scholarly journals Surface deposition of marine fog and its treatment in the WRF model

2021 ◽  
Author(s):  
Peter Allan Taylor ◽  
Zheqi Chen ◽  
Li Cheng ◽  
Soudeh Afsharian ◽  
Wensong Weng ◽  
...  
Keyword(s):  
Water Surface ◽  
Roughness Length ◽  
Deposition Velocity ◽  
Wrf Model ◽  
Liquid Water Content ◽  
Water Droplets ◽  
Surface Deposition ◽  
Near Surface ◽  
Fog Water ◽  
Model Studies

Abstract. There have been many studies of marine fog, some using WRF and other models. Several model studies report over-predictions of near surface liquid water content (Qc) leading to visibility estimates that are too low. This study has found the same. One possible cause of this overestimation could be the treatment of a surface deposition rate of fog droplets at the underlying water surface. Most models, including the Advanced Research Weather Research and Forecasting (WRF-ARW) Model, available from the National Center for Atmospheric Research (NCAR), take account of gravitational settling of cloud droplets throughout the domain and at the surface. However, there should be an additional deposition as turbulence causes fog droplets to collide and coalesce with the water surface. A water surface, or any wet surface, can then be an effective sink for fog water droplets. This process can be parameterized as an additional deposition velocity with a model that could be based on a roughness length for water droplets, z0c, that may be significantly larger than the roughness length for water vapour, z0q. This can be implemented in WRF either as a variant of the Katata scheme for deposition to vegetation, or via direct modifications in boundary-layer modules.

scholarly journals Surface deposition of marine fog and its treatment in the Weather Research and Forecasting (WRF) model

2021 ◽  
Vol 21 (19) ◽  
pp. 14687-14702
Author(s):  
Peter A. Taylor ◽  
Zheqi Chen ◽  
Li Cheng ◽  
Soudeh Afsharian ◽  
Wensong Weng ◽  
...  
Keyword(s):  
Water Surface ◽  
Roughness Length ◽  
Deposition Velocity ◽  
Wrf Model ◽  
Weather Research And Forecasting ◽  
Water Droplets ◽  
Surface Deposition ◽  
Near Surface ◽  
Fog Water ◽  
Weather Research

Abstract. There have been many studies of marine fog, some using Weather Research and Forecasting (WRF) and other models. Several model studies report overpredictions of near-surface liquid water content (Qc), leading to visibility estimates that are too low. This study has found the same. One possible cause of this overestimation could be the treatment of a surface deposition rate of fog droplets at the underlying water surface. Most models, including the Advanced Research Weather Research and Forecasting (WRF-ARW) Model, available from the National Center for Atmospheric Research (NCAR), take account of gravitational settling of cloud droplets throughout the domain and at the surface. However, there should be an additional deposition as turbulence causes fog droplets to collide and coalesce with the water surface. A water surface, or any wet surface, can then be an effective sink for fog water droplets. This process can be parameterized as an additional deposition velocity with a model that could be based on a roughness length for water droplets, z0c, that may be significantly larger than the roughness length for water vapour, z0q. This can be implemented in WRF either as a variant of the Katata scheme for deposition to vegetation or via direct modifications in boundary-layer modules.

scholarly journals Constant flux layers with gravitational settling: links to aerosols, fog and deposition velocities

2021 ◽  
Vol 21 (24) ◽  
pp. 18263-18269
Author(s):  
Peter A. Taylor
Keyword(s):  
Friction Velocity ◽  
Roughness Length ◽  
Settling Velocity ◽  
Deposition Velocity ◽  
Surface Boundary ◽  
Surface Deposition ◽  
Gravitational Settling ◽  
Constant Flux ◽  
Deposition Velocities ◽  
Roughness Lengths

Abstract. Turbulent boundary layer concepts of constant flux layers and surface roughness lengths are extended to include aerosols and the effects of gravitational settling. Interactions between aerosols and the Earth's surface are represented via a roughness length for aerosol which will generally be different from the roughness lengths for momentum, heat or water vapour. Gravitational settling will impact vertical profiles and the surface deposition of aerosols, including fog droplets. Simple profile solutions are possible in neutral and stably stratified atmospheric surface boundary layers. These profiles can be used to predict deposition velocities and to illustrate the dependence of deposition velocity on reference height, friction velocity and gravitational settling velocity.

