Automatic quality control for a nation-wide high-resolution network

Observations from local networks of surface stations, managed by local (regional) weather services, are collected in a nation-wide network, providing hourly observations in near real time, accessible through the MyDewetra Database, for the Italian national Civil Protection Department. Such national network provides detailed information on meteorological fields near the surface; it is inhomogeneous though, and affected by Gross Errors and Large Representativeness Errors of various origin. CIMA has undertaken an effort to operationally and automatically check such information for quality, in order to provide a dataset suitable for various uses, such as model verification, data assimilation, meteorological analysis of past events and climatological characterization of recent years and present time.

An important part of the work is devoted to ensure quality of basic station metadata, such as geographical coordinates and orographic elevation above mean sea level. A station archive for each variable is created and monthly checked and updated.

The main checks on observed meteorological variables are based on the idea of spatial consistency. The Spatial Consistency Test (SCT) represents a fine check based on Optimal Interpolation and leave-one-out Cross Validation. This and other tests have been recently included in the open-source library Titan (https://github.com/metno/titanlib).

The Titan library test functions are routinely used at CIMA to provide quality control of precipitation raingauge observations. Such quality control checks for precipitation are presently supervised by a meteorologist, aware of the current weather state.

For temperature data the SCT has actually been rewritten to ensure a detailed analysis of check behaviour on the Italian dataset and is monthly used to provide reliable data for model forecast verification.

Plans are in place to:

• extend the quality control to other meteorological variables, such as relative humidity;

• test the inclusion of existing high resolution observational network managed by private amateur citizens;

• test the impact of such quality-controlled local observations in data assimilation experiments for short-range forecasts;

• compare SCT results with those obtained by Titan library functions, also with the possible scope of contributing to that open-source software test and development.