CLIMATOLOGICAL NOTE NO.14 A SUMMARY

Transcription

1 CLIMATOLOGICAL NOTE NO.14 A SUMMARY OF CLIMATE AVERAGES FOR IRELAND BY SÉAMUS WALSH U.D.C (417) MET ÉIREANN, GLASNEVIN HILL, DUBLIN 9 MAY 2012

2 MET ÉIREANN INTRODUCES NEW LONG-TERM AVERAGES FOR DAY TO DAY WEATHER AND CLIMATE COMPARISONS Log-term averages decribe the climate of Irelad.It is usual to place curret weather evets i cotext by comparig them to logterm averages or Normals. These are defied as 30 year averages of a weather elemet e.g. raifall, sushie etc. The period of 30 years is cosidered log eough to smooth out year-to-year variatios. Stadard Climatological Normals or averages are compiled i 30 year cycles e.g , etc., ad allow for comparisos of curret weather elemets with log-term averages. Every coutry which is a member of the World Meteorological Orgaisatio (WMO) is obliged to calculate these Stadard Climatological Normals. However Climate Normals may also be calculated for ay 30 year period of complete decades e.g or Met Éirea has compiled a set of log-term averages for the period 1981 to 2010, coverig a rage of weather elemets. From May 2012 owards, weather ad climate statistics quoted will referece the ew log-term average period , uless otherwise stated. These will replace the log-term averages curretly i use. (The averages will still be refereced occasioally, particularly i climate chage studies). HOW ARE THE AVERAGES CALCULATED? Averages are calculated from readigs take at weather statios operated by Met Éirea ad its volutary observers. Values are averaged for each moth over a 30 year period to obtai the log-term average. Where there are gaps i data, estimates are made usig data from eighbourig statios. WHAT PRODUCTS ARE AVAILABLE? Raifall: Log-term averages of mothly, seasoal ad aual raifall totals ad days of raifall greater tha 0.2mm, 1mm ad 10mm have bee calculated at statios with sufficiet records. Gridded maps with values at 1 km resolutio have also bee produced. Temperature: Log-term averages of mothly, seasoal ad aual maxima, miima ad mea temperatures have bee calculated at statios with sufficiet records. Gridded maps with values at 1 km resolutio have also bee produced. Sushie: Log-term averages of mothly, seasoal ad aual sushie duratio have bee calculated at statios with sufficiet records. Gridded maps with values at 1 km resolutio have also bee produced. Wid: Mothly mea values have bee calculated ad 30-year wid roses have also bee produced. WHAT IS THE SIGNIFICANCE OF DIFFERENCES IN THE AND LONG-TERM AVERAGES? Because we are comparig two 30 year periods with a overlap of 10 years, the differeces relate to the o-overlap periods i.e ad WHAT DOES THIS MEAN IN TERMS OF CLIMATE CHANGE? Chages i climate are reflected i the logterm averages, however their mai use is as a baselie to put curret weather i cotext, it is ot possible to detect chages i extreme values from log-term averages. WHERE CAN I FIND MORE DETAILS OF THE ANALYSIS TECHNIQUES? Details of the methods used to ifill for missig data, ad iformatio o how the gridded data was produced are i preparatio ad will be published i due course.

3 LOCATION OF STATIONS USED IN CALCULATING AVERAGES AND TEMPERATURE, TEMPERATURE AND SUNSHINE WHERE CAN I GET SOME OF THE DATA? Maps ad uderlyig data for the log-term averages will be made freely available o as will a selectio of statio averages. For other data requests please Climate Equires at eq@met.ie ACKNOWLEDGEMENTS We are grateful to our volutary observers at climatological ad raifall statios without whom this work would ot be possible. Thaks also to the Uited Kigdom Meteorological Office for Norther Irelad statio data for griddig purposes.

