WMO/IOC/UNEP/ICSU
GLOBAL CLIMATE OBSERVING SYSTEM
______________
GCOS/WCRP
ATMOSPHERIC OBSERVATION PANEL FOR CLIMATE
SIXTEENTH SESSION
GENEVA, SWITZERLAND, 7 – 11 FEBRUARY 2011
AOPC-XVI
Doc. 7.3
(21.I.2011)
(Rev 1)
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Item 7.3
Status of a global observing network for aerosols
(Submitted by L.A. Barrie and S. Nickovic on behalf of GAW Aerosol SAG, chair J. Ogren)
Summary and Purpose of Document
To inform the panel of:
i.
progress since April 2009 in developing the components of an Integrated Global Aerosols Observing System (IGAOS) coordinated internationally within the framework of WMO-GAW;
ii.
planned activities in the next year.
ACTION PROPOSED
1. The Panel welcomed the progress made by WMO-GAW and the international community in coordinating global aerosol observations for climate. It noted three GAW aerosol meetings in 2010 at WMO Geneva, namely the GAW Aerosol LIDAR Observation Network (GALION) Workshop, 20-23 noon Sept.; the GAW Aerosol SAG meeting, 23noon-24 Sept.; and the IAGOS annual meeting, 29 Sept to 1 Oct, and recommended that the GCOS Secretariat provide appropriate support.
AOPC-XVI, Doc. 7.3, p. 2
Status of a global observing network for aerosols
1.
Following the IGACO strategy report suggestion (WMO TD. No. 1235; GAW report No. 159) that WMO should take a lead in implementing recommendations, the WMO-GAW programme was assigned, by the Fifteenth WMO Congress, the role of leading the implementation of IGACO and hence, an integrated global network for aerosols. The WMO-GAW Strategic Plan for 2008-2015 (WMO TD. No. 1384; GAW Report No. 172) assigns this task specifically to the Scientific Advisory Group for Aerosols (SAG-Aerosols) (
http://www.wmo.int/gaw). The components of an Integrated Global Aerosol Observing System (IGAOS) are shown in Figure 1.
Figure 1 Components of an integrated global aerosol observing system that is being implemented by the WMO-GAW programme. It is a system that fulfils many societal needs including those related to weather, climate, health and environment. Since aerosols are an essential climate variable, IAGOS is evolving as an important system of GCOS. It involves many players internationally including WMO, satellite agencies, European research infrastructure programmes, environmental agencies and, most importantly, national research and monitoring efforts.
The SAG-Aerosols is focussing on observational components and quality assurance/calibration and validation and data archival for climate research purposes. This document reports progress and implementation plans of relevance to climate.
2.
World Data Centres. Metadata related to aerosol measurements within GAW and its contributing networks is hosted by the GAW Station Information System (GAWSIS), while the data are archived by the World Data Centre for Aerosols (WDCA). WMO and the SAG-Aerosols are pleased to announce that as of January 2010 the WDCA was transferred through an MOU from JRC-ISPRA to NILU. The NILU effort is led by Kjetil Torseth and Marcus Fiebig, the latter having joined the SAG-Aerosols in conjunction with the transfer. The JRC-ISPRA is thanked for maintaining the centre for the past 15 years; the JRC manager and aerosol expert Julian Wilson will remain on the SAG.
AOPC-XVI, Doc. 7.3, p. 3
WMO-GAW and the SAG-Aerosols are pleased to announce the creation in July 2009 through an MOU between WMO and DLR of a WMO World Data Centre for Satellite observations (WDC-RSAT) at the German Aerospace Laboratory (DLR) in Oberpfaffenhoffen, Bavaria Germany. Aerosols are one focus of the centre which will develop for users a one-stop shop access portal to all satellite aerosol observations held by various data centres around the world. The SAG-Aerosols recommended that WDC RSAT engage in a close cooperation with other existing data centers for satellite observations. The WDC-RSAT leader is Michael Bittner and the WDC-RSAT aerosol leader and expert on the SAG-Aerosols is Thomas Holzer-Popp. A WMO-GAW endorsed workshop will be organized by WDC-RSAT at DLR in early 2011 to coordinate with users and major satellite aerosol archives in the world, such as ICAREWMO-GAW and its SAG-Aerosols are also pleased to announce the creation of a WMO World Data Centre for Satellite observations (WDC-RSAT) at the German Aerospace Laboratory (DLR) in Oberpfaffenhoffen, Germany.
