GLOBAL CLIMATE OBSERVING SYSTEM
ESSENTIAL CLIMATE VARIABLE - Aerosol |
| Domain | Atmospheric | Description | Atmospheric aerosols are minor constituents of the atmosphere by mass, but a critical component in terms of impacts on climate, and especially climate change. Aerosols influence the global radiation balance directly by scattering and absorbing radiation, and indirectly through influencing cloud reflectivity, cloud cover and cloud lifetime. IPCC (2013) identifies anthropogenic aerosols, including those formed following emissions of precursor species, as the constituents responsible for the greatest uncertainty in the radiative forcing of climate change in the troposphere since the pre- industrial era. [GCOS-195 4.7.5] |
| Sub-domain | Composition |
| Full Name | Aerosol |
| Satellite Signficant Contribution | Yes  |
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| GCOS Actions |
Action
Status* | Description | Who | Time Frame | Performance Indicator | Cost Implications |
A33
Cat-D | Develop and implement a coordinated strategy to monitor and analyse the distribution of aerosols and aerosol properties. The strategy should address the definition of a GCOS baseline network or networks for in situ measurements, assess the needs and capabilities for operational and research satellite missions for the next two decades, and propose arrangements for coordinated mission planning. | Parties’ national services, research agencies and space agencies, with guidance from AOPC and in cooperation with WMO GAW and AERONET. | Ongoing, with definition of baseline in situ components and satellite strategy by 2011. | Ongoing, with definition of baseline in situ components and satellite strategy by 2011. | 10-30M US$ (20% in non-Annex-I Parties). |
*GCOS-195 Status Categories:
Category A: Action completed, perhaps exceeding reasonable expectations. Very good progress on ongoing tasks.
Category B: Action largely completed according to expectation. Good progress on ongoing tasks.
Category C: Moderate progress overall, although progress may be good for some part of the action.
Category D: Limited progress overall, although progress may be moderate or good for some part of the action.
Category E: Very little or no progress, or deterioration rather than progress.
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| GCOS Products | |
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| CEOS Response | [A33 (A.10.1, A.10.2, A.10.3, A.10.4)]
2015 Update: Atmospheric aerosol was identified as an ECV by GCOS (2010) due to its important direct and indirect climate radiative forcing effects. The anthropogenic component of atmospheric aerosol is the most uncertain climate forcing constituent and the sign of its climate forcing is generally opposite to that of greenhouse gases. In the past two decades, significant advance in satellite and surface observations of aerosol optical and distribution properties (optical thickness, single scattering albedo, aerosol layer height, and aerosol extinction profiles) have been achieved due to dedicated aerosol observations from both space and surface.
Dedicated global satellite aerosol observations using multiple-spectral, -angles, and polarization retrieval techniques started in late 1990s and early 2000s from POLDER, SeaWiFS, MODIS, MISR, AATSR, GLI, OMI, etc (King et al., 1999) in order to better quantify aerosol loading (e.g., aerosol optical thickness), size parameter (e.g., aerosol angstrom exponent), aerosol type (e.g., dust and smoke), and absorbing characteristic (e.g., aerosol single scattering). CALIPSO lidar launched in the middle of 2000s on NASA A-Train constellation satellites (Winker et al., 2007) further added information of aerosol vertical distribution, such as aerosol layer height and aerosol extinction profiles. At the same time, GEWEX Global Aerosol Climatology Project (GACP) (Mishchenkoa et al., 2007) and NOAA aerosol climate data record (CDR) project (Zhao et al., 2008) reprocessed historical operational AVHRR satellite observations to generate more than 30-years aerosol climate datasets for aerosol trend detection. Dedicated satellite aerosol observations will continue and extend to next decade from both operational satellite missions (e.g., JPSS, GOES-R, EPS-SG, MTG) and research satellite missions (e.g., EarthCare, Sentinel- 4/5, PACE). NOAA CDR Program will incorporate both current and future satellite aerosol observations into its aerosol climate dataset so that the aerosol climate data record will be extended to over 50-years long.
Globally coordinated surface aerosol observations have also been enhanced greatly in recently two decades due to the establishment of AErosol RObotic NETwork (AERONET) program (Holben et al., 1997), which is a federation of ground-based remote sensing aerosol networks established by NASA and PHOTONS (PHOtométrie pour le Traitement Opérationnel de Normalisation Satellitaire) and is greatly expanded by collaborators from national/international agencies, institutes, universities, individual scientists, and partners. The program provides a long- term, continuous and readily accessible public domain database of aerosol optical, microphysical and radiative properties for aerosol research and characterization, validation of satellite retrievals, and synergism with other databases. The network currently contains more than 600 sites over the globe and imposes standardization of instruments, calibration, processing and distribution.
Both global observations and surface measurements dedicated to aerosol will be continued in parallel to next decade so that long term changes and variations of aerosol optical and distribution properties along with aerosol climate radiative forcing can be detected with less uncertainty and high confidence (Li et al., 2009).
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