Homogenisation of Maximum and Minimum Air Temperatures in Ireland. Mary Curley * and Seamus Walsh

Size: px

Start display at page:

Download "Homogenisation of Maximum and Minimum Air Temperatures in Ireland. Mary Curley * and Seamus Walsh"

Godfrey Esmond McCormick
5 years ago
Views:

1 Homogenisation of Maximum and Minimum Air Temperatures in Ireland Mary Curley * and Seamus Walsh

2 Homogenisation of monthly maximum and minimum temperature series HOMER 2.6

3 Number of stations homogenised 17 years or more of data Minimum: 99 stations Maximum: 100 stations Less than 17 years of data Minimum: 35 stations Maximum: 34 stations Total number of stations homogenised Minimum and Maximum: 134 stations

4 Number of stations homogenised 17 years or more of data Minimum temperature 99 stations (+48 N. Ireland reference stations) Maximum temperature 100 stations (+48 N. Ireland reference stations)

5 17 years or more of data

6 Irish stations with 17 years or more of data 50 years of data: 22 stations years of data: 19 stations years of data: 19 stations <30 years data: ~40 stations

9 Number of Breaks 17 years or more of data Minimum Maximum Total number of breaks % of stations with breaks % verified breaks 37 37

10 Verified breaks Minimum Maximum New site % Screen replaced % New observer % Degrees C thermometer % 5 5 New thermometer % 5 15 AWS % 5 - Other % 10 10

11 Non-verified breaks Minimum Maximum No metadata % No reason % Possible reason/no exact date % 25 23

12 Example of some minimum monthly data detected breaks Year month Reason TRALEE_CLASH v degrees c thermometer TRALEE_CLASH v new site BALLINACURRA v new obs TUAM_AIRGLOONEY n no metadata GLENAMOY v site move MILFORD_VOCSCH n no metadata KINSALEY_AGRRES v new screen LETTERKENNY_MAGHERENAN n no metadata LETTERKENNY_MAGHERENAN n observer poor around this time DUNGARVAN_CARRIGLEA v screen replaced and new fence DUNGARVAN_CARRIGLEA n replacement screen sent CLOOSH_FORSTN n no reason CLOOSH_FORSTN n no metadata

13 Number of breaks in stations Minimum Maximum # stations with breaks # stations with 1 break # stations with 2 breaks # stations with 3 breaks 9 5 # stations with 4 breaks 1 2 # stations with 5 breaks - 2

14 Dublin Airport site move Break amplitude Annual correction Monthly correction Minimum to -1.3 Maximum to -0.4

19 Markree Castle reason for breaks unknown Year Break amplitude Annual correction Monthly correction Minimum to to to -1.8 Maximum to to to to -1.6

21 Stations with little metadata but multiple breaks Oak Park Min: 3 breaks 1967, 1997 & 2006 Max: 5 breaks 1967, 1977, 1991, 1997 & 2006 Derrygreenagh Min: 3 breaks 1973, 1982 & 2007 Max: 4 breaks 1964, 1974, 1990 & 2002

22 HOMER 2.6 Outliers which were extreme events were reinserted after homogenisation In general interactive mode was used. A lot more breaks when non-interactive mode used

23 Comparison with MASH Some stations compared well for others there was a big difference

24 HOMER v MASH Jan Feb. Mar Apr May Jun Jul Aug Sep Oct Nov Dec Min T Dublin Airport Max T Dublin Airport Min T Markree

25 Stations with less than 17 years of data Minimum temperature 35 stations Maximum temperature 34 stations

26 Less than 17 years of data Infilled the series which had less than 17 years of data prior to homogenisation Used the homogenised data series from stations with 17 years or more of data as reference

28 Number of Breaks Less than 17 years of data Minimum Maximum Total number of breaks % of stations with breaks % verified breaks 34 37

29 Number of breaks in stations Minimum Maximum # stations with breaks # stations with 1 break # stations with 2 breaks 11 8 # stations with 3 breaks 4 2

30 Daily data

31 Daily data series Looking at parallel data series SPLIDHOM

32 Parallel data series When stations where automated we had parallel measurements for a number of months. Mullingar Valentia Belmullet Malin Head Sherkin Island

33 Parallel data series In general the difference seems bigger between minimum temperatures however for Sherkin Island the maximum temperature is more affected. The difference in the maximum thermometers can range from 0.5 up to 3 degrees C whilst for the minimum it is generally less than a degree.

34 SPLIDHOM Starting with Dublin stations long series with generally not too many breaks in monthly data dense network

35 Thanks to the Met Office, particularly Dan Hollis for providing Northern Ireland monthly maximum and minimum data

36 Thank you

Recreation Facility Hours

NORMAL HOURS Recreation Facility Hours August 1, 2016 July 31, 2017 Last Revised: July 29, 2016 Effective Dates 2016: AUG 23 31, SEP 1 2, SEP 6 16, SEP 18 23, SEP 25 30, OCT 1 7, OCT 9 18, OCT 24 30, NOV