Choose a map projection

You'll begin your map by adding Arctic sea ice data and choosing a projection that suits the polar region and your map's purpose.

  1. Start ArcGIS Pro. If prompted, sign in using your licensed ArcGIS organizational account.
    Note:

    If you don't have access to ArcGIS Pro or an ArcGIS organizational account, see options for software access.

  2. Under New Project, click Map.

    New Map template button

  3. In the Create a New Project window, for Name, type Arctic sea ice. Optionally, choose a location for your project. Click OK.

    A map appears.

  4. On the ribbon, click the View tab. In the Windows group, click Reset Panes and click Reset Panes for Mapping (Default).

    Reset Panes for Mapping

    This ensures that the Contents and Catalog panes are open and that other panes are closed. You'll use the Catalog pane to find the data you need for your map.

  5. In the Catalog pane, click the Portal tab and click the Living Atlas tab.

    Portal and Living Atlas tabs

  6. Search for Arctic Sea Ice Extent. In the search results, right-click the Arctic Sea Ice Extent feature layer and click Add To Current Map.

    Add To Current Map

    Note:

    If you are unable to access the Arctic Sea Ice Extent layer from ArcGIS Living Atlas, download and unzip the ArcticSeaIceExtent geodatabase.

    New data appears on the map, representing monthly ice extents for the Arctic since 1978. This data is from the National Snow and Ice Data Center, through ArcGIS Living Atlas of the World.

    Map with Arctic sea ice data

    The map's projection is not ideal for visualizing the Arctic. You'll find a more appropriate coordinate system for your map.

  7. In the Contents pane, right-click Map and click Properties.

    The Map Properties window appears.

  8. In the Map Properties window, click the Coordinate Systems tab.

    Coordinate Systems tab in the Map Properties pane

    The Current XY button tells you that the map's current coordinate system is WGS 1984 Web Mercator (auxiliary sphere). This is a common coordinate system for web maps, and is the coordinate system of the basemap layers, but it greatly distorts polar regions.

  9. Under Layers, expand WGS 1984 EPSG Alaska Polar Stereographic.

    Expand coordinate system

    This is the coordinate system used by the Arctic Sea Ice Extent layer. Stereographic projections are common for polar regions, but they do not preserve area. Your map will provide a visual comparison between areas of ice cover, so you should use an equal-area projection.

  10. In the search bar, type North Pole and press Enter.
  11. In the XY Coordinate Systems Available list, click the arrow next to Projected Coordinate System to expand it. Expand Polar. Click North Pole Lambert Azimuthal Equal Area.

    North Pole Lambert Azimuthal Equal Area coordinate system selected in the Map Properties pane.

    The Current XY button updates to the selected projected coordinate system.

  12. Click OK.

    The map redraws. This time the Bering Strait, between Alaska and Russia, is at the top of the map.

    Map with new projection

    Note:

    You can learn more about choosing appropriate projections in the tutorial Choose the right projection.

Copy and reproject the data

Next, you'll create a local copy of the data so you can reproject it into the same coordinate system as the map. You may need to use spatial analysis tools later to understand or visualize your data, and if you do, keeping the coordinate system consistent will be important to ensure consistent results. Additionally, ArcGIS Pro will perform a little faster if the data and the map use the same coordinate system.

Before creating a copy of the data, you'll ensure that all of the data is visible and available for copying.

  1. In the Contents pane, right-click Arctic Sea Ice Extent. Click Data Design and click Fields.

    Fields option within the Data Design menu

    The Fields table appears. All of the data's fields are listed here. The Visible column shows that only one field is currently visible. Only visible fields can be copied.

  2. Click the header of the Visible column twice to check all rows.

    Header of the Visible column in the Fields table

  3. On the ribbon, on the Fields tab, in the Manage Edits group, click Save.

    Save button on the Fields tab of the ribbon

  4. Close the Fields view.

    Now that all of the attributes are visible, you'll make a local copy of the layer. The current layer is a service layer, stored online. It's also a live-feed layer, receiving new data updates every month. When you save a local copy on your computer, the new layer will no longer receive updates, but you will have more control over the layer. For example, you can change its coordinate system.