Near Surface Research and Excitation Horizon Prediction Based on Old River Course of Xiaoqing River in Shan Dong

2013 ◽  
Vol 664 ◽  
pp. 94-98
Author(s):  
Guang De Zhang
Keyword(s):  
Seismic Data ◽  
Practical Significance ◽  
Cone Penetration ◽  
Surface Deposition ◽  
Near Surface ◽  
Sedimentary Characteristics ◽  
The Difference ◽  
Exploration Area ◽  
Data Requirements ◽  
Static Cone Penetration Test

Following deepened exploration and development in Shengli exploration area, seismic data requirements are also getting higher and higher. However, in recent years the difference of Xiaoqing river on both sides have made us know that the importance of this problem. In view of the above, this task is aimed at quaternary shallow of old river course within Xiaoqing River. Our analysis of lithology and sedimentary characteristics are using static cone penetration test and rock core exploration method, and we want to reappear near surface deposition of old river course within Xiaoqing River. The research is close combined with the exploration demand and theoretical study, so it has important theoretical and practical significance.

scholarly journals Biogenic isoprene emissions driven by regional weather predictions using different initialization methods: case studies during the SEAC<sup>4</sup>RS and DISCOVER-AQ airborne campaigns

2017 ◽  
Vol 10 (8) ◽  
pp. 3085-3104 ◽  
Author(s):  
Min Huang ◽  
Gregory R. Carmichael ◽  
James H. Crawford ◽  
Armin Wisthaler ◽  
Xiwu Zhan ◽  
...  
Keyword(s):  
Case Studies ◽  
Air Temperature ◽  
Initial Conditions ◽  
Wrf Model ◽  
Surface Air Temperature ◽  
Heat Fluxes ◽  
Aircraft Observation ◽  
Near Surface ◽  
Boundary Layer Height ◽  
Small Scales

Abstract. Land and atmospheric initial conditions of the Weather Research and Forecasting (WRF) model are often interpolated from a different model output. We perform case studies during NASA's SEAC4RS and DISCOVER-AQ Houston airborne campaigns, demonstrating that using land initial conditions directly downscaled from a coarser resolution dataset led to significant positive biases in the coupled NASA-Unified WRF (NUWRF, version 7) surface and near-surface air temperature and planetary boundary layer height (PBLH) around the Missouri Ozarks and Houston, Texas, as well as poorly partitioned latent and sensible heat fluxes. Replacing land initial conditions with the output from a long-term offline Land Information System (LIS) simulation can effectively reduce the positive biases in NUWRF surface air temperature by ∼ 2 °C. We also show that the LIS land initialization can modify surface air temperature errors almost 10 times as effectively as applying a different atmospheric initialization method. The LIS-NUWRF-based isoprene emission calculations by the Model of Emissions of Gases and Aerosols from Nature (MEGAN, version 2.1) are at least 20 % lower than those computed using the coarser resolution data-initialized NUWRF run, and are closer to aircraft-observation-derived emissions. Higher resolution MEGAN calculations are prone to amplified discrepancies with aircraft-observation-derived emissions on small scales. This is possibly a result of some limitations of MEGAN's parameterization and uncertainty in its inputs on small scales, as well as the representation error and the neglect of horizontal transport in deriving emissions from aircraft data. This study emphasizes the importance of proper land initialization to the coupled atmospheric weather modeling and the follow-on emission modeling. We anticipate it to also be critical to accurately representing other processes included in air quality modeling and chemical data assimilation. Having more confidence in the weather inputs is also beneficial for determining and quantifying the other sources of uncertainties (e.g., parameterization, other input data) of the models that they drive.

scholarly journals The composition of Europa's near-surface atmosphere

2008 ◽  
Vol 4 (S251) ◽  
pp. 327-328
Author(s):  
Mau C. Wong ◽  
Tim Cassidy ◽  
Robert E. Johnson
Keyword(s):  
Solar System ◽  
Surface Composition ◽  
Near Surface ◽  
Water Ice ◽  
Model Studies ◽  
Surface Atmosphere ◽  
Jovian Magnetosphere ◽  
Ice Surface ◽  
Geophysical Phenomenon ◽  
Inorganic Species

AbstractThe presence of an undersurface ocean renders Europa as one of the few planetary bodies in our Solar System that has been conjectured to have possibly harbored life. Some of the organic and inorganic species present in the ocean underneath are expected to transport upwards through the relatively thin ice crust and manifest themselves as impurities of the water ice surface. For this reason, together with its unique dynamic atmosphere and geological features, Europa has attracted strong scientific interests in past decades.Europa is imbedded inside the Jovian magnetosphere, and, therefore, is constantly subjected to the immerse surrounding radiations, similar to the other three Galilean satellites. The magnetosphere-atmosphere-surface interactions form a complex system that provides a multitude of interesting geophysical phenomenon that is unique in the Solar System. The atmosphere of Europa is thought to have created by, mostly, charged particles sputtering of surface materials. Consequently, the study of Europa's atmosphere can be used as a tool to infer the surface composition. In this paper, we will discuss our recent model studies of Europa's near-surface atmosphere. In particular, the abundances and distributions of the dominant O2 and H2O species, and of other organic and inorganic minor species will be addressed.

