4.1
GEBA
The Global Energy Balance Archive ( GEBA ) systematically stores
data on energy fluxes from around 1600 stations worldwide.
Energy fluxes at the earth’s surface largely determine global heat
transport and atmospheric circulation. To understand the climate
and climatic changes, therefore, a detailed knowledge of the
variations in the energy balance is essential.
Global measurements
The GEBA database holds about 250,000 records
of monthly mean energy fluxes measured at
1600 stations worldwide.
68
Klima_S68_69_GEBA.indd 68
The first version of the Global Energy Balance
Archive ( GEBA) database was implemented at
the ETH Zurich in 1988. In 1991, the database
was first made available to the global scientific
community. In 1994/95, GEBA was redesigned
and a large amount of data was added. The
6.3.2008 11:13:24 Uhr
Importance for GCOS
The data stored in GEBA serve a variety of important functions in climate research: (a) validating radiation products derived from satellite
data, (b) validating surface energy fluxes simulated by general circulation models, (c) studying absorption of solar radiation by clouds and
(d) evaluating the impact of aerosols released
from forest fires in equatorial regions. The longest energy flux data series come from European sites – Stockholm, Wageningen, Davos,
Potsdam and Locarno-Monti. At these five
stations, radiation measurements began before 1940. To date, observations have already
been analysed from 380 stations worldwide
with time series covering more than 40 years.
The GEBA energy balance components are of
fundamental importance in understanding other processes in the climate system (including
the cryosphere).
Global radiation at 10 European stations from the GEBA database
180
180
Changes in annual mean global ra-
170
170
diation at 10 European stations in-
160
160
cluded in the GEBA database where
150
150
radiation measurements are available going back at least 50 years.
140
140
The analysis shows that between
130
130
1960 and 1990 solar radiation at the
120
120
Earth’s surface declined by several
110
110
per cent (global dimming), and that
this trend has been reversed over
100
100
the past 10–15 years (global bright-
90
90
ening). The two longest data series
80
80
70
70
1920
International CENTRES
global radiation [ W/m2]
Annual means in W/m2
(Stockholm and Wageningen) show
an increase in global radiation of
1920
1930
1930
1940
Stockholm
St
Locarno-Monti
Lo
Taastrup
Taas
W
Wageningen
Wa
1940
1950
1950
1960
1960
1970
1970
1980
Hamburg
Ham
Toravere
To
Davos
Da
g
Hohenpeissenberg
Ho
1980
1990
1990
2000
Sodankyla
Potsdam
Mean
2000
2010
2010
about 20 W/m2 between 1922 and
1952 (Ohmura, 2006).
Poly. Mean
Responsibility
database is regularly updated, with great importance being attached to a series of quality
control procedures. The archive currently contains 250,000 records of monthly mean energy
fluxes measured at 1600 stations worldwide.
GEBA incorporates various energy balance
components, with a total of 19 different variables. These include, for example, global radiation, short- and long-wave radiation and turbulent heat fluxes.
It should be noted that the values have been
and are measured using different instruments.
In addition, at most sites, instruments have
been replaced over the years. Data consistency and details of changes in instrumentation
are integrated into GEBA as station history data
– an important element in data analysis.
Since November 1986, the Global Energy Balance Archive ( GEBA ) has been a World Climate Programme ( WCP ) project under the
lead of the World Meteorological Organiza-
tion ( WMO ), UNESCO and the International
Council for Science ( ICSU ). The database is located at the Institute for Atmospheric and Climate Science ( IAC) at the ETH Zurich.
Resources required
Continued operation of GEBA at the ETH Zurich
is no longer assured from 2008. Swiss GCOS
Office funding will be required to maintain and
regularly update the GEBA database and to ensure that it is readily accessible for the scientific community.
69
http://bsrn.ethz.ch/gebastatus
Klima_S68_69_GEBA.indd 69
6.3.2008 11:13:25 Uhr