scholarly journals Thermally Induced Convective Circulation and Precipitation over an Isolated Volcano

2016 ◽  
Vol 73 (4) ◽  
pp. 1667-1686 ◽  
Author(s):  
Alexandros P. Poulidis ◽  
Ian A. Renfrew ◽  
Adrian J. Matthews
Keyword(s):  
Surface Temperature ◽  
Wrf Model ◽  
Volcanic Hazards ◽  
Pyroclastic Flows ◽  
Weather Research And Forecasting ◽  
Atmospheric Conditions ◽  
Thermally Induced ◽  
Average Value ◽  
Wind Speeds ◽  
Precipitation Increase

Abstract Intense rainfall over active volcanoes is known to trigger dangerous volcanic hazards, from remobilizing loose volcanic surface material into lahars or mudflows to initiating explosive activity including pyroclastic flows at certain dome-forming volcanoes. However, the effect of the heated volcanic surface on the atmospheric circulation, including any feedback with precipitation, is unknown. This is investigated here, using the Weather Research and Forecasting (WRF) Model. The recent activity at the Soufrière Hills Volcano (SHV), Montserrat, is a well-documented case of such rainfall–volcano interaction and is used as a template for these experiments. The volcano is represented in the model by an idealized Gaussian mountain, with an imposed realistic surface temperature anomaly on the volcano summit. A robust increase in precipitation over the volcano is simulated for surface temperature anomalies above approximately 40°C, an area-average value that is exceeded at the SHV. For wind speeds less than 4 m s−1 and a range of realistic atmospheric conditions, the precipitation increase is well above the threshold required to trigger volcanic hazards (5–10 mm h−1). Hence, the thermal atmospheric forcing due to an active, but nonerupting, volcano appears to be an important factor in rainfall–volcano interactions and should be taken account of in future hazard studies.

scholarly journals Simulation of Severe Thunderstorms in Conjugation of Westerly and Easterly on 31 March 2019 in Bangladesh

2022 ◽  
Vol 12 (3) ◽  
pp. 29-43
Author(s):  
Samarendra Karmakar ◽  
Mohan Kumar Das ◽  
Md Quamrul Hassam ◽  
Md Abdul Mannan
Keyword(s):  
South Asian ◽  
Wrf Model ◽  
Horizontal Resolution ◽  
Weather Research And Forecasting ◽  
Atmospheric Conditions ◽  
Microphysics Scheme ◽  
Severe Thunderstorms ◽  
Synoptic Conditions ◽  
Pbl Scheme ◽  
Single Moment

The diagnostic and prognostic studies of thunderstorms/squalls are very important to save live and loss of properties. The present study aims at diagnose the different tropospheric parameters, instability and synoptic conditions associated the severe thunderstorms with squalls, which occurred at different places in Bangladesh on 31 March 2019. For prognostic purposes, the severe thunderstorms occurred on 31 March 2019 have been numerically simulated. In this regard, the Weather Research and Forecasting (WRF) model is used to predict different atmospheric conditions associated with the severe storms. The study domain is selected for 9 km horizontal resolution, which almost covers the south Asian region. Numerical experiments have been conducted with the combination of WRF single-moment 6 class (WSM6) microphysics scheme with Yonsei University (YSU) PBL scheme in simulation of the squall events. Model simulated results are compared with the available observations. The observed values of CAPE at Kolkata both at 0000 and 1200 UTC were 2680.4 and 3039.9 J kg-1 respectively on 31 March 2019 and are found to be comparable with the simulated values. The area averaged actual rainfall for 24 hrs is found is 22.4 mm, which complies with the simulated rainfall of 20-25 mm for 24 hrs. Journal of Engineering Science 12(3), 2021, 29-43

scholarly journals Assessment of Wind Pattern Accuracy from the QuikSCAT Satellite and the WRF Model along the Galician Coast (Northwest Iberian Peninsula)

