ArcGIS Pro

Build A Heat Risk Index for Local Climate Planning: Part 1 of 3

Three-step workflow for creating a heat resilience index.
Three steps to a climate resilience index.

Use Processing Templates to Derive Land Surface Temperature

Ever wondered how your neighborhood stacks up against others in your community regarding the urban heat island effect? In this three-blog series, you will learn about climate resilience indices. The series walks you through the steps to use a global collection of ready-to-use geographic information to derive input variables needed to calculate a heat resilience index (HRI). The resulting intervention-focused map can be used by local communities to prioritize census tracts for tree planting as one mitigation against urban heat islands.

Climate change impacts us all, and robust science says things will only worsen if we don’t act swiftly. According to NOAA, scientists say that by the year 2100, average global temperatures will increase by 2 to 9.7°F (1.1 to 5.4°C).

Add Data from Living Atlas of the World

Let’s begin with a new ArcGIS Pro project. The first variable for the HRI is land surface temperature in degrees Fahrenheit. You will derive this from the Multispectral Landsat imagery service in ArcGIS Living Atlas of the World. Using the Add Data button, search the Living Atlas for “Multispectral Landsat” and add it to the project. Be sure Living Atlas is selected under Portal on the left before typing your search text.

The Add Data pane showing Landsat text search.
Use the Add Data pane to add an image service to your project.

The Multispectral Landsat service contains decades’ worth of data, called scenes. The next few steps demonstrate how to use filtering and summarization tools to refine the data.

Change the Image Service Properties

You need to adjust the Landsat service properties to get the temperature data. Right-click the Multispectral Landsat service in Contents and select Properties.

Select Processing Templates and choose “Band 10 Surface Temperature in Celsius” from the Processing Template drop-down.

Processing Templates tab showing Band 10 Surface Temperature template selection.
Select a Processing Template.

Next, select Mosaic in the Properties pane and choose “Mean” for the Mosaic operator field. You are selecting the mean value because the service contains scenes across decades and for this project you are interested in the long-term average temperature for you study area.

Mosaic tab on the Properties pane selecting Mosaic Operator of Mean.
Change the Mosaic Operator to Mean.

Finally, select Definition Query. Delete any existing query and add a new one where “CloudCover <= 0.05.” Apply the query and close the Properties pane. This query will filter out all scenes with more than 5% cloud cover. Clouds and cloud shadows in Landsat scenes adversely impact the results of any analysis. Filtering out cloudy scenes will improve the overall quality of your analysis. Click ‘OK’ to apply the new properties. The online service may take a few minutes to update so be patient.

Definition Query tab showing Cloud Cover less than 5%.
Add a Definition Query to filter scenes.

While not necessary, if you wish to visualize the temperature data at this point, you can apply the following symbology settings.

Symbology pane showing Inferno color scheme, Min-Max stretch type, and DRA settings.
Optional symbology settings.

Filter the Service by Location

The last filter step for this input is to filter by location. This step allows you to focus on a smaller area of interest, so Copy Raster executes quickly in the next step. For this example, census polygons from a small area in Sevilla, Spain, are used to define an area of interest. These Census Section level boundaries are available in Living Atlas.

Using the Add Data button, search the Living Atlas for ‘spain census sections’ and add it to the project. Be sure Living Atlas is selected under Portal on the left before typing your search text.

The Add Data pane showing Spain census sections text search.
Use the Add Data pane to add a feature layer to the project.

Add a Definition Query to the hosted feature layer you just added to the project. Set the “Name” attribute equal to “Seville” and apply it to limit your area of interest to Seville census polygons. Rename the layer in Contents to something meaningful like “Seville Census Sections”.

Definition Query on the hosted feature layer.
Use a Definition Query to limit the area of interest.

Once you have chosen an area of interest, zoom the map to the area. Next, right-click the Landsat service again and choose Attribute Table. Be sure you have framed your area of interest in the map extent before completing the next step.

Sevilla, Spain framed in map extent.
Area of interest framed in map extent.

The Filter by Extent button is located in the lower-right corner of the Attribute Table.
Click this button to enable the filter based on the current extent of your map.

Attribute table showing Filter by Location button.
Enable Filter by Location.

By changing these properties of the image service, you have configured it to present the average temperature in degrees Fahrenheit across all the scenes in the service. Additionally, you used filtering to limit the scenes to only those with less than 5% cloud cover and spatially limited them to your area of interest.

Copy the Result

Copying this result allows you to focus on your area of interest instead of working with the entire global data set.

Use the Copy Raster Geoprocessing tool and copy to TIF format. You will need to enter an output file location that is a folder and give it a name ending in .tif. TIF files may not be output to file geodatabases.

Copy Raster tool pane with TIF format specified.
Copy the result to TIF format and give it a name.

Set the Processing Extent on the tool’s Environment tab by selecting the Sevilla Census Sections layer. This will clip the raster output to the boundary of the polygons.

Run Zonal Statistics as Table

Now that your area of interest’s surface temperate raster is copied to a local file, you will need to find census polygons for the same location. The example here, uses polygon features from Living Atlas for the area around the Guadalquivir River in Sevilla, Span. You can use the Zonal Statistics as Table tool to summarize all the temperature values within each census polygon to determine the maximum value. Open the Zonal Statistics as Table Geoprocessing tool. Select the Sevilla census sections polygon layer for Input Raster or Feature Zone Data, ID for Zone Field, the previous output you just copied as the Input Value Raster and select Maximum as Statistics Type.

Zonal Statistics as Table pane with zones, input, and statistics type specified.
Use the polygons as zones, temperate raster as value, and maximum as statistics type.

Leave these results in the table for now. In the final blog you will combine the three inputs into a single table for additional processing.

Conclusion

You have now completed the workflow for preparing the first input in the heat resilience index. First, using Living Atlas data, you derived land surface temperature for an area of interest using processing templates on the Multispectral Landsat image service. Then you adjusted properties on the service to filter the scenes by attribute and calculate average values across the filtered scenes. You also applied a spatial filter to limit the scenes to an area around the census boundaries.

The next blog will show how to prepare the tree canopy input from the landcover type. Stay tuned!

About the author

I am a Senior Product Engineer for Esri in Redlands, CA specializing in global data sets. I currently do work in support local climate resilience planning and mitigation using online data. I use a lot of Python, Jupyter Notebooks, and raster datasets in my daily work. I bring my experiences in aerospace engineering and information technology to help improve and automate global data processing workflows. Feel free to contact me at mgilbert@esri.com with questions or comments.

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