3.
Global surface-based remote sensing of aerosol column properties with sun-photometry. The main focus of these measurements is the determination of aerosol optical depth (AOD) at different solar spectral wavelengths. While AOD is an optical measure for aerosol load, its spectral dependence allows fractional association of AOD to larger (radii >0.5μm) and smaller (radii <0.5μm) aerosol sizes. Coordination of observations of AOD and related variables (e.g. Ångström exponent, fine mode fraction) is progressing well.
A sub-group of the GAW SAG-Aerosols has been assisting in discussions between several major networks that were identified at a workshop on “A Global Surface-Based Network for Long Term Observations of Column Aerosol Optical Properties” in March 2004 hosted by the GAW World Optical Depth Research and Calibration Centre, PMOD (GAW Report # 162) or by the SAG-Aerosols later. These networks operate surface-based sun-tracking sun-photometers and some deliver data within 3-6 hours. They consist of: AERONET (NASA-Goddard based), GAWPFR (Davos-based), SKYNET (University of Tokyo-based) and an Australian Bureau of Meteorology regional network (B. Forgan). An additional AERONET-like network in China called CARSNET is also to be added. The AERONET infrastructure has proven to be extremely powerful to the user community, and from a user's perspective, coordination of existing networks for measuring aerosol column properties with those sampling complementary data (e.g. aerosol vertical profiles, in-situ samples or cloud properties) are highly desirable.
The SAG-Aerosols in April 2009 agreed that the metadata for all contributing AOD stations should be registered in GAWSIS, and that GAWSIS and WDCA should develop an interface page that will introduce this network to prospective users by describing the networks and their data bases, showing a global map of sites and noting the importance of AOD as a component of the integrated global aerosol observing system (Fig. 1). Discussions are underway between AERONET, SKYNET, and GAWSIS to exchange metadata. WDCA will host GAWPFR and Australian BOM AOD data and point to the data centres of AERONET and SKYNET.
A third international Filter Radiometer Comparison was held from 27 September to 15 October 2010 at Davos with the aim to establish traceability of AOD observations to the WORCC standards according to recommendation 6 of CIMO XIX session.
Discussions are ongoing with the EU GEMS/MACC projects to test the added value of using AOD observations from 100-150 locations around the world in models that currently assimilate only satellite aerosol observations in near real time or in reanalysis mode. Here, of added interest are sky radiance measurements by AERONET and SKYNET, which are used to infer column aerosol properties such as size-distribution and absorption AOD.
AOPC-XVI, Doc. 7.3, p. 4
4.
Aerosol LIDAR vertical profiling International coordination of a largely research-based consortium of regional networks is being done by the GAW Aerosol LIDAR Observing Network (GALION), whose implementation plan was the outcome of a workshop in Hamburg in 2006 kindly hosted by leaders of the European EARLINET project (WMO TD No. 1443 GAW Report No. 178). The specific objective of GALION is to provide the vertical component of this distribution through advanced laser remote sensing in a network of ground-based stations globally distributed. The aerosol properties to be observed will include the identification of aerosol layers, profiles of directly measured optical properties (backscatter and extinction coefficients at selected wavelengths, lidar ratio, Ångström exponents, particle depolarization ratios) and indirectly inferred properties (e.g., profiles of light-absorption and single-scattering albedo), aerosol type (e.g. dust, maritime, fire smoke, urban haze), and microphysical properties (e.g., volume and surface concentrations, size distribution parameters, refractive index). Observations will be made with sufficient coverage, resolution, and accuracy to establish a comprehensive aerosol climatology, to evaluate model performance, to assist and complement space-borne observations, and to provide input to forecast models of "chemical weather". Good progress has been made, including inclusion of GALION in GAWSIS as a GAW Contributing Network, and WMO-GAW hosted the 2nd GALION workshop, 20-23 September in Geneva, organized by Dr. Gelsomina Pappalardo and Prof. Raymond Hoff of the SAG-Aerosols. Ways to standardize and enhance the usefulness of GALION products were the focus.
5.
