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Nested Grid Model

Nested Grid Model is a earth 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 Nested Grid Model rather than just read about it. In short: The Nested Grid Model (usually known as NGM for short) was a numerical weather prediction model run by the National Centers for Environmental Prediction, a division of the National Weather Service, in the United States. The NGM was, as its name suggested, derived from two levels of grids: a hemispheric-scale grid and a synoptic-scale grid, the latter of which had a resolution of approximately 90 kilometers.

Nested Grid Model — main illustration
Nested Grid Model — illustration

Key takeaways

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

Reference excerpt

The Nested Grid Model (usually known as NGM for short) was a numerical weather prediction model run by the National Centers for Environmental Prediction, a division of the National Weather Service, in the United States. The NGM was, as its name suggested, derived from two levels of grids: a hemispheric-scale grid and a synoptic-scale grid, the latter of which had a resolution of approximately 90 kilometers. Its most notable feature was that it assumed the hydrostatic equation. The NGM debuted in 1987, replacing the limited-area fine mesh (LFM) model. The NGM was also used to create model output statistics. Development of the model stopped in 1993. By 2000, the model was seen as obsolete, particularly for mesoscale features that were not hydrostatic, and was scheduled to be superseded by the Global Forecast System (GFS) in 2001. However, though the NGM ceased widespread use in the early 2000s due to the GFS and improvements in the Eta model (later the North American Mesoscale Model), and the NGM's short-range LAMP products were phased out in 2006, NGM MOS products continued to be in significant general use (alongside the Eta/NAM and GFS) until March 3, 2009, when the NGM MOS products were discontinued.

References

Illustrations

Nested Grid Model: An example geopotential height and relative humidity forecast by the NGM
An example geopotential height and relative humidity forecast by the NGM

Worked examples

Example 1 — a first encounter with Nested Grid Model

Start with the simplest possible case. Write down what Nested Grid Model claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In earth 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 Nested Grid Model 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 Nested Grid Model 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 Nested Grid Model

In research
Nested Grid Model appears in earth 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 Nested Grid Model 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
Nested Grid Model is common in secondary-school and first-year university syllabi. It links to neighbouring topics Meteorology stubs, National Weather Service numerical models, so understanding it makes those chapters shorter.
In everyday life
Look for Nested Grid Model 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.

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How to study Nested Grid Model in 20 minutes

  1. Read the reference excerpt below once, without taking notes.
  2. Close the page and write down what Nested Grid Model means in your own words.
  3. Compare your version with the excerpt and mark what you missed.
  4. Work through the three examples above with pen and paper.
  5. Explain Nested Grid Model out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Nested Grid Model in simple terms?

The Nested Grid Model (usually known as NGM for short) was a numerical weather prediction model run by the National Centers for Environmental Prediction, a division of the National Weather Service, in the United States. The NGM was, as its name suggested, derived from two levels of grids: a hemisph…

Why does Nested Grid Model matter?

Because it connects several earth 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 Nested Grid Model?

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 Nested Grid Model.

Tags

  • Meteorology stubs
  • National Weather Service numerical models

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