4 ANNUAL MEAN TEMPERATURE WINTER MEAN TEMPERATURE ( C) ( C) SPRING MEAN TEMPERATURE ( C) SUMMER MEAN TEMPERATURE ( C) ANNUAL MEAN TEMPERATURE The temperature regime i Irelad is greatly affected by the moderatig effect of the sea, ad height above sea level. Mea aual temperatures geerally rage betwee 9 C ad 10 C with the higher values i coastal regios. Mea aual miima show a stroger coastal effect tha mea maxima. SEASONAL MEAN TEMPERATURE Summer is the warmest seaso, followed by Autum, Sprig ad Witer. Highest temperatures occur ilad durig the summer, with mea seasoal maxima betwee 18 C ad 20 C while highest values occur i coastal regios durig the Witer. AUTUMN MEAN TEMPERATURE ( C) MONTHLY MEAN TEMPERATURE July is the warmest moth, followed by August ad Jue; the coldest moth is Jauary followed closely by February ad the December.

5 MONTHLY MEAN TEMPERATURE ( C) JANUARY FEBRUARY MARCH APRIL MAY JUNE JULY AUGUST SEPTEMBER OCTOBER NOVEMBER DECEMBER

6 ANNUAL WINTER (mm) (mm) SPRING (mm) SUMMER (mm) ANNUAL Highest raifall occurs i the Wester half of the coutry ad o high groud; raifall geerally decreases towards the Northeast. Averaged over all Irelad, the average aual raifall is approximately 1230 mm. SEASONAL The driest seasos are Sprig ad Summer, with a all Irelad average of approximately 260 mm, Autum ad Witer have all Irelad averages of approximately 350 mm. AUTUMN (mm) MONTHLY The driest moths are April, May, Jue ad July, with a all Irelad average of approximately 80 mm each moth. February, March, August ad September have average raifall totals of approximately 100 mm, while October, November, December ad Jauary have all Irelad averages of approximately 130 mm.

7 MONTHLY (mm) JANUARY FEBRUARY MARCH APRIL MAY JUNE JULY AUGUST SEPTEMBER OCTOBER NOVEMBER DECEMBER

8 TOTAL ANNUAL SUNSHINE TOTAL WINTER SUNSHINE (hours) (hours) TOTAL SPRING SUNSHINE (hours) TOTAL SUMMER SUNSHINE (hours) GLOBAL SOLAR RADIATION TABLE (MJ/sq.m.) STATION VALENTIA SHANNON MALIN HEAD BELMULLET CLONES KILKENNY BIRR JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC ANNUAL TOTAL AUTUMN SUNSHINE (hours)

9 MONTHLY AVERAGE DAILY SUNSHINE (hours) JANUARY FEBRUARY MARCH APRIL MAY JUNE JULY AUGUST SEPTEMBER OCTOBER NOVEMBER DECEMBER

10 WIND ROSES (kots) BELMULLET AVERAGES CLAREMORRIS MALIN HEAD CALM 0.3% CALM 2.4% CALM 0.9% MULLINGAR DUBLIN AIRPORT SHANNON AIRPORT CALM 3.1% CALM 0.2% CORK AIRPORT CASEMENT AERODROME CALM 0.9% CALM 1.5% VALENTIA OBSERVATORY CALM 1.9% CALM 0.2% WIND ROSE KEY < 5 kt 5-10 kt kt kt > 35 kt

11 DAILY TEMPERATURE ( C) AND (mm) 31-DAY MOVING AVERAGE MALIN HEAD TEMPERATURE TEMPERATURE BELMULLET TEMPERATURE TEMPERATURE MULLINGAR CASEMENT AERODROME TEMPERATURE SHANNON AIRPORT TEMPERATURE VALENTIA OBSERVATORY DAY MOVING AVERAGE DAY MOVING AVERAGE

12 ANNUAL & SEASONAL COMPARISONS OF LONG-TERM AVERAGE ANNUAL COMPARISON (%) AVERAGES AS A PERCENTAGE OF AVERAGES (%) WINTER COMPARISON (%) SPRING COMPARISON (%) SUMMER COMPARISON (%) ANNUAL O a aual basis, averaged over the coutry, there has bee a icrease of approximately 5% i raifall totals betwee the two ormal periods ( ad ), with the higher icreases i the Wester half of the coutry. SEASONAL All seasos show a overall icrease i raifall but there are regioal differeces. There are decreases of up to 10% i raifall i the South ad East i Witer, with correspodig icreases i the West ad Northwest. Sprig ad Summer show icreases of 5-10%. AUTUMN COMPARISON (%) MONTHLY While most moths show a icrease i raifall of 5-10%, Jauary ad February had decreases of 5-10% i the South ad East while September had a geeral decrease of up to 10%. I July the average icrease i raifall was i the order of 15%.

