Methodology and responsible use

Know what the reference can—and cannot—tell you.

IndianClimate turns a selected ERA5-Land archive into lightweight location reference sheets. This page records the source, location-processing method, definitions and limits needed to use those sheets responsibly.

2019 baseline test archive ERA5-Land reanalysis 0.1° grid · CDO bilinear interpolation Reference data · not live weather

01 · Source record

ECMWF ERA5-Land hourly reanalysis

ERA5-Land is a global, gridded land-surface reanalysis produced by replaying the land component of the ECMWF ERA5 climate reanalysis. It provides model-based estimates with uncertainty; it is not a network of weather-station observations.

Data type: Gridded reanalysis
Source grid: 0.1° × 0.1° regular latitude–longitude grid
Native resolution: approximately 9 km
Source frequency: Hourly
IndianClimate edition: 2019 test / base year
Official record: doi:10.24381/cds.e2161bac

Coverage distinction: the source ERA5-Land product extends from 1950 to the present, but IndianClimate currently publishes a selected 2019 test/base-year archive. Source-product coverage must not be mistaken for coverage on this site.

02 · Location processing

From a regular grid to a listed reference coordinate

Acquire: source variables are drawn from the ERA5-Land hourly reanalysis for the 2019 archive edition.
Interpolate: Climate Data Operators (CDO) bilinear interpolation is used to estimate values at each listed coordinate from surrounding source-grid cells.
Organise: hourly rows are grouped into monthly, seasonal, daily and existing day/night archive classifications.
Present: the site computes descriptive minima, maxima, averages, standard deviations, cloud classes and wind-frequency views from available rows.

Bilinear interpolation creates a smooth coordinate estimate; it does not add local measurements or resolve features below the source grid. Each location page therefore reports its actual available row count and record dates separately.

03 · Published variables

What the current reference desk exposes

Wind

Wind speed in m/s, direction-frequency wind roses, speed bins and calm-hour share. Calm is defined in the current wind-rose logic as wind speed below 0.5 m/s.

Air temperature

Near-surface air temperature in °C, summarised from available hourly rows.

Relative humidity

Relative humidity in percent, including monthly and existing day/night archive views.

Station pressure

Pressure at the reference surface in hPa. It is not labelled as mean sea-level pressure.

Cloud cover

Total cloud fraction presented in tenths and grouped into descriptive sky-cover classes.

Dew point

Dew-point temperature appears in the multi-parameter reference summary where rows are available.

04 · Glossary

Definitions used on data pages

Reference location: A named discovery label and coordinate at which ERA5-Land values have been interpolated. It is not a monitoring station.
Annual overview: A twelve-month summary of available rows in the published archive edition—not a multi-decadal climate normal.
Season: Winter: December–February; summer/pre-monsoon: March–May; monsoon: June–September; post-monsoon: October–November.
Day / night: The classification stored with existing hourly archive rows. Treat it as a descriptive split; the site does not currently claim a separately verified fixed-clock or solar-elevation definition.
Cloud classes: Clear: 0–0.1; scattered: above 0.1–0.5; broken: above 0.5–0.9; overcast: above 0.9–1.0 source cloud fraction.
Standard deviation: A descriptive measure of spread among available hourly values in the stated grouping; it is not an uncertainty bound for ERA5-Land.

05 · Intended use and limitations

A reference for screening and baseline context

Appropriate uses

Early EIA baseline context and scoping
Comparing seasonal and monthly patterns
Research screening and reproducible reference checks
Identifying where site-specific study is needed

Do not treat it as

Live weather, a forecast or an alerting service
Measured data from a weather station
A multi-decadal climate normal
A substitute for regulatory or project-specific requirements

Representation can be weaker in complex terrain, coastal zones, rapidly changing land cover and urban microclimates. Missing hourly rows can affect aggregates. Review the row count/date span on each location data sheet and use professional judgement before including results in a formal study.

06 · Attribution

How to cite the archive

Use the copyable location-specific citation on each data page. The source dataset should remain attributable to the Copernicus Climate Change Service / ECMWF ERA5-Land record.

Report-ready attribution

Cite this reference

IndianClimate.com. 2019 ERA5-Land baseline meteorological reference. Derived from ECMWF ERA5-Land hourly reanalysis using CDO bilinear interpolation. https://doi.org/10.24381/cds.e2161bac. Accessed 2026-11-15.

ERA5-Land DOI

Data Source & Attribution: Underlying meteorological fields are sourced from the public ECMWF ERA5-Land dataset via the Copernicus Climate Data Store (CDS). Contains modified Copernicus Climate Change Service information, used under the public Licence to Use Copernicus Products. Neither the European Commission nor ECMWF is responsible for any use that may be made of this information, and this site is an independent Envitrans utility with no official affiliation with ECMWF. Users remain responsible for verifying current CDS attribution terms for their own publications.

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