Abstract
Studies of entrainment across the top of the boundary layer rely to a great extent on identification of the boundary-layer top, inversion properties, entrainment-zone depth, and the temporal changes in all of these. A variety of definitions and techniques have been used to provide automated and objective estimates; however, direct comparisons between studies is made difficult by the lack of consistency in techniques. Here we compare boundary-layer depth, entrainment-zone thickness, and entrainment rate derived from several commonly used techniques applied to a common set of large-eddy simulations of the idealized, dry, convective boundary layer. We focus in particular on those techniques applicable to lidar backscatter measurements of boundary-layer structure. We find significant differences in all the quantities of interest, and further that the behaviour as functions of common scaling parameters, such as convective Richardson number, also differ, sometimes dramatically. The discretization of the possible values of some quantities imposed by the vertical grid is found to affect some of the results even when changes to model resolution does not affect the entrainment rate or scaling behaviour. This is a particular problem where entrainment parameters are derived from a single mean profile (e.g. the buoyancy-flux profile), but not where they are derived from the statistical properties of large numbers of individual profiles (e.g. the probability distribution of the local boundary-layer top at each model grid point).
Similar content being viewed by others
References
Angevine WM (2007) Transitional, entraining, cloudy, and coastal boundary layers. Acta Geophys 56: 2–20. doi:10.2478/s11600-007-0035-1
Angevine WM, White AB, Avery SK (1994) Boundary-layer depth and entrainment zone characterization with a boundary-layer profiler. Boundary-Layer Meteorol 68: 375–385
Ayotte KW, Sullivan PP, Andrén A, Doney SC, Holtslag AAM, Large WG, McWilliams JC, Moeng C-H, Otte MJ, Tribbia JJ, Wyngaard JC (1996) An evaluation of neutral and convective planetary boundary layer parameterizations relative to large-eddy simulations. Boundary-Layer Meteorol 79: 131–175
Beyrich F (1997) Mixing height estimation from sodar data—a critical discussion. Atmos Environ 31: 3941–3953
Beyrich F, Gryning S-E (1998) Estimation of the entrainment zone depth in a shallow convective boundary layer from sodar data. J Appl Meteorol 37: 225–268
Boers R, Eloranta EW (1986) Lidar measurements of the atmospheric entrainment zone and the potential temperature junp across the top of the mixed layer. Boundary-Layer Meteorol 34: 357–375
Boers R, Eloranta EW, Coulter RL (1984) Lidar observations of mixed layer dynamics: tests of parameterized entrainment models of mixed layer growth rate. J Clim Appl Meteorol 23: 247–266
Boers R, Spinhirne JD, Hart WD (1988) Lidar observations of the fine-scale variability of marine stratocumulus clouds. J Appl Meteorol 27: 797–810
Brooks IM (2003) Finding boundary layer top: application of a wavelet covariance transform to lidar backscatter profiles. J Atmos Ocean Technol 20: 1092–1105
Brooks IM, Fowler AM (2007) A new measure of entrainment zone structure. Geophys Res Lett 34(L16808). doi:10.1029/2007GL030958
Cohn SA, Angevine WM (2000) Boundary-layer height and entrainment zone thickness measured by lidars and wind profiling radars. J Appl Meteorol 39: 1233–1247
Coulter RL (1979) A comparison of three methods for measuring mixing-layer height. J Appl Meteorol 18: 1495–1499
Davis KJ, Lenschow DH, Oncley SP, Kiemle C, Ehret G, Giez A, Mann J (1997) Role of entrainment in surface–atmosphere interactions over the boreal forest. J Geophys Res 120: 29219–29230
Davis KJ, Gamage N, Hagelberg CR, Kiemle C, Lenschow DH, Sullivan PP (2000) An objective method for deriving atmospheric structure from airborne lidar observations. J Atmos Oceanic Technol 17: 1455–1468
Deardorff JW, Willis GE, Stockton BH (1980) Laboratory studies of the entrainment zone of a convectively mixed layer. J Fluid Mech 100: 41–64
de Haij M, Wauben W, Baltink HK (2007) Continuous mixing layer height determination using the LD-40 ceilometer: a feasibility study. KNMI Report WR 2007-01, 98 pp. http://www.knmi.nl/publications/fulltexts/rp_bsikinsa_knmi_20070117_wr200701.pdf. Accessed 4 Oct 2011
Emeis S, Schäfer K, Münkel C (2008) Surface-based remote sensing of the mixing-layer height—a review. Meteorol Z 17: 621–630. doi:10.1127/0941-2948/2008/0312
Fedorovich E, Conzemius R, Mironov D (2004) Convective entrainment into a shear-free, linearly stratified atmosphere: bulk models reevaluated through large eddy simulations. J Atmos Sci 61: 281–295
