Brugger, Peter

De Roo, Frederik

Mauder, Matthias

Zeeman, Matthias

KITopen

KIT – The Research University in the Helmholtz Association Institute for Meteorology and Climate: Atmospheric  Environmental Research (IMK-IFU): Turbulent processes in the atmospheric boundary-layer www.kit.edu  The Dependence of Energy Budget Components on the surface Characteristics of a shallow pre-Alpine Valley Frederik De Roo, Matthias Zeeman, Peter Brugger and Matthias Mauder IMK-IFU/TABLe 2 Frederik De Roo -- The Dependence of Energy Budget Components on the surface Characteristics of a shallow pre-Alpine Valley Energy balance closure problem of EC measurements Measurement bias 5-15% [Horst 2015; Frank et al 2012] Neglected terms, e.g. storage [Leuning et al 2012] Quasi-stationary motions carrying mean flux  [Mauder et al 2010 ; Foken 2008] Correlators u* and site heterogeneity [Stoy et al 2013]  28.07.2016 Linking of local fluxes with  organized boundary-layer structures Large heterogeneities induce BL motions: penetration to surface? Small: blended but local?  [Eder et al 2015a] evidence and correlation from measurements [Schalkwijk et al 2016]  year-long simulated dataset: u* IMK-IFU/TABLe 3 Scales of topography Alps: “Alpine pumping” Δz = 2.5km; Δx = 50km Nearby hill Δz = 300m ; Δx = 5km Local slope Δz = 150m ; Δx = 2km Frederik De Roo -- The Dependence of Energy Budget Components on the surface Characteristics of a shallow pre-Alpine Valley Data from measurement site Fendt in the pre-Alps German environmental monitoring network TERENO [Zacharias e.a. 2011] Intensive campaign ScaleX in summer 2015 and 2016 [Wolf e.a. review]                                        28.07.2016 Long-term EBR = 0.77 [Eder et al 2014] LES output PALM: [Maronga et al 2015] Virtual measurement tower (10 m resolution) Coordinated scan modes of Triple Doppler LiDARS: IMK-IFU/TABLe 4 [Webb et al 1980 ; Lee 2009 ; Eder et al 2015b]                                          Study of idealized surface flux heterogeneity and its influence on the energy budget  Parameter study of variable surface heat flux on tower measurements (318 cases) Main parameters: scales and amplitude Towers at up/downdrafts/borders  Domain: 6 x 6 x 2.4 km³ periodic in xy 10 m grid ; 1 Hz ; 5 x 1hr intervals C.v. gridpoints 5 x 5 x 5  Frederik De Roo -- The Dependence of Energy Budget Components on the surface Characteristics of a shallow pre-Alpine Valley In complex terrain: a volume approach to determine the simulated surface energy budget 28.07.2016 IMK-IFU/TABLe 5 Frederik De Roo -- The Dependence of Energy Budget Components on the surface Characteristics of a shallow pre-Alpine Valley  O(km) heterogeneity induces a circulation affecting the energy budget, but the tower position matters Heterogeneity of smaller scale O(hm) appears blended at tower height Smaller imbalances (ca 10%) and the tower budget appears more uniform 28.07.2016 IMK-IFU/TABLe 6 Frederik De Roo -- The Dependence of Energy Budget Components on the surface Characteristics of a shallow pre-Alpine Valley Variability of turbulent fluxes at scales smaller than the quasi-stationary up- and downdrafts 28.07.2016 Preliminary simulations: 3 hr spinup; 4 hrs of data ; 12.5m grid Initialization from measured profiles  Heterogeneity in topography and roughness Topography: Δz < 20 gp ; Δz/Δx < 10 % Buffer for domain <=> computational demands  IMK-IFU/TABLe 7 Frederik De Roo -- The Dependence of Energy Budget Components on the surface Characteristics of a shallow pre-Alpine Valley Variability of turbulent fluxes at scales smaller than the quasi-stationary up- and downdrafts 28.07.2016 IMK-IFU/TABLe 8 Frederik De Roo -- The Dependence of Energy Budget Components on the surface Characteristics of a shallow pre-Alpine Valley Conclusions Idealized simulations to investigate the influence of surface heterogeneity on energy budget Position of tower matters EBR down to 0.7 as in reality (but at z_m = 50 m) Flux-divergence has to be considered as well  Realistic complex terrain from site experiment to investigate the influence of boundary-layer structures on turbulent flux  Turbulent flux varies in space and time at scales smaller than the quasi-stationary up- and downdrafts Local structures in 30 minute averaged turbulent flux fields that penetrate down to the surface  Outlook: confirmation at higher resolution   28.07.2016 

The dependence of energy budget components on the surface characteristics of a shallow pre-Alpine valley

https://publikationen.bibliothek.kit.edu/1000061793/3935588

The dependence of energy budget components on the surface characteristics of a shallow pre-Alpine valley

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