Fog forecasting for Schiphol airport at sub-kilometre scale.  

2021 ◽  
Author(s):  
Gert-Jan Steeneveld ◽  
Roosmarijn Knol
Keyword(s):  
Spatial Resolution ◽  
Numerical Models ◽  
Wrf Model ◽  
Horizontal Resolution ◽  
Physical Processes ◽  
Radiation Fog ◽  
Fog Forecasting ◽  
Elevation Data ◽  
The Individual ◽  
The Impact

<p>Fog is a critical weather phenomenon for safety and operations in aviation. Unfortunately, the forecasting of radiation fog remains challenging due to the numerous physical processes that play a role and their complex interactions, in addition to the vertical and horizontal resolution of the numerical models. In this study we evaluate the performance of the Weather Research and Forecasting (WRF) model for a radiation fog event at Schiphol Amsterdam Airport (The Netherlands) and further develop the model towards a 100 m grid spacing. Hence we introduce high resolution land use and land elevation data. In addition we study the role of gravitational droplet settling, advection of TKE, top-down diffusion caused by strong radiative cooling at the fog top. Finally the impact of heat released by the terminal areas on the fog formation is studied. The model outcomes are evaluated against 1-min weather observations near multiple runways at the airport.</p><p>Overall we find the WRF model shows an reasonable timing of the fog onset and is well able to reproduce the visibility and meteorological conditions as observed during the case study. The model appears to be relatively insensitive to the activation of the individual physical processes. An increased spatial resolution to 100 m generally results in a better timing of the fog onset differences up to three hours, though not for all runways. The effect of the refined landuse dominates over the effect of refined elevation data. The modelled fog dissipation systematically occurs 3-4 h hours too early, regardless of physical processes or spatial resolution. Finally, the introduction of heat from terminal buildings delays the fog onset with a maximum of two hours, an overestimated visibility of 100-200 m and a decrease of the LWC with 0.10-0.15 g/kg compared to the reference.</p>

scholarly journals A Case Study of Observed and Modeled Barrier Flow in the Denmark Strait in May 2015

2017 ◽  
Vol 145 (6) ◽  
pp. 2385-2404 ◽  
Author(s):  
Alice K. DuVivier ◽  
John J. Cassano ◽  
Steven Greco ◽  
G. David Emmitt
Keyword(s):  
Wrf Model ◽  
Horizontal Resolution ◽  
Surface Energy Budget ◽  
Vertical Resolution ◽  
Structure Comparison ◽  
Denmark Strait ◽  
Pbl Scheme ◽  
Barrier Jets ◽  
The Impact ◽  
Jet Structure

Abstract Mesoscale barrier jets in the Denmark Strait are common in winter months and have the capability to influence open ocean convection. This paper presents the first detailed observational study of a summertime (21 May 2015) barrier wind event in the Denmark Strait using dropsondes and observations from an airborne Doppler wind lidar (DWL). The DWL profiles agree well with dropsonde observations and show a vertically narrow (~250–400 m) barrier jet of 23–28 m s−1 near the Greenland coast that broadens (~300–1000 m) and strengthens farther off coast. In addition, otherwise identical regional high-resolution Weather Research and Forecasting (WRF) Model simulations of the event are analyzed at four horizontal grid spacings (5, 10, 25, and 50 km), two vertical resolutions (40 and 60 levels), and two planetary boundary layer (PBL) parameterizations [Mellor–Yamada–Nakanishi–Niino, version 2.5 (MYNN2.5) and University of Washington (UW)] to determine what model configurations best simulate the observed jet structure. Comparison of the WRF simulations with wind observations from satellites, dropsondes, and the airborne DWL scans indicate that the combination of both high horizontal resolution (5 km) and vertical resolution (60 levels) best captures observed barrier jet structure and speeds as well as the observed cloud field, including some convective clouds. Both WRF PBL schemes produced reasonable barrier jets with the UW scheme slightly outperforming the MYNN2.5 scheme. However, further investigation at high horizontal and vertical resolution is needed to determine the impact of the WRF PBL scheme on surface energy budget terms, particularly in the high-latitude maritime environment around Greenland.

scholarly journals Impact of optimized mixing heights on simulated regional atmospheric transport of CO<sub>2</sub>

