An automatic weather station (AWS) is an automated version of the traditional

weather station A weather station is a facility, either on land or sea, with instruments and equipment for measuring atmospheric conditions to provide information for weather forecasts and to study the weather and climate. The measurements taken include tempera ...

, either to save human labour or to enable measurements from remote areas. An AWS will typically consist of a weather-proof enclosure containing the data logger, rechargeable battery,

telemetry Telemetry is the in situ collection of measurements or other data at remote points and their automatic transmission to receiving equipment (telecommunication) for monitoring. The word is derived from the Greek roots ''tele'', "remote", an ...

(optional) and the meteorological sensors with an attached solar panel or

wind turbine A wind turbine is a device that converts the kinetic energy of wind into electrical energy. Hundreds of thousands of large turbines, in installations known as wind farms, now generate over 650 gigawatts of power, with 60 GW added each yea ...

and mounted upon a mast. The specific configuration may vary due to the purpose of the system. The system may report in near real time via the

Argos System Argos is a global satellite-based system that collects, processes, and disseminates environmental data from fixed and mobile platforms around the world. The worldwide tracking and environmental monitoring system results from Franco-America ...

LoRa Lora is a female given name and family name in the Spanish language of French origin meaning from Lorraine, a region in Northeastern France. As a given name, Lora may also be a variant of Laura or derived from an Italian hypocoristic of either E ...

and the Global Telecommunications System, or save the data for later recovery. In the past, automatic weather stations were often placed where

electricity Electricity is the set of physical phenomena associated with the presence and motion of matter that has a property of electric charge. Electricity is related to magnetism, both being part of the phenomenon of electromagnetism, as describ ...

and communication lines were available. Nowadays, the solar panel,

and

mobile phone A mobile phone, cellular phone, cell phone, cellphone, handphone, hand phone or pocket phone, sometimes shortened to simply mobile, cell, or just phone, is a portable telephone that can make and receive calls over a radio frequency link whi ...

technology have made it possible to have wireless stations that are not connected to the electrical grid or hardline telecommunications network.

Sensors

Most automatic weather stations have *

Thermometer A thermometer is a device that measures temperature or a temperature gradient (the degree of hotness or coldness of an object). A thermometer has two important elements: (1) a temperature sensor (e.g. the bulb of a mercury-in-glass thermometer ...

for measuring

temperature Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measurement, measured with a thermometer. Thermometers are calibrated in various Conversion of units of temperature, temp ...

Anemometer In meteorology, an anemometer () is a device that measures wind speed and direction. It is a common instrument used in weather stations. The earliest known description of an anemometer was by Italian architect and author Leon Battista Alberti ...

for measuring

wind speed In meteorology, wind speed, or wind flow speed, is a fundamental atmospheric quantity caused by air moving from high to low pressure, usually due to changes in temperature. Wind speed is now commonly measured with an anemometer. Wind speed ...

* Wind vane for measuring

wind direction Wind direction is generally reported by the direction from which it originates. For example, a ''north'' or ''northerly'' wind blows from the north to the south. The exceptions are onshore winds (blowing onto the shore from the water) and offsho ...

Hygrometer A hair tension dial hygrometer with a nonlinear scale. A hygrometer is an instrument used to measure the amount of water vapor in air, in soil, or in confined spaces. Humidity measurement instruments usually rely on measurements of some other qu ...

for measuring

humidity Humidity is the concentration of water vapor present in the air. Water vapor, the gaseous state of water, is generally invisible to the human eye. Humidity indicates the likelihood for precipitation, dew, or fog to be present. Humidity dep ...

Barometer A barometer is a scientific instrument that is used to measure air pressure in a certain environment. Pressure tendency can forecast short term changes in the weather. Many measurements of air pressure are used within surface weather analysis ...

for measuring

atmospheric pressure Atmospheric pressure, also known as barometric pressure (after the barometer), is the pressure within the atmosphere of Earth. The standard atmosphere (symbol: atm) is a unit of pressure defined as , which is equivalent to 1013.25 millibars, ...

Some stations can also have * Ceilometer for measuring cloud height * Present weather sensor and/or

visibility The visibility is the measure of the distance at which an object or light can be clearly discerned. In meteorology it depends on the transparency of the surrounding air and as such, it is unchanging no matter the ambient light level or time o ...

sensor *

Rain gauge A rain gauge (also known as udometer, pluvia metior, pluviometer, ombrometer, and hyetometer) is an instrument used by meteorologists and hydrologists to gather and measure the amount of liquid precipitation over a predefined area, over a period o ...

for measuring liquid-equivalent

precipitation In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls under gravitational pull from clouds. The main forms of precipitation include drizzle, rain, sleet, snow, ice pellets, graupel and hail. ...

* Ultrasonic snow depth sensor for measuring depth of

snow Snow comprises individual ice crystals that grow while suspended in the atmosphere—usually within clouds—and then fall, accumulating on the ground where they undergo further changes. It consists of frozen crystalline water throughout ...

Pyranometer A pyranometer is a type of actinometer used for measuring solar irradiance on a planar surface and it is designed to measure the solar radiation flux density (W/m2) from the hemisphere above within a wavelength range 0.3 μm to 3 μm. The name pyra ...

for measuring

solar radiation Solar irradiance is the power per unit area (surface power density) received from the Sun in the form of electromagnetic radiation in the wavelength range of the measuring instrument. Solar irradiance is measured in watts per square metre ( ...

