science

Standardised Precipitation Evapotranspiration Index

Standardised Precipitation Evapotranspiration Index is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Standardised Precipitation Evapotranspiration Index rather than just read about it. In short: The Standardized Precipitation Evapotranspiration Index (SPEI) is a multiscalar drought index based on climatic data. It was developed by Vicente-Serrano et al.

Key takeaways

Standardised Precipitation Evapotranspiration Index belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Standardised Precipitation Evapotranspiration Index to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Standardised Precipitation Evapotranspiration Index from memory before moving on to harder problems.

Reference excerpt

The Standardized Precipitation Evapotranspiration Index (SPEI) is a multiscalar drought index based on climatic data. It was developed by Vicente-Serrano et al. (2010) at the Pyrenean Institute of Ecology in Zaragoza, Spain. It can be used for determining the onset, duration and magnitude of drought conditions with respect to normal conditions in a variety of natural and managed systems such as crops, ecosystems, rivers, water resources, etc. The SPEI accounts not only for precipitation deficit but also for the role of the increased atmospheric evaporative demand on drought severity. Evaporative demand is particularly dominant during periods of precipitation deficit. The SPEI calculation requires long-term and high-quality precipitation and atmospheric evaporative demand datasets. These can be obtained from ground stations or gridded data based on reanalysis as well as satellite and multi-source datasets.

Datasets Globally, the SPEIbase and Global Precipitation Climatology Centre (GPCC) drought index datasets are available at a relatively coarse spatial resolution. The SPEIbase is available at 0.5° resolution calculated from the Climatic Research Unit precipitation and potential evapotranspiration datasets. The GPCC drought index provides SPEI datasets at a 1.0° spatial resolution for limited timescales (1, 3, 6, 9, 12, 24, and 48 months). Inputs to SPEI datasets can include high-resolution potential evapotranspiration (PET) from the Global Land Evaporation Amsterdam Model (GLEAM) and hourly Potential Evapotranspiration (hPET). GLEAM is a set of algorithms designed to calculate actual evaporation, PET, evaporative stress, and root-zone soil moisture.

Classification

See also Keetch–Byram drought index – Estimate of soil moisture deficit Palmer drought Index – Regional drought index

References

External links SPEI world database, updated monthly R package that calculates the SPEI

Worked examples

Example 1 — a first encounter with Standardised Precipitation Evapotranspiration Index

Start with the simplest possible case. Write down what Standardised Precipitation Evapotranspiration Index claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Standardised Precipitation Evapotranspiration Index before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Standardised Precipitation Evapotranspiration Index ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Standardised Precipitation Evapotranspiration Index

In research: Standardised Precipitation Evapotranspiration Index appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Standardised Precipitation Evapotranspiration Index in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Standardised Precipitation Evapotranspiration Index is common in secondary-school and first-year university syllabi. It links to neighbouring topics Atmospheric science stubs, Droughts, Hydrology, so understanding it makes those chapters shorter.
In everyday life: Look for Standardised Precipitation Evapotranspiration Index outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

Ask Teacher Smith questions about this articleOpens your AI tutor with a question about “Standardised Precipitation Evapotranspiration Index” →

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study Standardised Precipitation Evapotranspiration Index in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Standardised Precipitation Evapotranspiration Index means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Standardised Precipitation Evapotranspiration Index out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Standardised Precipitation Evapotranspiration Index in simple terms?

The Standardized Precipitation Evapotranspiration Index (SPEI) is a multiscalar drought index based on climatic data. It was developed by Vicente-Serrano et al.

Why does Standardised Precipitation Evapotranspiration Index matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Standardised Precipitation Evapotranspiration Index?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Standardised Precipitation Evapotranspiration Index.