Issued by: CSIC and Predictia

Date: 29/05/2024

Service contract: 2022/C3S2_381_Contractor/SC1

Table of Contents

1. Introduction

This document describes the Copernicus Interactive Climate Atlas (C3S Atlas Application, or simply C3S Atlas), a web-based tool developed by the Copernicus Climate Change Service (C3S). It enables flexible temporal and spatial exploration of recent climate trends and future projections across a wide range of key variables, using multiple datasets commonly employed as complementary lines of evidence for climate change assessment (see the introductory paper in the ECMWF Newsletter and the introductory video in the YouTube channel). 

The complete dataset behind the Atlas is available as a single catalogue entry in the CDS (C3S Atlas Dataset, https://cds.climate.copernicus.eu/datasets/multi-origin-c3s-atlas). In addition, the software developed to generate both the dataset and the visual outputs displayed in the C3S Atlas is openly shared in the C3S Atlas User Tools (https://ecmwf-projects.github.io/c3s-atlas). This promotes transparency and supports reusability through the inclusion of well-documented, annotated notebooks.

2. The application explained/described

The C3S Atlas is organized in five main panels (header, selector, time period, description, and display), as shown in Figure 1. The header includes links to the user guidance and other components of the C3S Atlas (dataset and user tools). The selector panel (b) allows selecting the particular dataset, variable/index and dimension of analysis. The description and information panel (d) shows the details of the climate product resulting from the current selection and includes the information button providing full details on the description and provenance. The display panel (e) shows different interactive climatic products associated with the current selection, such as maps showing spatial information for the full geographical extent (as in Figure 1), or time series, stripes and other products displaying regional information for pre-defined (or customized) regions (not shown in the figure). In the following sections we describe these elements in detail.

Figure 1. Main screen of the C3S Atlas, showing the five primary panels: (a) Header, (b) Selector and configuration, (c) Time period, (d) Description and Information and (e) Display. Note that the User Guide (this document), the C3S Atlas Dataset, the C3S Atlas User Tools and the welcome window are all accessible via the links in the top-right corner of the header. The selector panel allows to configure the climate product of interest, choosing the particular variable or index, the dataset, the season, and the quantity and climatologies displayed in the Display panel (e.g. mean annual change of extreme hot days for CMIP6 adjusted using linear scaling in the figure). The time period panel allows to navigate across different historical and future periods for different pathways and global warming levels (e.g., changes for 2º global warming level relative to 1850-1900). The title panel summarises the current selection and full description and provenance details are provided in the information panel accessed from the information button included in this panel. Finally, the display graphically represents the product and allows interaction to define regions and explore regional information, with the support of different functionalities provided in the buttons of the right panel (this is explained later in the document).

2.1. The Information Panel: Description and Provenance

The information panel in Figure 1(d) displays the information (variable, dataset and dimension of analysis) for the current selection. This is used as the title of the corresponding graphical climate products displayed in panel (c). A full description with comprehensive information and provenance is provided in the Information Panel, accesible by clicking on the "i" information button on the right side of the information panel (see Figure 2). This panel includes a description of the product and provenance information of the input data sources used to build the product (CMIP6 in this case). Figure 2 shows the two panels (left and right) displaying the description of the different element involved in the definition of product displayed and provenance information on the data source and metadata details on the different elements of the ensemble forming the CMIP6 multi-model dataset. 

Figure 2. Information panel with comprehensive description (left) and provenance of the input data sources (right) used to define the selected climate product. This panel is available from the "i" information button in Figure 1(d). This figure shows the information corresponding to the default selection of the C3S Atlas displayed in Figure 1 (only the initial part is shown). 

2.2. The Selection Panel

The selection panel includes the different choices required to define the climatic product of interest and is organized in three main modules, as shown in Figure 3: (a) selection of variable/index and dataset, (b) selection of the dimension of analysis and (c) palette of color and range of displayed values (including autofit/reset options to adapt/restore the ranges according to the current view).

The two main choices of the C3S Atlas are the particular variable/index and dataset of interest, and can be selected from the “choice” buttons in the top of the selection panel (Figure 3a, panels a.1 and a.2). The C3S Atlas includes information for 39 variables and indices organized in different categories (heat and cold, wet and dry, drought, wind and radiation, snow and ice, ocean, and circulation) to simplify the selection; moreover the panel includes a secondary filter for mean values, extreme values, spells and count, standardized variables and bias adjusted variables (Figure 3a.1 illustrates the full list of available indices with no filters applied). These variables/indices are computed for a number of datasets from the C3S Climate Data Store (CDS) which are commonly used as complementary lines of evidence in climate change studies. In particular, the datasets are organized in three categories (panel 3a.2): Observations, reanalyses and climate projections. Observations include the Berkeley Earth (BERKEARTH) and Climate Prediction Center (CPC) global daily gridded temperature and precipitation observational datasets, the SST-CCI satellite-based sea surface temperature dataset and the regional (Europe) E-OBS daily gridded observations. Reanalyses include the ERA5 and ERA5-Land global atmospheric and land reanalysis, the CERRA regional (Europe) atmospheric reanalysis, and the ORAS5 global ocean reanalysis. Projections include CMIP5 and CMIP6 global climate projections, and CORDEX-EUR-11 and CORDEX-CORE regional climate projections (see the C3S Atlas Dataset documentation for specific details on datasets and variables available, as well as the harmonization and calculation of the underpinning dataset).