2013 ◽  
Vol 141 (2) ◽  
pp. 742-753 ◽  
Author(s):  
M. C. Sousa ◽  
I. Alvarez ◽  
N. Vaz ◽  
M. Gomez-Gesteira ◽  
J. M. Dias
Keyword(s):  
Wind Speed ◽  
Surface Wind ◽  
Wrf Model ◽  
Weather Research And Forecasting ◽  
Western Coast ◽  
Wind Pattern ◽  
Wind Speeds ◽  
Galician Coast ◽  
Key Factor

Abstract Surface wind along the Galician coast is a key factor allowing the analysis of important oceanographic features that are related to the great primary production in this area, as upwelling events. A comparative analysis between surface winds obtained from the Quick Scatterometer (QuikSCAT), the Weather Research and Forecasting (WRF) Model, and in situ observations from buoys along the Galician coast is carried out from November 2008 to October 2009. This comparison evaluates the accuracy of satellite and modeled data. The results show that the wind speeds derived from QuikSCAT and the WRF Model are similar along the coast, with errors ranging from 1.5 to 2 m s−1. However, QuikSCAT tends to overestimate wind speeds when compared to the buoys measurements. Regarding the wind direction, the RMSE values are about 35° for the stations under analysis. The bias presents a similar pattern between satellite and modeled data, with positive values at the western coast and negative values at the middle and northern coasts, the satellite data always being lower in absolute value than the modeled data. A spatial comparison between QuikSCAT and WRF data is also performed over the whole Galician coast to evaluate the differences between the two datasets. This comparison shows that the modeled wind speed tends to be lower than satellite winds over the entire domain, with the highest RMSE and bias values found for the wind speed and direction observed near the shoreline.

scholarly journals Evaluation of Weather Research and Forecasting Model (WRF) Simulations over Middle East

2018 ◽  
Vol 29 (2) ◽  
pp. 26
Author(s):  
Thaer Obaid Roomi
Keyword(s):  
Middle East ◽  
Initial Conditions ◽  
Wrf Model ◽  
Weather Research And Forecasting ◽  
Forecasting Model ◽  
Data Sets ◽  
Wind Speeds ◽  
Computing Skills ◽  
Predicted Values ◽  
Weather Research

The Weather Research and Forecasting model (WRF) is an atmospheric simulation system designed for both research and operational applications. This worldwide used model requires a sophisticated modeling experience and computing skills. In this study, WRF model was used to predict many atmospheric parameters based on the initial conditions extracted from NOMADS data sets. The study area is basically the region surrounded by the longitudes and latitudes: 15o-75o E and 10.5o-45o N which typically includes the Middle East region. The model was installed on Linux platform with a grid size of 10 km in the X and Y directions. A low pressure trough was tracked in its movement from west to east via the Middle East during the period from 1 to 7 January 2010 as a case study of the WRF model. MATLAB and NCAR Command Language (NCL) were used to display the model output. To evaluate the forecasted parameters and patterns, some comparisons were made between the predicted and actual weather charts. Wind speeds and directions in the prognostic and actual charts of 700 hPa were in agreement. However, the predicted values of geopotential heights in WRF are somewhat overestimate the actual ones. This may be attributed to the differences in the data sources and data analysis methods of the two data agencies, NOMADS and ECMWF.

scholarly journals The Contribution of Lake Enhancement to Extreme Snowfall within the Chicago–Milwaukee Urban Corridor during the 2011 Groundhog Day Blizzard

2017 ◽  
Vol 145 (6) ◽  
pp. 2405-2420 ◽  
Author(s):  
Nathan D. Owens ◽  
Robert M. Rauber ◽  
Brian F. Jewett ◽  
Greg M. McFarquhar
Keyword(s):  
Surface Temperature ◽  
Wrf Model ◽  
Lower Atmosphere ◽  
Weather Research And Forecasting ◽  
Structure Stability ◽  
Sea Level Pressure ◽  
Dewpoint Temperature ◽  
The Impact ◽  
Urban Corridor ◽  
The City