  5. On the ribbon, on the View tab, in the Windows group, click Geoprocessing.

    Geoprocessing button on the View tab of the ribbon

  6. In the Geoprocessing pane, search for Copy Features. In the search results, click Copy Features to open the tool.

    Copy Features tool in the Geoprocessing pane

  7. For Input Features, choose Arctic Sea Ice Extent. For Output Feature Class, delete the existing text and type IceExtent.

    Parameters for the Copy Features tool

    You were able to remove the path because, by default, any new data created by geoprocessing tools is stored in the project's geodatabase (Arctic sea ice extent.gdb).

    Note:

    A message explains that the input has a filter. However, the time filter that caused this message includes all features in the layer.

    You'll ensure that the output of the Copy Features tool is reprojected into the map's coordinate system.

  8. Click the Environments tab. For Output Coordinate System, choose Current Map [Map].

    Environments tab and Output Coordinate System set to Current Map.

    Note:

    Setting an Output Coordinate System is the same as running the Project geoprocessing tool after running the Copy Features tool.

  9. Click Run.

    Because the dataset is large, the tool may take a few minutes to run. When it finishes, a layer named IceExtent is added to the Contents pane.

  10. In the Contents pane, right-click Arctic Sea Ice Extent and click Remove.

    Remove option in the layer context menu

    You'll also remove the basemap layers, since they are not designed for mapping polar regions. You'll replace them with other background layers later.

  11. Remove World Topographic Map and World Hillshade (or other basemap layers).
  12. On the Quick Access Toolbar, click Save to save the project.

    Save button on the Quick Access Toolbar

Understand the data

Your goal is to create an effective visualization of this dataset, however, that is difficult to do until you understand the dataset. You'll take some time to explore its attributes, properties, and patterns before you design symbols. You'll explore the attribute table, create a chart, and choose a meaningful subset of the data on which to focus your visualization.

  1. In the Contents pane, right-click IceExtent and click Attribute Table.

    The layer's attribute table appears below the map.

  2. Examine the fields in the attribute table.

    IceExtent attribute table

    The Year and Month fields tell you that this layer has one feature for each month since November 1978. The Area and Extent fields both have values in million square kilometers. Often, field names are not enough to explain the data, and more research is needed. You found an explanation of the difference between sea ice area and extent on the National Snow and Ice Data Center's website. Ice extent includes any area with at least 15 percent ice cover. Extent is more commonly used than area to account for the difficulty in distinguishing between open water and meltwater on top of ice in satellite imagery.

    The name of the original layer (Arctic Sea Ice Extent) tells you that the polygons represent the Extent field, rather than the Area field.

    Note:

    You could also compare the automatically generated Shape_Area field. Its values (in square meters, determined by the unit of the coordinate system) are closer to the values in the Extent field than the Area field, but not exactly the same. If you consult the layer's metadata, you will learn that a smoothing algorithm was applied to the original data, which can account for the difference between the Shape_Area and Extent values.

  3. Close the attribute table.

    There's a time slider at the top of the Map view, indicating that this layer is time-enabled. Animation is a good method for showing this data, but you're making a static map, so you won't have this option. You'll disable the time property.

  4. In the Contents pane, right-click IceExtent and click Properties.
  5. Click the Time tab. For Filter using time, choose No time - content is always shown.

    Filter using time set to No time in the Layer Properties window.

  6. Click OK.

    The time slider disappears.

    There are many overlapping features in this layer—perhaps too many to be able to see and understand all in one image. You'll need to focus on showing the important patterns present in the data. Next, you'll make a chart to better understand these patterns.

  7. Right-click IceExtent, point to Create Chart, and click Line Chart.

    An empty chart view and the Chart Properties pane appear.

  8. In the Chart Properties pane, for Date or Number, choose Year.
  9. For Numeric field(s), click the Select button and check Extent (million km2). Click Apply.

