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and Clark 1999 ; Knupp 2006 ). Density currents are primarily horizontal mass flows driven by their greater density relative to their environments. Thunderstorm outflow boundaries, cold fronts, and sea breezes may all act at times as density currents. An atmospheric internal bore is a gravity-wave phenomenon that propagates on a low-level inversion surface and is typically generated when a density current (such as cold air from a thunderstorm) intrudes into a statically stable layer ( Maxworthy
and Clark 1999 ; Knupp 2006 ). Density currents are primarily horizontal mass flows driven by their greater density relative to their environments. Thunderstorm outflow boundaries, cold fronts, and sea breezes may all act at times as density currents. An atmospheric internal bore is a gravity-wave phenomenon that propagates on a low-level inversion surface and is typically generated when a density current (such as cold air from a thunderstorm) intrudes into a statically stable layer ( Maxworthy
, let k D in and ω D in be the wave vector and frequency of light returning from atmospheric scattering which is incident on the elevation mirror. Let ω D dete denote the frequency of the returned light at the detector in the detector’s reference frame. Similar to (7) – (8) we have where u D elev is the velocity of the elevation mirror relative to the detector. 6. The LO frequency at the detector equals the source’s frequency A light path on the lidar’s optical table from
, let k D in and ω D in be the wave vector and frequency of light returning from atmospheric scattering which is incident on the elevation mirror. Let ω D dete denote the frequency of the returned light at the detector in the detector’s reference frame. Similar to (7) – (8) we have where u D elev is the velocity of the elevation mirror relative to the detector. 6. The LO frequency at the detector equals the source’s frequency A light path on the lidar’s optical table from
. P. , Tsuda T. , and Furumoto J. , 2007 : Effects of atmospheric stability on wave and energy propagation in the troposphere. J. Atmos. Oceanic Technol. , 24 , 602 – 615 . 10.1175/JTECH2046.1 Angevine, W. M. , and Ecklund W. L. , 1994 : Errors in radio acoustic sounding of temperature. J. Atmos. Oceanic Technol. , 11 , 837 – 842 . 10.1175/1520-0426(1994)011<0837:EIRASO>2.0.CO;2 Angevine, W. M. , Avery S. K. , Ecklund W. L. , and Carter D. A. , 1993 : Fluxes of heat and
. P. , Tsuda T. , and Furumoto J. , 2007 : Effects of atmospheric stability on wave and energy propagation in the troposphere. J. Atmos. Oceanic Technol. , 24 , 602 – 615 . 10.1175/JTECH2046.1 Angevine, W. M. , and Ecklund W. L. , 1994 : Errors in radio acoustic sounding of temperature. J. Atmos. Oceanic Technol. , 11 , 837 – 842 . 10.1175/1520-0426(1994)011<0837:EIRASO>2.0.CO;2 Angevine, W. M. , Avery S. K. , Ecklund W. L. , and Carter D. A. , 1993 : Fluxes of heat and
1. Introduction Aerosols of both natural and anthropogenic origin perturb the atmospheric radiation field through direct and indirect interactions with solar radiation ( Charlson and Heintzenberg 1995 ; Ramanathan et al. 1989 ). Monitoring of the impacts of natural aerosols can also help in understanding the evolution of past environments and predicting future climate. Moreover, atmospheric aerosol characteristics vary significantly in space and time over different environments. Thus
1. Introduction Aerosols of both natural and anthropogenic origin perturb the atmospheric radiation field through direct and indirect interactions with solar radiation ( Charlson and Heintzenberg 1995 ; Ramanathan et al. 1989 ). Monitoring of the impacts of natural aerosols can also help in understanding the evolution of past environments and predicting future climate. Moreover, atmospheric aerosol characteristics vary significantly in space and time over different environments. Thus
the high-resolution TLS estimates of ε and C 2 T , which is typical of fully developed turbulence and is dominated by the intrinsic atmospheric processes and not the estimation error of approximately 10%–15% ( Frehlich et al. 2004 ). There are also large difference between the TLS and lidar-derived ε profiles, which reflects the large variability of the small-scale turbulence in the stable boundary layer, which has been observed previously with sodar and frequency-modulated continuous-wave
the high-resolution TLS estimates of ε and C 2 T , which is typical of fully developed turbulence and is dominated by the intrinsic atmospheric processes and not the estimation error of approximately 10%–15% ( Frehlich et al. 2004 ). There are also large difference between the TLS and lidar-derived ε profiles, which reflects the large variability of the small-scale turbulence in the stable boundary layer, which has been observed previously with sodar and frequency-modulated continuous-wave