Unlike manual weather stations,

automated airport weather station Airport weather stations are automated sensor suites which are designed to serve aviation and meteorological operations, weather forecasting and climatology. Automated airport weather stations have become part of the backbone of weather observin ...

s cannot report the class and amount of

cloud In meteorology, a cloud is an aerosol consisting of a visible mass of miniature liquid droplets, frozen crystals, or other particles suspended in the atmosphere of a planetary body or similar space. Water or various other chemicals may ...

s. Also,

measurements are difficult, especially for

, as the gauge must empty itself between observations. For present weather, all phenomena that do not touch the sensor, such as fog patches, remain unobserved. The change from manual observations to automatic weather stations is a major non-climatic change in the climate record.Begert, M., Schlegel, T., and Kirchhofer, W.: Homogeneous temperature and precipitation series of Switzerland from 1864 to 2000. Int. J. Climatol., 25, 65–80, 2005. The change in instrumentation, enclosure and location can lead to a jump in, for example, the measured temperature or precipitation values, which can lead to erroneous estimates of climate trends. This change, and related non-climatic changes, have to be removed by homogenization.

Data-logger

The data-logger is the heart of the Automatic Weather Station.
In high quality weather stations, the data-logger may be designed by the supplier to be the perfect solution for a particular meteorological client. Indeed, usually data-loggers found in the market don't fit the requirement in terms of power consumption, inputs, communication, protection against animals (ants, rats, etc.), humidity, salty air, sand, etc.
The main functions of a data-logger are: * Measurement: the data-logger collects the information from every sensor and archives it. * Calculation: the data-logger processes most of the meteorological data for the users (avg, min, max...). * Data storage: the data-logger saves all the data either on its own memory or on uSD memory card. * Power supply: the data-logger manages the power supply of the Automatic Weather Station, using a solar panel for instance. * Communication: the data-logger manages the communication protocols with the remote server. The different communication protocols are usually

GSM The Global System for Mobile Communications (GSM) is a standard developed by the European Telecommunications Standards Institute (ETSI) to describe the protocols for second-generation ( 2G) digital cellular networks used by mobile devices such ...

, GPRS, RTC,

WiFi Wi-Fi () is a family of wireless network protocols, based on the IEEE 802.11 family of standards, which are commonly used for local area networking of devices and Internet access, allowing nearby digital devices to exchange data by radio wa ...

uSD The United States dollar (symbol: $; code: USD; also abbreviated US$ or U.S. Dollar, to distinguish it from other dollar-denominated currencies; referred to as the dollar, U.S. dollar, American dollar, or colloquially buck) is the official ...

, and

RS-232 In telecommunications, RS-232 or Recommended Standard 232 is a standard originally introduced in 1960 for serial communication transmission of data. It formally defines signals connecting between a ''DTE'' (''data terminal equipment'') such ...

Enclosures

Enclosures used with automatic weather stations are typically weather proof

fiberglass Fiberglass (American English) or fibreglass ( Commonwealth English) is a common type of fiber-reinforced plastic using glass fiber. The fibers may be randomly arranged, flattened into a sheet called a chopped strand mat, or woven into glass clo ...

, ABS or stainless steel, With ABS being the cheapest, cast aluminium paint or stainless steel the most durable and fiberglass being a compromise. AWS(Automatic Weather station)

Power supply

The main power source for an automatic weather station depends on its usage. Many stations with lower power equipment usually use one or more solar panels connected in parallel with a regulator and one or more rechargeable batteries. As a rule of thumb, solar output is at its optimum for only 5 hours each day. As such, mounting angle and position are vital. In the Northern Hemisphere, the solar panel would be mounted facing south and vice versa for the Southern Hemisphere. The output from the solar panels may be supplemented by a wind turbine to provide power during periods of poor sunlight, or by direct connection to the local electrical grid. Most automated airport weather stations are connected to the commercial power grid due to the higher power needs of the ceilometer and present weather sensors, which are active sensors and emit energy directly into the environment.

Mast

The standard mast heights used with automatic weather stations are 2, 3, 10 and 30 meters. Other sizes are available, but typically these sizes have been used as standards for differing applications. *The 2 meter (6.6 feet) mast is used for the measurement of parameters that affect a human subject. The mast height is referenced to head height. *The 3 meter (9.8 feet) mast is used for the measurement of parameters that affect crops (such as wheat, sugar cane etc.) The mast height is referenced to crop top. *The 10 meter (32.8 feet) mast is used for the measurement of parameters without interference from objects such as trees, buildings or other obstructions. Typically the most important weather parameter measured at this height is wind speed and direction. *The 30 meter (98.4 feet) mast is used for the measurement of parameters over stratified distances for the purposes of data modelling. A common application is to take measurements of

wind Wind is the natural movement of air or other gases relative to a planet's surface. Winds occur on a range of scales, from thunderstorm flows lasting tens of minutes, to local breezes generated by heating of land surfaces and lasting a few ho ...

and

at 30, 10, and 2 meters. Other sensors are mounted around the 2 meter or lower height.

References

{{Earth-based meteorological observation Meteorological instrumentation and equipment

Sensors

Data-logger

Enclosures

Power supply

Mast

See also

References