GCOS - IGOS Cryosphere

STATUS REPORT ON THE KEY CLIMATE VARIABLES









TECHNICAL SUPPLEMENT TO THE
Second Report on the Adequacy of the
Global observing systemS for Climate (GCOS-82)







DRAFT*

version 2.7, 10 SEPTEMBER 2003






* THIS DRAFT COPY OF THE TECHNICAL SUPPLEMENT IS BEING MADE AVAILABLE VIA
THE GCOS WEB SITE TO ENSURE TIMELY ACCESSIBILITY TO ITS CONTENTS. ANY
COMMENTS OR SUGGESTIONS ON THE DOCUMENT ARE WELCOME AND CAN BE SENT
DIRECTLY TO THE GCOS SECRETARIAT (GCOSJPO@GATEWAY.WMO.CH).

SUMMARY

THE SECOND REPORT[1] ON THE ADEQUACY OF THE GLOBAL OBSERVING SYSTEMS FOR
CLIMATE WAS PREPARED IN RESPONSE TO UNFCCC DECISION 5/CP.5 AND ENDORSED BY
THE SUBSIDIARY BODY ON SCIENTIFIC AND TECHNOLOGICAL ADVICE (SBSTA) AT IT
15TH SESSION. THE GOALS OF THE REPORT WERE TO:
. Determine what progress has been made in implementing climate observing
networks and systems since the First Adequacy Report in 1998;
. Determine the degree to which these systems meet with scientific
requirements and conform with associated observing principles; and
. Assess how well these current systems, together with new and emerging
methods of observation, will meet the needs of the Convention.

The Report concludes that there have been improvements in implementing
global observing systems for climate, especially in the use of satellite
information and provision of some ocean observations. However, serious
deficiencies remain in the ability of global observing systems for climate
to meet the identified needs of the UNFCCC in that:
. Atmospheric networks are not operating with the required global coverage
and quality;
. Ocean networks lack coverage and commitment to sustained operation; and
. Global terrestrial networks remain to be fully implemented.

The key atmospheric variables required are surface air temperature (daily
maximum and minimum), precipitation (type, frequency, intensity, amount),
pressure, wind, humidity and surface radiation. The surface observing
networks of the World Weather Watch (WWW) Global Observing System (GOS)
provide the basis for a comprehensive network for all of these variables
except surface radiation. While observations of surface climate are
essential, detailed information on the three-dimensional state of the
atmosphere is necessary to ensure that we can understand and predict
climate on all scales. The specific variables of interest are upper-air
temperature, wind, humidity, clouds and the earth radiation budget. The
radiosonde network of the WWW/GOS provides the basis of a comprehensive
network for these variables.

The monitoring of the forcing of climate involves variables from natural
sources including solar irradiance and volcanic aerosols. It also includes
those anthropogenically-influenced atmospheric components of aerosols and
the greenhouse gases including carbon dioxide, methane, ozone and other
long-lived greenhouse gases. The Global Atmosphere watch (GAW) currently
has a network for determining the long-term trends in the meridional
distribution of non-reactive greenhouse gases, currently the network is
being enhanced to determine the global distribution of these non-reactive
greenhouse gases and to include the monitoring of certain short-lived
greenhouse gases and aerosols.

The key variables required to characterize the state of the climate and its
variability at the ocean-surface are sea-surface temperature (SST),
salinity, atmospheric pressure, winds, sea level, sea state, sea ice, ocean
currents, and ocean colour (for biological productivity), as well as the
air/sea exchange of water (precipitation, evaporation), momentum (wind
stress), heat and gases (especially CO2). The surface ocean networks for
these variables consist of satellites and in situ observational components.

The key variables required to characterize the three-dimensional state of
the oceans and their variability are temperature, salinity, ocean
circulation, ocean tracers, carbon, nutrients, and key ecosystem variables
such as phytoplankton. Ocean dynamic height, which is a derived quantity,
and sea level anomaly, which can be observed directly, are also important
measures of the state of the sub-surface ocean circulation.