: Structure of the entrainment zone capping the convective atmospheric boundary layer. J. Atmos. Sci. , 55 , 3042 – 3064 . 10.1175/1520-0469(1998)055<3042:SOTEZC>2.0.CO;2 Tatarskii, V. I. , 1961 : Wave Propagation in a Turbulent Medium . McGraw-Hill, 285 pp . Taylor, G. I. , 1938 : The spectrum turbulence. Proc. Roy. Soc. London , 164A , 476 – 490 . VanZanten, M. C. , Duynkerke P. G. , and Cuijpers J. W. M. , 1999 : Entrainment parameterization in convective boundary layers. J
: Structure of the entrainment zone capping the convective atmospheric boundary layer. J. Atmos. Sci. , 55 , 3042 – 3064 . 10.1175/1520-0469(1998)055<3042:SOTEZC>2.0.CO;2 Tatarskii, V. I. , 1961 : Wave Propagation in a Turbulent Medium . McGraw-Hill, 285 pp . Taylor, G. I. , 1938 : The spectrum turbulence. Proc. Roy. Soc. London , 164A , 476 – 490 . VanZanten, M. C. , Duynkerke P. G. , and Cuijpers J. W. M. , 1999 : Entrainment parameterization in convective boundary layers. J
1. Introduction The vertical exchange of sensible heat (temperature), latent heat (moisture), particles, and trace gases between the surface and the lower troposphere has a strong influence on weather and climate and atmospheric composition, as well as on smog and haze conditions at the ground. Vertical exchange depends in a complicated way on surface characteristics and meteorological conditions in the planetary boundary layer (PBL). The mechanisms within the PBL and in the entrainment zone
1. Introduction The vertical exchange of sensible heat (temperature), latent heat (moisture), particles, and trace gases between the surface and the lower troposphere has a strong influence on weather and climate and atmospheric composition, as well as on smog and haze conditions at the ground. Vertical exchange depends in a complicated way on surface characteristics and meteorological conditions in the planetary boundary layer (PBL). The mechanisms within the PBL and in the entrainment zone
large concern in this respect is that many instruments currently cannot achieve such measurement accuracy without thorough calibration and validation. The Stratospheric Processes and Their Role in Climate (SPARC) Assessment of Upper Tropospheric and Stratospheric Water Vapor ( Kley et al. 2000 ) pointed out many discrepancies in the water vapor profiles measured by different techniques. To contribute to the understanding of the processes involving atmospheric water vapor as well as to support the
large concern in this respect is that many instruments currently cannot achieve such measurement accuracy without thorough calibration and validation. The Stratospheric Processes and Their Role in Climate (SPARC) Assessment of Upper Tropospheric and Stratospheric Water Vapor ( Kley et al. 2000 ) pointed out many discrepancies in the water vapor profiles measured by different techniques. To contribute to the understanding of the processes involving atmospheric water vapor as well as to support the
operational radiosonde network with its typically 12-hourly observations is by far not sufficient for evaluating model performance on small time (short term 0 ± 18 h) and spatial (model resolution <3 km) scale. Because satellite instruments are also not able to resolve BL variables well, strong efforts have been undertaken within the last decade to enhance the development of ground-based remote sensing instrumentation. However, no single instrument is capable to observe all relevant atmospheric variables
operational radiosonde network with its typically 12-hourly observations is by far not sufficient for evaluating model performance on small time (short term 0 ± 18 h) and spatial (model resolution <3 km) scale. Because satellite instruments are also not able to resolve BL variables well, strong efforts have been undertaken within the last decade to enhance the development of ground-based remote sensing instrumentation. However, no single instrument is capable to observe all relevant atmospheric variables
instruments, a Vaisala CT25K ceilometer and a 78-GHz frequency-modulated continuous-wave (FMCW) cloud radar were installed and operated at the measurement site from mid-November 2003 to mid-February 2004. In this paper a method to determine fog and low stratiform cloud layers from cloud radar and ceilometer data is described. The efficacy of the combination of the two systems during the winter 3-month period is assessed. In section 2 , the instruments and the method of the determination of cloud or fog
instruments, a Vaisala CT25K ceilometer and a 78-GHz frequency-modulated continuous-wave (FMCW) cloud radar were installed and operated at the measurement site from mid-November 2003 to mid-February 2004. In this paper a method to determine fog and low stratiform cloud layers from cloud radar and ceilometer data is described. The efficacy of the combination of the two systems during the winter 3-month period is assessed. In section 2 , the instruments and the method of the determination of cloud or fog