2014 ◽  
Vol 14 (14) ◽  
pp. 7149-7172 ◽  
Author(s):  
R. Kretschmer ◽  
C. Gerbig ◽  
U. Karstens ◽  
G. Biavati ◽  
A. Vermeulen ◽  
...  
Keyword(s):  
Dispersion Model ◽  
Synthetic Data ◽  
Wrf Model ◽  
Horizontal Resolution ◽  
Particle Dispersion ◽  
Random Errors ◽  
Tracer Transport ◽  
European Continent ◽  
Co2 Transport ◽  
The Impact

Abstract. The mixing height (MH) is a crucial parameter in commonly used transport models that proportionally affects air concentrations of trace gases with sources/sinks near the ground and on diurnal scales. Past synthetic data experiments indicated the possibility to improve tracer transport by minimizing errors of simulated MHs. In this paper we evaluate a method to constrain the Lagrangian particle dispersion model STILT (Stochastic Time-Inverted Lagrangian Transport) with MH diagnosed from radiosonde profiles using a bulk Richardson method. The same method was used to obtain hourly MHs for the period September/October 2009 from the Weather Research and Forecasting (WRF) model, which covers the European continent at 10 km horizontal resolution. Kriging with external drift (KED) was applied to estimate optimized MHs from observed and modelled MHs, which were used as input for STILT to assess the impact on CO2 transport. Special care has been taken to account for uncertainty in MH retrieval in this estimation process. MHs and CO2 concentrations were compared to vertical profiles from aircraft in situ data. We put an emphasis on testing the consistency of estimated MHs to observed vertical mixing of CO2. Modelled CO2 was also compared with continuous measurements made at Cabauw and Heidelberg stations. WRF MHs were significantly biased by ~10–20% during day and ~40–60% during night. Optimized MHs reduced this bias to ~5% with additional slight improvements in random errors. The KED MHs were generally more consistent with observed CO2 mixing. The use of optimized MHs had in general a favourable impact on CO2 transport, with bias reductions of 5–45% (day) and 60–90% (night). This indicates that a large part of the found CO2 model–data mismatch was indeed due to MH errors. Other causes for CO2 mismatch are discussed. Applicability of our method is discussed in the context of CO2 inversions at regional scales.

scholarly journals Dynamical Precipitation Downscaling for Hydrologic Applications Using WRF 4D-Var Data Assimilation: Implications for GPM Era

2015 ◽  
Vol 16 (2) ◽  
pp. 811-829 ◽  
Author(s):  
Liao-Fan Lin ◽  
Ardeshir M. Ebtehaj ◽  
Rafael L. Bras ◽  
Alejandro N. Flores ◽  
Jingfeng Wang
Keyword(s):  
Data Assimilation ◽  
Spatial Resolution ◽  
Numerical Experiments ◽  
Wrf Model ◽  
Stage Iv ◽  
Small Scale ◽  
Point Scale ◽  
Precipitation Estimates ◽  
Environmental Prediction ◽  
The Impact

Abstract The objective of this study is to develop a framework for dynamically downscaling spaceborne precipitation products using the Weather Research and Forecasting (WRF) Model with four-dimensional variational data assimilation (4D-Var). Numerical experiments have been conducted to 1) understand the sensitivity of precipitation downscaling through point-scale precipitation data assimilation and 2) investigate the impact of seasonality and associated changes in precipitation-generating mechanisms on the quality of spatiotemporal downscaling of precipitation. The point-scale experiment suggests that assimilating precipitation can significantly affect the precipitation analysis, forecast, and downscaling. Because of occasional overestimation or underestimation of small-scale summertime precipitation extremes, the numerical experiments presented here demonstrate that the wintertime assimilation produces downscaled precipitation estimates that are in closer agreement with the reference National Centers for Environmental Prediction stage IV dataset than similar summertime experiments. This study concludes that the WRF 4D-Var system is able to effectively downscale a 6-h precipitation product with a spatial resolution of 20 km to hourly precipitation with a spatial resolution of less than 10 km in grid spacing—relevant to finescale hydrologic applications for the era of the Global Precipitation Measurement mission.

