Surface weather observation

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Victoria, Australia
.

Surface weather observations are the fundamental data used for safety as well as

Cooperative Observers
make a daily record of summary weather and sometimes water level information.

History

Reverend John Campanius Holm is credited with taking the first systematic weather observations in Colonial America. He was a chaplain in the Swedes Fort colony near the mouth of the Delaware River. Holm recorded daily observations without instruments during 1644 and 1645. While numerous other accounts of weather events on the East Coast were documented during the 17th Century. President George Washington kept a detailed weather diary during the late 1700s at Mount Vernon, Virginia. The number of routine weather observers increased significantly during the 1800s. In 1807, Dr. B. S. Barton of the University of Pennsylvania requested members throughout the Union of the Linnaean Society of Philadelphia to maintain instrumented weather observing sites to establish a climatological history.During the early 1900s, numerous observer stations moved from farms to residential districts of towns, where service was available to mail the observation forms. By 1926, more than 5000 observing locations were located throughout the U.S., West Indies, and the Caribbean.In 1939, the Bureau of Aeronautics in the U. S. Navy began to actively develop automated weather stations.[5]

Airports

ASOS sensors, located at Salinas, California

Surface weather observations have traditionally been taken at

sea level pressure (SLP) where it can then be used on weather maps.[7]

In the United States, the FAA mandates the taking of weather observations at larger airports for safety reasons. To help facilitate the purchase of an automated airport weather station, such as ASOS, the FAA allows federal dollars to be used for the installation of certified weather stations at airports.[8] The airport observations are then transmitted worldwide using the METAR observing code. METAR reports typically come from airports or permanent weather observation stations. Reports are generated once an hour; however, if conditions change significantly, they may be updated in special reports called SPECIs.[9][10][11][12]

Data reported

Surface weather observations can include the following elements:

  • The Station Identifier, or Location identifier, consists of four characters for METAR observations,[13] with the first representing the region of the world the station lies within. For example, the first letter for areas in and around the Pacific Ocean is P, and for Europe is E. The second character may represent the country/state the location lies within. For Hawaii, the first two letters are "PH" while for Great Britain, the first two letters of the station identifier are "EG". Canada and the contiguous United States are an exception, with the first letters C and K representing the regions, respectively. The final two or three letters normally represent the name of the location or airport.
  • Visibility, measured in meters for most sites worldwide, except in the United States where statute miles are reported.[14]
  • Runway visibility, measured in meters in many locations worldwide, or feet within the United States.[14]
  • degree Fahrenheit temperature scale is used by most lay people, industry, popular meteorology, and government.[14]
    Despite this, METAR reports from the United States also report the temperature (and dewpoint, see below) in degrees Celsius.
  • specific humidity of the air. The dew point is an important statistic for general aviation pilots, as it is used to calculate the likelihood of carburetor icing and fog. When used with the air temperature, a formula can be used to estimate the height of cumuliform, or convective, clouds.[18]
  • aerovanes, located a standard 10 metres (33 ft) above ground level (AGL). Average wind speed is measured using a two-minute average in the United States,[19] and a 10-minute average elsewhere.[20] Wind direction is measured using degrees, with north representing 0 or 360 degrees, with values increasing from 0 clockwise from north. Wind gusts are reported when there is variation of the wind speed of more than 10 knots (5.1 m/s) between peaks and lulls during the sampling period.[19]
  • isobars on a weather map meaningful and useful tools.[21]
  • QNH airfield.[22]
  • Present weather, which present restrictions to visibility or presence of thunder or squalls, are reported in observations to indicate to aviation any possible threats during landings and takeoffs from airports. Types included in surface weather observations include precipitation, obscurations, other weather phenomena such as, well-developed dust/sand whirls, squalls, tornadic activity, sandstorms, volcanic ash, and dust storms.[23]
  • Intensity of precipitation is primarily measured for meteorological concerns. However, it can be of concern to aviation as heavy precipitation can limit visibility. Also, intensity of freezing rain can determine how hazardous it is for pilots to fly nearby certain locations since it can be an in-flight hazard by depositing ice on the wings of aircraft, which can be detrimental to flight.[24]
  • Precipitation amount over the past 1, 3, 6 or 24 hours is of particular interest to meteorologists in verifying forecast amounts of precipitation and determining station climatologies.
  • Snowfall
    amount     during the past 6 hours is taken for meteorological and climatological concerns. However, it may also be reported hourly using "SNOINCR" remarks to provide air field technicians information on how frequently snow must be plowed from runways and taxiways.
  • Snow depth is measured for meteorological and climatological concerns once a day. However, during periods of snowfall, it is measured each six hours to determine amount of recent snowfall.[25]

