Earlscliffe - Howth Weather

Data quality

Earlscliffe is a member of the Citizen Weather Observer Program (CWOP), a private-public partnership with the National Oceanic & Atmospheric Administration (NOAA). CWOP is a global network of volunteer-run personal weather stations. Participants share observations in near real time, usually via the APRS network, making the data available to researchers, meteorological agencies, and public services.

Because CWOP stations vary widely in siting, equipment, and maintenance, their data is not assumed to be perfect. Instead, CWOP observations are evaluated using an independent quality-control system called MADIS.

MADIS (Meteorological Assimilation Data Ingest System) is also operated by NOAA. It ingests weather observations from many sources, including CWOP stations, airports, buoys, ships, and official national networks. Before data is used for analysis or forecasting, MADIS applies a set of automated quality checks, including:

• values that fall outside physically plausible ranges,
• internal inconsistencies, for example dew point higher than air temperature,
• sudden unrealistic jumps between successive readings,
• observations that disagree strongly with nearby stations or expected background conditions.

Each observation is assigned quality flags based on these checks. Stations are not labelled as permanently “good” or “bad”. Instead, performance is assessed over time, report by report.

A high-quality CWOP station is one whose observations consistently pass these independent MADIS tests, indicating that the data is reliable enough to be used alongside official networks.

MADIS quality control does not guarantee absolute accuracy. Rather, it provides a statistical measure of confidence based on consistency, plausibility, and agreement with surrounding observations. This makes CWOP data especially useful for understanding local conditions and trends, while remaining open about its limitations.

The Earlscliffe CWOP quality report is available via the link below. In this report, the MADIS value shows the percentage of observations that have passed the MADIS quality checks.

• A green thumbs-up indicates performance within acceptable limits.
• A red cross indicates that quality checks have not been met.
• Two green thumbs-up represent the highest overall quality rating.

Many thanks go to Phillip Gladstone at CWOP for his dedication to providing the needed accuracy and quality checks for the amateur weather observer.