Transcript No Slide Title

U.S. Radiosondes
• Jan. 2000, NWS awarded contracts to two radiosonde
manufacturers, Sippican and InterMet Systems, for the
development and submission of GPS radiosondes for the
NWS Radiosonde Replacement System.
• NWS is replacing all radiosonde systems with GPS sondes.
• All U.S. commutators are electronic chronometric type,
switching between sensors and reference at a set time
interval.
• Sippican Inc. - purchased VIZ
– VIZsonde
• Carbon Hygristor
• Bead thermistor
• Aneroid Pressure sensor
– GPS Mark II Microsonde
• GPS system
– Wind derived from GPS system
• Pressure data derived from hydrostatic
equation incorporating GPS altitude,
temperature, humidity and surface
pressure
• May also include Capacitance Aneroid
Pressure sensor
– ±0.5 mb
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Temperaure - Thin rod thermistor, ±0.2oC
Humidity - Carbon hygristor ±2% RH
Transmits on 403 MHz frequency
Samples all parameters every 1.2 sec. Electronic Chronometric
– Sippican GPS W-9000 Meteorological Processing
System.
• PC based processer.
• Receives data on 403 or 1680
MHz frequency
• Produces WMO Upper air
messages
• Produces plots of temp. dew point, height
• Produces index of refraction tables
• Intermet
– Produces a Telemetry
Receiver System
– Required for non-GPS
radiosondes.
– Receives data on
1680 MHz
– Systems computer
generates upper air messages
• Vaisala
– Produces RS80 Series
radiosondes.
• 403 or 1680 MHz transmitter
• RS80-15G Latest GPS sonde
• Pressure Sensor: BAROCAP capacitive aneroid
– Accuracy: ±0.7 to 1.5 hPa
• Temperature Sensor: THERMOCAP capacitive bead
– Accuracy: ±0.5oC
• Humidity Sensor: HUMICAP thin film capacitor
– Accuracy: ±5%
• RS-90 radiosonde
– 403MHz or 1680 MHz
transmitter
– Loran-C or GPS
– Same sensors as in RS-80
series
– Uses 2 HUMICAP humidity
sensors. Operate in two
phases. While one sensor is
measuring, the other sensor is
heated and then allowed to
recover before being used to
measure.
– Top wire is thermistor
– Bottom white sensors are
humicap sensors.
• Vaisala Dropsonde
• Developed by NCAR
• Vaisala Radiotheodolite
• Operates on the 1680 MHz
band.
• Rocketsonde
• Releases parachute and sonde
when reaches apogee.
• Measures temperature, pressure,
humidity as it descends.
• Low - altitude, small rockets.
Accuracy of Radio/Rawinsonde
Systems
• Temperature: Overall ±1oC
– Warmer temperatures: ~0.1oC
• Humidity: Overall ±5% for temperatures above
freezing
• Pressure: ± 1 - 2 hPa
• Pressure Altitude (using radiodirection finders)
10 gpm at 500 hPa, 20 at 300 hPa, 50 at 50 hPa
Errors in altitude due to
systematic error of 1oC
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50 hPa
100 hPa
200 hPa
300 hPa
400 hPa
500 hPa
600 hPa
87.7 gpm
67.5 gpm
47.1 gpm
35.3 gpm
26.8 gpm
20.7 gpm
15.3 gpm
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700 hPa
800 hPa
900 hPa
1000 hPa
10.7 gpm
6.7 gpm
3.1 gpm
0.0 gpm
Typical Radio-theodolite wind
finding accuracy
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Altitude <30 kts
10,000 ft 1 kt
20,000 ft 2 kt
40,000 ft 4 kt
60,000 ft 2 kt
80,000 ft 3 kt
100,000 ft 4 kt
33 - 60 kts
3 kt
5 kt
10 kt
7 kt
10 kt
12 kt
60 - 90 kts
6 kt
11 kt
21 kt
15 kt
21 kt
26 kt
• Azimuth errors: ~0.05o
• Elevation errors: ~0.05o
• Greater the elevation and stronger the wind,
the greater the error.
• Wind direction: Errors increase with
altitude and decreasing elevation angles
– 700 hPa: 1.3o to 9.5o.
– 500 hPa: 1.8o to 13.4o
Navigation Aid Methods
• Systems to improve the position
determination of radiosondes
• Most common systems
– LORAN C
– GPS
Loran C
• Long Range
Navigation
• Utilizes reception
by
the radiosonde
of the pulses
transmitted on a carrier wave from a master Loran
station and two or more slave stations in the same
group of stations. The phase difference between pulses
from the slave station referenced to the master station
provides position information.
GPS
• Global positioning
system
• Radiosonde receives
signal from a number
of the 24 GPS satellites
and retransmits them to
ground station. Phase difference between
reception of the signals from the satellites is
used to determine position information.
Micro-Lab 1 (Orbview) Satellite
• Measures doppler shift of signals from GPS
satellites which are passing through the limb of the
Earth’s atmosphere and being occulted (altered in
amplitude and phase) by the atmosphere.
• Vertical temperature and pressure profiles can be
obtained from the measurements.
• Accuracies of 1 to 2oK for altitudes from 5 km to
35 km.
Automated Aircraft Observing
and Reporting System
• AMDAR: Aircraft Meteorological Data Relay
– Program to input automatically sensed aircraft data
into the Global Telecommunications System
– Two main Systems
• 1. ASDAR: Aircraft to Satellite Data Relay. Processor
automatically reports winds, temperature, position to
satellite every 7 minutes.
• 2. ACARS: Aeronautical radio incorporated
Communication Addressing and Reporting System.
– Processor automatically reports winds, temperature and
position to one of 600+ VHF ground stations in North and
Central America, Hawaii, Caribbean, U.S. Territories.
– Weather info. Can be transmitted to the aircraft using the
same system.
• MOZAIC: Automatic system developed to
measure ozone, water vapor and
temperature. Currently used on European
Aerobus 340 aircraft.
• FANS: Future Air Navigation System
– Digital air-ground, air-satellite-ground, data
exchange system to transmit sensed weather
data: position, heading, temperature, winds,
humidity, turbulence, etc.
Non-Automated Aircraft Observing and
Reporting Systems
• AIREPS: Inflight Weather Reports: Weather information,
temperature, turbulence, icing, cloud types, bases, tops,
frontal positions, hail, thunderstorms.
• SIGMETS: Significant Meteorological Conditions: Active
thunderstorm area, tropical storm, severe squall line, heavy
hail, severe turbulence, severe icing, marked mountain
waves, widespread sandstorm/duststorm.
• Position, altitude, heading, weather information radioed to
ground controllers
End