Surface Energy Components and Land Characteristics of a Rice Paddy

Abstract

Many meteorological and air-quality models require land characteristics as inputs. A field experiment was conducted to study the surface energy budget of a rice paddy in Taiwan. During the day, the energy balance ratio measured by an eddy covariance (EC) system was found to be 95% after considering the photosynthetic and local advected heat fluxes. The observations by the EC system suggest that the Bowen ratio was about 0.18 during the daytime. The EC system also measured the daytime absorbed carbon dioxide flux. The equivalent photosynthetic energy flux was about 1% of the net solar radiation. A reference table describing the land characteristics of rice paddies for use in meteorological and air-quality models is listed that shows that the albedo and the Bowen ratio measured over rice paddies were lower than those listed in many state-of-the-art models. This study proposes simulating latent heat flux by assigning proper values for canopy resistance rather than by assigning constant values for Bowen ratio or surface moisture availability. The diurnal pattern of the canopy resistance of the rice paddy was found to be "U" shaped. Daytime canopy resistance was observed to be 87 s m Ϫ1 , and a high canopy resistance (ϳ900 s m Ϫ1 ) should be assigned during nighttime periods.

Predicting water surface evaporation in the paddy field by solving energy balance equation beneath the rice canopy

“…The energy balance has been studied extensively for different purposes (Oue 2001;Harazono et al 1998;Tsai et al 2007;Tyagi et al 2000;Campbell et al 2001a, b;Yoshimoto et al 2005). A number of models have been developed to simulate processes of surface energy flux (Sellers et al 1986;Meyers and Paw 1987;Maruyama and Kuwagata 2010).…”

A more accurate scheme for calculating Earth’s skin temperature

“…It can be seen that qG 0 /qT 0 increases with ST, but decreases with aerodynamic and canopy resistances. In general, during the daylight hours, aerodynamic and canopy resistances are much lower than those during the nights (Blondin 1991;Tsai et al 2007). Typical values of daytime aerodynamic and canopy resistances observed in various land covers in the summer can be found in Wilson et al (2002).…”

Effects of soil heat storage and phase shift correction on energy balance closure of paddy fields

“…Paddy fields are one of the typical terrestrial ecosystems in the Asian monsoon region (Alberto et al, 2011), and the surface energy balance components measured in rice ecosystem are different from other crops because they are affected by the presence of water on the ground or the variation of soil moisture content (Tsai et al, 2007;Masseroni et al, 2015). However, most of the large amount of research on energy balance measurement and energy closure calculation has been conducted in ecosystems such as forests, grasslands, wetlands, and upland crop fields (Meyers and Hollinger, 2004;Castellvi et al, 2008;Cava et al, 2008;Oncley et al, 2007;Mauder et al, 2013;Masseroni et al, 2014), and few studies have been conducted in flooded rice paddy ecosystems (Oue, 2005;Castellvi et al, 2006;Tsai et al 2007).…”

“…However, most of the large amount of research on energy balance measurement and energy closure calculation has been conducted in ecosystems such as forests, grasslands, wetlands, and upland crop fields (Meyers and Hollinger, 2004;Castellvi et al, 2008;Cava et al, 2008;Oncley et al, 2007;Mauder et al, 2013;Masseroni et al, 2014), and few studies have been conducted in flooded rice paddy ecosystems (Oue, 2005;Castellvi et al, 2006;Tsai et al 2007). With the increasing water scarcity, water saving irrigation (WSI) techniques were applied to rice paddies (Belder et al, 2004;Kato et al, 2011;Rothenberg et al, 2011;Uphoff et al, 2010), which exposed rice fields to drying-wetting cycles and greatly reduced seepage and evaporation losses (Bouman et al, 2007).…”