Boundary-Layer Meteorology

, 134:61

Airborne Lidar Observations of the Transition Zone Between the Convective Boundary Layer and Free Atmosphere During the International H2O Project (IHOP) in 2002

  • Jeffrey S. Grabon
  • Kenneth J. Davis
  • Christoph Kiemle
  • Gerhard Ehret
Article

Abstract

Airborne, light detection and ranging (lidar) backscatter observations of the convective boundary layer from the International H2O Project (IHOP) in 2002 are analysed to study the structure of the transition zone; the backscatter gradient between the convective boundary layer and free atmosphere. A new mathematical algorithm is developed and used to extract high-resolution (15 m) transition-zone boundaries from 6,500 km (flight legs) of airborne observations. The cospectra of transition-zone boundaries and its thickness indicate that thickness changes occur from boundaries moving in opposite directions (vertically) at small wavelengths (<1 km), while at longer wavelengths (>1 km) both boundaries move coherently, with the lower boundary changing altitude more rapidly. Daily probability distributions of the transition-zone thickness are positively skewed with a mode of 60 m. The structure of the transition zone shows no dependence on the “overall” Richardson number, unlike the entrainment zone. This study provides the first quantitative characterization of the structure of the instantaneous transition zone, a contribution towards an improved understanding of convective boundary-layer entrainment.

Keywords

Convective boundary layer Entrainment zone International H2O project Lidar Transition zone 

Supplementary material

10546_2009_9431_MOESM1_ESM.doc (89 kb)
ESM 1 (DOC 89 kb)
10546_2009_9431_MOESM2_ESM.doc (116 kb)
ESM 2 (DOC 116 kb)
10546_2009_9431_MOESM3_ESM.doc (254 kb)
ESM 3 (DOC 254 kb)

