Aspects of climate extremes in Finland

Ari Venäläinen, Kirsti Jylhä, Andrea Vajda, Tiina Kilpeläinen, Seppo Saku…

CLIMATE RISKS IN FINLAND

• storms low pressures, tornadoes, down bursts

• snow• slipperiness• icing• fox• turbulence• floods an drought• hot and cold spells• lightning

0

20

40

60

80

100

120

140

160

1801961

1962

1963

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1965

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1969

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1980

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Vuosi

Tu

uli

tap

au

ste

n l

uku

määrä

maa-a

sem

illa

Above 11 ms-1 wind cases on land areas (17 stations)

Number of storm days (>21 ms-1) at sea areas

Number of deep low pressures and rapid change of air pressure in Kajaani

Helsinki, Jokioinen, Sodankylä storms

0

50

100

150

200

250

1959 1963 1967 1971 1975 1979 1983 1987 1991 1995 1999 2003

Year

Dev

iati

on

fro

m m

ean

(%

)

980 hPa cases Above 20 hPa change

Above 9 hP gradient

How high wind speed we may experience?

TORNADOESKontiolahti 20.8.2004

Tornadoes in Finland

Tornadoes in different fujita classes

02468

10121416182022242628303234

X F0 F1 F2 F3 F4

F-SCALE

NU

MB

ER

OF

TO

RN

AD

OE

S

1796-1996 1997-2003

F2+

1796-1996: 45 %

1997-2003: 8 %

1(2)

Climatological characteristics of precipitation in Helsinki

20 50 500

Daily precipitation

Helsinki

0

50

100

150

200

10 100 1000

Return period (years)

Pre

cip

tati

on

(m

m/d

ay)

20 50 500

Return period of the duration (hour) of a rain event

Summer rain events in Helsinki in 1951-2000: duration and precipitation amount

Return period of precipitationamount (mm) in a rain event

Ref: Tiina Kilpeläinen

1, 2, 3, 6 and 12 month precipitation amounts in Finland

Monthly Two months Three months

Six months Twelve months

1- month2- months3- months6- months12- months

Snow damages

-40

-35

-30

-25

-20

-15

-10

-5

0

5

10

15

1.1

0.

1.1

1.

1.1

2.

1.1

.

1.2

.

1.3

.Date

Win

d s

pe

ed

(m

/s)

tem

ep

era

ture

(°C

)

0

5

10

15

20

25

30

35

40

45

Pre

cip

ita

tio

n (

mm

) a

cc

um

ula

ted

sn

ow

(

kg

/m2

)

wind tempaccum. prec

Kuusamo 1993-1994

Above 20 kg snow load on tree branches, days / 10 years

ACCLIM• part of Finnish adaptation research

• ”Climate extremes and estimated climate change based on the latest climate scenarios”

• In the first part of the study return periods of several parameters are calculated

Parameter StationHelsinki Turku Jokioinen Utti Jyväskylä Kauhava Joensuu Oulu Kuusamo Sodankylä Muonio Ivalo

TEMPERATUREMonthly mean X X X X X X X X X X X XDaily mean X X X X X X X X X X X XDaily maximum X X X X X X X X X X X XDaily minimum X X X X X X X X X X X XLength of hot spells (> 25 °C) X X X X X X X X X X X XLength of cold spells (< -20 °C) X X X X X X X X X X X XLength of cold spells (< -30 °C) X X X X X X X X X X X XDaily temperature range X X X

PRECIPITATIONMonthly X X X X X X X X X X X X14 days X X X X X X X X X X X X5 days X X X X X X X X X X X XDaily X X X X X X X X X X X X6 hours X XLength of dry spells X X X X X X X X X X X X (<10, <25, <50, <100 and <200 mm)

SNOWThe maximum snow depth X X X X X X X X

WIND Bågaskär Kallbodagrund Kuopio Hailuoto Lahti10 average X X X X Xgusts X X X X X

DRY SPELL (< 50 mm), summer

ret.per. 304 Helsinki Kaisaniemi 1101 Turku lentoasema1201 Jokioinen

observatorio1501 Utti lentokenttä

2401 Jyväskylä lentoasema

3201 Kauhava lentokenttä

(years) 95 % ka 95 % 95 % ka 95 % 95 % ka 95 % 95 % ka 95 % 95 % ka 95 % 95 % ka 95 %

10 82 90 102 70 82 92 68 74 85 65 74 84 62 67 75 73 78 87

20 90 100 120 75 90 109 74 82 99 69 82 101 67 74 86 79 86 99

50 98 110 148 80 100 137 81 92 120 74 91 123 74 82 104 87 93 117

100 103 117 164 84 106 148 86 98 130 77 97 134 78 88 114 91 98 129

500 111 127 183 90 116 166 96 111 152 84 108 155 87 101 135 98 107 143

Ret.per. 3801 Joensuu lentoasema 5401 Oulu lentoasema6801 Kuusamo

lentoasema7501 Sodankylä 8201 Muonio kk 9601 Inari

(years) 95 % ka 95 % 95 % ka 95 % 95 % ka 95 % 95 % ka 95 % 95 % ka 95 % 95 % ka 95 %

10 62 68 77 74 81 94 65 67 85 73 75 91 67 75 88 70 81 92

20 68 76 91 81 91 116 70 72 93 78 80 100 74 84 111 75 89 108

50 75 86 111 89 103 138 73 76 77 83 85 86 83 96 135 80 97 131

100 81 93 123 95 112 155 75 78 79 85 88 88 88 105 152 83 103 141

500 91 108 147 107 135 196 78 81 82 88 92 92 98 127 192 90 114 160

And the future?

December 2006 mean temperature in Helsinki was +4.0 ºC and March 2007 temperature +3.1ºC. The return periods of this high temperatures is more than 500 years

This two months demonstrate the difficulty to estimate the reliably the return periods in rapidly changing climate. How to explain all this to media and general public?