GCOS Implementation Plan - WMO

Implementation Plan for the Global Observing System for Climate in Support of the UNFCCC
(2010 Update)
There is a record of ozone observation from space that extends back over more than thirty years. It
comprises both nadir UV and IR measurements and limb measurements in the spectral range from
the UV to the microwave. Combining data from the nadir sounders with the higher vertical resolution
data from limb sounders provides essential information on tropospheric ozone amounts. Established
capability exists to assimilate ozone data in operational NWP and reanalysis systems. Combination of
ground and satellite observations has provided unique information on the evolution of the Antarctic
ozone hole and global ozone trends. These datasets along with research-satellite measurements of
other species involved in ozone chemistry (chlorine and nitrogen compounds and water vapour) are
being used on a continuing basis in WMO/UNEP Assessments supporting the Montreal Protocol and
its Amendments. There is an ongoing need to extend and refine the existing data records and
integrated products, taking account of the biases seen between the datasets produced from the
various instruments.
Nadir measurements of ozone are set to continue for the foreseeable future from operational satellite
systems, but measurements of high vertical resolution profiles will cease under present plans when
the last of the current and near-future missions comes to an end in about 2015. Space agencies are
considering follow-on capabilities, but missions may not be in place in time to avoid a serious gap in
provision of this crucial type of data. Action A26 calls for continuation of vertical profile measurements
from space using limb sounding.
Action A32
Action: Continue production of satellite ozone data records (column, tropospheric ozone and
ozone profiles) suitable for studies of interannual variability and trend analysis. Reconcile residual
differences between ozone datasets produced by different satellite systems.
Who: Space agencies.
Time-Frame: Ongoing.
Performance Indicator: Statistics on availability and quality of data.
Annual Cost Implications: 10-30M US$ (Mainly by Annex-I Parties).
ECV – Aerosol Properties
In situ aerosol measurements are included in the WMO GAW observing programme, where the intent
has been to obtain measurements representative of the major geographical and exposure regimes,
including the Aerosols Robotic System (AERONET), the GAW Aerosol Lidar Observations Network
(GALION) and BSRN sites. In addition, several limited regional networks of measurements directly
related to aerosol properties are in place for addressing air quality and acidification issues, as well as
for supporting satellite system calibration and validation. Satellite measurements beginning with those
from AVHRR provide long-term information on aerosol optical depth, and recent dedicated aerosol
research missions are providing not only more accurate measurements of optical depth, but also data
on aerosol size, type and vertical profile.
Although there is an increasing amount of aerosol data available, more in situ and space-based
measurements are needed in both the troposphere and the lower stratosphere. A concerted effort to
integrate the available measurements of aerosol optical properties and to expand the measurements
has begun, and may be viewed as an important step in developing a concerted system for global
aerosol monitoring. The development and generation of consistent products combining the various
sources of data are essential. The physical and chemical composition of aerosols needs to be
routinely monitored at a selected number of globally-distributed surface sites. There is likely to be an
ongoing need for future operational capabilities for aerosol monitoring from space to be augmented by
research missions, and the strategy for an integrated international system for global aerosol
measurement from space needs developing. There is also an ongoing need for reprocessing of past
satellite observations using better calibration, cloud screening and aerosol microphysics to obtain a
historical record.
There is also an important source of long-term records on atmospheric aerosol abundance and
composition in glacial ice (see Actions C15 to C17). Joint measurements of cloud and aerosol
properties are required for quantifying aerosol-cloud interactions (see ECV Cloud Properties).
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