Connect the layers. Check the joins.
Continue Lecture 6 from slide 58, “Plotting Multiple Layers,” and extend Classwork 5 with fire detections, burned areas, smoke plumes, and monitors. Check how spatial joins and aggregation change what each map measures.
The Research Kick-off Report is due Tuesday, October 20. Review the report requirements and document the data, initial visual evidence, and analysis plan for your project.
This week
Multiple layers
- Combine fire detections, burned-area outlines, smoke plumes, and county boundaries.
- Use compatible coordinate reference systems and a clear layer order.
- Keep dates, measurements, and units visible when comparing layers.
Spatial joins
- Convert longitude–latitude tables into spatial points.
- Use st_filter() and st_join() to connect points, plumes, and counties.
- Check unmatched rows, multiple matches, and the relationship before counting.
Summaries and interpretation
- Use population weights when aggregating county smoke estimates to states.
- Distinguish smoke overhead from estimated smoke at breathing height.
- Choose a line chart when timing is clearer there than on a map.
Lecture slides
Classwork
Classwork 5: Map Canadian Wildfire Smoke with geom_sf()
Continue with Parts 5–6 and 8–10: map monitors and Canadian fires, compare smoke plumes with surface estimates, audit spatial joins, and build population-weighted state summaries. Refer back to Parts 0–4 and 7 when checking keys, projections, color scales, and comparisons across days.
Research and data guides
When Canadian smoke crosses the border
Use the guides to connect your research question to a documented data stack. Record each file’s source, observation unit, dates, variables, and missing-data rules, then explain what your initial figures establish and what remains uncertain.
By the end of Week 9
Prepare the following:
- the Research Kick-off Report, including a feasible question, documented data, initial visual evidence, and an analysis plan;
- a layered map with its dates, units, sources, and geographic scope stated;
- a spatial-join audit showing the matching relationship and any unmatched or repeated observations; and
- a population-weighted summary with its denominator and interpretation explained.