Abstract This paper examines the impact of the Laurentian Great Lakes (GL) on atmospheric structure, stability, and precipitation within the Chicago–Milwaukee urban corridor during the passage of the 1–2 February 2011 extratropical cyclone. This storm produced the third largest snowfall [53.8 cm (21.2 in.)] recorded in a 130-yr period in the city of Chicago. Two simulations of the storm using the Weather Research and Forecasting (WRF) Model are described: the first with the GL present, and the second with the lakes replaced with land having characteristics of adjacent shores. The GL were found to alter the surface temperature and moisture fields in their lee during cyclone passage. The changes were limited to the layer below the frontal inversion, but were significant enough to reduce the mean sea level pressure in some locations by 2.0–2.5 hPa, and raise the surface temperature and dewpoint temperature by 2°–4°C across several states downwind. In the Chicago–Milwaukee metropolitan corridor where the heavy snow occurred, the surface temperature and dewpoint temperature increased from +3° to +6°C as a result of heating and moistening of the lower atmosphere by the GL. Enhanced convergence also occurred along the downwind shoreline. Despite these changes, the areal impact on precipitation was surprisingly small, with liquid equivalent precipitation increases exceeding 5 mm limited to a small area over metropolitan Chicago late in the storm. The reason for the limited impact appeared to be the shallow nature of the cold air mass below the frontal inversion. Nevertheless, over metropolitan Chicago, as much as 20% of the snowfall could be attributed to the presence of the GL.

scholarly journals A wind-albedo-wind feedback driven by landscape evolution

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Jordan T. Abell ◽  
Alex Pullen ◽  
Zachary J. Lebo ◽  
Paul Kapp ◽  
Lucas Gloege ◽  
...  
Keyword(s):  
Landscape Evolution ◽  
Dust Emission ◽  
Wrf Model ◽  
Gobi Desert ◽  
Surface Winds ◽  
Atmospheric Conditions ◽  
Near Surface ◽  
Fine Grained ◽  
Wind Speeds ◽  
Modify Surface

AbstractThe accurate characterization of near-surface winds is critical to our understanding of past and modern climate. Dust lofted by these winds has the potential to modify surface and atmospheric conditions as well as ocean biogeochemistry. Stony deserts, low dust emitting regions today, represent expansive areas where variations in surficial geology through time may drastically impact near-surface conditions. Here we use the Weather Research and Forecasting (WRF) model over the western Gobi Desert to demonstrate a previously undocumented process between wind-driven landscape evolution and boundary layer conditions. Our results show that altered surficial thermal properties through winnowing of fine-grained sediments and formation of low-albedo gravel-mantled surfaces leads to an increase in near-surface winds by up to 25%; paradoxically, wind erosion results in faster winds regionally. This wind-albedo-wind feedback also leads to an increase in the frequency of hours spent at higher wind speeds, which has implications for dust emission potential.

Explicit Numerical Diffusion in the WRF Model

2007 ◽  
Vol 135 (11) ◽  
pp. 3808-3824 ◽  
Author(s):  
Jason C. Knievel ◽  
George H. Bryan ◽  
Joshua P. Hacker
Keyword(s):  
Boundary Layers ◽  
Wrf Model ◽  
Weather Research And Forecasting ◽  
Numerical Diffusion ◽  
Wind Speeds ◽  
Flux Limiter ◽  
Advection Schemes ◽  
Diffusion Scheme ◽  
Physical Phenomena ◽  
Relative Wind