    Numeric field(s) set to Extent (million km2)

    A chart appears. It shows a general downward trend. There is a large jump at the start of the chart, and possibly another jump at the end. This is because the first and last years do not contain all months.

    Line chart

    Note:

    The latest available month in your data will depend on when you copied it from the live-feed layer.

    For a clearer picture, you'll show each month as its own line.

  10. In the Chart Properties pane, for Split by (optional), choose Month. In the Chart properties warning window, click Yes.

    The chart now shows 12 lines, all of them descending.

    Line chart with 12 lines

    The chart tells you that February and March consistently have the largest ice extents while September (9) consistently has the smallest. In September, all of the summer's melting has completed and the winter's freezing has not yet begun.

    One of the best methods for communicating the story of a large dataset is to display only a small subset of the data. The challenge to this method is in choosing a meaningful subset. For this map, you'll only map September ice extent. September is the most dramatic month to show, since it contains the smallest extents and shows most clearly the approach of an ice-free Arctic Ocean. September may also be the most meaningful month to show, since only ice that persists through September becomes multiyear ice, which is more resilient to melting. A smaller September ice extent means a weaker ice pack for the coming winter.

  11. In the Contents pane, double-click IceExtent to open its Layer Properties window.
  12. Click the Definition Query tab and click New definition query.

    New definition query button in the Layer Properties window

  13. For Where, choose Month. Leave the second menu set to is equal to. In the third menu, choose 9.

    Definition query Where Month is equal to 9

  14. Click Apply and click OK.

    The chart filters to only show the 9 line.

    Line chart for September only

    You'll return to the chart later. For now, you'll close it so you can focus on the map.

  15. Close the chart and the Chart Properties pane.

    The map has also filtered to show a smaller and more compact group of features.

    Map of September ice extents

Symbolize the ice data

Now that you've chosen a meaningful subset of the data (September), you'll symbolize it to show areas that are more often or more rarely covered in ice.

  1. In the Contents pane, right-click IceExtent and click Symbology.

    The Symbology pane appears. You'll choose quantitative symbols to depict change over time.

  2. In the Symbology pane, for Primary symbology, choose Graduated Colors.

    Graduated Colors

    This map shows you the last year when any area has been ice-covered. Yellow areas haven't been ice-covered in several decades. Red areas have been ice-covered in recent years. This symbolization would work well if the decline of sea ice was a steady phenomenon, but it's not: some recent years have seen more ice than some earlier years. This overlap means that much of the story is obscured.

    Instead of mapping the most recent year to be ice-covered, you'll map how often each area has been ice-covered. You can determine this using the Count Overlapping Features tool.

  3. Below the Symbology pane, click the Geoprocessing tab to open the Geoprocessing pane.

    Geoprocessing tab below other panes

    Tip:

    If there is no Geoprocessing tab, on the ribbon, click the View tab. In the Windows group, click Geoprocessing.

  4. At the top of the Geoprocessing pane, click the Back button twice, or until a search bar appears.
  5. Search for and open the Count Overlapping Features tool.
  6. For Input Features, choose IceExtent. For Output Feature Class, type IceExtent_Overlap.

    Count Overlapping Features tool

    The toggle button below Input Features indicates that only a subset of the data will be processed. This is due to the definition query filter you set earlier. Since the number of filtered records represents the number of Septembers since measurements began, you may see a higher number than the one shown in the image above, depending on when you retrieved the data.

  7. Click Run.

    The tool may take several minutes to run.

  8. In the Contents pane, uncheck the box next to the IceExtent layer to turn it off.

    IceExtent layer unchecked

    The new layer shows bands of color. The white areas on the edge have only been ice-covered in September a few times since 1979. The dark blue areas in the center have almost always been ice-covered.

    Ice extent data symbolized with bands of blue.

    You'll change the symbology to a method that can map this transition with a smoother gradient.

  9. In the Contents pane, click IceExtent_Overlap to select this layer. Open the Symbology pane.
    Tip:

    The Symbology pane will always display properties for the selected layer.