Figure 3. Elements of the selection panel of the C3S Atlas showing the particular choices of the default  configuration: (a) variable/index and dataset, (b) dimension of analysis and (c) palette of color and range of values displayed (including autofit/reset options to adapt/restore the ranges according to the current view). The options available for the variable and dataset selectors are shown in panels (a.1) and (a.2) and for the Quantity and Climatology statistics, and the Bias adjustment are shown in panels (b.1) and (b.2), respectively.

The "dimensions of analysis" available in the C3S Atlas can be selected from the second block of selectors (Figure 3b). The “season” selector allows selecting the particular "season" of interest (month, season, annual) to explore the selected index; note that indices are originally defined with either monthly or annual aggregation, and the latter are not available for particular months/seasons (see the Atlas dataset documentation for full details). The aggregation of the monthly values to obtain the seasonal/annual time series of interest (with one value per year) is performed using the mean, with the exception of the extreme indices Minimum/Maximum of daily minimum temperature and Maximum of 1-day/5-day accumulated precipitation, which are aggregated using the corresponding minimum or maximum (i.e. seasonal/annual extremes are the extremes of the corresponding monthly values), and the "count" indices extreme and very extreme hot days, tropical nights, frost days, wet days, heavy and very heavy precipitation days, which are aggregated using the sum (i.e. seasonal/annual counts are the sum of the monthly counts). Full information about the particular aggregation followed to compute each index is provided in the information panel (see Section 2.1).

The "quantity" selector allows users to choose the particular quantities of interest (values, changes –absolute or relative– and trends, see Figure 3b panel b.1), with different options available for observations/reanalysis and for climate projections (e.g. trends are only available for the former group).

The options values and changes allow users to explore raw values and changes (relative to a baseline) for a number of pre-defined reference historical periods (common for all datasets) and also for future periods (and global warming levels) for projection datasets; the particular reference and baseline (for changes) periods can be selected from the "Time period" panel, described in Section 2.3. Note that for some variables and indices from the wet and dry, drought and wind and radiation categories, both absolute or relative (reference-baseline)/baseline (as percentage) changes are available. The particular selection determines the climatological information displayed in the map (in the display panel, Figure 1e). The default value is the mean climatology, obtained by averaging the annual series of values/changes in the period of interest at a grid box level (with the particular resolution of the selected dataset). Additionally, for extreme indices, the "climatology statistics" selector allows users to choose between  mean and extreme climatologies. The latter displays the 1-in-20-year annual value for the selected period, computed as the empirical percentile of the monthly/seasonal/annual time-series values (one value per year within the period of interest). Note that this option is only available and visible for extreme indices; for all other indices, the mean climatology option is displayed.

The trends option in the quantity selector allows users to explore long-term (1950-2020) and recent (1991-2020) trends in the monthly/seasonal/annual time series. In this mode, the values displayed on the map correspond to the estimated trends over the selected analysis period.

For threshold dependent indices, an extra selector "Bias adjustment" allows to chose the bias adjustment method available for these indices: None, ISIMIP, Linear Scaling (see Figure 3b, panel b.2, and the C3S Atlas Dataset documentation Sec. 2.7 for more details). 

Finally, the colourbar on the bottom (Figure 3c) is interactive and allows user-defined selection of colour palettes and colour ranges. The colours are displayed on both continuous or discrete scales and the minimum/maximum values can be adjusted by clicking and dragging the labels, or using the autofit tool. The box next to the colourbar (see Figure 1) shows the legend for the methods representing robustness/uncertainty (significance for observations/reanalysis trends, and robustness for model projection changes). 

2.3. The Period Selection Panel

The period selection panel includes the different pre-defined periods available in the C3S Atlas to display global and regional information (see Figure 4). 

Observational and reanalysis datasets share the same predefined periods. For trends, the predefined periods are the long-term (1950-2020) and recent (1991-2020) modern periods (Figure 4a). For values and changes, the predefined historical periods are (Figure 4b): 1961-1990, 1981-2010 and 1991-2020 (three 30-year periods recommended by WMO to define climate normals) and 1986-2005 and 1995-2014 (the 20-year common periods used in IPCC AR5 and AR6, respectively, to define modern climatic conditions). A single reference period can be selected for "values" whereas an additional baseline can be selected for "changes" as shown in Figure 4b (changes are calculated as reference-baseline, or (reference-baseline)/baseline as percentage, for relative changes).

