Naslov
Surface energy balance closure in the Owens Valley, CA

Autori
Marinović, Ivana ; Babić, Nevio ; Stiperski, Ivana ; Večenaj, Željko ; De Wekker, Stephan F.J.

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, ostalo, znanstveni

Skup
Joint Congress of the 6th International Conference on Meteorology and Climatology of the Mediterranean (MetMed) & Challenges in Meteorology 5 (MI5)

Mjesto i datum
Zagreb, Hrvatska, 20.02.2017. - 22.02.2017

Vrsta sudjelovanja
Predavanje

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
surface energy balance ; closure ; heat flux ; complex terrain ; T-REX experiment

Sažetak
All weather and climate models apply conservation of energy at the earth's surface. In that ideal case the sum of the net radiation and ground heat flux (the available energy) balances the surface turbulent fluxes of sensible and latent heat which drive atmospheric boundary layer processes. However, such a closure in the surface energy balance is rarely achieved, resulting in a residual. This residual is typically on the order of 10-30 % of the total available energy with the sum of the turbulent fluxes smaller than the available energy. It is now well established that this residual cannot be solely attributed to measurement uncertainties. Other reasons for a non-closure in the energy balance include the presence of surface heterogeneities and large scale eddies, the presence of thermally and terrain forced flows, and varying flux footprints. The objective of this study is to identify and quantify the sources of non-closure in the energy balance using data collected during the Terrain- Induced Rotor Experiment in Owens Valley, California, from 1 March to 30 April 2006. In particular, we use the 5 min data for sensible and latent heat fluxes collected at 5 m and 30 m heights, and for net radiation and ground heat flux collected at the 2 m height. Data were collected at three 34 m tall towers distributed along the valley's central axis and its western sidewall. We are also investigating a possibility that contribution of low frequency structures could be one of the processes that cause non- closure in the energy balance at slope and valley locations during daytime. To select only the daytime conditions, two criterions were applied: short incoming radiation > 30 W/m2 and stability parameter < 0. We determine the ratio between turbulent fluxes and available energy as a function of the measurement level of the turbulent fluxes, averaging time, the location in the valley, friction velocity, stability and the presence of valley and slope flows (wind speed and wind direction). We demonstrate that knowledge of the dependency of the surface energy balance ratio on these factors is crucial for a proper evaluation of surface layer parameterizations in complex mountainous terrain.

Izvorni jezik
Engleski

Znanstvena područja
Geofizika

POVEZANOST RADA