Example of a METAR surface weather observation

METAR LBBG 041600Z 12003MPS 090V150 1400 R04/P1500N R22/P1500U +SN BKN022 OVC050 M04/M07 Q1020 NOSIG 9949//91=[26]

Personal weather stations, maintained by citizens rather than government officials, do not use METAR code. Software allows information to be transmitted to various sites, such as the Weather Underground globally,[3] or the CWOP within the United States,[27] which can then be used by the appropriate meteorological organizations either to diagnose real-time conditions, or be used within weather forecast models.

Use of weather maps

Main articles: Weather map and Station model
Station model used on surface weather maps

Data collected by land locations coding in METAR are conveyed worldwide via phone lines or wireless technology. Within many nations' meteorological organizations, this data is then plotted onto a weather map using the station model. A station model is a symbolic illustration showing the weather occurring at a given reporting station.[28] Meteorologists created the station model to plot a number of weather elements in a small space on weather maps.[29] Maps filled with dense station-model plots can be difficult to read, but they allow meteorologists, pilots, and mariners to see important weather patterns.

Weather maps are used to display information quickly showing the analysis of various meteorological quantities at various levels of the atmosphere, in this case the surface layer.

low pressure
.

Ship and buoy reports

Different shapes and sizes of buoys

For over a century, reports from the world's oceans have been received real-time for safety reasons and to help with general weather forecasting. The reports are coded using the synoptic code, and relayed via radio or satellite to weather organizations worldwide.[32] Buoy reports are automated, and maintained by the country that moored the buoy in that location. Larger moored buoys are used near shore, while smaller drifting buoys are used farther out at sea.[33]

Due to the importance of reports from the surface of the ocean, the

anemometers
have issues with determining wind speeds at higher wind speeds due to blockage of the instruments by increasing high seas.

Use in establishing climate of a location

Main article: Climate

Climate, (from Ancient Greek klima) is commonly defined as the weather averaged over a long period of time.[35] The standard averaging period is 30 years for an individual location,[4] but other periods may be used. Climate includes statistics other than the average, such as the magnitudes of day-to-day or year-to-year variations. The Intergovernmental Panel on Climate Change (IPCC) glossary definition is:

Climate in a narrow sense is usually defined as the "average weather", or more rigorously, as the statistical description in terms of the mean and variability of relevant quantities over a period of time ranging from months to thousands or millions of years. The classical period is 30 years, as defined by the World Meteorological Organization (
WMO). These quantities are most often surface variables such as temperature, precipitation, and wind. Climate in a wider sense is the state, including a statistical description, of the climate system.[36]

The main difference between climate and everyday weather is best summarized by the popular phrase "Climate is what you expect, weather is what you get."

rainfall
on a regional level.

