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Introduction

Directive (EU) 2016/2284 on the reduction of national emissions of certain atmospheric pollutants (“the NEC Directive” or NECD) states in Article 5(2) that:

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NECD Recital (17) explains that this comes from the revised Gothenburg Protocol. Indeed, the amended Gothenburg Protocol says: “5. If in a given year a Party finds that, due to a particularly cold winter, a particularly dry summer or unforeseen variations in economic activities, such as a loss of capacity in the power supply system domestically or in a neighbouring country, it cannot comply with its emission reduction commitments, it may fulfil those commitments by averaging its national annual emissions for the year in question, the year preceding that year and the year following it, provided that this average does not exceed its commitment.”

Purpose of the application

The current application helps to identify if a specific year for a Member State is considered an exceptionally cold winter or an exceptionally dry summer.

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The application automatically updates in the month following the end of the required season. For the JFM temperature, this is on day 30 of April. For the JJA precipitation it is day 30 of September.

Application interface

The application presents an interactive map of Europe displaying the representative temperature and representative total precipitation for each Member State (Figure 1, left panel). The variable to be displayed is selected via a dropdown menu situated above the map. The representative temperature is the temporally averaged and spatial median temperature described in the previous section. Likewise, the representative total precipitation is the temporal sum and spatial median precipitation value described above. A time slider positioned at the bottom of the map frame allows the user to manually select a required year or automatically scroll through each year in the period (1991-2021).

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Figure 3: The interactive map displaying the total precipitation variable for June, July, August 1991. Other years may be displayed on the time slider situated at the bottom of the map. The application’s detailed view displaying the exceptionally dry summers for the selected Member State (right panel). The years for which exceptionally dry summers occur are displayed in red.

Detailed view:

Clicking on a Member State in the interactive map will open a detailed view for that Member State and present a timeseries graph – line- or bar-graph depending on the variable selected (Figure 1, right panel). The graph presents the representative values calculated for each year together with the threshold identified by the 10th percentile (red line). The exceptionally cold winters are identified by the red data points and are situated below the threshold line.

Input data

The temperature and precipitation data are obtained from the monthly mean ERA5 catalogue entry* in the Copernicus Climate Data Store (CDS). All CDS data are freely available and accessible for everyone to use. The data used are:

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*(https://cds.climate.copernicus.eu/cdsapp#!/dataset/reanalysis-era5-single-levels-monthly-means)

Methodology

The application performs the following steps for calculating the below threshold years for temperature:

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