Ferrare RA, Schols JL, Eloranta EW (1991) Lidar observations of banded convection during BLX83. J Appl Meteorol 30: 312–326
Flamant C, Pelon J, Flamant PH, Durand P (1997) Lidar determination of the entrainment zone thickness at the top of the unstable marine atmospheric boundary layer. Boundary-Layer Meteorol 83: 247–284
Grabon JS, Davis KJ, Kiemle C, Ehret G (2010) Airborne lidar observations of the transition zone between the convective boundary layer and free atmosphere during the International H2O Project (IHOP) in 2002. Boundary-Layer Meteorol 134: 61–83. doi:10.1007/s10546-009-9431-1
Hägeli P, Steyn DG, Strawbridge KB (2000) Spatial and temporal variability of mixed-layer depth and entrainment zone thickness. Boundary-Layer Meteorol 97: 47–71
Hennemuth B, Lammert A (2006) Determination of the atmospheric boundary layer height from radiosonde and lidar backscatter. Boundary-Layer Meteorol 120: 181–200. doi:10.1007/s10546-005-9035-3
Kiemle C, Ehret G, Davis KJ, (1998) Airborne lidar studies of the entrainment zone. In: AMS, Proceedings 19th international conference on laser radar, Annapolis, Maryland, 6–10 June 1998, pp 395–398
Lammert A, Bösenberg J (2006) Determination of the convective boundary-layer height with laser remote sensing. Boundary-Layer Meteorol 119: 159–170. doi:10.1007/s10546-005-9020-x
Lenschow DH, Krummel PB, Siems ST (1999) Measuring entrainment, divergence, and vorticity on the mesoscale from aircraft. J Atmos Oceanic Technol 16: 1384–1400
Lock AP (1998) The parameterization of entrainment in cloudy boundary layers. Q J Roy Meteorol Soc 124: 2729–2753
Lock AP, Macvean MK (1999) The generation of turbulence and entrainment by buoyancy reversal. Q J Roy Meteorol Soc 125: 1017–1038
Melfi SH, Sphinhirne JD, Chou SH, Palm SP (1985) Lidar observations of the vertically organized convection in the planetary boundary layer over the ocean. J Clim Appl Meteorol 24: 806–821
Morille Y, Haeffelin M, Drobinski P, Pelon J (2007) STRAT: an automated algorithm to retrieve the vertical structure of the atmosphere from single channel lidar data. J Atmos Oceanic Technol 24: 761–775
Nelson E, Stull RB, Eloranta EW (1989) A prognostic relationship for entrainment zone thickness. J Appl Meteorol 28: 885–903
Nicholls S, Turton JD (1986) An observational study of the structure of stratiform cloud sheets: part 2. Entrainment. Q J Roy Meteorol Soc 112: 461–480
Piironen AK, Eloranta EW (1995) Convective boundary layer mean depths and cloud geometrical properties obtained from volume imaging lidar data. J Geophys Res 100(D12): 25569–25576
Russell LM, Lenschow DH, Laursen KK, Krummel PB, Siems ST, Bandy AR, Thompson DC, Yates TS (1998) Bidirectional mixing in an ACE 1 marine boundary layer overlain by a second turbulent layer. J Geophys Res 103: 16411–16432
Sicard M, Perez C, Rocadenbosch F, Baldansano JM, Garcia-Vizcaino D (2006) Mixed-layer depth determination in the Barcelona coastal area from regular lidar measurements: methods, results and limitations. Boundary-Layer Meteorol 119: 135–157
Stevens B (2002) Entrainment in stratocumulus topped mixed layers. Q J Roy Meteorol Soc 128: 2663–2690
Steyn DG, Baldi M, Hoff RM (1999) The detection of mixed layer depth and entrainment zone thickness from lidar backscatter profiles. J Atmos Oceanic Technol 16: 953–959
Sullivan PP, Moeng C-H, Stevens B, Lenschow DH, Mayor SH (1998) Structure of the entrainment zone capping the convective atmospheric boundary layer. J Atmos Sci 55: 3042–3064
Träumner K, Kottmeier Ch, Corsmeier U, Wieser A (2011) Convective boundary-layer entrainment: short review and progress using doppler lidar. Boundary-Layer Meteorol. doi:10.1007/s10546-011-9657-6
Tucker SC, Brewer WA, Banta RM, Senft CJ, Sandberg SP, Law DC, Weickmann A, Hardesty RM (2009) Doppler lidar estimation of mixing height using turbulence, shear, and aerosol profiles. J Atmos Oceanic Technol 26: 673–688
Wiegner M, Emeis S, Freudenthaler V, Heese B, Junkermann W, Munkel C, Schafer K, Seefeldner M, Vogt S (2006) Mixing layer height over Munich, Germany: variability and comparisons of different methodologies. J Geophys Res 111(D13201). doi:10.1029/2005JD006593
Wilde NP, Stull RB, Eloranta EW (1985) The LCL zone and cumulus onset. J Clim Appl Meteorol 24: 640–657
Yi C, Davis KJ, Berger BW, Bakwin PS (2001) Long-term observations of the dynamics of the continental planetary boundary layer. J Atmos Sci 58: 1288–1299
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Brooks, I.M., Fowler, A.M. An Evaluation of Boundary-Layer Depth, Inversion and Entrainment Parameters by Large-Eddy Simulation. Boundary-Layer Meteorol 142, 245–263 (2012). https://doi.org/10.1007/s10546-011-9668-3
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s10546-011-9668-3