Abstract Diffusion that is implicit in the odd-ordered advection schemes in early versions of the Advanced Research core of the Weather Research and Forecasting (WRF) model is sometimes insufficient to remove noise from kinematical fields. The problem is worst when grid-relative wind speeds are low and when stratification is nearly neutral or unstable, such as in weakly forced daytime boundary layers, where noise can grow until it competes with the physical phenomena being simulated. One solution to this problem is an explicit, sixth-order numerical diffusion scheme that preserves the WRF model’s high effective resolution and uses a flux limiter to ensure monotonicity. The scheme, and how it was added to the WRF model, are explained. The scheme is then demonstrated in an idealized framework and in simulations of salt breezes and lake breezes in northwestern Utah.

scholarly journals Evaluation of WRF Model Resolution on Simulated Mesoscale Winds and Surface Fluxes near Greenland

2013 ◽  
Vol 141 (3) ◽  
pp. 941-963 ◽  
Author(s):  
Alice K. DuVivier ◽  
John J. Cassano
Keyword(s):  
Wrf Model ◽  
Deep Ocean ◽  
Surface Fluxes ◽  
Weather Research And Forecasting ◽  
Flow Distortion ◽  
Model Simulations ◽  
Wind Speeds ◽  
Region Model ◽  
Wind Events

Abstract Southern Greenland has short-lived but frequently occurring strong mesoscale barrier winds and tip jets that form when synoptic-scale atmospheric features interact with the topography of Greenland. The influence of these mesoscale atmospheric events on the ocean, particularly deep ocean convection, is not yet well understood. Because obtaining observations is difficult in this region, model simulations are essential for understanding the interaction between the atmosphere and ocean during these wind events. This paper presents results from the Weather Research and Forecasting (WRF) Model simulations run at four different resolutions (100, 50, 25, and 10 km) and forced with the ECMWF Re-Analysis Interim (ERA-Interim) product. Case study comparisons between WRF output at different resolutions, observations from the Greenland Flow Distortion Experiment (GFDex), which provides valuable in situ observations of mesoscale winds, and Quick Scatterometer (QuikSCAT) satellite data highlight the importance of high-resolution simulations for properly capturing the structure and high wind speeds associated with mesoscale wind events and surface fluxes of latent and sensible heat. In addition, the longer-term impact of mesoscale winds on the ocean is investigated by comparison of surface fluxes and winds between model resolutions over a two-month period.

Lake and Orographic Effects on a Snowstorm at Lake Constance

2016 ◽  
Vol 144 (12) ◽  
pp. 4687-4707 ◽  
Author(s):  
Lukas Umek ◽  
Alexander Gohm
Keyword(s):  
Wrf Model ◽  
Heavy Precipitation ◽  
Lake Constance ◽  
Weather Research And Forecasting ◽  
Thermally Induced ◽  
Orographic Effects ◽  
First Case ◽  
Convergence Line ◽  
Orographic Enhancement ◽  
Unstable Layer

Abstract This is one of the first case studies of a snowstorm at Lake Constance, located between Austria, Germany, and Switzerland, which assesses the influence of the lake and the orography on the generation of heavy precipitation. The analysis is based on surface and radar observations and numerical simulations with the Weather Research and Forecasting (WRF) Model. On 8 February 2013, a rather stationary and banded radar reflectivity pattern was observed during postfrontal conditions with northwesterly flow. The associated snowband affected the downstream shore and the adjacent mountainous region with 36 mm of precipitation within 5 h at the shore. Surface observations show a convergence in the wind field over the lake during the period of banded precipitation. The control simulation captures the formation of a convergence line and a snowband near the shoreline and over the downstream orography. A lake-induced, low-level conditionally unstable layer is essential for the snowband formation. Orographically and thermally induced convergence provides the lifting to release conditional instability and to trigger convection. Orographic enhancement of precipitation occurs downstream of the lake. Sensitivity experiments with modified orography, land use, and lake surface temperature show that the lake is a crucial factor controlling the amount and distribution of snowfall. However, neither the lake nor the orography alone would have been able to form a snowband. This study highlights the complex interaction between lake and orographic effects and shows that Lake Constance is large enough to impact the formation of precipitation.

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