A Sensitivity Research of Numerical Simulation about Winter Sea-Land Breeze

2013 ◽  
Vol 380-384 ◽  
pp. 1800-1803
Author(s):  
Xiao Lan Tang ◽  
Shui Yuan Cheng
Keyword(s):  
Numerical Simulation ◽  
Wind Field ◽  
Wrf Model ◽  
Horizontal Resolution ◽  
Land Breeze ◽  
Threshold Values ◽  
Tropical Island ◽  
Wind Field Simulation ◽  
Field Simulation ◽  
The Impact

Using the WRF model and NCEP data, a typical winter sea-land breeze progress in China tropical island was simulated, analyzing the impact of wind field simulation with the horizontal resolution, analog range, nesting level, and analog time. The results showed: the simulate effects of the WRF model could not always keep step with the increase of horizontal resolution. Obviously there was a threshold for the model horizontal resolution. By the same token, analog range, nesting level, and analog time have its threshold. The accuracy of the simulation reduced when the threshold values were exceeded.

scholarly journals Comparison of Image Quality and Spatial Resolution Between 18F, 68Ga and 64Cu Phantom Measurements Using a Digital Biograph Vision PET/CT

2022 ◽  
Author(s):  
Anja Braune ◽  
Liane Oehme ◽  
Robert Freudenberg ◽  
Frank Hofheinz ◽  
Jörg van den Hoff ◽  
...  
Keyword(s):  
Image Quality ◽  
Spatial Resolution ◽  
Ct Scans ◽  
Reconstruction Method ◽  
Recovery Coefficient ◽  
Positron Energy ◽  
Pet Ct ◽  
The Individual ◽  
The Impact

Abstract Background: The PET nuclide and reconstruction method can have a considerable influence on spatial resolution and image quality of PET/CT scans, which can, for example, influence the diagnosis in oncology. The individual impact of the positron energy of 18F, 68Ga and 64Cu on spatial resolution and image quality of PET/CT scans acquired using a clinical, digital scanner was compared. Furthermore, the impact of different reconstruction parameters on image quality and spatial resolution was evaluated for 18F-FDG PET/CT scans acquired with a scanner of the newest generation. Methods: PET/CT scans of a Jaszczak phantom and a NEMA PET body phantom, filled with 18F-FDG, 68Ga-HCl and 64Cu-HCl, respectively, were performed on a Siemens Biograph Vision. Images were assessed using spatial resolution and image quality (Recovery Coefficients (RC), coefficient of variation within the background, Contrast Recovery Coefficient (CRC), Contrast-Noise-Ratio (CNR), and relative count error in lung insert). In a subsequent analysis, the scan of the NEMA PET body phantom filled with 18F-FDG was reconstructed applying different parameters (with/without the application of Point Spread Function (PSF), Time of Flight (ToF) or post-filtering; matrix size). Spatial resolution and quantitative image quality were compared between reconstructions. Results: We found that image quality was comparable between 18F-FDG and 64Cu-HCl PET/CT measurements featuring similar maximal endpoint energy. In comparison, RC, CRC and CNR were worse in 68Ga-HCl data, despite similar count rates. Spatial resolution was up to 18 % worse in 68Ga-HCl compared to 18F-FDG images. Post-filtering of 18F-FDG acquisitions changed image quality the most and reduced spatial resolution by 52 % if a Gaussian filter with 5 mm FWHM was applied. ToF measurements especially improved the recovery of the smallest lesion (RCmean = 1.07 compared to 0.65 without ToF) and improved spatial resolution by 29 %.Conclusions: The positron energy of PET nuclides influences spatial resolution and image quality of digital PET/CT scans. Image quality of 68Ga-HCl PET/CT images was worse compared to 18F-FDG and 64Cu-HCl, respectively, despite similar count rates. Reconstruction parameters have a high impact on image quality and spatial resolution and should be considered when comparing images of different scanners or centers.

scholarly journals Differing responses of the quasi-biennial oscillation to artificial SO<sub>2</sub> injections in two global models

