Site Selection
Guidance for choosing a deployment site with representative exposure, safe access, and minimal measurement interference.
Overview
Selecting an appropriate site is one of the most important factors in ensuring high-quality observations from a 3D-PAWS station. Even when sensors are functioning correctly, poor siting can result in measurements that are biased or not representative of local conditions.
Site selection should prioritize exposure, representativeness, practical constraints, and instrument-specific siting requirements.
Key Considerations
When selecting a site, evaluate these factors:
Exposure – Are sensors unobstructed by buildings, trees, or terrain?
Representativeness – Does the site reflect the surrounding environment you want to measure?
Solar Access – Will the solar panel receive sufficient sunlight throughout the day?
Communications – Is cellular or WiFi connectivity available and reliable?
Security – Is the site protected from theft, vandalism, or accidental damage?
Accessibility – Can the station be safely installed and maintained over time?
Instrument Siting Guidelines
Different instruments have different siting requirements. Consider these when selecting a location.
Rain Gauge
Open exposure, free-falling precipitation, away from irrigation and runoff
Wind Sensors
Minimal obstructions, consider prevailing winds and obstacle distance
Radiation Shield
Good airflow, no shading, away from heat sources
Solar Panel
Maximum sun exposure throughout the day
Soil Sensors
Representative soil conditions and minimal disturbance
Rain Gauge
Place in an open area
Avoid obstructions such as trees, buildings, towers, and other structures
Ensure precipitation can fall freely into the gauge
Avoid locations where water may drip or flow into the gauge from overhead objects, including tree branches, roofs, overhangs, and nearby structures
Avoid locations influenced by artificial irrigation, including sprinklers and irrigation systems
Keep clear of roof runoff, drainage systems, and other non-natural water sources
Wind Sensors
Install with minimal obstruction
Avoid areas where airflow is blocked or channeled
Consider prevailing wind direction
Whenever possible, maintain a distance from obstacles of at least 30 times the obstacle height (30:1 rule) to minimize turbulence and flow distortion
Avoid nearby buildings, trees, towers, and other structures that may alter wind measurements
Example: A 10 m tree should ideally be at least 300 m from the wind sensor.
Radiation Shield (Temperature / Humidity / Pressure)
Install in well-ventilated air
Avoid shaded or enclosed areas
Avoid heat sources such as buildings, pavement, and bodies of water
Ensure the sensor is exposed to representative ambient conditions
Solar Panel
Ensure maximum sun exposure throughout the day
Avoid shading from objects or terrain
Consider seasonal changes in sun angle
Position the panel for optimal solar exposure based on local latitude and hemisphere
Soil Sensors (if installed)
Place in representative soil conditions
Avoid artificially shaded or disturbed areas
Avoid locations affected by irrigation unless irrigation monitoring is an objective of the deployment
Balancing Siting Tradeoffs
Perfect sites are rare. In many deployments, it may not be possible to meet all siting recommendations simultaneously.
When compromises are required:
prioritize rain gauge and wind sensor exposure
maintain good airflow around temperature and humidity sensors
ensure adequate solar power and communication for reliable operation
document any known limitations that may affect observations
Record all siting limitations in the station metadata.
Observing Practices and Standards
3D-PAWS follows guidance from the World Meteorological Organization (WMO) Guide to Instruments and Methods of Observation (WMO-No. 8), which provides detailed recommendations for sensor exposure, siting, and measurement practices.
Applying these principles improves data quality, consistency, and comparability with other observing networks.
Summary
A well-chosen site will:
minimize measurement bias
improve data reliability
reduce troubleshooting needs
support long-term station operation and maintenance
Site selection is a critical step that directly affects the quality and value of the observations collected.
Instruction Slides for Site Selection
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