In aviation, weather service is a combined effort of the National Weather Service (NWS), the Federal Aviation Administration (FAA), the Department of Defense (DOD), and other aviation groups and individuals.
Because of the increasing need for worldwide weather services, foreign weather organizations also provide vital input.
While weather forecasts are not 100 percent accurate, meteorologists, through careful scientific study and computer modeling, have the ability to predict the weather patterns, trends, and characteristics with increasing accuracy. Through a complex system of weather services, government agencies, and independent weather observers, pilots and other aviation professionals receive the benefit of this vast knowledge base in the form of up-to-date weather reports and forecasts. These reports and forecasts enable pilots to make informed decisions regarding weather and flight safety.
OBSERVATIONS
The data gathered from surface and upper altitude observation form the basis of all weather forecasts, advisories, and briefings. There are three types of weather observations: surface, upper air, and radar.
SURFACE AVIATION WEATHER OBSERVATIONS
Surface aviation weather observations (METARs) are a compilation of weather elements of the current weather at ground stations across the United States. The network is made up of government run facilities and privately contracted facilities that provide up-to-date weather information. Automated weather sources such as automated weather observing systems (AWOS) and automated surface observing systems (ASOS), as well as other automated facilities, also play a major role in the gathering of surface observations.
Surface observations provide local weather conditions and other relevant information. This information includes the type of report, station identifier, date and time, modifier (as required), wind, visibility, runway visual range (RVR), weather phenomena, sky condition, temperature/dewpoint, altimeter reading, and applicable remarks. The information gathered for the surface observation may be from a person, an automated station, or an automated station that is updated or enhanced by a weather observer. In any form, the surface observation provides valuable information about airports around the country.
UPPER AIR OBSERVATIONS
Observations of upper air weather prove to be more challenging than surface observations. There are only two methods which upper air can observe weather phenomena: radiosonde observations and pilot weather reports (PIREPs). Using radio telemetry, radiosonde observations are made by sounding balloons from which weather data is received twice daily. These upper air observations provide temperature, humidity, pressure, and wind data for heights up to and above 100,000 feet. In addition to this, pilots provide vital information regarding upper air weather observations. Pilots remain the only real-time source of information regarding turbulence, icing, and cloud heights, which is gathered from pilots in flight, through the filing of pilot weather reports or PIREPs. Together, pilot reports and radiosonde observations provide information on upper air conditions important for flight planning. Many U.S. and international airlines have equipped their aircraft with instrumentation that automatically transmits in-flight weather observations through the DataLink system to the airline dispatcher who disseminates the data to appropriate weather forecasting authorities.
RADAR OBSERVATIONS
Weather observers use three types of radar to provide information about precipitation, wind, and weather systems. The WSR-88D NEXRAD radar, commonly called Doppler radar, provides in-depth observations that inform surrounding communities of impending weather. FAAterminal doppler weather radar (TDWR), installed at some major airports around the country, also aids in providing severe weather alerts and warnings to airport traffic controllers. Terminal radar ensures pilots are aware of wind shear, gust fronts, and heavy precipitation, all of which are dangerous to arriving and departing aircraft. The third type of radar commonly used in the detection of precipitation is the FAA airport surveillance radar. This radar is used primarily to detect aircraft; however, it also detects the location and intensity of precipitation which is used to route aircraft traffic around severe weather in an airport environment.
No comments:
Post a Comment