Figure 4. Options for the Time Period panel (Figure 1c) according to the different dimensions of analysis selected in the selection panel (Section 2.2). The slider allows to select the reference period of interest for (a) trends, (b) values and changes for observations and reanalysis, (c) and (d) values and changes for projection datasets for periods (across pathway scenarios) and global warming levels, respectively. For projections, the selector in the right end of the Time Period panel (panel f) allows to change between global warming levels and periods across different scenario pathways (RCPs for CORDEX and CMIP6 and SSP for CMIP6). Note that the global warming levels provide a suitable dimension of analysis to intercompare different projection datasets and, therefore, is the default option for projections.

For the climate projection datasets, besides the historical periods common with observations and reanalysis the C3S Atlas includes 1850-1900 period, which is considered an approximation to pre-industrial conditions. The value and change options allow users exploring future periods (long-, medium- and long-term, defined as 2021-40, 2041-60 and 2081-2100, respectively) across different emission scenarios (RCPs or SSPs depending on the dataset), as illustrated in Figure 4c. The choice menu on the right allows selecting the particular scenario pathway of interest. An additional dimension of analysis is the policy-relevant “Global Warming Levels” (GWL) used extensively in the IPCC AR6 report. In particular the C3S Atlas allows selecting 1.5°, 2°, 3° and 4°, as shown in Figure 4d. Global warming levels have been computed following the methodology used in the IPCC AR6 WGI Atlas; in particular a single scenario (RCP8.5 or SSP5-8.5, depending on the datasets) was used to define the 20-year periods when models first reach the particular global warming levels (1.5°C, 2°C, 3°C and 4°C, relative to the pre-industrial 1850-1900 period). Note that similar GWL results are obtained for different scenarios (e.g. 2°C changes produced using SSP1-2.6 and SSP5-8.5; see AR6 WGI Cross-Chapter Box 11.1). 

Note also that for the climate projection datasets, some of the historical past periods (in particular the more recent periods) are not fully covered by the historical scenario data (e.g. the historical simulations for CMIP5/CORDEX and CMIP6 end in 2005 and 2014, respectively). A pragmatic approximation to deal with this issue is to use scenario data to fill the missing segments, for example for 2006–2020 use the first years of RCP8.5-driven transient projections, which are the most common scenarios available and in which the emissions are close to those observed (this approach is used, for instance, in the IPCC WGI AR6 Atlas chapter and Chapter 12).

2.4. The Display Panel

A particular choice of the selection panel (variable, dataset, period and dimension of analysis) determines a climate product (e.g. mean temperature (°C) - CMIP6 - change - warming 2°C - annual - relative to 1850-1900, see Figure 1) which is graphically represented in the display panel in the form of a map. The map represents gridbox information for the full spatial extent of the dataset (global or regional, with different spatial resolutions, from 2º to 0.05º depending on the selected dataset; see the Atlas dataset documentation  for details). The map shows the temporally aggregated mean of the seasonal/annual values for the reference period (or changes relative to a baseline), and is dynamically updated when changing any choice in the selection panel; note that for projection datasets the map represents the ensemble mean values (detailed information on individual ensemble members is available only for regional products). 

Figure 1 shows the different controls available in the display panel (labeled with numbers 3 to 13). The tools button bar on the right allows to interact and modify the figure and export the content: (3) fullscreen mode, (4-6) zooming in (+), going back to the initial graphical configuration, and zooming out (-), (7) side-by-side comparison of datasets, (8) changing the projection (WGS-84, Robinson, Pacific-centric Robinson, stereographic North and South, and 3D globe); note that the 3D globe is computational demanding and is not available for some systems, (9) obtaining gridbox information (pin), (10) displaying or hiding robustness information, (11) exporting the graphics in PNG format, (12) exporting the underpinning data as GeoTIFF/NetCDF files (including both the signal and the robustness information), and (13) obtaining a permalink for referring to the particular configuration of the C3S Atlas (both the choices and the particular configuration of the graphic).

The side-by-side comparison tool is a new feature of the C3S Atlas that allows users to compare the current product with the same variable and configuration derived from an alternative dataset. To ensure scientifically meaningful comparisons, the tool is designed to compare only equivalent product categories: observational and reanalysis datasets can only be compared with other observational/reanalysis datasets, and climate projections can only be compared with other projection datasets. This restriction avoids potentially misleading interpretations arising from differences in datasets of different nature; for instance, climate projections are affected by internal climate variability, meaning that direct comparison between a single model realisation and observations may not be representative without additional context. Figure 5 illustrates an example comparing the ERA5 and CERRA reanalyses for mean temperature climatology over the 1991–2020 period using the side-by-side visualization mode.