13 ANNUAL & SEASONAL COMPARISONS OF LONG-TERM AVERAGE TEMPERATURES DIFFERENCE BETWEEN AVERAGES AND AVERAGES ( C) ANNUAL TEMPERATURE COMPARISON WINTER COMPARISON ( C) ( C) SPRING COMPARISON ( C) SUMMER COMPARISON ( C) ANNUAL MEAN TEMPERATURE Geerally, there has bee a icrease of approximately +0.5 C i mea temperature betwee the ad the periods, with the highest icreases i the Southeast. Maximum ad miimum temperatures have also icreased by approximately +0.5 C. SEASONAL MEAN TEMPERATURE All seasos show a rise i mea temperature with the Sprig ad Summer seasos displayig the largest differeces betwee the two periods of approximately +0.7 C. AUTUMN COMPARISON ( C) MONTHLY MEAN TEMPERATURE Almost all mea mothly temperatures show a icrease except October ad December which show small decreases of up to -0.2 C i the West ad Northwest.

14 CASEMENT AERODROME MONTHLY AND ANNUAL MEAN AND EXTREME VALUES TEMPERATURE ( C) JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC YEAR MEAN DAILY MAX MEAN DAILY MIN MEAN TEMPERATURE HIGHEST MAXIMUM LOWEST MAXIMUM HIGHEST MINIMUM LOWEST MINIMUM MEAN NO. OF DAYS WITH AIR FROST MEAN NO. OF DAYS WITH GROUND FROST MEAN 5 CM SOIL MEAN 10 CM SOIL MEAN 20 CM SOIL RELATIVE HUMIDITY (%) MEAN AT 0900 UTC MEAN AT 1500 UTC SUNSHINE (hours) MEAN DAILY DURATION GREATEST DAILY DURATION MEAN NO. OF DAYS WITH NO SUN (mm) MEAN MONTHLY TOTAL GREATEST DAILY TOTAL MEAN NO. OF DAYS WITH >= 0.2 mm MEAN NO. OF DAYS WITH >= 1.0 mm MEAN NO. OF DAYS WITH >= 5.0 mm WIND (kots) MEAN MONTHLY SPEED MAX. GUST MAX. MEAN 10-MINUTE SPEED MEAN NO. OF DAYS WITH GALES WEATHER (MEAN NO. OF DAYS WITH...) SNOW OR SLEET SNOW LYING AT 0900 UTC HAIL THUNDER FOG

15 VALENTIA OBSERVATORY MONTHLY AND ANNUAL MEAN AND EXTREME VALUES TEMPERATURE ( C) JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC YEAR MEAN DAILY MAX MEAN DAILY MIN MEAN TEMPERATURE HIGHEST MAXIMUM LOWEST MAXIMUM HIGHEST MINIMUM LOWEST MINIMUM MEAN NO. OF DAYS WITH AIR FROST MEAN NO. OF DAYS WITH GROUND FROST MEAN 5 CM SOIL MEAN 10 CM SOIL MEAN 20 CM SOIL RELATIVE HUMIDITY (%) MEAN AT 0900 UTC MEAN AT 1500 UTC SUNSHINE (hours) MEAN DAILY DURATION GREATEST DAILY DURATION MEAN NO. OF DAYS WITH NO SUN (mm) MEAN MONTHLY TOTAL GREATEST DAILY TOTAL MEAN NO. OF DAYS WITH >= 0.2 mm MEAN NO. OF DAYS WITH >= 1.0 mm MEAN NO. OF DAYS WITH >= 5.0 mm WIND (kots) MEAN MONTHLY SPEED MAX. GUST MAX. MEAN 10-MINUTE SPEED MEAN NO. OF DAYS WITH GALES WEATHER (MEAN NO. OF DAYS WITH...) SNOW OR SLEET SNOW LYING AT 0900 UTC HAIL THUNDER FOG TABLES OF MONTHLY AND ANNUAL MEAN EXTREME VALUES FOR OTHER SYNOPTIC STATIONS ARE AVAIALBLE AT

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