2020 ◽  
Vol 20 (14) ◽  
pp. 8975-8987
Author(s):  
Ulrike Niemeier ◽  
Jadwiga H. Richter ◽  
Simone Tilmes
Keyword(s):  
General Circulation ◽  
Climate Model ◽  
Numerical Models ◽  
General Circulation Models ◽  
Horizontal Resolution ◽  
Injection Rate ◽  
Quasi Biennial Oscillation ◽  
Vertical Advection ◽  
The Impact ◽  
Biennial Oscillation

Abstract. Artificial injections of sulfur dioxide (SO2) into the stratosphere show in several model studies an impact on stratospheric dynamics. The quasi-biennial oscillation (QBO) has been shown to slow down or even vanish under higher SO2 injections in the equatorial region. But the impact is only qualitatively but not quantitatively consistent across the different studies using different numerical models. The aim of this study is to understand the reasons behind the differences in the QBO response to SO2 injections between two general circulation models, the Whole Atmosphere Community Climate Model (WACCM-110L) and MAECHAM5-HAM. We show that the response of the QBO to injections with the same SO2 injection rate is very different in the two models, but similar when a similar stratospheric heating rate is induced by SO2 injections of different amounts. The reason for the different response of the QBO corresponding to the same injection rate is very different vertical advection in the two models, even in the control simulation. The stronger vertical advection in WACCM results in a higher aerosol burden and stronger heating of the aerosols and, consequently, in a vanishing QBO at lower injection rate than in simulations with MAECHAM5-HAM. The vertical velocity increases slightly in MAECHAM5-HAM when increasing the horizontal resolution. This study highlights the crucial role of dynamical processes and helps to understand the large uncertainties in the response of different models to artificial SO2 injections in climate engineering studies.

The impact of SST on the weather forecast quality in the Bulgarian Antarctic Base area on Livingstone Island

2020 ◽  
Author(s):  
Boriana Chtirkova ◽  
Elisaveta Peneva
Keyword(s):  
Prediction Models ◽  
Weather Prediction ◽  
Wrf Model ◽  
Weather Forecast ◽  
Horizontal Resolution ◽  
Initial Time ◽  
Test Cases ◽  
Validation Data ◽  
The Impact ◽  
Forecast Quality

&lt;p&gt;The weather forecast of good quality is essential for the humans living and operating in the Bulgarian Antarctic Base. The numerical weather prediction models in southern high latitude regions still need improvement as the user community is limited, little test cases are documented and validation data are scarce. Not lastly, the challenge of distributing the output results under poor internet conditions has to be addressed.&lt;/p&gt;&lt;p&gt;The Bulgarian Antarctic Base (BAB) is located on the Livingstone Island coast at 62&amp;#8304;S and 60&amp;#8304;W. The influence of the Southern ocean is significant, thus important to be correctly taken into account in the numerical forecast. The modeling system is based on the WRF model, configured in three nested domains down to 1 km horizontal resolution, centered in BAB. The main objective of the study is to quantify the Sea Surface Temperature (SST) impact and to recommend the frequency and way to perform measurements of the SST near the base. The focus is on prediction of right initial time and period of &amp;#8220;bad&amp;#8221; weather events like storms, frontal zones, and severe winds. Several test cases are considered with available measurements of temperature, pressure and wind speed in BAB during the summer season in 2017. The numerical 3 days forecast is performed and the model skill to capture the basic meteorological events in this period is discussed. Sensitivity experiments to SST values in the nearby marine area are concluded and the SST influence on the model forecast quality is analyzed.&lt;/p&gt;

Impact of increasing horizontal and vertical resolution during the HWRF hybrid EnVar data assimilation on the analysis and prediction of Hurricane Patricia (2015)

2020 ◽  
Author(s):  
Jie Feng ◽  
Xuguang Wang
Keyword(s):  
Data Assimilation ◽  
Horizontal Resolution ◽  
Tropical Storm ◽  
Weather Research And Forecasting ◽  
Vertical Resolution ◽  
Model Resolution ◽  
Warm Core ◽  
The Individual ◽  
The Impact ◽  
Hwrf Model

