Copernicus Service catalogue

This application provides visualisations of historical climate statistics averaged over spatial and temporal domains, and volcanic eruptions.

Major explosive volcanic eruptions can cause short-term effects on the Earth climate, contributing to natural climate variability on global and regional scales. During such explosive volcanic eruptions, large quantities of ash and aerosols are released into the atmosphere which can potentially reach the stratosphere. Once in the stratosphere, fast-moving winds can quickly spread the ash cloud around the world, giving a local eruption a global impact.
The effect of the volcanic eruptions on the climate variability depends on the amount of sulphur dioxide contained in the cloud dust, how high the dust cloud reaches in the atmosphere and the geographical position of the eruption. Major volcanic eruptions may cause cooling of the troposphere and, if the dust cloud reaches the stratosphere, they cause heating of the stratosphere and may impact stratospheric ozone. These effects are mainly caused by sulphur dioxide that is quickly converted into sulphate aerosols. These aerosols, alongside the fine volcanic ash, absorb incoming solar radiation, resulting in stratospheric heating, and scatter it back out into space providing a partial barrier to incoming solar radiation, thus resulting in tropospheric cooling.
During the eruption of Mt. Pinatubo in June 1991, a large amount of sulphur dioxide was emitted into the stratosphere, with the enhancement of the stratospheric aerosol burden for 2 to 4 years after the eruption. The aerosol layer perturbed the Earth's radiative balance, resulting in a global mean radiative forcing up to −3 W m−2, a global surface cooling of ∼ 0.4 - 0.5 K, and a temperature increase of ∼ 2.5 - 3.5 K in the tropical lower stratosphere. The observed temperature perturbations were then connected to many feedbacks in the Earth system, including dynamical and chemical effects on stratospheric ozone.

This application does not provide a detailed analysis of the effects of the volcanic eruptions on the Earth's climate, but offers a quick look at climate statistics and highlights the behaviour of these statistics in response to natural events such as volcanic eruptions. The signal in the climate variable statistics does not automatically imply a connection to a selected volcanic eruption, but is indicative of when the eruption occured.
The response of the climate statistics to a certain volcanic eruption can overlap with the response to another source of climate variability. See documentation for more information.

Users have a choice of several climate Variables and Regions/Volcanoes. Spatial aggregation and volcanic eruptions are presented on the livemap as selectable layers. The user can select a specific region or a specific volcanic eruption by clicking on the map. By selecting a region users can study signals in the time series climate data and compare with the timeline of the major volcanic eruptions. By selecting a volcanic eruption users will be presented with a map that will help to analyse the possible effects of the eruption on the data 6, 12 and 24 months after the eruption.

This application is driven by ERA5 - the fifth generation ECMWF atmospheric reanalysis of the global climate, and CAMS EAC4 (ECMWF Atmospheric Composition Reanalysis 4) - the fourth generation ECMWF global reanalysis of atmospheric composition. ERA5 currently describes the global history of the atmosphere for the period from 1979 till present time, using a combination of forecast models and data assimilation systems to "reanalyse" past observations. The CAMS EAC4 is only available from 2003 onwards.

User-selectable parameters

• Variable: monthly mean climate fields. Some variables are available from several datasets. Variables from different datasets have undergone a unit conversion to make them homogeneous across different datasets.
• Regions/Volcanoes: switch between a map of geographical zones or volcanic eruptions. Options are: Geographical zones, Whole globe, Volcanoes.
  Geographical zones (Arctic, Northern mid-latitudes, Equatorial region, Southern mid-latitudes, Antarctic) for spatial averaging are displayed as a selectable layer on the map.
  Volcanic eruptions comprise of events of category 4 and above which can affect climate data, displayed as a selectable layer on the map.

Output

• Time series anomalies for a range of statistics: 4-months rolling mean, 12-months rolling mean, winter mean, spring mean, summer mean, autumn mean, yearly mean, decadal mean. Statistics are calculated from monthly mean anomalies taking into account weighting by days in a month where applicable. Anomalies are calculated with respect to the data availability period with only full years included.

• Gridded Global anomalies averaged over 1, 6, 12 and 24 months from the start of the selected volcanic eruption. Also given are gridded anomalies averaged over the time period, equil to the duration of the volcanic eruption in months, from the start of the selected volcanic eruption, where possible.

Description of the graphical output

The application consists of one of 2 charts depending on the selected feature on the map:

• geographical region - time series anomalies with overplotted volcanic eruptions;

• volcanic eruption - carousel map of global anomalies averaged over 1, 6, 12 and 24 months from the start of the eruption. Also shown are maps of global anomalies averaged over the time period, equil to the duration of the volcanic eruption in months, from the start of the selected volcanic eruption, where possible.