Figure 5. Example of the side-by-side comparison tool in the C3S Atlas, showing the comparison between ERA5 (left) and CERRA (right) reanalysis datasets for mean annual temperature climatology over the Alps regions during the 1991–2020 reference period.

Besides the global map displaying spatial information, the C3S Atlas allows exploring regionally aggregated information for a number of predefined regions, displayed in the “region set” selector (labeled as (1) in Figure 1); a single (or multiple) regions can be selected by clicking on the map (the button (2) allows selecting all the regions, e.g. to produce global averaged information for global datasets). Predefined regions include 1) the IPCC AR6 reference regions (used in the AR6 WGI report for regional climate change assessment), 2) European countries (including those countries covered by the regional European datasets: E-OBS and CORDEX-EUR), 3) the EUCRA regions (which are used in the European Climate Risk Assessment), and 4) selected cities (including a selection of cities where urban climate information is available from some of the high-resolution datasets). The regional information displayed by the C3S Atlas for these predefined regions is pre-computed and can be explored interactively by clicking in the “regional information” button at the top of the panel, which is visible when a region is selected. 

The user can also select customized regions which can be defined using the “user defined” option in the regions selector. This option allows defining a new region by clicking on the “pencil” button and drawing a polygonal line. This creates an offline job which is executed by a queue system passing through different states (such as pending and running), until completion. Jobs are displayed at the bottom of the display panel as shown in Figure 6 (bottom) and regional products can be explored when the job is completed, clicking on the “eye” icon labeled as (1) in the figure. As with the predefined regional values, the regional mean is calculated using the underlying data model based on regular latitude-longitude grids, applying cosine latitude weighting. To ensure consistency with this data model, the calculation is only available in the standard WGS-84 coordinate system (or EPSG:4326 projection), commonly used for global regular lat-lon grids. When this option is selected, the application automatically switches to this projection, as shown in Figure 5 (bottom). To facilitate the definition of customised regions, the C3S Atlas allows users to upload region definitions in standard geospatial formats, including WKT, GeoJSON, and GeoTIFF.

Figure 6. Display panel showing a global map for the default selection (extreme hot days for a 2º global warming from CMIP6) and the selection of (top) predefined and (bottom) customized regions. The panel on the top shows the predefined Mediterranean region selected (from the IPCC AR6 reference regions) with the button “regional information” to display the different graphical products for regional information. The bottom panel shows the definition of a customized region created over Iberia drawing a polygonal; in this case the option is first “create a job” to launch a job to compute the requested information. All jobs will be available from the “job” button appearing in the right toolbar of buttons; regional information would be displayed when clicking in the “eye” icon in the corresponding job in the list. The details of the job, including the machine-readable definition of the selected region (in WKT format) are available when clicking on the the "?" icon. The three buttons in the "user defined" toolbar (bottom panel) allow users to create a new region, delete the current region, and upload an existing region definition in WKT, GeoJSON, or GeoTIFF format.

Different aspects of regional information are displayed using different graphical products, as illustrated in Figure 7 for the Mediterranean region considering changes in mean temperature for a 2º global warming level (relative to 1850-1900) from the CMIP6 dataset. Some of these products are general and available for all feasible datasets and variables: 1) time series, 2) climate stripes, 3) annual cycle plots, 4) seasonal climate stripes, and 5) summary table; all these graphical elements are dynamically updated when changing the choices in the selection panel (including the reference and baseline periods indicated with the gray shading in the figures, when applicable). 



Figure 7. Different graphical products for regional information of mean temperature changes for 2º global warming: over the predefined IPCC AR6 Mediterranean region: time series, climate stripes, annual cycle plot, seasonal climate stripes and summary table, from top to bottom. The bottom panel includes various selection and export options. All graphical regional information products support exporting results in PDF and PNG formats, as well as exporting the underlying numerical data in CSV format. The map inset highlights the selected region(s), and the 'Select models' option allows users to choose specific models or sub-ensembles of interest for ensemble products. 

The time series panel displays the annual/seasonal values year by year, along the historical or historical and future climate periods. For observations/renalysis, the time-series panel displays the regionally aggregated annual/seasonal series. For climate projections, the time-series displays the regionally aggregated annual/seasonal series for the raw values or the changes (anomalies relative to the selected baseline in this case) for all the model simulations forming the ensemble, as well as the ensemble median. A gray shading indicates the particular period selected, as represented in the map; in the case of global warming levels, the shading area exhibits different grey shading intensities according to the overlaps of 20-year periods where the warming level is first reached by the different models (higher shade intensity indicates years with higher overlap). Detailed (percentile) information is provided by hovering the pointer over the individual lines. 