scholarly journals Result of modeling temperature anomalies on the water surface of the research basin of the institute of hydromechanics NAS of Ukraine

2018 ◽  
pp. 40-45
Author(s):  
Oleksandr Fedorovsky ◽  
Vitalii Filimonov ◽  
Iryna Piestova ◽  
Stanislav Dugin ◽  
Vladyslav Yakymchuk ◽  
...  
Keyword(s):  
Water Surface ◽  
Water Layer ◽  
Sea Surface ◽  
National Academy Of Sciences ◽  
Near Surface ◽  
Aerial Photos ◽  
Temperature Anomalies ◽  
Structural And Textural Parameters ◽  
The Difference ◽  
Hydrocarbon Deposits

The results of the research and physical modeling of temperature anomalies of natural or man-made origin on the water surface are presented.  The information for the research was obtained from the experimental basin of the Institute of Hydromechanics of the National Academy of Sciences of Ukraine from the self-propelled model as the generator of hydrodynamic processes. The information obtained after image processing allowed to significantly expand the existing ideas about the mechanism of formation of anomalies on the open surface with the hydrodynamic disturbances from hydrocarbon deposits and moving submerged object. The interaction of the emerging hydrodynamic disturbances with the near-surface water layer and the occurrence of unmasking temperature anomalies on the open sea surface have a lot in common between the hydrocarbon deposits and the moving submerged object. The application of the difference of the above structural and textural parameters by calculating the value of "entropy" has been proposed as the informative feature for decoding the images of the water surface with the presence of hydrocarbon deposits or moving immersed objects. The decoding of temperature anomalies consists of two stages: learning and proper decoding. The first stage is the supervised learning, during which the system is being researched using the existing set of images, in which only the background and no hydrocarbon deposits or moving submerged object. Training is carried out in order to determine the signs of belonging to the background or hydrocarbon deposits, moving submerged object. It was determined that the background has minimal entropy values, and with the appearance of an anomaly, the entropy grows to the maximum value, after which, as the temperature trace dissipates, it begins to fall to background values. This confirms the informativity of the entropy feature for decoding the optical anomalies of man-made and natural origin on the sea surface from aerial photos.

scholarly journals Numerical Evidence of Turbulence Generated by Nonbreaking Surface Waves

2015 ◽  
Vol 45 (1) ◽  
pp. 174-180 ◽  
Author(s):  
Wu-ting Tsai ◽  
Shi-ming Chen ◽  
Guan-hung Lu
Keyword(s):  
Surface Waves ◽  
Water Surface ◽  
Nonlinear Boundary Conditions ◽  
Turbulent Shear ◽  
Turbulent Shear Flow ◽  
Langmuir Turbulence ◽  
Near Surface ◽  
Order Of Magnitude ◽  
Turbulence Production ◽  
Wave Induced

AbstractNumerical simulation of monochromatic surface waves propagating over a turbulent field is conducted to reveal the mechanism of turbulence production by nonbreaking waves. The numerical model solves the primitive equations subject to the fully nonlinear boundary conditions on the exact water surface. The result predicts growth rates of turbulent kinetic energy consistent with previous measurements and modeling. It also validates the observed horizontal anisotropy of the near-surface turbulence that the spanwise turbulent intensity exceeds the streamwise component. Such a flow structure is found to be attributed to the formation of streamwise vortices near the water surface, which also induces elongated surface streaks. The averaged spacing between the streaks and the depth of the vortical cells approximates that of Langmuir turbulence. The strength of the vortices arising from the wave–turbulence interaction, however, is one order of magnitude less than that of Langmuir cells, which arises from the interaction between the surface waves and the turbulent shear flow. In contrast to Langmuir turbulence, production from the Stokes shear does not dominate the energetics budget in wave-induced turbulence. The dominant production is the advection of turbulence by the velocity straining of waves.

