How well does the observation match the calculation?

Lab 8 – The Geostrophic Wind and ENSO

All questions subsets are worth 5 points.

1.) Recall that the Coriolis force can be computed as where V is the wind speed (in ms-1),   is the earth’s angular rotation rate about its axis, and  is the latitude.

On an isobaric map, the pressure gradient force is computed as where g is the gravitational constant of 9.8 ms-2, Z is altitude,  is the difference between two altitude lines, and d is the distance between the altitude lines.

The geostrophic wind is balance between CF and PGF. To avoid sign confusion, and since wind is always a positive value, we’ll use absolute values. Solving for V gives where  represents the geostrophic wind.

Consider this 300-mb map from Nov 1, 0000 UTC. The fastest winds are surrounded by shaded isotachs. Label the polar jet with PJ and the subtropical jet with SJ. (5 pts)

If one zooms into Washington

Compute the geostrophic wind. Assume the latitude is 48.2486ºN, m, and d = 175000 m.

Convert this value to knots, where 1 m s-1 = 1.94 kts. How well does the observation match the calculation?

Draw two arrows depicting the balance between the Coriolis force and pressure gradient force on the map in 2b.

If this situation were in a trough, the observed wind will be ( more less ) than the geostrophic wind.

2.) The Troup SOI is used by the Australian Bureau of Meteorology to assess ENSO conditions. The equation is:

= (average Tahiti MSLP for the month) – (average Darwin MSLP for the month)

= long-term average of  for the month in question

= long-term standard deviation of  for the month in question

Tahiti’s average pressure is usually larger than Darwin’s average pressure, and the differences also vary monthly.

Hence, it’s the monthly pressure anomaly differences, normalized by their monthly PDIFF standard deviation, which best measures the Southern Oscillation. The multiplication by 10 simply provides a more relatable value range.

Using this convention, the Troup SOI ranges from about –35 to about +35. It is often rounded to a whole number. Sustained negative values of the Troup SOI < −8 indicate an El Niño episode. Sustained positive values of the Troup SOI > +7 indicate a La Niña episode. Sustained values between -8 and +7 indicate “neutral” ENSO conditions.

Column B in the assignment spreadsheet contains  for January from 1866 to 2022. Years are listed in Column A.

What is for January? Show the answer here and the uploaded spreadsheet computation in Cell E3.

What is for January? Show the answer here and the uploaded spreadsheet computation in Cell E4.

in January 2021 was 7.9 mb. Show the Troup SOI calculation below.

In January 2021, was there an El Niño episode, La Niña episode, or a neutral ENSO condition? Assume this value’s magnitude has been sustained for a few months.

Read . What is February 2023’s ONI? Is there currently an El Niño episode, La Niña episode, or a neutral ENSO condition?


Calculate the price of your order

550 words
We'll send you the first draft for approval by September 11, 2018 at 10:52 AM
Total price:
The price is based on these factors:
Academic level
Number of pages
Basic features
  • Free title page and bibliography
  • Unlimited revisions
  • Plagiarism-free guarantee
  • Money-back guarantee
  • 24/7 support
On-demand options
  • Writer’s samples
  • Part-by-part delivery
  • Overnight delivery
  • Copies of used sources
  • Expert Proofreading
Paper format
  • 275 words per page
  • 12 pt Arial/Times New Roman
  • Double line spacing
  • Any citation style (APA, MLA, Chicago/Turabian, Harvard)

Our guarantees

Delivering a high-quality product at a reasonable price is not enough anymore.
That’s why we have developed 5 beneficial guarantees that will make your experience with our service enjoyable, easy, and safe.

Money-back guarantee

You have to be 100% sure of the quality of your product to give a money-back guarantee. This describes us perfectly. Make sure that this guarantee is totally transparent.

Read more

Zero-plagiarism guarantee

Each paper is composed from scratch, according to your instructions. It is then checked by our plagiarism-detection software. There is no gap where plagiarism could squeeze in.

Read more

Free-revision policy

Thanks to our free revisions, there is no way for you to be unsatisfied. We will work on your paper until you are completely happy with the result.

Read more

Privacy policy

Your email is safe, as we store it according to international data protection rules. Your bank details are secure, as we use only reliable payment systems.

Read more

Fair-cooperation guarantee

By sending us your money, you buy the service we provide. Check out our terms and conditions if you prefer business talks to be laid out in official language.

Read more