The climate stripes plot is inspired by the “warming stripes” graphics (introduced by Ed Hawkins, https://www.ShowYourStripes.info), which are simple and compelling visual representations of the change in temperature using a series of coloured stripes chronologically ordered; stripes reflect a minimalist style, conceived to use colour alone to avoid technical distractions when conveying information to non-scientists. Climate stripes are implemented in the C3S  Atlas using chronologically ordered vertical bars along the 1950-2100 period (spanning historical and projected simulations) to represent annual/seasonal raw values or changes (anomalies relative to the selected baseline in this case) of the selected variable and scenario. The stripes are divided vertically to represent each of the simulations/models (for climate projections) forming the ensemble (with the ensemble median at the top). Colors blue/brown to red/green indicate negative to positive changes (or minimum to maximum values).

The annual cycle plot displays the regionally aggregated monthly climatologies for the selected variable and period. For climate projections it displays the regionally aggregated monthly climatologies of the selected period for the raw values or the changes (anomalies relative to the selected baseline in this case) for all the simulations forming the ensemble, as well as the ensemble median. Detailed (percentile) information is provided by hovering the pointer over the individual months. 

The seasonal stripe plot is like the climate stripes panel but including monthly values vertically instead of model results, displaying results for the ensemble multi-model median.

The summary table facilitates access to numeric information providing summary information (median values of the ensemble and uncertainty ranges) of the regionally aggregated values (climatologies or changes) for the different historical or future periods.

In addition to the above general regional products, available for all datasets and variables (excluding the annual cycle and seasonal stripe for annual variables), two specialized products offer further insights for specific datasets: 1) Monitoring, available for observational and reanalysis datasets, and 2) Urban Climate, available for high-resolution climate projections.

The monitoring regional product. Some of the datasets included in the C3S Atlas (in particular the ERA5 reanalysis family) provide near real-time information which is suitable to monitor the state of the climate as with the Climate Pulse (https://pulse.climate.copernicus.eu/) C3S application. The Monitoring regional product offers a year-by-year comparative analysis of the selected variable (either climatology or change relative to a baseline) complementing the annual cycle plot by presenting annual values instead of period averages. This enables tracking climate trends and identifying record-breaking events. For instance, Figure 8 shows an illustrative example displaying monthly global temperature anomalies (relative to 1961-1990) for all the available years (up to 2025) highlighting the record breaking values of the year 2025.


Figure 8. Monitoring panel displaying global mean temperature from ERA5 and illustrating the 2025 event. The shading shows the range of values corresponding to the reference period selected in the selection panel.

The urban climate regional product. Given the growing importance of city-scale climate information, the urban climate product has been designed aligned with the CORDEX URBAN Flagship Pilot Study, which focuses on advancing the representation of urban-scale climate projections, particularly in relation to the urban heat island effect. The Urban Climate regional plot is available for the high-resolution datasets CORDEX-CORE, CORDEX-EUR-11, and CERRA for a subset of pre-defined cities representing a diverse and heterogeneous sample of urban areas worldwide. The plot can be invoked when the "Selected cities" regional selection is applied. Specifically, the plot presents the climatology of the annual cycle for the chosen period, emphasizing the 'urban signal', defined as the difference between urban and rural values and calculated using model-specific urban masks within each dataset. Results are shown only for models with available urban mask information, thereby constituting a subensemble of the original dataset. The resulting data is presented either as absolute magnitudes (see the example in Figure 9) or as relative changes with respect to a chosen baseline. This plot complements other regional products, such as time-series plots, which represent data from gridboxes fully enclosed within city boundaries (or the nearest available gridbox) and may therefore not capture the unique characteristics of the urban climate signal. The new set of pre-defined regions, labeled “selected cities” includes an initial selection of 34 cities: Athens, Baghdad, Beijing, Berlin, Bogota, Buenos Aires, Cairo, Chengdu, Chicago, Delhi, Dhaka, Istanbul, Jakarta, Johannesburg, Khartoum, London, Los Angeles, Melbourne, Mexico City, Montreal, Moscow, Mumbai, New York, Paris, Quezon City, Riyadh, São Paulo, Seoul, Shanghai, Singapore, Sydney, Tashkent, Tehran, Tokyo. 


Figure 9. Urban climate panel displaying the urban-rural signal (differences between urban and surrounding rural areas) for the CORDEX-EUR-11 regional projections for the city of Paris. This plot complements the other regional products, such as time series and annual cycle plots, which represent data from gridboxes fully enclosed within city boundaries (or the nearest available gridbox) and may therefore not capture the unique characteristics of the urban climate signal. 

