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User experience with extended range forecasts -- climatic aspects of ECMWF products. Christof Appenzeller Wolfgang Müller Heike Kunz Mark Liniger ERA-40 compared to Swiss observations Verification of seas. forecasts monthly forecasts in electricity market seas. forecasts in media.
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User experience with extended range forecasts-- climatic aspects of ECMWF products Christof Appenzeller Wolfgang Müller Heike Kunz Mark Liniger ERA-40 compared to Swiss observations Verification of seas. forecasts monthly forecasts in electricity market seas. forecasts in media
ERA-40 T2 Upscaling ZERA-40 - ZSchw.Stat. ~ 40m
Temperature: ERA-40, Swiss Stations Temperature difference: ERA-40 – Swiss Stations 1.2 16 14 0.8 12 10 0.4 DT[°C] Temperature[°C] 8 6 0.0 4 2 -0.4 0 - 2 -0.8 JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC ERA-40 T2 seasonal Cycle • ERA-40 in Summer 0.8°C too high • ERA-40 in Winter 0.4°C too low
ERA-40 & GPS IWV: Correlation Morland et al., submitted
IWV: Height dependent bias Morland et al., submitted
System 2: Climate variability DJF North Atlantic Oscillation (NAO)EOF Z500 ERA-401959 - 2001 System 2Nov. Fcsts.1987 - 2001 Müller et al. (2005), Clim. Dyn.
Predictability of NAO regression of Z500 fields Müller et al. (2005), Clim. Dyn.
Impact of climate variability DJF North Atlantic Oscillation (NAO)SVD Z500 & T2m ERA-401959 - 2001 System 2Nov. Fcsts.1987 - 2001 Müller et al. (2005), Clim. Dyn.
Predictability of NAO Impact regression of T2m fields Müller et al. (2005), Clim. Dyn.
Verification grid point against ERA-40 Perfect model approach RPSSdT2m, 1987 – 2002, fc234, 3 cat. Schwierz et al., subm.
extended range forecast products at MeteoSwiss Klimagramm • seasonal forecasts • T2m, Precip. • Klimagramms • probability maps • monthly forecasts • T2m, Precip, Geopot. • tercile maps
temperature anomaly months Probabilistic Downscaling Weather risk application Seasonal Forecast local weather risk
Electricity Market • Electricity company in Southern Switzerland • Monthly forecasts
T2 Zurich Contracts for peak load in week 12 (21.-27.3.2005) EEX Eu/MWh lowermost tercile % Lead time Using monthly forecasts • Contracts at EEX (European Energy Exchange) • Lowermost tercile for S-Germany (spatial avg). • persistence? • other forecasts? • ?
Klimagramm for Swiss-Temperature Summer 2005 in Switzerland ProbabilityT2m > norm
Media Basis • MeteoSwiss does not intend to publish seasonal forecasts for Switzerland. • Public presentation of Swiss climate research programme. Interview • Probability of Temperature in JJA > norm. Signal: 40-50%. • Norm value: 17 oC. (JJA daily avg). • Hit rate around 55 to 60%. • Ocean information is important. Published • Headline: “MeteoSwiss: Summer will be cool” • 40% used as signal. • Hit rate compared to skill of 84% for next day forecast. • Map of current buoys as basis for forecasts.
same and next days: • prime time news on national television (French and German). • several radio interviews. • copied by several news paper (without feedback). • scientific facts and context somewhat distorted and wrongly quoted. main message: cool summer
Competing Sunday Press Journal • Front page“Summer 05: Weather-forecast destroys tourism!Tourism directors criticize meteorologists” • Headline“Weather forecasters drive away tourists” • Short street interviews → people would use seasonal forecasts for holiday planning. • Tourism industry: • “Other countries would never have the idea to talk badly about their own products” • Forecasts are reason for low earnings in tourism industry ?! • “Would the forecasts predict a nice summer, we would be happy”
Conclusions for handling press • JJA average of 17 oC is cool. • Give clear numbers, no ranges/choices → extremes will be chosen • Available actual forecasts will be published and used. A “scientific” context or “experimental” label can get lost. • Observations are preferred to models as technological basis for forecasts. • Should seasonal forecasts be published for the public? if yes, how? • Bulletin, press release, selected interviews, individually on request • Tourism industry: stronger fluctuations due to weather and climate forecasts? • Tourists (would) use forecasts for booking, industry seems not to.