Impact of global dimming and brightening on reference evapotranspiration in Greece

Abstract

[1] In this study, the consistency of trends in radiation and temperature records and their implications for the hydrological cycle and especially the trends in reference evapotranspiration are examined during the period 1950-2001. The new reference evapotranspiration model for complex terrains (REMCT), with monthly time step, is used for estimating trends of reference evapotranspiration in Greece. REMCT is applied after developing a methodology for calibrating its parameter values with Penman-Monteith estimates. The calibrated REMCT estimates are independently validated against available pan evaporation measurements. The evolution of available sunshine duration anomalies measured in Athens during the period 1951-2001 are used for highlighting global dimming or brightening periods in Greece. The sign of trends in the modeled reference evapotranspiration and precipitation are examined according to the dimming or brightening periods 1950-1983 and 1958-1983 (for 16 and 22 stations, respectively) or 1983-2001 (for 16, 22, and 29 stations). The trends of REMCT estimates, precipitation, number of rainy days, and mean, maximum, and minimum air temperature for all sets of stations considered "as a whole" are evaluated during the same periods. The results show that the annual calibrated reference evapotranspiration trend shows a decline from 1950 until the early 1980s, followed by an upward trend until 2001, while the annual precipitation and rainy days indicate a downward trend during the whole period 1950-2001. The trends of mean, maximum, and minimum air temperature are found almost negligible during the dimming period and rather increased during the brightening period.

Evaporation trends in Spain: a comparison of Class A pan and Piché atmometer measurements

“…Equally, this increase in pan evaporation is also in line with a widespread increase in potential evaporation reported over the Mediterranean since the 1980s (e.g. Matsoukas et al 2011, Papaioannou et al 2011, for review see Vicente-Serrano et al 2014b).…”

“…The important role of surface solar radiation to drive evaporation is well known, and, consequently, a link between the dimming/brightening phenomenon (Wild 2009) and the trends in actual and potential evaporation has been shown in previous studies (Roderick & Farquhar 2002, Wild et al 2008, Teuling et al 2009, Fu et al 2009, Papaioannou et al 2011. In fact, both solar radiation (Sanchez-Lorenzo et al 2013) and Piché and pan trends in Spain since the mid-1980s seem to agree, not only qualitatively, but also quantitatively.…”

Why has catchment evaporation increased in the past 40 years? A data-based study in Austria

“…In Greece, non-significant increases in E pan over 1983-1999 were observed for a pooled series from 14 stations (Papaioannou et al, 2011). Three out of eight sites in Ireland showed a significant increase in E pan over 1963-2005, and one site showed a significant decrease (Stanhill and Möller, 2008).…”

“…In Europe, most studies found increasing trends of E pan (e.g. Ireland (1963Ireland ( -2005 (Stanhill and Möller, 2008), England (1957-2004 and 1986 (Stanhill and Möller, 2008;Clark, 2013), Greece (1983Greece ( -1999 (Papaioannou et al, 2011), and the Czech Republic (Trnka et al, 2015)). In this paper, we use the term atmospheric conditions to summarize the drivers available energy and atmospheric demand.…”

Variação temporal dos elementos climáticos e da ETo em Catalão, Goiás, no período de 1961-2011

“…No Brasil há poucos trabalhos sobre tendência na velocidade do vento (Alencar et al, 2011;. McVicar et al (2012) relatam que em vários estudos tem-se procurado entender as causas da dinâmica de evapotranspiração sem considerar as tendências da velocidade do vento (Golubev et al, 2001;Silva, 2004;Papaioannou et al, 2011). Isto é, implicitamente, os autores consideram que a velocidade do vento não apresenta tendência.…”