3. Robustness and Uncertainty

The representation of robustness in the C3S Atlas is based on the same approaches used in the IPCC WGI AR6 report (Cross-Chapter Box Atlas.1). For observation/reanalysis trends, robustness is defined using the significance of the linear trends as obtained from standard hypothesis testing (and obscuring regions with non-significant trends using "x"). 

For future climate changes, robustness is defined based on three categories: No overlay indicates that the change is robust and likely emerges from internal variability (at least 80% of the models agree on the sign of change and at least 66% of the models show a change greater than the internal-variability threshold); diagonal lines (\) indicate no change or no robust change (fewer than 66% of the models show change greater than the internal-variability threshold); crossed lines (X) indicate conflicting signals where at least 66% of the models show change greater than the internal-variability threshold but fewer than 80% of all models agree on the sign of change.

Note that robustness results are computed at a gridbox level and are not representative of regionally aggregated results over larger regions (less influenced by local variability). 

4. Application updates

The last version of the C3S Atlas Application has been launched on 1 June 2026, aligned with version 2.5 of the C3S Atlas Dataset (v2.5; see the dataset documentation). 

The following table describes the different version and periodic updates, detailing the changes and the different fixes (typos and not-substantial changes, improvements and errors/bugs) that have been implemented (in chronological order with new versions on the top).

VersionChanges description

Version 2.5

 

  • (change-Atlas) New design of the application:
    • the time period selector is now located below the figure, displaying the full range of periods and marking those available for each specific dataset. This provides a unified view and improves the user experience when navigating across datasets. This new layout also includes the “Scenario” or “GWL” selectors as a dropdown menu on the right-hand side of the period selector allowing to configure the future “periods” of analysis. 

    • the analysis choice has been simplified: previously, users had to choose between “Climatology and Changes,” “Global Warming Levels,” or “Trends”, depending on the dataset (projections vs observations/reanalysis). Now, users only need to select the quantity to be displayed (Quantity selector), either “Value”, “Change” or “Trend”, depending on the dataset.

    • optimize layouts of PDF/PNG charts.

    • new welcome window aligned with other C3S applications and including different informative tabs with license, support, versions. This new tab includes the “versions” and “introductory video” which were located before in the top panel. The top panel now highlights the three components of the C3S Atlas (application - user guidance, dataset and user tools).
    • new filtering categories in the selector of variables, including types of variables (All, Mean, Extreme, Spells and count, Standardized, Bias adjusted) besides the Climatic Impact-Driver types. These new categories are aligned with special functionalities of the C3S Atlas, which are available only for some types of variables: 1) bias-adjusment for threshold-defined variables; 2) extreme 1-in-20 year climatologies for “extreme” variables, 3) indicators of server conditions for “standardised” indices.
  • (change-Atlas) New functionalities:

    • new extreme climatologies: 1-in-20-year event besides the standard mean climatology for all “extreme” indices (mean of the annual series).

    • side by side comparison of maps for datasets in the same category (observations/reanalysis and projections). A new button has been added to the right toolbar.

    • use of WKT/GeoJSON for user-defined regional information, so users can use their own region definitions (in the above standard formats) to define customized regions in the Atlas.

    • the selector panel can now be hidden using the full screen for the main panel.

    • fixed visualization issues with the Robinson Pacific-centered projection.

    • colorbar redesign (including interactive indicative of the hovered value) and discrete palettes allowing a more precise definition of maps.

  • (change-Atlas) New variables and indices:
    • new indices introduced characterizing severe standardised conditions: In particular four indices of wet/dry severe conditions (above/below 1.5 standard deviations) has been included associated with SPI6/SPEI6 and indicated as percentage (%). These allow for the same analysis capabilities, including regional information. 
    • standardised SPI6/SPEI6 indices are now defined using the same reference period 1971-2005 for both historical and future scenarios.
  • (change-Atlas) New information component (provenance). The information panel “i” has been expanded with “provenance” information, with enhanced metadata of the data sources, in particular the models and versions for climate projection datasets (this component is being adjusted with the final metadata schema1, we will inform you when the final version is deployed).  
  • (error-data) See the fixes implemented in the C3S Atlas Dataset v2.5 (v2.5; see the dataset documentation).

Version 2.3


  • (change-Atlas) Included a link to the C3S Atlas introductory YouTube video.
  • (error-Atlas) An error was identified for three products due to corrupted files that produced not data results. The affected products have been corrected and replaced in the C3S Atlas application. The corrupted products were:
    • Time series for European Countries reference regions had no data for variable wet days and the the ssp245 scenario (permalink)
    • Time series for Selected Cities reference regions had no data for variable solar radiation downwards for the historical scenario (permalink)
    • Time series for European Countries reference regions had no data for variable heavy precipitation days (ISIMIP) for the historical scenario (permalink)

Version 2.2

  • (error-Atlas, error-data) An error was identified in the ERA5-Land temperature indices for December 1969, caused by a corrupted input file that produced incorrect extreme values especially in high-latitude regions. The affected products have been corrected and replaced in the C3S Atlas application.