AbstractAlthough numerous studies have demonstrated that increasing model spatial resolution in free forecasts can potentially improve tropical cyclone (TC) intensity forecasts, studies on the impact of model resolution during data assimilation (DA) on TC prediction are lacking. In this study, using the ensemble-variational DA system for Hurricane Weather Research and Forecasting (HWRF) model, we investigated the individual impact of increasing the model resolution of first guess (FG) and background ensemble (BE) forecasts during DA on initial analyses and subsequent forecasts of Hurricane Patricia (2015). The impacts were compared between horizontal and vertical resolutions and also between the tropical storm (TS) and hurricane assimilation during Patricia.The results show that increasing the horizontal or vertical resolution in FG has a larger impact than increasing the resolution in BE on improving the analyzed TC intensity and structure for the hurricane stage. The result is reversed for the TS stage. These results are attributed to the effectiveness of increasing the FG resolution in intensifying the background vortex for the hurricane stage relative to the TS stage. Increasing the BE resolution contributes to improving the analyzed intensity through the better-resolved background correlation structure for both the hurricane and TS stages. Increasing horizontal resolution has an overall larger effect than increasing vertical resolution in improving the analysis at the hurricane stage and their effects are close for the analysis at the TS stage. Additionally, the more accurately analyzed primary, secondary circulation, and warm core structures via the increased resolution in DA lead to improved TC intensity forecasts.

scholarly journals A Sensitivity Study on the Soil Parameter-Boundary Layer Height Interrelationship

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Hajnalka Breuer ◽  
Ferenc Ács ◽  
Ákos Horváth ◽  
Borbála Laza ◽  
István Matyasovszky ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Wrf Model ◽  
Sensitivity Study ◽  
Horizontal Resolution ◽  
Layer Height ◽  
Soil Parameter ◽  
Boundary Layer Height ◽  
Soil Information ◽  
Parameter Values ◽  
The Impact

Simulations with the WRF model have been carried out with high resolution soil data to analyze its effect on planetary boundary layer (PBL) development. The default soil texture distribution of 5′ horizontal resolution has been replaced with a 30′′ one on the basis of the Digital Kreybig Soil Information System and Hungarian Agrogeological Database in Hungary. Soil parameter values determined from HUNSODA and MARTHA Hungarian soil databases were also compared. Comparison of PBL height simulations and measurements obtained by radiometer and windprofiler shows that the impact of soil parameter differences on PBL height evolution is not negligible. The latent heat flux and PBL height daytime courses show significant (P<0.01) differences over more than 50% of the model domain covering the Carpathian basin.

scholarly journals The Impact of Vertical Resolution on Fog Forecasting in the Kilometric-Scale Model AROME: A Case Study and Statistics

2016 ◽  
Vol 31 (5) ◽  
pp. 1655-1671 ◽  
Author(s):  
A. Philip ◽  
T. Bergot ◽  
Y. Bouteloup ◽  
F. Bouyssel
Keyword(s):  
Weather Prediction ◽  
Winter Season ◽  
Scale Model ◽  
Strong Impact ◽  
Vertical Resolution ◽  
Radiation Fog ◽  
Fog Forecasting ◽  
High Vertical Resolution ◽  
The Impact

Abstract The impact of vertical resolution on numerical fog forecasting is studied in detail for a specific case and evaluated statistically over a winter season. Three vertical resolutions are tested with the kilometric-scale Applications of Research to Operations at Mesoscale (AROME) numerical weather prediction model over Paris Charles de Gaulle Airport (Paris-CDG) in Paris, France. For the case studied, the vertical resolution has a strong impact on fog onset. The nocturnal jet and the turbulence created by wind shear at the top of the nocturnal boundary layer are more pronounced with a finer vertical resolution, and the turbulence close to the ground is also stronger with high vertical resolution. Local circulations created by the terrain induce different simulated processes during the fog onset. The fog is simulated as advection–radiation fog in the finer vertical resolution run and as radiation fog in the others. The vertical resolution has little impact on the mature and dissipation phases. A statistical study over a winter season confirms the results obtained in the fog case study. High vertical resolution simulates earlier onset, as well as longer-lasting and more spatially heterogeneous fogs. The high vertical resolution configuration simulates more fog events than are found at low resolution (LR); these fog events generally form north of Paris-CDG. No observations are available in this area, leading to many simulated but no observed fog events in the fine-resolution runs. The ceiling of low clouds is not well simulated by the numerical model no matter what vertical resolution is used.

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