2014 and

9 MMF-TAD Approach Measured precipitation concentrations Modelled precipitation concentrations Measured air concentrations Modelled air concentrations Fusion method Fusion method Precipitation concentration maps Air concentration maps Wet deposition maps Total deposition maps Dry deposition maps Modelled dry deposition of unmeasured species Precipitation depth map Measured precipitation depth Fusion method Modelled precipitation depth Modelled dry deposition velocities

10 Participants Experts in: Ecosystem health (INI, INMS, GESAMP) Human health (WHO) Measurement-model fusion, data assimilation, objective analysis Ground-based gas, aerosol and wet deposition measurements Dry deposition Satellite observations and applications Global and regional modelling and evaluation Data management, analysis and distribution WMO/GAW Scientific Advisory Groups and Expert Teams

11 Workshop Structure Keynote speakers o Policy and Science drivers/clients (international biodiversity, critical loads, nitrogen, human health) Science presentations and panel discussions o Existing MMF-TAD projects and activities worldwide o Surface and satellite measurements o Global/hemispheric and regional modelling, evaluation and comparability (HTAP2, AQMEII3, MICS3, ECMWF/Copernicus) Breakout and Plenary Sessions o Is it feasible to create a MMF-GTAD project? o How, what, who, when and where?

12 Key conclusions: International policy and science drivers Ecosystem sustainability o UN Convention for Biological Diversity (Strategic Plan for Biodiversity and Aichi Target 8) o 2015 Sustainable Development Goals (targets and indicators) Biogeochemical cycles Nitrogen o International Nitrogen Management System o International Nitrogen Initiative Human Health o World Health Organization(WHO Air Quality Guidelines, Global Burden of Disease Assessment) o Global Platform on Air Quality and Health o Climate and Clean Air Coalition Climate Change o UN Framework Convention on Climate Change

13 Key conclusions: MMF-TAD projects Commonalities and differences in the existing national MMF-TAD projects. All approaches are retrospective and typically based on model reanalyses(except for the UK). Data assimilation or fusion methods involve the derivation of correlation lengths or radii of influence (different methods used). Assimilation is performed with concentrations (not fluxes) and dry deposition velocities and precipitation amounts need to be determined separately. High quality data sets with good temporal resolution at selected global and regional measurement sites are extremely valuable. An ensemble model approach is likely the best option; however, models in ensemble must be shown to perform to reasonable specifications.

14 Key conclusions: Measurements Need to extend the GAW measurement network into regions that are presently poorly covered. Organic nitrogen, ammonia, nitrogen oxides, iron (over the ocean) and dust deemed highest priority globally for measurement in new and/or existing networks. Publicly-available, integrated, high quality global data sets were identified as critical to the success of the MMF-GTAD Project. Need to establish consistency in methods for estimating/measuring dry deposition (e.g. a common inferential modelling framework) Satellite measurements and their products are evolving rapidly and should be included in future measurement-model fusion activities. All available measurements should be further exploited and understood.

15 Key conclusions: Modelling A significant body of chemical transport modelling work exists and is suitable for use in a future MMF-GTAD Project (including HTAP, AQMEII, EMEP, etc.). Some aspects of deposition modelling are still very uncertain, including land use and dry deposition schemes in models and emissions data. Need to better link land use/land cover to deposition in order to understand the sensitivity and response of receptors to deposition. Need to use new techniques (e.g. inverse modelling) to improve emissions, as well as satellite data as potentially valuable for small emission corrections (e.g., updating emission inventories to a more recent year) and for deducing natural sources. When providing the 'best estimate' of total (dry+wet) deposition, it is important at the same time to make uncertainty estimates and constrain the results.

16 Major Outcomes Agreement to establish a formal WMO/GAW MMF-GTAD Project, with initial focus on S, N and O 3. A plan for a three phase project: Phase 1 Short Term.MMF of existing 2010 ensemble global model results with existing data sets (HTAP, AQMEII). Products: comprehensive data set and model ensemble output files and gridded MMF maps. Phase 2 Medium Term. Stitching together existing and new regional/global MMF-TAD maps (Canada, USA, UK, Sweden, Norway, Asia, Europe) to produce global maps + a journal article Phase 3 Long Term. Ongoing operational re-analysis using data assimilation (ECMWF/Copernicus)

17 Major Outcomes (cont d) An Ad Hoc Data Group to investigate workload and needs for gathering data from existing science assessments/modelling activities Buy-in from major modelling and measurement groups including GAW Scientific Advisory Groups, and clear link to policy and science drivers Workshop Report (draft) A Roadmap to the Future Report

18 Relevance to this community Global maps of wet plus dry deposition, aerosolspecies and reactive gases are valuable for the assessment of ecosystem critical loads/levels and effects = important user group! Expertise/needs of this community to assist in the MMF-GTAD project. The atmospheric and ecosystem impacts communities need to work together to: improve dose-response functions and determine which atmospheric species are important to model and measure better match depositionschemes in CTMs to the receptors that are sensitive to the pollutants tune into the atmospheric and ecosystem process scale to look at different sources and sinks (feedback from ecosystems to the atmosphere)

19 Thank you Merci For more information / to get involved contact: Robert Vet(Robert.vet@canada.ca) or Silvina Carou(scarou@wmo.int) For workshop presentations and report go to ponmeasurementmodelfusion.html