The utility of long-term reconstructions with regional climate models Hans von Storch, Frauke Feser,...
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Transcript of The utility of long-term reconstructions with regional climate models Hans von Storch, Frauke Feser,...
The utility of long-term reconstructions with
regional climate models
Hans von Storch, Frauke Feser, Ralf Weisse and Lars
Bärring
The Third Workshop on Regional Climate Modeling for Monsoon System (RCM)17-21 February 2004, East-West Center, University of Hawaii, Honolulu,
The purpose of regional models is not to validate and improve them by making them more complex but to apply them in building of new knowledge about the real world.
Long term reconstruction
• Use of model SN-REMO (REMO + spectral nudging operating on wind above 850 hPa) – details, recall Feser‘s talk
• Forcing with NCEP re-analyses 1958-2002
• Gridding: 50 km• Time step stored: 1 hourly• Area: Europe• Data freely available
Quality of reconstruction
• Is difficult to assess since specific high-resolution analyses hardly exist.
• Comparison with local data always questionable.
• Use of „integrating“ variables such as storm surges and wave heights yield favorable results.
• Wind data likely of high quality over sea – not over land.
Marcos Garcia Sotilla, 2003
Assimilated into NCEP(Atlantic)
Not assimilated into NCEP (Ionic Sea)
Wind speed at two bouys
20-year return values of wind speed, * based on daily 1992-97 data (color codes)
Southern North Sea
Extreme wind speeds
* plus from station data in NL (numbers in black)
Insa
Mei
nke,
per
s. c
omm
.
Accuracy of ISCCP estimates: about 10%
Applications
1. Assessment of changing storminess 2. Storm surges 3. Ocean wave conditions 4. Long-range pollution –
examples: gasoline lead and benzapyren
5. Commercial applications – Wind energy planning and shipbuilding
6. Emergency planning – risk of coastal oil spills
Stormcount 1958-2001
Weis
se , p
ers
. co
mm
.
C/year
t t
High tides in Helgoland (SE North Sea) in January 1995
Try
gve A
spelie
n, G
KSS
Ess
elb
orn
, pers
. co
mm
.
The Helgoland case of wave conditions in Oct 1998
Buoy at 54o 9’ N, 7o 52’ E, depth 22m(data available 1.10.1998 – 20.10 1998, every 3 hours)
Radar (WAMOS) 54º10’N, 7º53’E, depth 7m(data available 9.10.1998-31.10.1998)
Model output vs radar and buoy measurements
Lid
ia G
asl
ikova,
pers
. co
mm
.
Significant wave height
Wave mean direction (coming from)
Comparison of significant wave height from ERS (Meteomer) and HIPOCAS hindcast for the Southern North Sea for 1993.
Comparison with Satellite Data
Ocean wave height
reconstruction Solid: HIPOCAS RCM/NCEP reconstruction
Dashed: WASA/DNMI SLP reconstruction
Red: Local observations
50%, 90%, 95% and 99%iles.
Estimatedlead emissions(from Pacyna and Pacyna, 2000)
1955
19951955
1975
deposition
Calculated depositions
1995
model estimate
Estimated lead depositions into the Baltic Sea, compared to analyses based on observational evidence
0
20
40
60
80
100
120
140
160
1982 1984 1986 1988 1990 1992 1994 1996
time [a]
lead
lo
ad [
t a
-1]
lead loads at Schnackenburg/D
simulated lead loads river Elbe
Estimated transport in the Elbe river
Further Applications• Assessment of oil drifts in case of coastal accidents
• Assessment of fatigue in ships and off-shore constructions (with FGS Flensburg)
• Planning of harbor constructions (Jade Port)
• Planning of off-shore wind energy (commercial)
• Assessment of coastal defense measures (ALR)
• Wave conditions in the Elbe estuary.
Ulrich Callies, GKSS
source
Conclusions
• Regional models can be used to reconstruct detailed weather in the past decades by downscaling global re-analyses.
• In particular information about marine wind can be used for assessing past developments and contemporary risk assessments.
Mean monthly
precipitation [mm/month]
for 1999.
REMO
Frauke F
ese
r, p
ers
. co
mm
.
NCEP