Atmospheric icing and meteorological variables: Full scale experiment and testing of models

Icing on structures occurs as rime ice, clear ice or wet snow deposit. Reliable forecasts of duration and intensity of this icing requires prognoses of standard meteorological parameters, in addition to more specific parameters such as the density (ρLWC) of cloud Liquid Water Content (LWC). Icing conditions on the mountain Brosviksåta (723 m a.s.l., 61o 2` N, 5o 9` E), on the western coast of Norway were investigated from March 21-24, 2003. A nonrotating vertical steel rod mounted on a scale was used to measure the accumulated ice load. Air temperature, relative humidity and wind were measured at three levels along the mountain slope. The maximum build-up of ice, in this case study, was measured to 4.5 kg on a 1 m high 0.14 m diameter rod. Comparison of measured ice-growth rate and calculated ρLWC gave a correlation coefficient of 0.85. A mesoscale atmospheric model (MM5) has also been tested at a high horizontal resolution (1km) in order to evaluate its ability to reproduce weather conditions where freezing occurs. Comparison from the direct measurements and calculations, with results from MM5, gave 58% of the measured accumulated ice growth. Further studies of real-time cases on a real-time system at a coarser model resolution will reveal its capability for forcasting freezing events.

[1]  N. D Mulherin,et al.  Atmospheric icing and communication tower failure in the United States , 1998 .

[2]  Weeratunge Malalasekera,et al.  An introduction to computational fluid dynamics - the finite volume method , 2007 .

[3]  P. F. Hearty,et al.  The Icing of an Unheated, Nonrotating Cylinder. Part I: A Simulation Model , 1983 .

[4]  T. Warner,et al.  Separate and Coupled Testing of Meteorological and Hydrological Forecast Models for the Susquehanna River Basin in Pennsylvania , 1991 .

[5]  H. Pan,et al.  Nonlocal Boundary Layer Vertical Diffusion in a Medium-Range Forecast Model , 1996 .

[6]  Lasse Makkonen,et al.  Ice Loads on a Lattice Tower Estimated by Weather Station Data , 1998 .

[7]  Ying-Hwa Kuo,et al.  Regional Real-Time Numerical Weather Prediction: Current Status and Future Potential , 1998 .

[8]  John S. Kain,et al.  Convective parameterization for mesoscale models : The Kain-Fritsch Scheme , 1993 .

[9]  P. McComber,et al.  Validation of ice accretion models for freezing precipitation using field data , 1996 .

[10]  V. R. Noonkester,et al.  Droplet Spectra Observed in Marine Stratus Cloud Layers , 1984 .

[11]  George A. Isaac,et al.  Thermodynamics of Icing Cylinder for Measurements of Liquid Water Content in Supercooled Clouds , 2001 .

[12]  Edward P. Lozowski,et al.  On the median volume diameter approximation for droplet collision efficiency , 1988 .

[13]  Lasse Makkonen,et al.  Modeling of Ice Accretion on Wires , 1984 .

[14]  Lasse Makkonen,et al.  Models for the growth of rime, glaze, icicles and wet snow on structures , 2000, Philosophical Transactions of the Royal Society of London. Series A: Mathematical, Physical and Engineering Sciences.

[15]  L. R. Koenig,et al.  A Short Course in Cloud Physics , 1979 .

[16]  G. Grell,et al.  A description of the fifth-generation Penn State/NCAR Mesoscale Model (MM5) , 1994 .

[17]  R. Treadon,et al.  A Tutorial on Lateral Boundary Conditions as a Basic and Potentially Serious Limitation to Regional Numerical Weather Prediction , 1997 .

[18]  S. Nicholls.  The dynamics of stratocumulus: Aircraft observations and comparisons with a mixed layer model , 1984 .

[19]  F. Ludlam.  The heat economy of a rimed cylinder , 1951 .

[20]  Lasse Makkonen,et al.  Modeling power line icing in freezing precipitation , 1998 .

[21]  G. Poots.  Ice and snow accretion on structures , 1996 .

[22]  I. Langmuir,et al.  mathematical investigation of water droplet trajectories , 1946 .

[23]  Kenneth J. Westrick,et al.  Does Increasing Horizontal Resolution Produce More Skillful Forecasts , 2002 .

[24]  Vickie S. Connors,et al.  The Great African Plume from biomass burning: Generalizations from a three-dimensional study of TRACE A carbon monoxide , 1998 .

[25]  David Bolton.  The Computation of Equivalent Potential Temperature , 1980 .

[26]  S. Islam,et al.  Issues of Soil Moisture Coupling in MM5: Simulation of the Diurnal Cycle over the FIFE Area , 2000 .

[27]  J. Faundeen,et al.  The 1 km AVHRR global land data set: first stages in implementation , 1994 .

[28]  R. Stull.  An Introduction to Boundary Layer Meteorology , 1988 .

[29]  R. Rasmussen,et al.  Explicit forecasting of supercooled liquid water in winter storms using the MM5 mesoscale model , 1998 .

[30]  Lasse Makkonen,et al.  Experiments on the Cloud Droplet Collision Efficiency of Cylinders , 1987 .

[31]  Lasse Makkonen,et al.  Climatic mapping of ice loads based on airport weather observations , 1995 .

[32]  Edward P. Lozowski,et al.  A Computational Investigation of Water Droplet Trajectories , 1988 .

[33]  K. Emanuel,et al.  The Representation of Cumulus Convection in Numerical Models , 1993 .