See also

References

  1. ^ Office of the Federal Coordinator of Meteorology. Surface Weather Observation Program. Archived 2009-05-06 at the Wayback Machine Retrieved on 2008-01-12.
  2. ^ "WOW - A new weather website for everyone". Met Office. 2011-02-11. Archived from the original on 2014-08-15.
  3. ^ a b Weather Underground. Personal Weather Station. Retrieved on 2008-03-09.
  4. ^ a b MetOffice. Climate Averages. Archived 2009-07-06 at the Wayback Machine Retrieved on 2008-03-09.
  5. ISSN 0012-8252
    .
  6. ISBN 92-9194-004-6
  7. ^ Patricia M. Pauley. An Example of Uncertainty in Sea Level Pressure Reduction. Retrieved on 2008-03-29.
  8. ^ Allweatherinc. Why buy an AWOS? Archived 2007-02-14 at the Wayback Machine Retrieved on 2008-01-12.
  9. ^ National Climatic Data Center. METAR Home Page. Retrieved on 2008-01-12.
  10. ^ Canada, Environment and Climate Change (2021-12-02). "Manual of Surface Weather Observation Standards (MANOBS) 8th Edition, Amendment 1". www.canada.ca. Retrieved 2023-02-04.
  11. ^ Training Guide in Surface Weather Observations (PDF). U.S. DEPARTMENT OF COMMERCE NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION National Weather Service Office of Systems Operations Systems Integration Division Observing Systems Branch. May 1998.
  12. ^ U.S. DEPARTMENT OF TRANSPORTATION FEDERAL AVIATION ADMINISTRATION ORDER JO 7900.5E. U.S. DEPARTMENT OF TRANSPORTATION FEDERAL AVIATION ADMINISTRATION. 15 January 2020.{{cite book}}: CS1 maint: date and year (link)
  13. ^ Texas A&M University. Coding the Type of Report, Station Identifier, Date/Time, and Report Modifier groups. Archived 2008-04-09 at the Wayback Machine Retrieved on 2008-04-06.
  14. ^ a b c National Weather Service. Frequently Asked Questions about METAR/SPECI and TAF. Retrieved on 2008-04-06.
  15. ^ Glossary of Meteorology. Temperature. Archived 2008-04-16 at the Wayback Machine Retrieved on 2008-04-06.
  16. ^ Glossary of Meteorology. Air Temperature. Archived 2008-06-22 at the Wayback Machine Retrieved on 2008-04-06.
  17. ^ Glossary of Meteorology. Dewpoint. Archived 2011-06-06 at the Wayback Machine Retrieved on 2008-04-06.
  18. ^ Glossary of Meteorology. Dewpoint Formula. Archived 2007-08-16 at the Wayback Machine Retrieved on 2008-04-06.
  19. ^ a b Office of the Federal Coordinator for Meteorology. Federal Meteorological Handbook No. 1 - Surface Weather Observations and Reports September 2005 Appendix A: Glossary. Retrieved on 2008-04-06.
  20. ^ Hurricane Research Division. Frequently Asked Questions Subject D4) What does "maximum sustained wind" mean? How does it relate to gusts in tropical cyclones? Retrieved on 2008-04-06.
  21. ^ Patricia M. Pauley. An Example of Uncertainty in Sea Level Pressure Reduction. Retrieved on 2008-04-14.
  22. ^ USA Today. Understanding Air Pressure. Retrieved on 2008-04-14.
  23. ^ Texas A&M University. Present Weather Group w'w'(ww). Archived 1997-07-11 at the Wayback Machine Retrieved on 2008-04-14.
  24. ^ Ben C. Bernstein, Thomas P. Ratvasky, Dean R. Miller, and Frank McDonough. Freezing Rain as in In-Flight Icing Hazard. Archived 2009-03-21 at the Wayback Machine Retrieved on 2008-04-14.
  25. NOAA Meteorological Assimilation Data Ingest System. How to Take Snow Measurements. Archived 2008-07-23 at the Wayback Machine
    Retrieved on 2008-04-14.
  26. ^ National Climatic Data Center. Key to METAR Surface Weather Observations. Retrieved on 2008-03-09.
  27. ^ Russ Chadwick. Citizen Weather Observer Program. Retrieved on 2008-03-09.
  28. ^ Steve Ackerman and Tom Whittaker.Station Model. Retrieved on 2008-03-27.
  29. ^ Illinois Central College. LAB J: Weather Maps and Humidity. Retrieved on 2008-03-27.
  30. ^ Encarta. Chart. Archived 2007-11-01 at the Wayback Machine Retrieved on 2007-11-25.
  31. ^ DataStreme. AIR TEMPERATURE PATTERNS. Archived 2008-08-21 at the Wayback Machine Retrieved on 2007-11-25.
  32. ^ National Weather Service. National Weather Service Observing Handbook 1: Marine Surface Weather Observations. Archived 2011-06-17 at the Wayback Machine Retrieved on 2008-01-13.
  33. ^ National Data Buoy Center. Moored Buoy Program. Archived 2017-12-21 at the Wayback Machine Retrieved on 2008-01-13.
  34. ^ National Data Buoy Center. The WMO Voluntary Observing Ships (VOS) Scheme. Retrieved on 2008-01-13.
  35. ^ Glossary of Meteorology. Climate. Retrieved on 2008-03-09.
  36. ^ Intergovernmental Panel on Climate Change. Appendix I: Glossary. Retrieved on 2007-06-01.
  37. ^ National Weather Service Office Tucson, Arizona. Main page. Retrieved on 2007-06-01.

External links

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