What De Martonne Aridity Index represents
The empirical index divides annual precipitation by annual mean temperature plus 10°C. The additive constant avoids ordinary temperate temperatures near a zero denominator.
De Martonne Aridity Index begins with annual precipitation, annual mean temperature. Label each input as observed, homogenized, modeled, assumed, or derived, and preserve its site, spatial support, calendar period, reference interval, and aggregation method.
Assembling compatible climate inputs
Use annual precipitation and annual mean temperature for the same site and period. Preserve units because the traditional numerical scale assumes millimetres and Celsius.
For De Martonne Aridity Index, record station or grid identifier, coordinates, elevation, dataset version, valid calendar, reference period, missing-data rule, homogenization status, spatial weighting, units, and quality flags as applicable.
Interpreting De Martonne aridity index
At 20°C and 600 mm, the index is 20. It is an empirical climate descriptor, not a water-balance closure.
Compare De Martonne Aridity Index outputs only after aligning variable definition, temporal scale, season, reference record, threshold, distribution method, and spatial support. Similar numbers can represent different climate constructs.
Boundary and sanity checks
Temperature must remain greater than −10°C so the denominator is positive.
Change one De Martonne Aridity Index input at a time and predict the response. This exposes reversed frost dates, inclusive-versus-exclusive duration errors, zero denominators, mismatched Celsius and Kelvin, and threshold equality mistakes. For De Martonne Aridity Index, also record how leap days, trace values, incomplete periods, ties, and endpoint inclusion were handled so later recalculation uses the same climate convention.
Where the climate model stops
Snow storage, PET physics, seasonal timing, soils, runoff, and regional calibration are absent. The denominator fails at −10°C.
De Martonne Aridity Index is transparent arithmetic, not an official climate normal, drought declaration, seasonal forecast, attribution study, agricultural recommendation, water allocation, or operational safety authority.
Uncertainty and sensitivity
Vary the least certain De Martonne Aridity Index input over a credible range and report how far de martonne aridity index moves. Display digits cannot overcome short records, station moves, retrieval changes, sampling gaps, or uncertain PET coefficients.
That De Martonne Aridity Index range is a sensitivity check, not automatically a confidence interval. It omits autocorrelation, spatial dependence, structural breaks, reference-period uncertainty, and model-form error outside the displayed fields.
Continue the De Martonne Aridity Index workflow with the related Snow Season Length Calculator, retaining the same calendar, reference period, and dataset support.
Probability and percentile conventions
Percentiles in De Martonne Aridity Index depend on sample, tie handling, and empirical ranking. Date probabilities additionally depend on the selected distribution and whether the event is defined as occurring by or after a target date.
A 50% fitted De Martonne Aridity Index probability at a mean date is not a deterministic forecast. Climate nonstationarity and small tail samples can make historical probabilities poor descriptions of a future year.
Water balance and PET conventions
Precipitation, PET, actual evapotranspiration, runoff, and soil storage are distinct. De Martonne Aridity Index should preserve the PET method because Hargreaves, Thornthwaite, and physically based methods can disagree.
Annual ratios inside De Martonne Aridity Index hide seasonality. The same annual precipitation and PET can accompany very different monthly water availability, snow storage, and ecosystem response.
Keeping an auditable record
Save raw De Martonne Aridity Index inputs, conversions, thresholds, coefficient sources, formula version, unrounded output, rounded result, and flags. A reviewer should reproduce the answer without guessing calendar, reference period, or missing-data treatment.
When a source series changes, create a dated De Martonne Aridity Index revision and preserve the prior result. Label quality-control corrections separately from a later observation or alternative scenario.
Formula and unit path
The working relationship is I = P ÷ (T + 10). De Martonne Aridity Index uses only displayed inputs and retrieves no station series, gridded data, normals, forecasts, or climate classifications.
Carry temperature scale, precipitation depth, day-of-year calendar, duration, and denominator units through De Martonne Aridity Index. Keep an absolute anomaly separate from a standardized anomaly, and keep a fitted probability separate from an observed frequency.
Continue the De Martonne Aridity Index workflow with the related Thornthwaite Potential Evapotranspiration Calculator, retaining the same calendar, reference period, and dataset support.
Checked numerical example
Six hundred divided by 20 plus 10 gives exactly 20.
Reset restores this De Martonne Aridity Index example. Repeat it independently with the stated threshold, endpoint, tie, or distribution convention before substituting climate observations.
Frequent climate-calculation errors
Typical De Martonne Aridity Index errors include averaging averages with unequal support, counting missing precipitation as zero, mixing calendar and water years, using maximum width instead of mean, or fitting a trend from only selected endpoints.
Reject impossible De Martonne Aridity Index combinations rather than forcing an answer. Preserve true zero, trace, censored, and missing states separately; keep threshold equality explicit; and test whether the result changes when the reference period changes.
Climate calculation questions
How should the answer be rounded?
Keep full precision inside De Martonne Aridity Index, then round no more finely than the least certain observation or model assumption supports.
When should I recalculate?
Recalculate De Martonne Aridity Index when the dataset, site, valid period, reference interval, threshold, method, or source value changes.
What does De Martonne Aridity Index calculate?
De Martonne Aridity Index calculates de martonne aridity index from the displayed climate inputs and formula.
Can forecast or scenario values be entered?
Yes. Label the De Martonne Aridity Index output as a scenario; the page does not fetch or validate a forecast.
How can I verify De Martonne Aridity Index?
Repeat I = P ÷ (T + 10) with recorded conversions, then test the checked example and a boundary.
Why could an official source differ?
Official products may use different station histories, grids, reference periods, missing-data rules, distributions, PET methods, thresholds, or rounding than De Martonne Aridity Index.