TY - JOUR
T1 - Micrometeorological measurements in an arid environment
T2 - Diurnal characteristics and surface energy balance closure
AU - Nelli, Narendra Reddy
AU - Temimi, Marouane
AU - Fonseca, Ricardo Morais
AU - Weston, Michael John
AU - Thota, Mohana Satyanarayana
AU - Valappil, Vineeth Krishnan
AU - Branch, Oliver
AU - Wizemann, Hans Dieter
AU - Wulfmeyer, Volker
AU - Wehbe, Youssef
N1 - Publisher Copyright: © 2019 Elsevier B.V.
PY - 2020/4
Y1 - 2020/4
N2 - The goal of this study is to assess the surface energy balance closure (SEBC) in an arid environment through a comprehensive analysis of surface radiation, heat fluxes, and other micrometeorological measurements. These were taken from a 2.3-m eddy covariance (EC) flux tower at Al Ain (24°16′26.5535″ N, 55°37′03.2196″ E; 243 m a.m.s.l.) during the periods April – October 2017 and February 2018 – January 2019. The SEBC is investigated on seasonal and diurnal time-scales using the Energy Balance Ratio (EBR) and residual flux (ΔE) values. An analyses of the SEBC reveals that during daytime a three-way balance between the sensible heat, ground heat fluxes and the net surface radiative flux prevails, while at night the last two essentially balance each other. These fluxes are roughly 25% larger in the summer compared to the winter season. The surface downward shortwave radiation flux and latent heat flux peak in spring, despite the latter having rather small magnitudes (<20 W m−2) throughout the year. The EBR during daytime is in the range 0.60 to 0.75. The mean ΔE during daytime (nighttime) is 30 W m−2 (−14 W m−2) respectively. Further analysis of the SEBC with respect to the prevailing wind direction revealed that the maximum closure is observed for north-northwesterly winds and the minimum for southerly winds. This may be explained by the surface heterogeneity and the presence of a building to the south of the site. The SEBC is better for daytime and for periods when the friction velocity is higher.
AB - The goal of this study is to assess the surface energy balance closure (SEBC) in an arid environment through a comprehensive analysis of surface radiation, heat fluxes, and other micrometeorological measurements. These were taken from a 2.3-m eddy covariance (EC) flux tower at Al Ain (24°16′26.5535″ N, 55°37′03.2196″ E; 243 m a.m.s.l.) during the periods April – October 2017 and February 2018 – January 2019. The SEBC is investigated on seasonal and diurnal time-scales using the Energy Balance Ratio (EBR) and residual flux (ΔE) values. An analyses of the SEBC reveals that during daytime a three-way balance between the sensible heat, ground heat fluxes and the net surface radiative flux prevails, while at night the last two essentially balance each other. These fluxes are roughly 25% larger in the summer compared to the winter season. The surface downward shortwave radiation flux and latent heat flux peak in spring, despite the latter having rather small magnitudes (<20 W m−2) throughout the year. The EBR during daytime is in the range 0.60 to 0.75. The mean ΔE during daytime (nighttime) is 30 W m−2 (−14 W m−2) respectively. Further analysis of the SEBC with respect to the prevailing wind direction revealed that the maximum closure is observed for north-northwesterly winds and the minimum for southerly winds. This may be explained by the surface heterogeneity and the presence of a building to the south of the site. The SEBC is better for daytime and for periods when the friction velocity is higher.
KW - Arid environment
KW - Eddy covariance technique
KW - Friction velocity
KW - Micrometeorological measurements
KW - Soil temperature
KW - Surface energy balance closure
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U2 - 10.1016/j.atmosres.2019.104745
DO - 10.1016/j.atmosres.2019.104745
M3 - Article
SN - 0169-8095
VL - 234
JO - Atmospheric Research
JF - Atmospheric Research
M1 - 104745
ER -