Mobile Mesonets

Instrument specifications for each mobile mesonet. (N/A: not applicable)

R. M. YOUNG 05103VWIND SPEED0 – 100 m s–1, ±0.3 m s–12.7 m [distance constant]
R. M. YOUNG 05103VWIND DIRECTION0 – 360°, ±3.0°1.3 m [distance constant]
VAISALA HMP35CSLOW AIR TEMPERATURE–35 – +55°C, ±0.9°C63% in +15 s
VAISALA HMP35CRELATIVE HUMIDITY0 – 100%, ±3.0%63% in 15 s
APOGEE INST. ST-110FAST AIR TEMPERATURE–50 – +70°C, ±0.15°C63% in 7 s
R. M. YOUNG 61402VAGL PRESSURE500 – 1100 hPa, ±0.3 hPaN/A
GARMIN GPS16-HVSVEHICLE SPEED0 – 999 kts, 0.1 ktsN/A

Wind Speed and Direction

An R. M. Young 05103 Wind Monitor is used in conjunction with a Garmin GPS16-HVS Receiver and KVH Industries C100 Fluxgate Compass Engine to record wind speed and direction. While in motion, vehicle vector derived from GPS can be subtracted from apparent wind readings on the vehicle to deduce estimated environmental wind. While stationary, the C100 fluxgate compass is used to correct vehicle heading.

The anemometer is mounted at the highest point of the vehicle to mitigate any influence the slipstream might have on it. The fluxgate compass is housed within an electrical conduit junction box mounted at the rear of the rack to prevent magnetic induced error. The GPS receiver is also mounted at the rear of the rack to ensure satellite view at all times.

Temperature, Relative Humidity, and Dew Point

Air temperature is measured using a fast response Apogee Instruments ST-110 Thermistor Temperature Sensor. Relative humidity is derived using the air temperature measurement of the ST-110 and dew point measurement of the Vaisala HMP35C. Dew point is derived using the temperature and relative humidity measurement of the Vaisala HMP35C Temperature and Relative Humidity Probe.

Both ST-110 and HMP35C are housed within a fan aspirated radiation shield called the U-Tube. This apparatus was created by Sean Waugh to address issues encountered with the J-Tube. The U-Tube is mounted up and forward of the vehicle to mitigate effects of vehicle slipstream and solar radiation.

Barometric Pressure

Atmospheric pressure is measured using an R. M. Young 61402V Barometric Pressure Sensor. Above Ground Level (AGL) pressure is recorded and converted to Mean Sea-Level Pressure (MSLP) using GPS elevation data via hypsometric equation derivative.

A Randall T. Nishiyama and Alfred J. Bedard Jr. quad plate pressure port is employed to mitigate wind induced errors caused by pressure perturbations. This port is mounted far in front of the rack and above the vehicle to escape any effects of vehicle slipstream or rack turbulence.

Randall T. Nishiyama and Alfred J. Bedard Jr. Quad Plate Pressure Port

Data Logging and Acquisition

Our mobile mesonet data logging and acquisition is accomplished using a Campbell Scientific CR23X Micrologger. These data loggers record measurements every second and display them in real time using LoggerNet. Parameters not directly observed such as equivalent potential temperature and mixing ratio are also derived. All data are stored locally on a laptop and uploaded offsite for later viewing and analysis.

Real-time display of data is accomplished using RTMC, a program within the LoggerNet software suite. This display serves as an “at-a-glance” reference to observations being made in the field before laboratory analysis. Much thought went into the layout to provide as much information in as organized of a way as possible.

Mobile Mesonet Real-Time Display