Analysis of evaporation from water surface measured automatically by the EWM evaporimeter at the weather station in Ústí nad Orlicí between 2001 and 2014

  • Mojmír KOHUT Czech Hydrometeorological Institute, branch office Brno, Czech Republic
  • Jaroslav ROŽNOVSKÝ Czech Hydrometeorological Institute, branch office Brno, Czech Republic
  • Gražyna KNOZOVÁ Czech Hydrometeorological Institute, branch office Brno, Czech Republic
  • Jáchym BRZEZINA Czech Hydrometeorological Institute, branch office Brno, Czech Republic
Keywords: evaporation, statistical analysis, trend in evaporation, Ústí nad Orlicí

Abstract

Evaporation from water surface at the station in Ústí nad Orlicí was measured
using an automatic EWM evaporimeter. The analysed period was from May 1st to
September 30th in the years 2001 to 2014. Statistical analysis of the daily evaporation
showed that the values ranged between 0.0 mm and 7.3 mm (July 17, 2007). This maximum
value was analysed in detail and considered to be realistic based on the unusual
weather conditions on that day. The highest average daily evaporation was observed in
July (2.8 mm), followed by August (2.5 mm). On the other hand the lowest average
daily evaporation was found to be in September (1.6 mm). Average monthly evaporation
totals in the analysed period (2001–2014) ranged from 49.1 mm (September) to 86.1 mm
(July). The absolute lowest monthly evaporation total in the analysed period was measured
in September 2002 (34.4 mm), on the other end of the scale, the absolute highest
monthly evaporation in the period of interest was measured in August 2003 (114.5 mm).
Statistics of annual data show that out of the 14 years analysed, the lowest evaporation
was observed in 2005 (263.5 mm), while the highest in 2007 (426.1 mm). Average annual
(May-September) evaporation for the 14 years is 355.0 mm. The trend in evaporation
for May and August is negative, in the other months it is positive. The largest change
was seen in July, where the linear index value is +1.555. However, the trends in monthly
values are not statistically significant.

Published
2015-12-30
How to Cite
KOHUT, M., ROŽNOVSKÝ, J., KNOZOVÁ, G., & BRZEZINA, J. (2015). Analysis of evaporation from water surface measured automatically by the EWM evaporimeter at the weather station in Ústí nad Orlicí between 2001 and 2014. Contributions to Geophysics and Geodesy, 45(4), 269-283. https://doi.org/10.1515/congeo-2015-0024
Section
original research papers