science

MESO-SAILS

MESO-SAILS 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 MESO-SAILS rather than just read about it. In short: Multiple Elevation Scan Option for Supplemental Adaptive Intra-Volume Low-Level Scan (abbreviated MESO-SAILS), is a dynamic scanning option for the WSR-88D, controllable by the operator of the radar, when in VCP mode 12 and 212, and additionally 35 and 215 with the Build 18 update scheduled for October 2017. When active, anywhere from one to three supplemental low-level scans can be added to any volume, increasing o…

Key takeaways

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

Reference excerpt

Multiple Elevation Scan Option for Supplemental Adaptive Intra-Volume Low-Level Scan (abbreviated MESO-SAILS), is a dynamic scanning option for the WSR-88D, controllable by the operator of the radar, when in VCP mode 12 and 212, and additionally 35 and 215 with the Build 18 update scheduled for October 2017. When active, anywhere from one to three supplemental low-level scans can be added to any volume, increasing overall low-level data availability and improves general severe weather detection, as needed. When active, per the National Weather Service, low-level updates will be available "every 75 to 90 seconds".

Concept WSR-88D radars scan a number of elevation angles to scan the atmosphere around the site. The number of angles and the length of each scan depend on the meteorological situation (no precipitation, scattered, generalized, or deep convective precipitation). These schemes are called Volume Coverage Patterns (VCP). The more angles scanned, the longer between scans at the lowest elevation. Data at that level can be crucial in summer thunderstorm situations when Doppler patterns for rotations and windshifts, as well as dual polarized information, are indicative of severe weather like tornadoes. Shortening the time between two scans at low level is therefore an important factor for convective storm detection. The first step of this program is SAILS (Supplemental Adaptive Intra-Volume Low-Level Scan) which inserts an extra scan of the elevation defined in the VCP definition (normally 0.5°). This is done by forcing the antenna to go back down to the base elevation after scanning a certain number elevations up to the "middle" of the atmosphere, this "middle" elevation being dependent of the VCP used. Doing this provides two low-level scans for each total volume scan while only adding 30 to 35 seconds to the total scan. To increase the number of low-level scans, one can redo the same process as SAILS many times: MESO-SAILS (Multiple Elevation Scan Option for SAILS). These additional supplemental low-level elevation scans are evenly spaced, in time (as close as possible given the defined VCP rotation rates), throughout the volume scan. The radar operator may choose 1 to 3 extra scans, depending on the weather situation. This lengthens the time of the total scan but provide low-level coverage more often.

History and deployment During the summer of 2013, the Radar Operations Center, in order to facilitate "proof of concept" testing of MESO-SAILS, defined two VCPs that were based on VCP-12 that included hardcoded additional low-level split-cut scans. For the first testing, which commenced on June 26, 2013, SAILSx2 (2 supplemental low-level soundings) was executed for approximately 4+1⁄2 hours, and during the testing a radar technician observed the behavior of the pedestal/antenna assembly. No excessive wear was noted to the assembly of the KOUN radar in Norman, Oklahoma. Two days later, June 28, 2013, SAILSx3 (3 supplemental low-level soundings) was executed, also within the KOUN RPG. During this 1+1⁄2-hour test of SAILSx3, a ROC radar hardware engineer accompanied the ROC electronics maintenance technician to observe the antenna/pedestal assembly. Again, no excessive wear was noted. MESO-SAILS was thus deployed with Build 14 update in the spring of 2014 and is still in operations when needed. The operator can choose between 1, 2, or 3 supplemental low-level scans with MESO-SAILS active.

MESO-SAILS in tornado cases A study published in 2016 looked at how the MESO-SAILS radar scanning regime performed with respect to tornado debris signature (TDS) detection during the 2016 tornado season in the Iowa Region, compared to the distribution before its implementation. When tornado watches were active, MESO-SAILS was active 100% reflecting the National Weather Service expectations for such situations. Overall, it was found that the use of MESO-SAILS led to an enhancement in detection and possibly an increased effective range at which TDSs could be detected. The use of MESO-SAILS dropped to 41% during severe thunderstorms watches however, which may suggest some benefit in keeping MESO-SAILS active during severe thunderstorm watches as well.

References

Bibliography Daniel, Amy E.; Chrisman, Joe N.; Smith, Steven D.; Miller, Michael W. (February 5, 2014). New WSR-88D Operational Techniques: Responding to recent Weather Events (PDF). 30th Conference on Environmental Information Processing Technologies. Atlanta, GA: AMS. Amy E. Daniel; J. N. Chrisman; C. A. Ray; S. D. Smith; M. W. Miller. "5.2 New WSR-88D Operational Techniques: Responding to Recent Weather Events". American Meteorological Society (Abstract). Edwards, Roger; Picca, Joseph C. Tornadic Debris Signatures in Tropical Cyclones (PDF). Preprints, 28th Conf. Severe Local Storms. No. P162. Portland, OR. Tuftedal, Kristofer S. (December 2016). Radar Detection of Tornadogenesis (pdf) (Thesis). Iowa State University. doi:10.31274/mteor_stheses-180813-2. hdl:20.500.12876/55813. Porter, Chris (September 17, 2015). Recent challenges and opportunities for operational radar algorithms afforded by the NEXRAD radar network. 37th Conference on Radar Meteorology. AMS.

Illustrations

Worked examples

Example 1 — a first encounter with MESO-SAILS

Start with the simplest possible case. Write down what MESO-SAILS 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 MESO-SAILS 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 MESO-SAILS 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 MESO-SAILS

In research: MESO-SAILS 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 MESO-SAILS 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: MESO-SAILS is common in secondary-school and first-year university syllabi. It links to neighbouring topics Radar meteorology, so understanding it makes those chapters shorter.
In everyday life: Look for MESO-SAILS 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 MESO-SAILS in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what MESO-SAILS 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 MESO-SAILS out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is MESO-SAILS in simple terms?

Why does MESO-SAILS 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 MESO-SAILS?

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 MESO-SAILS.