library(sf)
library(dplyr)
library(dygraphs)
library(tmap)
load('.RData')
ms_rain <- rain %>%
group_by(Station,Month) %>%
summarise(median_rain = median(Rainfall))
ja_rain <- ms_rain %>% filter(Month == 'Jan')
stat_dat <- st_as_sf(stations,coords=c('Long','Lat'),crs=4326) %>%
st_transform(29902) %>%
left_join(ja_rain)
tmap_mode('view')
tm_shape(stat_dat) + tm_bubbles(col='median_rain',alpha=0.9,
popup.vars='median_rain',
popup.format=list(suffix=' cc',
prefix=' = '))Assignment 2 GY672 - Irish map of median rainfall in January
Data used
The rainfall data (referred to as “. Rdata” in the code) has been converted to an R binary data file. It contains two objects such as the rain and the weather stations. The dataset covers the period between 1850 and 2014 every month without any missing value. These values have been provided by Prof. Conor Murphy and Dr. Simon Noone. Two active members of The Irish Climate Analysis and Research UnitS known by its acronym ICARUS, part of the Department of Geography at Maynooth University.
The weather stations are 25 observations corresponding to each of the measurements taken at the following reference locations: 1) Athboy; 2) Foulksmills; 3) Mullingar; 4) Portlaw; 5) Rathdrum; 6) Strokestown; 7) University College Galway; 8) Drumsna; 9) Ardara; 10) Armagh; 11) Belfast; 12) Birr; 13) Cappoquinn; 14) Cork Airport; 15)Derry; 16) Dublin Airport; 17) Enniscorthy; 18) Killarney; 19) Malin Head; 20) Markree Castle; 21) Phoenix Park; 22) Roches Point; 23) Shannon Airport; 24) Valentia and 25) Waterford.
Each weather station observation is composed of 9 values: station name, elevation, easting, northing, latitude, longitude, county, abbreviation, and source. This included information allows a better interpretation of the rainfall values. For example, the rain can be interpreted with an elevation that oscillates between 6 meters at the lowest station corresponding to Shannon Airport and 154 meters at the highest station in Cork Airport. It also includes the source of origin of the data, giving added value to the dataset since they are nationally and internationally recognized: Armagh Observatory, Briffa, CRU Met Eireann, Met Eireann, and Tabony.
The rain is a total of 49500 observations (165 years for 12 months for 25 weather stations). In this case, each of the measurements is made up of 4 variables: year, month, rainfall, and name of the weather station. The monthly rainfall for these 165 years ranges from 0 cubic centimeters recorded up to 9 times at 5 different weather stations (Markree Castle, Valentia, Rathdrum, Killarney, and Waterford) to 460.5 cubic centimeters recorded at Cork Airport in December 1899.
Running Code
The R code used to generate a map of rainfall in Ireland for the 25 weather stations can be seen below. The result has been a map of Ireland with the 25 weather stations located in it with a circle and classified by colors based on the median rainfall for each location in the month of January.
Discussion
The Dublin Airport weather station has the lowest median rainfall in the whole country. The median for this station is 63 cubic centimeters in January. Phoenix Park’s values are very similar due to their closeness at 67.6 cubic centimeters. The other two stations with measurements below 80 cc are Armagh (75.0 cc) and Birr (77.5 cc).
At the opposite extreme are the stations with the highest medians in the entire country. There are 3 (Killarney, Valentia, and Ardara) that exceed 160 cc. Killarney weather station has the highest measurement on record at 177.7 cc.
These first distribution patterns indicate a trend in which the weather stations with the highest precipitation are located on the west coast and those with the lowest precipitation are on the east coast. This fact corroborates the theory that most of the storms and rainfall come from the Atlantic Ocean, leaving more rain on the oceanic coast. It must be taken into account that January is one of the wettest months in the Irish climate together with December, which explains the high values measured in the different stations.
The remaining 18 meteorological stations median rainfall ranges from 80 to 160 cc in January. The pattern of 8 places all being on the island’s south and southeast coasts is notable. Cork Airport, Roches Point, Cappoquinn, Portlaw, Waterford, Foulksmills, Enniscorthy, and Rathdrum in particular. Its readings vary from 102.6 cc in Waterford (lowest) to 147.4 cc in Cappoquinn (highest), indicating a region of heavy rainfall along this stretch of the Irish coast. Less than those in the west, although approximately twice as the rainfall collected in the capital region (Dublin Airport and Phoenix Park).