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GIS Monthly Maps

Map of the Month January

Cartographers: Dr Jesko Zimmermann

MAP: Blue skies over Ireland

The first map of 2019 illustrates the more pleasant side of 2018s weather.

Optical sensors mounted on satellites do not have the capacity to penetrate cloud cover. Especially in Ireland this can cause issues for people working in remote sensing as much of the recorded imagery will be partially or fully obstructed by clouds.

As 2018 was a year of quite extreme weather, we wondered if the particularly warm summer led to a less cloudy year, or if this effect was negated by the wet spring.

In order to help users, many providers of satellite imagery supplement their products with a cloud mask which help identify cloudy pixels. In the NASA MODIS surface reflectance product (MOD9AGA), this mask is provided on a 1 km2 cell grid. In this map we use the cloud mask of this product, which is available on an almost daily basis and generally covers the whole of the island of Ireland, as an indicator for cloudy days. To assess the cloudiness of 2018, we took the sum of cloudy days for each pixel in 2018 and compared it to the average number of cloudy days per year in the decade prior (2008 to 2017).

The map clearly illustrates that Ireland was for most parts slightly less cloudy in 2018, with some notable exceptions in the midlands and on the Ards Peninsula. The spot with lowest relative cloud cover (36 cloudy days less than average) was recorded on the Iveragh Peninsula close to Killorglin; other particularly sunny spots were on the Cork/Limerick Border and south of Wicklow town.

About Map of the Month

In addition to undertaking geographical analyses and producing maps for research projects, the spatial analysis lab responds to ad hoc requests for contributions.  The latter may be for in-house purposes or to inform policy submissions. While dissemination is a key objective of research projects, maps produced in response to such requests rarely get a wider audience. We’ve decided that we’ll take the most interesting map we have produced in each month and to present it here to hopefully find a wider audience and promote discussion and debate on both the contribution of spatial analysis to Irish agriculture and food and on the specific maps produced.

Whilst this map can be shared please check with us before reproducing it in a publication. Many of the data sets we use are under licence with conditions attached.

For general enquiries contact Stuart Green or the author above for information on this month’s map.