26 · Spatial III: exposures

Tuesday, Nov 24, 2026

Materials for this session are not published yet. They appear here before class.

Objectives

By the end of this session you can:

• Decompose u/v wind components into speed and direction — correctly.
• Build an upwind/downwind exposure flag relative to a source.
• Compute network distances and least-cost paths.
• Validate a constructed exposure against independent data.

What we cover

• Why economists prize variables the actors didn’t choose: downwind pollution, market access, distance to everything.
• Vector fields: u/v into speed and direction, and the classic direction mistake.
• Upwind/downwind flags relative to a source.
• Network distances and least-cost paths.
• Which product you pick is a result. Nine gridded rainfall products cover the same place and disagree, and conclusions flip depending on which one you take. The choice belongs in the methods section, with a reason. Run your exposure through two products and report both when they diverge.

Verification habit. Does the smoke go downwind? A constructed exposure gets checked against independent measurements, and against a second product.