METER ATMOS 14 Second-Generation Vapor Pressure, Temperature, Humidity & Barometric Pressure Sensor
| Brand | METER |
|---|---|
| Origin | USA |
| Model | ATMOS 14 |
| Measurement Parameters | Water Vapor Pressure, Air Temperature, Relative Humidity, Atmospheric Pressure |
| Communication Protocols | SDI-12, DDI Serial Interface |
| Operating Temperature Range | -40 °C to +80 °C |
| RH Range | 0–100 % RH (Resolution: 0.1 % RH |
| Accuracy | ±0.8 % RH typical hysteresis |
| Long-term drift | ±0.25 % RH/year) |
| Temperature Accuracy | ±0.2 °C |
| Drift | <0.03 °C/year |
| Vapor Pressure Range | 0–47 kPa (Resolution: 0.01 kPa) |
| Barometric Pressure Range | 1–120 kPa (Accuracy: ±0.05 kPa @ 25 °C |
| Drift | <0.1 kPa/year) |
| Response Time (τ₆₃) | <25 s (RH), <165 s (T), <10 ms (P) |
| Physical Dimensions | Ø20 mm × 54 mm |
| Cable | Standard 5 m (up to 75 m customizable) |
| Power Supply | 4.0–15.0 VDC |
| Current Draw | 3.5 mA typical during measurement, 0.03 mA in standby |
| Compliance | ISO 9001:2015, EN 61326-1:2013, EN 50581:2012, 2004/108/EC, 2011/65/EU |
Overview
The METER ATMOS 14 is a second-generation, multi-parameter environmental sensor engineered for high-fidelity, long-term field monitoring of four critical atmospheric variables: water vapor pressure, air temperature, relative humidity, and barometric pressure. Unlike conventional single-parameter sensors, the ATMOS 14 integrates co-located, thermally stabilized sensing elements within a compact, weather-resistant housing—enabling synchronous acquisition with minimized inter-sensor lag and cross-parameter error propagation. Its measurement architecture relies on a dual-capacitive polymer humidity element combined with a precision thermistor and piezoresistive pressure transducer, all calibrated traceably to NIST-traceable standards. The sensor operates on the physical principle that water vapor pressure (ev) is derived directly from simultaneous, high-resolution measurements of temperature (T) and relative humidity (RH) via the Magnus–Tetens equation, eliminating reliance on lookup tables or interpolation. This first-principles approach ensures metrological integrity across wide climatic gradients—from arctic tundra to tropical rainforest microsites—while maintaining compliance with ISO/IEC 17025-aligned calibration practices.
Key Features
- Simultaneous quad-parameter output: Delivers time-synchronized readings of vapor pressure (kPa), temperature (°C), RH (%), and barometric pressure (kPa) on a single digital interface—reducing spatial aliasing and improving energy-balance modeling fidelity.
- Ultra-compact, ruggedized form factor: Cylindrical design (Ø20 mm × 54 mm) with PTFE hydrophobic membrane enabling rapid vapor diffusion while rejecting liquid water ingress and particulate contamination—even under sustained rainfall (IP67-rated enclosure).
- Low-power, multi-protocol interface: Supports both SDI-12 (v1.3 compliant) and proprietary DDI serial communication over a single 3.5 mm TRS jack or tinned lead wires—compatible with METER ZL6 data loggers and third-party systems accepting 4.0–15.0 VDC supply and SDI-12 command sets.
- Field-deployable thermal stability: Integrated thermal mass compensation and low-drift analog signal conditioning ensure <0.03 °C/year temperature drift and <0.25 %RH/year humidity drift—validated per ISO 9001:2015 manufacturing controls.
- Optimized response dynamics: RH τ63% <25 s at 1 m/s airflow; pressure τ63% <10 ms; enables capture of transient boundary-layer events without temporal smoothing artifacts.
Sample Compatibility & Compliance
The ATMOS 14 is designed for unattended, continuous deployment in open-field, forest canopy, greenhouse, and eddy-covariance tower applications. Its PTFE membrane permits unrestricted gaseous H2O transport while excluding liquid-phase interference—making it suitable for high-humidity, condensing, or dusty environments where traditional capacitive sensors exhibit hysteresis or coating degradation. All electronics conform to EN 61326-1:2013 (EMC for laboratory and industrial use) and EN 50581:2012 (RoHS compliance documentation). Manufacturing adheres to ISO 9001:2015 quality management requirements, with full traceability of component-level calibration certificates. While not intrinsically safe for Class I Div 1 locations, the sensor meets CE marking directives 2004/108/EC (EMC) and 2011/65/EU (RoHS), and supports GLP-aligned data provenance when paired with audit-trail-enabled data loggers.
Software & Data Management
Data acquisition is facilitated through METER’s ZL6 Logger software (v3.0+), which auto-detects ATMOS 14 units, configures SDI-12 polling intervals (1 min to 24 h), and applies factory-applied nonlinearity corrections embedded in firmware. Raw sensor outputs are timestamped with microsecond resolution and stored in CSV or NetCDF-4 format, preserving SI-unit metadata (e.g., “vapor_pressure_kPa”, “air_temperature_C”). For integration into enterprise SCADA or cloud-based IoT platforms (e.g., AWS IoT Core, Azure IoT Hub), the sensor’s ASCII-based SDI-12 output supports direct parsing via Modbus TCP gateways or Python-driven edge agents using PySDI12. No proprietary drivers are required; all register maps and command syntax are publicly documented in the ATMOS 14 Technical Manual (Rev. F, 2023). Firmware updates are delivered via UART bootloader and validated using SHA-256 checksums to ensure integrity.
Applications
- Soil-plant-atmosphere continuum (SPAC) studies requiring precise vapor pressure deficit (VPD) calculation for stomatal conductance modeling.
- Microclimate monitoring in precision agriculture—especially orchard frost prediction, irrigation scheduling, and post-harvest storage validation.
- Long-term ecological research networks (e.g., NEON, ILTER) where sensor interchangeability, interannual drift stability, and metadata-rich output are mandatory.
- Calibration reference for unmanned aerial systems (UAS) carrying miniaturized environmental payloads.
- Validation of numerical weather prediction (NWP) model surface layer parameterizations at flux tower sites.
FAQ
Is the ATMOS 14 compatible with non-METER data loggers?
Yes—any SDI-12–compliant logger supporting 1200-baud asynchronous serial communication and 4.0–15.0 VDC power can acquire ATMOS 14 data. Verified compatibility includes Campbell Scientific CR1000X, Onset HOBO RX3000, and Delta-T DL6.
What is the recommended mounting configuration for optimal accuracy?
Mount horizontally inside a naturally aspirated, white-painted radiation shield (e.g., METER NR01) to minimize solar loading errors. Avoid direct exposure to precipitation without the optional vented shield.
Can vapor pressure be calculated independently from RH and temperature readings?
No—the ATMOS 14 computes vapor pressure internally using the August–Roche–Magnus formula with sensor-specific coefficients; raw RH and T values are not exposed separately in standard output mode.
Is firmware update capability available in the field?
Yes—via UART connection using a TTL-to-USB adapter and METER’s open-source DFU utility; no hardware modification or return-to-factory service is required.
Does the sensor require periodic recalibration?
METER recommends annual verification against traceable reference standards (e.g., chilled-mirror hygrometer, barometric standard) per ISO/IEC 17025 guidelines; full recalibration is optional and performed at METER’s Bellevue, WA facility.