References

  1. Ayotte KW et al (1996) An evaluation of neutral and convective planetary boundary layer parameterizations relative to large eddy simulations. Boundary-Layer Meteorol 79: 131–175CrossRefGoogle Scholar
  2. Boers R (1989) A parameterization of the depth of the entrainment-zone. J Appl Meteorol 28: 107–111CrossRefGoogle Scholar
  3. Boers R, Eloranta EW (1986) Lidar measurements of the atmospheric entrainment-zone and the potential temperature jump across the top of the mixed layer. Boundary-Layer Meteorol 34: 357–375CrossRefGoogle Scholar
  4. 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: 247–266CrossRefGoogle Scholar
  5. Brooks IM (2003) Finding boundary layer top: application of a wavelet covariance transform to lidar backscatter profiles. J Atmos Ocean Technol 20: 1095–1105CrossRefGoogle Scholar
  6. Brooks IM, Fowler AM (2007) A new measure of entrainment-zone structure. Geophys Res Lett 34: L16808CrossRefGoogle Scholar
  7. Chen F, Manning KW, LeMone MA, Trier SB, Alfieri JG, Roberts R, Tewari M, Niyogi D, Horst TW, Oncley SP, Basara JB, Blanken PD (2007) Description and evaluation of the characteristics of the NCAR high-resolution land data assimilation system. J Clim Appl Meteorol 46: 694–713CrossRefGoogle Scholar
  8. Conzemius RJ, Fedorovich E (2006) Dynamics of sheared convective boundary layer entrainment. Part 1: methodological background and large-eddy simulations. J Atmos Sci 63: 1151–1178CrossRefGoogle Scholar
  9. 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 102: 29219–29230CrossRefGoogle Scholar
  10. 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 Ocean Technol 17: 1455–1467CrossRefGoogle Scholar
  11. Deardorff JW, Willis GE, Stockton BH (1980) Laboratory studies of the entrainment-zone of a convectively mixed layer. J Fluid Mech 100: 41–64CrossRefGoogle Scholar
  12. Ellison TH, Turner JS (1959) Turbulent entrainment in stratified flows. J Fluid Mech 6: 423–448CrossRefGoogle Scholar
  13. Flamant C, Pelon J, Flamant P, Durand P (1997) Lidar determination of the entrainment-zone thickness at the top of the unstable marine atmospheric boundary layer. Boundary-Layer Meteorol 83: 247–284CrossRefGoogle Scholar
  14. 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: 281–295CrossRefGoogle Scholar
  15. Hageli P, Steyn DB, Strawbridge KB (2000) Spatial and temporal variability of mixed-layer depth and entrainment-zone thickness. Boundary-Layer Meteorol 97: 47–71CrossRefGoogle Scholar
  16. Kaimal JC, Wyngaard JC, Izumi Y, Cote OR (1972) Spectral characteristics of surface-layer turbulence. Q J Roy Meteorol Soc 98: 563–589CrossRefGoogle Scholar
  17. Kang SL, Davis KJ, LeMone M (2007) Observations of the ABL Structures over a Heterogeneous Land Surface during IHOP_2002. J Hydrometeorol 8: 221–244CrossRefGoogle Scholar
  18. Kato H, Phillips OM (1969) On the penetration of a turbulent layer into stratified fluid. J Fluid Mech 37: 643–655CrossRefGoogle Scholar
  19. Kiemle C, Ehret G, Giez A, Davis KJ, Lenschow DH, Oncley SP (1997) Estimation of boundary layer humidity fluxes and statistics from airborne differential absorption lidar (DIAL). J Geophys Res 102: 29189–29203CrossRefGoogle Scholar
  20. Kiemle C, Brewer WA, Ehret G, Hardesty RM, Fix A, Senff C, Wirth M, Poberaj G, LeMone M (2007) Latent heat flux profiles from collocated airborne water vapour and wind lidars during IHOP_2002. J Atmos Ocean Technol 24: 627–639CrossRefGoogle Scholar
  21. Kunkel KE, Eloranta EW, Shipley ST (1977) Lidar observations of the convective boundary layer. J Appl Meteorol 16: 1306–1311CrossRefGoogle Scholar
  22. LeMone MA, Chen F, Alfieri JG, Cuenca RH, Hagimoto Y, Blanken P, Niyogi D, Kang S, Davis K, Grossman RL (2007) NCAR/CU surface, soil, and vegetation observations during the International H2O Project 2002 field campaign. Bull Am Meteorol Soc 88: 65–81CrossRefGoogle Scholar
  23. 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: 806–821CrossRefGoogle Scholar
  24. Moeng CH, Sullivan PP, Stevens B (1999) Including radiative effects in an entrainment rate formula for buoyancy-driven PBLs. J Atmos Sci 56: 1031–1049CrossRefGoogle Scholar
  25. Otte MJ, Wyngaard JW (2001) Stably stratified interfacial-layer turbulence from large-eddy simulation. J Atmos Sci 58: 3424–3442CrossRefGoogle Scholar
  26. Pino D, Arellano J, Duynkerke PG (2003) The contribution of shear to the evolution of a convective boundary layer. J Atmos Sci 60: 1913–1925CrossRefGoogle Scholar
  27. Poberaj G, Fix A, Assion A, Wirth M, Kiemle C, Ehret G (2002) Airborne all-solid-state DIAL for water vapour measurements in the tropopause region: system description and assessment of accuracy. Appl Phys B 75: 165–172CrossRefGoogle Scholar
  28. Reen BP (2007) Data assimilation strategies and land-surface heterogeneity effects in the planetary boundary layer. Doctoral Dissertation, Penn State University, 246 ppGoogle Scholar
  29. Stevens B, Moeng CH, Sullivan PP (1999) Large-eddy simulations of radiatively driven convection: sensitivities to the representation of small scales. J Atmos Sci 56: 3963–3984CrossRefGoogle Scholar
  30. Steyn DG, Baldi M, Hoff R (1999) The detection of mixed layer depth from lidar backscatter profiles. J Atmos Ocean Technol 16: 953–959CrossRefGoogle Scholar
  31. Stull RB (1988) An introduction to boundary-layer meteorology. Kluwer Academic, Norwell, MA, pp 666Google Scholar
  32. Sullivan PP, Moeng CH, Stevens B, Lenschow DH, Mayor SD (1998) Structure of the entrainment-zone capping the convective atmospheric boundary layer. J Atmos Sci 55: 3042–3064CrossRefGoogle Scholar
  33. Turner JS (1968) The influence of molecular diffusivity across a density interface. J Fluid Mech 33: 639–656CrossRefGoogle Scholar
  34. Weckwerth TM, Parsons DB, Koch SE, Moore JA, LeMone MA, Demoz BB, Flamant C, Geerts B, Wang J, Feltz WF (2004) An overview of the international H2O project (IHOP_2002) and some preliminary highlights. Bull Am Meteorol Soc 85: 253–277CrossRefGoogle Scholar
  35. Wyngaard JC (2009) Turbulence in the atmosphere, Vol. 1. Cambridge University Press, 408 ppGoogle Scholar

Copyright information

© Springer Science+Business Media B.V. 2009

Authors and Affiliations

  • Jeffrey S. Grabon
    • 1
  • Kenneth J. Davis
    • 1
  • Christoph Kiemle
    • 2
  • Gerhard Ehret
    • 2
  1. 1.The Pennsylvania State UniversityUniversity ParkUSA
  2. 2.Institut für Physik der Atmosphäre, Deutsches Zentrum für Luft- und RaumfahrtCopenhagenDenmark

Personalised recommendations