imd_terrain: IMD heatwave terrain class of a location
In varunayan: Download and Process 'ERA5', IMD, 'HadEX3' and 'CRU TS' Data

imd_terrain

R Documentation

IMD heatwave terrain class of a location

Description

Classifies locations as "hilly", "coastal" or "plains" for the IMD heatwave definition in heatwave_days(). IMD sets the Tmax floor by terrain but does not define it. A location is hilly when it lies in Jammu and Kashmir, Ladakh, Himachal Pradesh or Uttarakhand, whose sub-divisions IMD treats as hilly down to the Jammu plains, or when its india_elevation() reaches hill_elevation, the 1200 m boundary of the mid-hill regions by default. Otherwise it is coastal when land and open sea both lie within about 9 km.

Usage

imd_terrain(latitude, longitude, hill_elevation = 1200, cell_size = NULL)

Arguments

`latitude`, `longitude`	Coordinates in decimal degrees.
`hill_elevation`	Elevation (m) at or above which a location is hilly.
`cell_size`	Grid spacing in degrees when the coordinates are cell centres, such as 1 for the IMD temperature grid; `NULL` for points.

Details

For gridded data set cell_size to classify whole cells from their Indian land: a cell is hilly when most of it lies in those states or its median elevation reaches hill_elevation, and coastal when any of it is.

Value

A character vector of "hilly", "coastal" or "plains", NA outside the grid or over sea.

References

NOAA National Centers for Environmental Information (2022). ETOPO 2022 15 Arc-Second Global Relief Model. \Sexpr[results=rd]{tools:::Rd_expr_doi("10.25921/fd45-gt74")}

Ministry of Panchayati Raj. Local Government Directory district boundaries, via https://bharatviz.org.

Examples

# Shimla, Jammu, Delhi, Chennai
imd_terrain(c(31.10, 32.73, 28.61, 13.08), c(77.17, 74.86, 77.21, 80.27))
# IMD 1 degree cells holding Jammu and Rajkot
imd_terrain(c(32.5, 22.5), c(74.5, 70.5), cell_size = 1)

varunayan documentation built on Oct. 30, 2026, 1:07 a.m.