  10. For Primary symbology, choose Unclassed Colors. Ensure that Field is set to COUNT_.

    Symbology pane set to Unclassed Colors.

    A warning appears at the top of the Symbology pane. It says Maximum sample size reached. Not all records are being used to classify data. This means that the minimum and maximum values that were used to create the symbology may not be correct. The legend in the Contents pane shows a color ramp ranging from 1 to 6. You know that there's more than 40 years of data, so you expect the maximum number to be at least 40.

  11. At the top of the Symbology pane, click the Advanced symbology options tab and expand Sample size.

    Sample size on the Advanced symbology options tab

    The Maximum sample size is set to 10,000. This means that only the first 10,000 records of your layer were sampled. You'll change this number to one that's large enough to encompass your entire dataset.

  12. In the Contents pane, right-click IceExtent_Overlap, point to Selection and click Select All.

    Below the Map view, the Zoom to selected features button tells you that there are more than 60,000 features in the layer.

    66,484 selected features

    Note:

    Your map may show a different number of selected features. This is expected, since you copied the live-feed data on a different date.

  13. In the Symbology pane, for Maximum sample size, type a number larger than your selected features number, such as 100,000. Press Enter.

    Maximum sample size set to 100,000.

    The warning message disappears. The legend in the Contents pane now shows a larger value range.

  14. Right-click anywhere on the map and click Clear.
  15. In the Symbology pane, click the Primary symbology tab.

    Primary symbology tab

    You'll reverse the color scheme so areas still covered in ice are white and areas where the ice has retreated and left open ocean are blue.

  16. Above the histogram, click the More button and click Reverse color scheme.

    Reverse color scheme in the More menu

    You'll also remove the gray outlines, which obscure the data.

  17. Next to Template, click the symbol.

    Template symbol

  18. If necessary, click the Properties tab and click the Symbol tab. Change Outline width to 0 pt.

    Outline width set to 0 pt.

  19. At the bottom of the pane, ensure that Auto Apply is turned on.

    Auto Apply

    The map shows a smooth gradation from white to blue, mimicking melting ice.

    Map of Arctic sea ice symbolized with blue and white color scheme.

Symbolize the base data

Next, you'll add and symbolize base data. The symbology of your thematic data (in this case, the ice extent data) will only be clear and effective if the background data is designed to complement and promote it. You'll make symbology choices for the base data that give it a lower visual hierarchy than the thematic data: you will make the base data appear to sit in the background of the map.

  1. Download the IceMapData geodatabase and unzip it to a location on your computer, for example, your C:\ drive.

    This geodatabase contains base data for your map. The data is from Esri and Natural Earth. You can find the original sources for each of the layers on the item page.

  2. On the ribbon, click the Map tab. In the Layer group, click Add Data.
  3. In the Add Data window, browse to IceMapData.gdb. Select all four feature classes (ArcticCircle, Countries, Graticule, and NorthernMarineRegions.
    Tip:

    Hold the Ctrl key to select multiple items at once.

  4. Click OK.

    Four layers selected in the Add Data window.

    Four layers are added to the map.

  5. In the Contents pane, turn off the NorthernMarineRegions layer.

    You'll use this layer later to create labels.

  6. Click the symbol for the Countries layer.

    Countries layer symbol

    The Symbology pane appears. You'll create a custom color for this layer.

  7. In the Symbology pane, on the Symbol tab, click the Color menu and click Color Properties.

    Color Properties

  8. In the Color Editor window, for Hex #, type F8EBCE and press Enter.

    HEX # set to F8EBCE.

    The Current color preview updates to a pale beige color. You'll save this color to your favorites style, where it will be easy to access later.

  9. Click Save color to style. In the Save Color As window, for Name, type Land. Click OK and click OK.
  10. In the Symbology pane, change Outline width to 0 pt.

    Outline width set to 0 pt.

