MEWS: Marine Electronics Wiki

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====== Meteorological Measurements ======

Terms and standards for automated weather station reports.

===== Essential Climate Variables =====

<blockquote>An Essential Climate Variable (ECV) is a physical, chemical or biological variable or a group of linked variables that critically contributes to the characterization of Earth’ s climate. GCOS currently specifies 55 ECVs.

<cite>[[https://gcos.wmo.int/en/essential-climate-variables/about|ECV - About]]</cite>
</blockquote>

The interesting bit for me is the specifications of accuracy that are required for data to be useful for climatology. Measurements for weather forecasts are probably more helpful. I don't know if they are different.

===== Wind =====

[[https://gcos.wmo.int/en/essential-climate-variables/surface-wind]]

==== Gust ====

I've found a few unclear and different definitions. This one seems reasonable and doable: "Maximum value, over the observing cycle, of the 3-second running average wind speed". From [[https://space.oscar.wmo.int/variables/view/wind_gust]].

 [[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5948875/|Interesting review of gust measurement]]
 - different types of anemometers and their history.

From the Met Office [[https://www.metoffice.gov.uk/weather/guides/observations/how-we-measure-wind]]:

"Because wind is an element that varies rapidly over very short periods of time it is sampled at high frequency (every 0.25 sec) to capture the intensity of gusts, or short-lived peaks in speed, which inflict greatest damage in storms. The gust speed and direction are defined by the maximum three second average wind speed occurring in any period.

A better measure of the overall wind intensity is defined by the average speed and direction over the ten minute period leading up to the reporting time. Mean wind over other averaging periods may also be calculated. A gale is defined as a surface wind of mean speed of 34-40 knots, averaged over a period of ten minutes. Terms such as 'severe gale', 'storm', etc are also used to describe winds of 41 knots or greater."


===== Equipment =====

Waters and Stanton have a few weather stations from about 60 to 200 GBP.

Sparkfun wind instruments: https://www.sparkfun.com/products/15901
80 USD. Wind direction seems to be detected by switches - not continuous.

[[https://calypsoinstruments.com/shop/product/ultra-low-power-ultrasonic-wind-meter-ulp-std-6?category=2#attr=38,71,65|Calypso Ultrasonic (Wired, NMEA0183)]] - 475 EUR.