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Frequently Asked Questions

Frequently Asked Questions

ATMOS 22

  • ATMOS 22 - ATMOS 41 - ATMOS What is the highest resolution scan rate for the ATMOS 22 and ATMOS 41?
    • With the ATMOS 41 and the M command, using a non-METER data logger, you can make measurements every 3 seconds.
    • With the ATMOS 22 and the M command, using a non-METER data logger, you can make measurements every 1 second.
    • Consult the integrator guides for more information.
    • Contact METER if your application requires more frequent measurements.
  • ATMOS 22 - ATMOS How frequently are measurements taken?
    The ZL6 makes a measurement from each of the sensor ports in use every 60 s. However, the minimum measurement interval is five minutes for uploading data to ZENTRA Cloud. One-minute measurement interval is possible if you disable uploading data to ZENTRA Cloud, and these instructions are available upon request. The ATMOS 22 measures the wind speed and direction once every 10 s and records the instantaneous wind vector components. When queried, the ATMOS 22 outputs the average of the instantaneous measurements since the last query for wind speed and direction and the maximum instantaneous wind speed value for wind gust.

     

    If using a non-METER logger, then the ATMOS 22 can be scanned every 1 second, but it is not necessary to oversample the ATMOS 22 and compute averages, accumulations, and maximums in external data systems because it has an internal measurement sequence [see the integrator guide for more information]. Less frequent sampling has the additional benefit of decreasing data acquisition systems and ATMOS 22 power consumption.
  • ATMOS 22 - ATMOS What do the ATMOS 22 output data look like in a downloaded excel file from a ZL6?

    See image below. NOTE: The ATMOS 22 temperature measurement should not be used as an accurate measurement of air temperature. Testing has shown errors of as much as 2 °C between the ATMOS 22 temperature sensor and the true air temperature under sunny conditions. The speed of sound is temperature dependent, so the ATMOS 22 temperature measurement is important for the wind speed and direction calculations, but the lower accuracy of air temperature measurements is not an issue for the wind calculations.

  • ATMOS 22 Can I install my ATMOS 22 at a 90 deg angle for vertical wind speed?
    The ATMOS 22 should measure in any orientation if its measurement path is parallel to the wind flow. However, it should not be mounted at 90 degrees outside. This is due to rain obstructing the measurement during rain storms and possibly that water could be retained where the sonic transducers are, which would affect the measurement. Vertical wind speed outside is also associated with upward and downward eddies. These have both a horizontal and vertical component to them. If you mount an ATMOS 22 sideways, you would block the horizontal movement of these eddies and, presumably, negate any reason for doing it in the first place. The ATMOS 22 would be appropriate for measuring vertical wind velocity in certain indoor situations where the sensor is protected from pooling water and the wind vector is vertical (e.g., velocity in vertical HVAC ductwork).
  • ATMOS 22 - ATMOS 41 - ATMOS What is the practical lower limit of the wind speed measurement for the ATMOS 22 and ATMOS 41?

    The practical lower limit for wind speed is about 0.03 m/s for our sonic anemometer. This is much better than cup anemometers, for example, which struggle making measurements below 0.5 m/s at the minimum because of difficulty starting and stopping. Sonic anemometers can read five times lower than that, yet they don’t necessarily read absolute zero.

  • ATMOS 14 - SRS - IRT - ECT - PAR - PYR - ATMOS 22 - ATMOS 41 - PHYTOS 31 - ECRN-100 - ECRN-50 How do I assemble the anemometer mast?

    The anemometer mast is suitable to mount METER’s above-ground sensors: ATMOS 41, ATMOS 22, ATMOS 14, PAR, PYR, IRT, SRS, PHYTOS 31, ECRN-100, ECRN-50, and ECT. Additional brackets may be required for some products.

    Anemometer mast kit: 1 extendable mast (fiberglass), 1 guy ring, 1 guy rope (7.6 m nylon rope), 3 guy rope anchors, and 1 mast base with center peg and set screw.

    Mast diameter: 4.5 cm

    Mast adjustable length: 1.3 to 2.3 m

    Tools to bring to the field: measuring tape, long metal screwdriver, mallet, wrench, level, scissors, optional shovel, and lighter.

    Installation:  Position the mast base in the desired installation location, avoiding large rocks. Install the center peg using a mallet. Insert the mast into the base so that the center peg is inside the mast tube. With the mast in the base, turn the set screw so it is hand-tight against the mast. Then, gently turn the set screw with a wrench. Do not over tighten or the fiberglass pole will break. Put the guy ring over the extendable mast. Cut the guy rope into thirds (approximately 2.5 m each) and burn the ends with a lighter to prevent fraying. Position the rope anchors equidistant apart to be about 1 meter away from the mast. Screw the anchors into the soil at the same angle as the guy rope using a long metal screwdriver as a make-shift turning handle. Attach the guy rope to the guy ring in 3 equidistant holes (show below) using knots. Then knot each guy rope in the corresponding anchor. Pull the rope very tight and ensure the mast is level and straight.

    Once the mast is secure, move the adjustable lever up to release the extendable mast. Move the lever down to secure the mast to the correct height. Install instruments following the sensor quick start guides and manuals.

    Limitations: Rocky soils, long-term monitoring sites, locations with high animal traffic. The SRS extension arm may be too heavy for the fiberglass mast.