Relationship between GGI-3000 pan evaporation measurements and common daily evaporation estimates: a case study of the Tušimice station

Evaporation is an important component of the water balance in many water-management, environmental and engineering applications. This study presents an observational comparison of daily GGI-3000 pan evaporation measurements with twelve common evaporation-estimation methods at the Tušimice station in the Czech Republic. The comparison shows that the measured pan evaporation is generally lower than the corresponding calculated estimates, although the magnitude of the difference varies among methods and from day to day. The relationship between measured and estimated evaporation also exhibits both meteorological and temporal structure. Serial-dependence-adjusted GLS analysis confirmed that meteorological conditions and time provide complementary information, while a moving-block bootstrap showed that the overall difference in level remained robust to short-term serial dependence. A temporal-resolution sensitivity analysis further showed that the daily application of methods commonly formulated using monthly or mean daily conditions did not materially affect the main comparison.

The results indicate that the relationship between GGI-3000 measurements and common evaporation estimates should not be represented by a single universal conversion coefficient. The two approaches should instead be regarded as related, but not identical, representations of evaporation.