Air humidity in Cracow (Poland) in the period – daily data quality control and homogenization methods Agnieszka Wypych, Katarzyna Piotrowicz Institute of Geography and Spatial Management Jagiellonian University

Krakow - location Krakow lies in the southern part of Poland on the Vistula River in a valley at the foot of the Carpathian Plateau, 219 meters above sea level. The city covers an area of 327 sq meters. Neighbourhood of Krakow with the Wieliczka Foothils and the Krakow Upland, located metres higher, results in modification of many climate features within the town area. AIR HUMIDITY – DATA QUALITY CONTROL

The Sniadecki Collegium The station was established as early as in 1792 by Jan Sniadecki as part of the Astronomical Observatory AIR HUMIDITY – DATA QUALITY CONTROL

The Historical Station is located 12m a.g.l. (NNW) AIR HUMIDITY – DATA QUALITY CONTROL

Since 1826 meteorological measurements have been conducted: 1. Permanently in the same place Krakow – city developement before 1792 in 1792 in 1915 in 1941 in 1951 in 1973 in With nearly unchanged surroundings AIR HUMIDITY – DATA QUALITY CONTROL

1847 AIR HUMIDITY – DATA QUALITY CONTROL

2007 AIR HUMIDITY – DATA QUALITY CONTROL

3. According to contemporary meteorological Instructions The hours of observation and methods of calculating the mean daily air temperature in Krakow Since 1826 meteorological measurements have been conducted: AIR HUMIDITY – DATA QUALITY CONTROL

The only measurement series to have undergone homogeneity testing thus far are series of air temperature, atmospheric pressure and precipitation. Fluctuation of climate in Krakow ( ) Secular change of climate on the basis of the Krakow meteorological series … Janina Trepińska (ed.) AIR HUMIDITY – DATA QUALITY CONTROL

Saussure Higrometer Higrometer - XIX century Air humidity measurements have begun 20 May 1792 (19 May 1792) AIR HUMIDITY – DATA QUALITY CONTROL

Psychrometric measurements Permanent data - December – 2007 (144 years) The homogeneity of air humidity parameters has not been investigated, mainly due to the methodical difficulties related to the analysis of numerical material. AIR HUMIDITY – DATA QUALITY CONTROL

RESEARCH PURPOSE Examine the quality of Cracow’s air humidity measurement series. Daily values of selected air humidity parameters calculated on the basis of psychometric measurements ( ) – morning, noon, evening observation time DATA AIR HUMIDITY – DATA QUALITY CONTROL METHODS - Psychrometric measurements values quality - Air humidity parameters calculating methods - Series homogeneization

AIR HUMIDITY – DATA QUALITY CONTROL A comparison of air temperature (T), whose homogeneity has previously been checked, with the appropriate readings of a wet bulb thermometer (T’). The missing data concerning the state of the cambric during the measurements - water/ice (completed ) Air humidity measurements - methodical difficulties - psychrometer localisation: distance from vegetation, water reservoirs - wet-bulb thermometer moisteing - wind speed (ventilation) Temperature measurements – different thermal scales (recalculated)

AIR HUMIDITY – DATA QUALITY CONTROL Cambric state during the measurements - water/ice Psychrometric formulas (-10 o C) – (+8 o C) Frequency of ice/water cambic state (Krakow ) Statistics ( )

AIR HUMIDITY – DATA QUALITY CONTROL Statistics ( ) Difference (%) between relative air humidity values counted using „ice formulas” and „water formulas” (-5  t  5) Error range (%)

AIR HUMIDITY – DATA QUALITY CONTROL Cambric state during the measurements - water/ice Psychrometric formulas (-10 o C) – (+8 o C) Statistics ( ) ( ) (-5 o C) – (+5 o C) Missing data t<-3 o C - ice -3 o C<t<-2 o C – ice (t’<-2 o C) (t’<-2 o C) -1,9 o C<t<1,9 o C compared with weather conditions t>2 o C - water

Values of air humidity parameters - psychrometric models, identical for the entire series AIR HUMIDITY – DATA QUALITY CONTROL Psychrometric formulas modyfied: G. Magnus (1844); M. Robitzsch (1928); O. Tatens (1930) waterice

Extreme cases, which gave rise to doubts – compared with the records about the state of the atmosphere: - circulation conditions, - the occurrence of foehn - atmospheric phenomena AIR HUMIDITY – DATA QUALITY CONTROL

Homogeneity test AIR HUMIDITY – DATA QUALITY CONTROL Air humidity values – no visible inhomogeneity ( modified form of SNHT Alexandersson ( modified form of SNHT Alexandersson) The controversial values - further verification Corrections of numerical data - not performed CONCLUSION The content of air vapour in the air is a result of the interaction of numerous factors and processes, which need to be taken into account before correcting the values. In light of the lack other objective possibilities of verification of air humidity in Krakow, the analysed data were considered as relatively homogeneous.

AIR HUMIDITY – DATA QUALITY CONTROL Long term course of the relative air humidity (f%) in Krakow ( )

AIR HUMIDITY – DATA QUALITY CONTROL Long term course of the number of very wet (f  86%) and dry (f  55%) days in Krakow ( )

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