Over 80 terrestrial variables have been identified as needing to be
observed to fully characterize the climate system. At present, technical,
economic and logistical constraints make measurements of all these
variables in baseline or comprehensive global networks impossible. Though
the terrestrial networks are the least integrated component of the global
climate observing system, progress is being made. Of the 80+ variables
required, river discharge, water use, ground water, lake levels, snow-
cover, glaciers and ice caps, permafrost and seasonally frozen ground,
albedo, land cover, Fraction of Absorbed Photosynthetically Active
Radiation (FAPAR), Leaf Area Index (LAI), biomass and fire disturbance have
been highlighted for early implementation because they are important for
climate, the technology to make adequate measurements is by-and-large
proven, and an infrastructure exists that could provide the measurements
operationally.

Satellites now provide the single most important means of obtaining
observations of the climate system from a near-global perspective and
comparing the behaviour of different parts of the globe. A global climate
record for the future critically depends upon a major satellite component,
but for satellite data to contribute fully and effectively to the
determination of long-term records the system must be implemented and
operated in an appropriate manner to ensure that these data are accurate
and homogenous.

This Technical Supplement provides additional material on the current
status of systematic observation for the Essential Climate Variables, as
defined in the Second Adequacy Report and listed below, as well as some
additional key variables. The report outlines the current state of
observation for each variable, data management issues and analysis
products, and identifies specific issues and priorities for action.


|Domain |Essential Climate Variables |
|Atmospheri|Surface |Air temperature, precipitation, air pressure, |
|c | |surface radiation budget, wind speed and |
|(over |Upper-air |direction, water vapour. |
|land, sea | |Earth radiation budget (including solar |
|and ice) | |irradiance), upper air temperature (including |
| |Compositio|MSU radiances), wind speed and direction, |
| |n |water vapour, cloud properties. |
| | |Carbon dioxide, methane, ozone, other |
| | |long-lived greenhouse gases, aerosol |
| | |properties. |
|Oceanic |Surface |Sea-surface temperature, sea surface salinity,|
| | |sea level, sea state, sea ice, current, ocean |
| | |colour (for biological activity), carbon |
| |Sub-surfac|dioxide partial pressure. |
| |e |Temperature, salinity, current, nutrients, |
| | |carbon, ocean tracers, phytoplankton. |
|Terrestria|River discharge, water use, ground water, lake levels, |
|l |snow cover, glaciers and ice caps, permafrost and |
| |seasonally-frozen ground, albedo, land cover (including |
| |vegetation type), fraction of absorbed |
| |photo-synthetically active radiation (FAPAR), leaf area |
| |index (LAI), biomass, fire disturbance. |







ESSENTIAL CLIMATE VARIABLES FOR GCOS:
CLICK ON THE HYPERLINKS TO GO TO THE ANALYSIS.




Atmosphere (M. Manton)

Surface variables
< Air temperature (P. D. Jones, T. Peterson)
< Humidity (P. D. Jones)
< Air pressure (R. Allan)
< Wind speed and direction (P. Groisman, E. Harrison)
< Precipitation (P. Arkin, B. Rudolf)
< Radiation budget (E. Dutton with B. Forgan)
Upper atmosphere variables
< Temperature (including MSU radiances) (D. Parker)
< Humidity (S. Schroeder with D. Siedel and B. Eskridge)
< Wind speed and direction (K. Trenberth)
< Clouds (K. Trenberth)
< Earth radiation budget (including solar irradiance) (J. Schmetz)
Atmospheric composition
< Carbon dioxide (P. Tans)
< Methane and other long-lived GHGs and halocarbons (CH4, N2O,
CFCs, etc.) (J. Elkins)
< Ozone (H. Claude)
< Aerosols (tropospheric and stratospheric) (U. Baltensperger with
F. McGovern, T. Nagajima, J. Ogren, V. Ramaswamy and M
Verstraete and P. McCormick)




Ocean (E. Harrison)

Surface variables
< Sea-surface temperature (E. Harrison)
< Sea-surface salinity (A. Clarke et al)
< Sea level (and sea level extremes) (J. Church with L. Fu and P.
Woodworth)
< Sea state (M. Holt)
< Sea ice (area, volume) (A. Clarke, R. Barry)
< Currents (surface and subsurface) (J. Gould, A. Clarke et al)
< Biological activity (including ocean colour) (T. Dickey, M.
Hood)
< CO2 partial pressure (for air-sea flux) (C. Sabine)
Sub-surface variables
< Upper ocean temperature (E. Harrison, J. Gould)