  11. In the Contents pane, click the symbol for the ArcticCircle layer.

    ArcticCircle line

  12. In the Symbology pane, click the Gallery tab. Search for marker only and click the Marker Only dotted line symbol.

    Marker Only symbol in the Gallery

    Dotted and dashed lines are often used in maps for nonphysical lines such as borders (as opposed to physical lines such as roads and rivers). Next, you'll choose a color that has low contrast with the land color. This will ensure that the ArcticCircle line is visible but not prominent.

  13. Click the Properties tab. For Color, choose Tecate Dust. (Point to colors to read their names.)

    Tecate Dust color

  14. In the Contents pane, right-click the symbol for the Graticule layer. Under Favorites, click Land.

    Land color in the Favorites list

    The graticule lines are only visible against the ocean, not the land. They look good against the white of the ice data, converging to show the location of the north pole, but they are too prominent against the blue ice data. They distract attention away from the map's theme.

    Map with graticule lines covering ice data

    You'll use a blend mode to ensure that the lines are still visible against the white areas but not against the blue areas.

  15. With the Graticule layer selected, on the ribbon, click the Feature Layer tab. In the Effects group, for Layer Blend, choose Darken.

    Layer Blend set to Darken on the Appearance tab of the ribbon

    The Darken blend mode ensures that the layer only draws on top of colors that are lighter than itself.

    Map with graticule lines partially covering ice data

Create a background layer

The background of your map is white, which might be confused with the white color in the ice layer. You'll create a background layer to symbolize the ocean.

  1. On the ribbon, click the Insert tab. In the Layer Templates group, click Polygon Map Notes.

    Polygon Map Notes in the Layer Templates gallery

    A new layer is added to the Contents pane. It is empty. You'll add a new feature to this layer.

  2. On the ribbon, click the Edit tab. In the Snapping group, click the bottom part of the Snapping button.
  3. Make sure that the Snapping toggle is on and the Endpoint snaps to the nearest start or endpoint of a polyline feature button is highlighted in blue.

    Snapping button and menu

  4. On the ribbon, in the Features group, click Create.
  5. In the Create Features pane, click Polygon Notes. Click the Circle template.

    Circle template in the Create Features pane

  6. On the map, point to the north pole. When the snapping label reads Graticule : Endpoint, click the map.

    Snapping for Graticule : Endpoint

  7. Zoom out until you can see the entire world. Click the map near Antarctica but do not click outside of the map's circle.

    Map of entire world with new feature ending before Antarctica

  8. On the ribbon, in the Selection group, click Clear.
  9. In the Manage Edits group, click Save. In the Save Edits window, click Yes.
  10. Close the Create Features pane.
    Note:

    It's possible to change the background color of the map in the Map Properties window. You created a new layer instead because it offers more flexibility that will be useful later in the tutorial.

  11. In the Contents pane, click Polygon Notes. On the keyboard, press F2 to make the layer name editable. Rename the layer Ocean.

    Ocean layer in the Contents pane

  12. If necessary, expand the Ocean layer. Right-click the layer's symbol and click Color Properties.

    You'll choose a lighter version of the beige land color for the ocean. This will result in a very low contrast between the land and ocean, helping both layers to have low visual hierarchy and appear as background information.

  13. In the Color Editor window, change Transparency to 0 percent. For Hex #, type FBF4E5.

    Transparency set to 0 percent and HEX # set to FBF4E5.

  14. Click OK.
  15. In the Contents pane, drag and drop Countries above Ocean.
  16. Drag and drop IceExtent_Overlap above Countries.
  17. Ensure that Graticule and ArcticCircle are at the top of the layer list.

    Map and Contents pane

  18. Save the project.

In this tutorial, you mapped Arctic sea ice extent for each September since 1979. You reprojected and explored the data, chose an appropriate subset of the data to display, and designed symbology for both the thematic and base data. In the next tutorial, you'll refine the symbology further to best express the story of Arctic sea ice decline.

You can find all of the tutorials in this series at Cartographic creations in ArcGIS Pro. You can find more cartography tutorials on the Introduction to Cartography page.