Global Change Abstracts The Swiss Contribution - SCNAT

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resolution of the snow scheme, and autumnal
runoff from the Mediterranean part of the Rh ne
is sensitive to the spatial resolution of precipitation.
Journal of Hydrometeorology, 2007, V8, N5, OCT,
pp 1002-1015.
08.1-68
Direct assessment of international consistency
of standards for ground-level ozone: strategy
and implementation toward metrological
traceability network in Asia
Tanimoto H, Mukai H, Sawa Y, Matsueda H, Yonemura
S, Wang T, Poon S, Wong A, Lee G, Jung J Y,
Kim K R, Lee M H, Lin N H, Wang J L, Ou Yang C F,
Wu C F, Akimoto H, Pochanart P, Tsuboi K, Doi H,
Zellwegern C, Klausenn J
Japan, Peoples R China, South Korea, Taiwan,
Switzerland
Meteorology & Atmospheric Sciences , International
Relations
An international exercise to directly assess consistency
of standards for ground-level ozone in
East Asia was conducted as part of the East Asian
Regional Experiment 2005 (EAREX 2005) in the
framework of the Atmospheric Brown Clouds
(ABC) project. Ten organizations collaboratively
participated in the intercomparison. Four groups
representing Japan, Korea, Hong Kong, and Taiwan
made comparisons at the Gosan super observatory,
Jeju Island, Korea, in March 2005, with
ozone instruments calibrated to their national
standards, and four Japanese groups made off-site
comparisons with laboratory-level standards. All
comparisons generally indicated good agreement
with the standard reference photometer (SRP) 35,
built by the National Institute of Standards and
Technology (USA) and maintained by the National
Institute for Environmental Studies (Japan). The
assessment was expanded to measurement networks
contributing to the World Meteorological
Organization’s Global Atmospheric Watch (WMO/
GAW) program as part of off-site comparisons,
and excellent agreement was achieved. These efforts
contribute to propagating traceability of the
national metrology standards among the atmospheric
science community, to ensuring comparability
of the existing ozone measurements, and to
establishing an integrated network of air quality
monitoring in Asia.
Journal of Environmental Monitoring, 2007, V9,
N11, pp 1183-1193.
Global Change Abstracts – The Swiss Contribution | Atmosphere
08.1-69
The influence of a weakening of the Atlantic
meridional overturning circulation on ENSO
Timmermann A, Okumura Y, An S I, Clement A,
Dong B, Guilyardi E, Hu A, Jungclaus J H, Renold
M, Stocker T F, Stouffer R J, Sutton R, Xie S P, Yin J
USA, South Korea, England, France, Germany,
Switzerland
Oceanography , Meteorology & Atmospheric Sciences
, Modelling
The influences of a substantial weakening of
the Atlantic meridional overturning circulation
(AMOC) on the tropical Pacific climate mean state,
the annual cycle, and ENSO variability are studied
using five different coupled general circulation
models (CGCMs). In the CGCMs, a substantial
weakening of the AMOC is induced by adding
freshwater flux forcing in the northern North
Atlantic. In response, the well- known surface
temperature dipole in the low- latitude Atlantic
is established, which reorganizes the large- scale
tropical atmospheric circulation by increasing
the northeasterly trade winds. This leads to a
southward shift of the intertropical convergence
zone (ITCZ) in the tropical Atlantic and also the
eastern tropical Pacific. Because of evaporative
fluxes, mixing, and changes in Ekman divergence,
a meridional temperature anomaly is generated
in the northeastern tropical Pacific, which leads
to the development of a meridionally symmetric
thermal background state. In four out of five CGC-
Ms this leads to a substantial weakening of the
annual cycle in the eastern equatorial Pacific and
a subsequent intensification of ENSO variability
due to nonlinear interactions. In one of the CGCM
simulations, an ENSO intensification occurs as
a result of a zonal mean thermocline shoaling.
Analysis suggests that the atmospheric circulation
changes forced by tropical Atlantic SSTs can
easily influence the large- scale atmospheric circulation
and hence tropical eastern Pacific climate.
Furthermore, it is concluded that the existence of
the present- day tropical Pacific cold tongue complex
and the annual cycle in the eastern equatorial
Pacific are partly controlled by the strength of
the AMOC. The results may have important implications
for the interpretation of global multidecadal
variability and paleo- proxy data.
Journal of Climate, 2007, V20, N19, OCT, pp
4899-4919.