Summary of observed Summary of observed changes in precipitation and changes in precipitation and

temperature extremes temperature extremes (D9)(D9)

ObjectiveObjective

Are extremes becoming more severe?Are extremes becoming more severe?

Are they becoming more frequent?Are they becoming more frequent?

How is the spatial pattern of the observed How is the spatial pattern of the observed

changes?changes?

Is there seasonal variability in the changes?Is there seasonal variability in the changes?

Method of analysisMethod of analysis

Time series of Time series of Daily precipitation, Daily precipitation,

Daily max/min temperaturesDaily max/min temperatures

Definition of indices that correspond to extremesDefinition of indices that correspond to extremes

Calculation of annual seasonal values of the indicesCalculation of annual seasonal values of the indices

Linear regression applied on the time series of the Linear regression applied on the time series of the

calculated indicescalculated indices

Non-parametric test of significanceNon-parametric test of significance

Study regions and numbers of stations Study regions and numbers of stations investigatedinvestigated

RegionRegion PartnerPartner No. P.statNo. P.stat No. T.statNo. T.stat

EuropeEurope UEAUEA 481481 481481

EnglandEngland UEAUEA 4040 2121

GermanyGermany USTUTT-IWSUSTUTT-IWS 611611 232232

GreeceGreece AUTHAUTH 2222 2222

N. ItalyN. Italy ARPA-SMRARPA-SMR 6262 4444

SwitzerlandSwitzerland ETHETH 104104 NoneNone

French AlpsFrench Alps CNRSCNRS 3+gridded 3+gridded datadata

33

Extreme indices investigatedExtreme indices investigated

DesignationDesignation DescriptionDescription

Precipitation related indicesPrecipitation related indices

Prec90pPrec90p 90th percentile of rainday amounts (mm/day)90th percentile of rainday amounts (mm/day)644R5d644R5d Greatest 5-day total rainfallGreatest 5-day total rainfall646SDII646SDII Simple Daily Intensity (rain per rainday)Simple Daily Intensity (rain per rainday)641CDD641CDD Max no. of consecutive dry daysMax no. of consecutive dry days691R90T691R90T % of total rainfall from events > long-term 90th percentile% of total rainfall from events > long-term 90th percentile692R90N692R90N No. of events > long-term 90th percentile of raindaysNo. of events > long-term 90th percentile of raindays

Temperature related indicesTemperature related indices

Tmax90pTmax90p Tmax 90th percentileTmax 90th percentileTmin10pTmin10p Tmin 10th percentileTmin 10th percentile125Fd125Fd Number of frost days Tmin < 0 °CNumber of frost days Tmin < 0 °C144HWDI144HWDI Heat wave DurationHeat wave Duration

ResultsResultsEuropeEurope

Heavy precipitation extremes:Heavy precipitation extremes:

WinterWinter

Increased in central Europe, the UK and Scandinavia.Increased in central Europe, the UK and Scandinavia. Decreased in Eastern Europe, Greece, and western Iberian Peninsula.Decreased in Eastern Europe, Greece, and western Iberian Peninsula.

SummerSummer

increased across northern Scandinavia and Russiaincreased across northern Scandinavia and Russia decreased across the UK and NE Europedecreased across the UK and NE Europe increased through SW Europeincreased through SW Europe decreased across the northern Iberian Peninsula.decreased across the northern Iberian Peninsula.

Dry day persistenceDry day persistence

WinterWinter

increased in the southern part of the region increased in the southern part of the region decreased in the northdecreased in the north the increase is generally greater than the decreasethe increase is generally greater than the decrease

SummerSummer

Less coherent signalLess coherent signal Most stations in the central part, the UK, and southern Most stations in the central part, the UK, and southern

Scandinavia Scandinavia

showed an increase.showed an increase.

Temperature extremesTemperature extremes

WinterWinter Extreme maximum temperature increased over most of the Extreme maximum temperature increased over most of the

region except the SEregion except the SE

Extreme minimum temperature Extreme minimum temperature increased over the entire increased over the entire region apart from small decreases in parts of Greece, the region apart from small decreases in parts of Greece, the Iberian Peninsula and ScandinaviaIberian Peninsula and Scandinavia

Extreme minimum temperature increased to a larger degree Extreme minimum temperature increased to a larger degree

than the corresponding extreme maximum temperaturethan the corresponding extreme maximum temperature

SummerSummer Extreme maximum temperature incresed in most area of Extreme maximum temperature incresed in most area of

the region except the region except in northern Scandinavia, Eastern Europe, in northern Scandinavia, Eastern Europe, and Russiaand Russia

Extreme minimum temperature increaded in most areas Extreme minimum temperature increaded in most areas except that a few stations showed a decreaseexcept that a few stations showed a decrease

Local scale trends in extreme heavy Local scale trends in extreme heavy precipitation indicesprecipitation indices

RegionRegion WinterWinter SpringSpring SummerSummer AutumnAutumn

EnglandEngland ++++ ----

GermanyGermany ++++ ++ ---- ++

N. ItalyN. Italy -- -- ++ ++

GreeceGreece -- --

SwizerlaSwizerlandnd

++++ ++ ++ ++++

French French AlpsAlps

VariableVariable variablevariable variablevariable ++

Local scale trends in extreme maximum Local scale trends in extreme maximum temperaturetemperature

RegionRegion WinterWinter SpringSpring SummerSummer AutumnAutumn

EnglandEngland ++ ++ ++ ++

GermanyGermany ++ ++ ++

N. ItalyN. Italy ++ ++ ++ ++

GreeceGreece ++ ++ ++ ++

SwizerlaSwizerlandnd

------------ ------------ ------------ ------------

French French AlpsAlps

++ ++ ++++

Precipitation trends / FloodsPrecipitation trends / Floods

Areal precipitation vs. Point Areal precipitation vs. Point precipitationprecipitation

Simultaneous occurrence of extremesSimultaneous occurrence of extremes Differences between trends Differences between trends

corresponding to nearby stationscorresponding to nearby stations Trend Trend Interpolation or Interpolation or

InterpolationInterpolation Trend Trend

Trends in the areal precipitation indicesTrends in the areal precipitation indices

Point scale Grid size of 10km x10km

Winter trends in the 5 day total rainfall amount

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SummarySummary

There are significant trends in the There are significant trends in the extreme indicesextreme indices

Variability increases Variability increases (Ex.: dry day duration and 5 day (Ex.: dry day duration and 5 day sums both increase)sums both increase)

Trends in downscaled seriesTrends in downscaled series