Surface In Situ Aerosol Observations: There is a growing number of stations globally that conform to the “WMO/GAW Aerosol Measurement Procedures Guidelines and Recommendations” established by the SAG-Aerosols in 2004 (WMO TD No. 1178; GAW report #153). Standard operating procedures for measurements of aerosol mass, light scattering, and light absorption are currently being finalized and will be published as GAW reports. New high mountain GAW observatories measuring aerosols have been announced for Bolivia and Mexico. The European EU-FP7 projects EUSAAR and its successor ACTRIS are providing a test-bed for development of future GAW procedures and guidelines, as well as developing fully integrated observations at 10 major sites and 10 developing sites in Europe. For instance, standardization of methods to measure elemental carbon and organic carbon in aerosols is being tested and compared with North American standards. In the next five years the ACTRIS project will produce recommendations for measuring aerosol chemical properties using the emerging technology of mass spectrometry. All of this activity is connected with the European Monitoring and Evaluation Programme (EMEP) including data management that is conducted for EUSAAR/ACTRIS by NILU.
Another benefit of the transfer of WDCA to NILU, and of the cooperation between GAW and EUSAAR/ACTRIS, is development of the capability of providing in-situ aerosol data in near-real-time to forecast models. Currently, light scattering data from 10 GAW and EUSAAR/ACTRIS stations are available at WDCA with less than three hours delay. That number is expected to grow to around 30 within the next year, with a comparable number of stations providing NRT light absorption data.
6.
Commercial aircraft aerosol observations: The European EC infrastructure project IAGOS, which developed an aerosol package for regular flights on Airbus aircraft operated by Lufthansa and other European airlines, is nearing completion. The transmission of near-real time data is being arranged with AMDAR in cooperation with the Observations Department of WMO. Also, aerosols are measured on two flights per month by a comprehensive gas and aerosol package flown on a Lufthansa commercial aircraft from Frankfurt to distant parts of the world under CARIBIC, a project that is part of IAGOS. L. Barrie of WMO chairs the advisory group of IAGOS. He and Geir Braathen jointly represent WMO in an IAGOS sub-activity on international liaison. The annual meeting of IAGOS was hosted by WMO-GAW in Geneva from 29 Sept to 1 October 2010.
AOPC-XVI, Doc. 7.3, p. 5
7.
Satellite Observations:
GAW Aerosols SAG members are involved in advising ESA on how to implement measurements of aerosols for climate in the future.
Also, the WMO Sand and Dust Warning Advisory and Assessment System (SDS-WAS) is a particularly strong user sector for IGAOS through its need for observations in prediction and assessment (
http://wmo.int/sdswas ). There are currently approximately thirteen forecast/analysis modelling groups coordinated under two nodes; one for Northern Africa, Europe and Middle East served by the Barcelona super-computing centre and one for Asia served by the China Meteorological Administration in Beijing. An ESA/WMO Expert Consultation Meeting For Development of Satellite Products Relevant to Sand and Dust Storm Prediction and Assessment was held in Barcelona, Spain September 8-9, 2009. Twenty-seven experts from the sand and dust community (BSC, WMO), meteorological organizations (CMA, UKMO), ground-based community (AEMet, UMBC), satellite retrieval (DLR, FMI, Harvard U., KNMI, NASA, NILU, U. Lille), and modelling communities (BSC, ECMWF, LSCE, NASA, TNO, UKMO) participated in the meeting. Topical sessions were followed by a discussion leading to the formulation of requirements for satellite products in support of SDS-WAS. In turn, this has resulted in a 1 MEuro call for proposal for an ESA/DUE project to develop satellite products for sand and dust aerosols (see
http://dup.esrin.esa.it/news/news191.asp).
8.
Planned coordination activities The GAW SAG-Aerosols met 23-24 September 2010 in Geneva following the GALION workshop (see parag. 3 and 4 above). They discussed all aspects of an Integrated Global Aerosol Observations System (Fig.1) led by WMO-GAW and in particular, the development of an implementation plan. The GCOS AOPC will play an important role in reviewing this plan and in advising and assisting in implementation tasks.
A third international Filter Radiometer Comparison was held from 27 September to 15 October 2010 at Davos Switzerland for establishing traceability of AOD observations to the WORCC standards according to recommendation 6 of the WMO CIMO XIX session.
