Extracts Land Surface Temperature (LST) from MODIS MOD11A1

Extracts daytime or nighttime Land Surface Temperature (LST) for a user-defined region and time range using the MODIS MOD11A1.061 product. The function supports summarizing the temperature data over each date using a selected statistic (e.g., mean or median).

Usage

l4h_surface_temp(
  from,
  to,
  region,
  band = "day",
  level = "strict",
  scale = 1000,
  stat = "mean",
  sf = TRUE,
  quiet = FALSE,
  force = TRUE,
  ...
)

Arguments

from: Character or Date. Start date of the analysis (e.g., "2020-01-01").
to: Character or Date. End date of the analysis (e.g., "2020-12-31").
region: A spatial object defining the region of interest. Accepts an sf, sfc, or SpatVector object.
band: Character. LST type to extract: "day" (LST_Day_1km) or "night" (LST_Night_1km). Default is "day".
level: Character. Quality filter level to apply to MODIS LST pixels. Use "strict" to retain only high-quality observations (QA bits 0–1 equal to 00), or "moderate" to allow both high and acceptable quality (QA bits 0–1 equal to 00 or 01). Default is "moderate".
scale: Numeric. Spatial resolution in meters. Default is 1000 (native resolution).
stat: Character. Summary statistic to apply per image per region. One of "mean", "median", "min", "max". Passed to ee_extract().
sf: Logical. If TRUE, returns an sf object; if FALSE, returns a tibble. Default is TRUE.
quiet: Logical. If TRUE, suppresses progress bars and messages. Default is FALSE.
force: Logical. If TRUE, forces the extraction even if results are cached. Default is FALSE.
...: Additional arguments passed to rgee::ee_extract().

Value

A sf or tibble object with LST values (in degrees Celsius) extracted from MODIS MOD11A1.

Details

The MODIS MOD11A1.061 product provides daily Land Surface Temperature and quality information. This function filters out low-quality or cloud-contaminated pixels based on the QC_Day or QC_Night band. Only pixels where the quality control bits 0–1 equal 00 (high quality) are retained.

LST values are originally stored as Kelvin multiplied by 0.02. This function automatically converts them to degrees Celsius using the formula: LST = (value × 0.02) - 273.15.

Credits

Pioneering geospatial health analytics and open‐science tools. Developed by the Innovalab Team, for more information send a email to imt.innovlab@oficinas-upch.pe

References

Wan, Z., Hook, S., & Hulley, G. (2015). MOD11A1 MODIS/Terra Land Surface Temperature and Emissivity Daily L3 Global 1km SIN Grid V006 (Version 6.1). NASA EOSDIS Land Processes DAAC. https://doi.org/10.5067/MODIS/MOD11A1.061

MODIS MOD11A1.061 - Google Earth Engine Dataset Catalog. https://developers.google.com/earth-engine/datasets/catalog/MODIS_061_MOD11A1

Examples

if (FALSE) { # \dontrun{
library(land4health)
ee_Initialize()

# Define a bounding box region in Ucayali, Peru
region <- st_as_sf(st_sfc(
  st_polygon(list(matrix(c(
    -74.1, -4.4,
    -74.1, -3.7,
    -73.2, -3.7,
    -73.2, -4.4,
    -74.1, -4.4
  ), ncol = 2, byrow = TRUE))),
  crs = 4326
))

# Extract daytime LST for 2020
lst_day <- l4h_surface_temp(
  from = "2020-01-01",
  to = "2020-12-31",
  region = region,
  band = "day",
  stat = "mean")

head(lst_day)

# Extract nighttime LST
lst_night <- l4h_surface_temp(
 from = "2020-01-01",
 to = "2020-12-31",
 region = region,
 band = "night",
 stat = "mean")

head(lst_night)
} # }