Process IMPROVE aerosol monitoring data

The process_improve() function reads pipe-delimited IMPROVE (Interagency Monitoring of Protected Visual Environments) measurement files downloaded by download_improve() and joins them with a site metadata table to attach geographic coordinates and auxiliary site attributes. Returns a SpatVector, sf, or data.table object.

Usage

process_improve(
  path = NULL,
  product = c("raw", "rhr2", "rhr3"),
  date = NULL,
  sites_file = NULL,
  return_format = c("terra", "sf", "data.table"),
  extent = NULL,
  ...
)

Arguments

path: character(1). Directory containing downloaded IMPROVE .txt files.
product: character(1). Product type: "raw" (default), "rhr2", or "rhr3".
date: character(1 or 2). Date ("YYYY-MM-DD") or start/end date pair to filter measurements. Defaults to no filtering when NULL.
sites_file: character(1) or NULL. Path to a site metadata file. When NULL (default), the function first looks for a file named improve_sites.txt inside path, then falls back to an embedded IMPROVE aerosol site table included in amadeus.
return_format: character(1). Return object type: "terra", "sf", or "data.table".
extent: numeric(4) or NULL. Optional crop extent c(xmin, xmax, ymin, ymax) in WGS84 / EPSG:4326. Applied only when return_format is "terra" or "sf".
...: Placeholders.

Value

a SpatVector, sf, or data.table object depending on return_format.

Details

Three product types are supported via product:

"raw": IMPAER speciated aerosol mass concentrations. Key columns: SiteCode, FactDate, ParamCode, FactValue, Units.
"rhr2": IMPRHR2 Regional Haze Rule II light extinction (bext, \(Mm^{-1}\)).
"rhr3": IMPRHR3 Regional Haze Rule III deciview index (dv).

Measurement values are not filtered by Status; callers may apply their own validity flags (e.g., keep only Status == "V0").

Note

IMPROVE data are measured on an every-third-day sampling schedule. Gaps between measurement dates are expected.

Examples