Inhomogeneity introduced to the climate data series by instrumentation changes of the thermometer shields and rain gauges

Abstract

Recently we can see the trend of introducing a new instrumentation and
automatization in the field of information and monitoring systems for the meteorology,
hydrology and crisis centers. Nowadays a great number of sensors are used in projects in
many countries of various climates. Therefore it is crucial to deeply understand how the
change of sensor types will affect the accuracy of measurements and how is accuracy of
individual sensor type affected by different weather conditions.
We analyzed several screen/shields and rain gauges at the premises of faculty of Meteorology
and Climatology of FMFI UK. On the basis of our results we can recommend
as a most accurate and not depending on weather condition artificially ventilated screen
although it is the most expensive. Our second choice would be a large naturally ventilated
shield. In case of Stevenson screens we would recommend painting it with a high gloss
coating. Our last choice would be a small naturally ventilated screen because of its high
sensitivity to the global radiation.
Our first choice of the participating rain gauges would be the weighing rain gauge because
of its best results in both cases, of rainfalls up to 2 mm and also over 2 mm. The
tipping bucket rain gauge gave also agreeable result in both cases. The optical sensor gave
very good results in rainfalls over 2 mm but it is unsuitable for rainfalls up to 2 mm. The
radar sensor is also completely unsuitable for low intensity rainfalls and his performance
for rainfalls over 2 mm was just average.