AMMS and WMO standards ~ let's find out what they are

How we comply with WMO regulations in our weather ecosystem, and future ideas regarding the AMMS project

Introduction

Welcome back to the workshop! Today we are going to tackle an important topic that my co-workers and I are very often asked about in connection with our weather project, namely:

"Are your stations OMM compatible?"

Before answering this question, we would like to shed some light on this acronym that is very often heard in meteorological circles, but at the same time is a source of confusion.

What are WMO standards?

The World Meteorological Organisation (WMO) standards for a meteorological station are a set of 'stakes' that define international standards for the collection, processing and dissemination of meteorological data. These standards are designed to ensure the consistency and reliability of meteorological information collected from stations around the world, and to validate a station they must be properly adhered to and maintained over time.

The main areas covered by the standards include:

1. Location and InstallationStations must be positioned in locations that accurately represent the climate of the surrounding region, avoiding obstacles that could influence measurements. Equipment must be correctly installed and regularly maintained to ensure data accuracy.
2. InstrumentationStations must be equipped with standardised meteorological instruments to measure parameters such as temperature, humidity, atmospheric pressure, precipitation, wind direction and speed, solar radiation and other relevant data.
3. Calibration and Maintenance: It is essential that instruments are regularly calibrated and stations are subject to periodic maintenance to ensure data accuracy and reliability.
4. Recording and Transmission of Data: Meteorological data must be recorded accurately and in a timely manner and transmitted to national or international meteorological authorities according to specific procedures and timescales.
5. Data Storage: It is essential to maintain an accurate and reliable record of weather data collected for research, climate analysis and long-term weather forecasting purposes.
6. Safety and Security: Weather stations must be protected from physical damage, external interference and unauthorised access to ensure continuity of operations and data security.
7. Reporting Standards and Data Classification: Meteorological data must be presented in a standardised way to allow easy interpretation and comparison between different stations and regions.

What about the AMMS project?

Following the WMO standards ensures that meteorological stations provide accurate and reliable data, which are essential for understanding and predicting climate change, monitoring extreme weather conditions and making informed decisions for the management of applications and tools based on this data.

This obviously also affects our project AMMSas we are constantly striving to obtain the most accurate data possible, also with a view to validating it for the calibration of new stations and for parallel use in our IoT devices.

Over time, we are working on making all the stations OMMs, prioritising the 'reference stations' of Sovramonte (BL) and Sedico (BL), and drawing up a series of parameters to be respected also within the working team for the construction and design of new stations and hardware connected to the AMMS ecosystem.

The WMO parameters we adopt for reference stations

Sensor type	Sensor height above ground	Additional notes
Thermo-hygrometer	Between 1.70 m and 2.00 m	The thermo-hygrometer must be placed in an approved sun screen (Davis screen or higher) at a height between 1.70 m and 2.00 m above the ground on grass surface and distant at least 10 metres from nearby buildings or obstacles.
Pluviometer	At least >0.50 m	It must be positioned in the open field at least 10 metres away from obstacles, and in any case at such a distance that any vertical obstacles (trees, buildings) cannot impede the correct recording of data in the event of cross rainfall.
Anemometer	Between 2.50 m and 10.00 m	Positioned in an open field and away from vertical obstacles that could prevent proper detection of gusts and turbulence.
Solar radiation and UV	'at will'	The sensor should be positioned at the top of the pole with a good view and in such a place that it is not caught in the shadows of surrounding objects.
Soil temperature and Humidity superficial and inside the ground	5cm above the ground and within the ground	The same types of sensors are used to measure surface temperature (the one at 5cm) and the temperature inside the ground. In these cases, the sensing elements are protected by a smaller metal container, which allows a more correct localised measurement. In addition, the surface temperature sensor is shielded from direct sunlight.
Leaf watering (only in Col de Mich (BL))	'open field in the rain'	The operation of the sensor is based on measuring the electrical conductivity value between two electrodes consisting of a printed circuit board applied on flat surfaces differently oriented and inclined downwards to avoid water stagnation made of inert material (vetronite). The sensing element simulates fairly faithfully the state of vegetation under the effect of rain or as a result of water vapour condensation. Maximum conductivity is obtained when the surfaces are wet ('wet leaf' state); in the absence of water, on the other hand, resistance is very high ('dry leaf' state).

For urban and courtyard stations in addition to the above parameters, there is forced ventilation of the Thermo-Hygrometer and increased heights from the surface (at least 2m for all sensors from the nearest surface) in order to avoid measurements distorted by the thermal release of non-grass materials, of course maintaining transverse distances from obstacles.

Reference stations and calibrations

We currently have two reference stations in the system, stations that are calibrated and certified in order to calibrate new stations and systems using meteorological sensors.
When we need to calibrate a new device we place it close to the station and for the duration of at least one month we collect the data and compare it to verify the average error between the two stations. When it remains within a certain range (~0.5%) the station is considered calibrated, and is installed at the target location and entered into the database.

The reference stations run on dedicated hardware that has been verified by several electronic designers from all over Italy, in order to stay within the ranges required by the regulations, and we are currently evaluating certification by specialised bodies in order to start marketing and increase the number of AMMS reference stations. In the meantime, we also exploit opensource data from other certified bodies to verify that our systems are reliable