Forecast of low clouds over a snow surface in the Arctic using WRF model

2021 ◽  
Author(s):  
M. Hagman ◽  
G. Svensson ◽  
W.M. Angevine
Keyword(s):  
Forecast Error ◽  
Wrf Model ◽  
Armed Forces ◽  
The Arctic ◽  
Bulk Liquid ◽  
Wave Radiation ◽  
Initial Profile ◽  
Near Surface ◽  
Low Clouds ◽  
Ice Water

AbstractThe Swedish Armed Forces configuration of the Weather Research and Forecasting Model (WRF) has problems in forecasting low clouds in stably stratified conditions when the ground is covered by snow. Reforecasts for January and February 2018, together with observations from Sodankylä in northern Finland, are analyzed to find the cause. The investigation is done iteratively between the Single Column Model (SCM), applied at Sodankylä, and the full 3D version. Our experiments show that the forecast error arises due to inadequate initialization of Stratocumulus (Sc) clouds in WRF using the ECMWF global model, Integrated Forecast System (IFS). By including bulk liquid water and bulk ice water content, from IFS in the initial profile, the downwelling long wave radiation increases and prevents the near surface temperature from dropping abnormally. This, in turn, prevents artificial clouds from forming at the first model level. When no clouds are present in the IFS initial profile, the Sc clouds can be initialized using information from the observed vertical profiles. Generally, initialization of Sc clouds in WRF improves the forecast substantially.

scholarly journals Fine particle pH and sensitivity to NH<sub>3</sub> and HNO<sub>3</sub> over summertime South Korea during KORUS-AQ

2020 ◽  
Author(s):  
Ifayoyinsola Ibikunle ◽  
Andreas Beyersdorf ◽  
Pedro Campuzano-Jost ◽  
Chelsea Corr ◽  
John D. Crounse ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Deposition Velocity ◽  
Liquid Water Content ◽  
Aerosol Formation ◽  
Aerosol Composition ◽  
New Approach ◽  
South Korean ◽  
Inorganic Nitrate ◽  
Nitrate Availability ◽  
Trace Species

Abstract. Using a new approach that constrains thermodynamic modeling of aerosol composition with measured gas-to-particle partitioning of inorganic nitrate, we estimate the acidity levels for aerosol sampled in the South Korean planetary boundary layer during the NASA/NIER KORUS-AQ field campaign. The pH (mean ± 1σ = 2.43 ± 0.68) and aerosol liquid water content determined were then used to determine the chemical regime of the inorganic fraction of particulate matter (PM) sensitivity to ammonia and nitrate availability. We found that the aerosol formation is always sensitive to HNO3 levels, especially in highly polluted regions, while it is only exclusively sensitive to NH3 in some rural/remote regions. Nitrate levels are further promoted because dry deposition velocity is low and allows its accumulation in the boundary layer. Because of this, HNO3 reductions achieved by NOx controls prove to be the most effective approach for all conditions examined, and that NH3 emissions can only partially affect PM reduction for the specific season and region. Despite the benefits of controlling PM formation to reduce ammonium-nitrate aerosol and PM mass, changes in the acidity domain can significantly affect other processes and sources of aerosol toxicity (such as e.g., solubilization of Fe, Cu and other metals) as well as the deposition patterns of these trace species and reactive nitrate.

Examination of Errors in Near-Surface Temperature and Wind from WRF Numerical Simulations in Regions of Complex Terrain

2013 ◽  
Vol 28 (3) ◽  
pp. 893-914 ◽  
Author(s):  
Hailing Zhang ◽  
Zhaoxia Pu ◽  
Xuebo Zhang
Keyword(s):  
Complex Terrain ◽  
Forecast Error ◽  
Wrf Model ◽  
Atmospheric Temperature ◽  
Lower Atmosphere ◽  
Forecast Errors ◽  
Atmospheric Conditions ◽  
Near Surface ◽  
System A ◽  
Synoptic Forcing

Abstract The performance of an advanced research version of the Weather Research and Forecasting Model (WRF) in predicting near-surface atmospheric temperature and wind conditions under various terrain and weather regimes is examined. Verification of 2-m temperature and 10-m wind speed and direction against surface Mesonet observations is conducted. Three individual events under strong synoptic forcings (i.e., a frontal system, a low-level jet, and a persistent inversion) are first evaluated. It is found that the WRF model is able to reproduce these weather phenomena reasonably well. Forecasts of near-surface variables in flat terrain generally agree well with observations, but errors also occur, depending on the predictability of the lower-atmospheric boundary layer. In complex terrain, forecasts not only suffer from the model's inability to reproduce accurate atmospheric conditions in the lower atmosphere but also struggle with representative issues due to mismatches between the model and the actual terrain. In addition, surface forecasts at finer resolutions do not always outperform those at coarser resolutions. Increasing the vertical resolution may not help predict the near-surface variables, although it does improve the forecasts of the structure of mesoscale weather phenomena. A statistical analysis is also performed for 120 forecasts during a 1-month period to further investigate forecast error characteristics in complex terrain. Results illustrate that forecast errors in near-surface variables depend strongly on the diurnal variation in surface conditions, especially when synoptic forcing is weak. Under strong synoptic forcing, the diurnal patterns in the errors break down, while the flow-dependent errors are clearly shown.

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