Products affected:
ERA5-Land for the following variables: t, tx, tn, txx, tnn, tx35, tx40, dtr, tr, cd, hd, fd, pet, spei6. See the full variable names in Table 2, Section 2.2 of the C3S Atlas Dataset documentation

  • (change-Atlas) ERA5-Land trends prior to 1978 have been disabled a potential inconsistency reported for a deprecated ERA5 forcing used for this period (see ECMWF reference).
  • (edit-doc) Fixed minor typos in the messages of the tooltip and exported figures.
  • (edit-Atlas) Fixed permalink generation not working properly in some specific cases.
  • (edit-doc, edit-Atlas) Included observation/satellite datasets (E-OBS, SST-CCI, CPC , BERKEARTH and WFDE5 used as reference for bias adjustment) in the documentation and exports.
  • (edit-Atlas) Included the Atlas version in figure and data exports (PNG, TIFF, NetCDF, etc.).
  • (error-Atlas) Fixed hatching angle in export legends (the angle was wrong in the legend).

Version 2.1

 

  • (change-Atlas) Included a link to the user survey.
  • (change-Atlas) Included a link to the Dataset and changed the link to the Repository (it now links the "User Tools" component).
  • (change-Atlas) Fixed colorbar to divergent for changes of wind and heating degree days and fixed the range for changes of wet days.

Version 2.0

Second version of the C3S Atlas based on the second version (v2) of the C3S Atlas Dataset (see the dataset documentation for details on the new datasets and variables included in this version). This version includes the following new elements:

  • Datasets (CDS catalogues): Three new observational datasets: NOAA Climate Prediction Center dataset (CPC) for precipitation, Berkeley Earth (BERKEARTH) for air temperatures, and the European Space Agency (ESA) SST Climate Change Initiative (SST-CCI) project for sea surface temperature. In addition, version v2 includes the regional reanalysis CERRA (ERA5 downscaled by a regional limited area model using data assimilation). 
  • Variables and indices: Seven new indices have been included: 
    • tr: Monthly tropical nights (minimum temperature above 20 degC)
    • dtr: Monthly daily temperature range
    • r01: Monthly wet days (precipitation above 1 mm)
    • sdii: Monthly precipitation intensity
    • r10: Monthly heavy rain days (precipitation above 10 mm)
    • r20: Monthly very heavy rain days (precipitation above 20 mm)
    • pet: Monthly potential evapotranspiration. 
      The definition of the SPEI index has been updated, using a more standard implementation for the Potential Evapotranspiration component (pet), based on the Hargreaves formulation, replacing the old Thornthwaite version used in v1. Additionally, SPI and SPEI indices are available with full period normalizations too. 
  • New configuration options for standardised indices (SPI-6 and SPEI-6) for projection datasets, displaying the version of the indices standardised with the historical and full periods in the historical (values and changes) and future (only changes) periods, respectively. 
  • Bias adjustment: For threshold-dependent indices the C3S Atlas includes a new selector in the configuration panel to chose raw or bias-adjusted values (linear scaling and ISIMIP for temperature related indices and ISIMIP for precipitation related indices). 
  • New regional panels: A new regional panel with summary tables and two new regional panels with specific information for a selections of regions/datasets: monitoring (for observational and reanalysis products, to monitor recent changes year by year) and the urban climate regional panels (for a number of pre-defined cities) to represent the urban-rural signal (urban heat island): differences between the urban and surrounding rural areas.
  • Ensemble granularity for the projection datasets, allowing to select individual models (or sub-ensembles) in the regional products.  
  • New WGS-84 projection as default for customized regions. This projection is common for representing regular longitude-latitude grids and represents constant lat/lon lines as straight lines, aligning with the underlying data model.  
  • Software and reproducibility: The software and processing workflow used to produce this dataset is available from the C3S Atlas GitHub https://ecmwf-projects.github.io/c3s-atlas (including the underlying software and illustrative notebooks).

Version 1.5

  • (error-Atlas, error-data) Error in SPEI-6 products: The calculation of the SPEI-6 index was affected by an error due to wrong units in the precipitation component (daily accumulation) as compared with the water evaporation demand (PET) component (monthly accumulation). As a result the index reflects broadly the PET component of SPEI (SPEI is based on the water balance obtained as PRECIP-PET). As a result, this index has been disabled from the Atlas application and a warning has been included in the catalogue of the dataset.

Version 1.4

  • (error-Atlas) Error in customized regional products (extreme and count indices): Regional products of extreme and count indices for user-defined regions were wrongly computed using the default (mean) temporal aggregation function to obtain the seasonal/annual time series from the original monthly ones. This affected the regional extreme and count indices and resulted in strong underestimations (see next item for more details on seasonal aggregation).
  • (edit-doc) Temporal aggregation: Clarified and expanded the Information about the temporal aggregation performed by the C3S Atlas (from the monthly time series of the underpinning dataset to the seasonal/annual time series and climatologies of the visualized products) included in the user guidance, in particular in Section 2.2 ("season" selector). 

Version 1.3 

 

  • (error-Atlas) Error in customized regional products:  Customized regions are now available only in the standard Robinson projection, since there was a bug in the definition of regions in other projections producing wrong results for the corresponding spatially aggregated data in some cases. This has been documented in Section 2.3 of this document.
  • (change-Atlas) Changes in menu navigation: Unavailable options have been disabled (grayed out) instead of hiding them. In line with other C3S tools (e.g., dataset widgets), the variables are disabled (and not suitable for selection) until the choice that forces them to be disabled is undone; e.g. the choice of the dataset conditions the variables available for analysis. 
  • (edit-Atlas) Seasonal tags Winter, etc. have been expanded to Winter (DJF), etc. to provide complete information.
  • (change-Atlas) Cookies: This version fixes a bug that in some cases prevented data from being sent to Google Analytics even if the user accepted it.

Version 1.2 

  • (error-Atlas) Wrong trend units: Trend units are "per decade" (this information was missing and is now indicated on the labels of maps and regional products).
  • (change-Atlas) File export: The exported NetCDF/Tiff files include the full geographic domains available (in the previous version, trimmed versions were exported in some cases). 

Version 1.1

 

  • (new-feature) Including versions' section in user guidance: Included information about periodic updates in a "Versions" link in the Atlas next to the "User Guidance"
  • (error-Atlas) Google analytics: The first version collected data from google analytics prior to accepting the cookies. This has been fixed and no data is collected prior to acceptance. 
  • (error-doc) Reference period: The reference period used to compute the inter-annual variability threshold for the advanced uncertainty method is 1971-2005, which is the common historical period for all projection datasets (the period "1850-1900" included originally in the online Atlas information was wrong).
  • (error-doc) Information on PET version: The method for computing the PET component of the SPEI index is Thornthwaite (the online Atlas information wrongly included Hargreaves).
  • (change-doc) Improving index documentation: The dataset documentation of non-direct indices has been improved providing further details on the definition and calculation. 
  • (change-Atlas) Displaying uncertainty for relative changes: Uncertainty was not displayed for relative changes (the uncertainty mask is the same for both absolute and relative, but is was disabled for relative changes).
  • (change-Atlas) Removing an incomplete baseline period: The 1961-1990 baseline option has been removed for CORDEX datasets, since data was incomplete in this period. This affects the maps for changes and global warming levels (time series were already available from 1970). 
  • (change-Atlas) Customized regional products: Computation of large regions have been optimized to reduce computing time and some configuration problems resulting in job failure for some datasets have been fixed. 
  • (edit-Atlas) Typo: A typo in filenames of exported timeseries regional product has been fixed ("timeseries" instead of "timeserie"). 
  • (edit-Atlas) Layout: The button for closing the left side has been moved higher up, since the footer covered it partially.
  • (edit-Atlas) Typo: Typo when hovering to the download icons ("mas" instead of map and truncated info for NetCDF/Tiff).

Version 1.0

 

First version of the C3S Atlas based on the first version (v1) of the C3S Atlas Dataset (see the documentation for details on the different versions).

Note: The following categories are used for the changes above in intermediate versions: 

  • edit (typos and minor issues), 
  • change (improving existing elements), 
  • error (substantial amendments).

Changes and fixes can correspond to the different elements of the Atlas: 

  • documentation (doc, both for the online Atlas information and the dataset documentation),
  • data,
  • Atlas.

New features are indicated with a special tag (new-feature).

Known-problems and update plans: We are working in the following known problems to include fixes in the coming versions:

  • Optimize layouts of exported PDF/PNG figures.
  • The mobile version of the application requires improvement. 


This document has been produced in the context of the Copernicus Climate Change Service (C3S).

The activities leading to these results have been contracted by the European Centre for Medium-Range Weather Forecasts, operator of C3S on behalf of the European Union (Delegation Agreement signed on 11/11/2014 and Contribution Agreement signed on 22/07/2021). All information in this document is provided "as is" and no guarantee or warranty is given that the information is fit for any particular purpose.

The users thereof use the information at their sole risk and liability. For the avoidance of all doubt , the European Commission and the European Centre for Medium - Range Weather Forecasts have no liability in respect of this document, which is merely representing the author's view

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