Comparison of Two-Moment Bulk Microphysics Schemes in Idealized Supercell Thunderstorm Simulations

2011 ◽  
Vol 139 (4) ◽  
pp. 1103-1130 ◽  
Author(s):  
Hugh Morrison ◽  
Jason Milbrandt
Keyword(s):  
Three Dimensional ◽  
Wrf Model ◽  
Weather Research And Forecasting ◽  
Cold Pool ◽  
Fall Velocity ◽  
Surface Precipitation ◽  
Single Category ◽  
Supercell Thunderstorm ◽  
Drop Size Distributions ◽  
Reduced Surface

Idealized three-dimensional supercell simulations were performed using the two-moment bulk microphysics schemes of Morrison and Milbrandt–Yau in the Weather Research and Forecasting (WRF) model. Despite general similarities in these schemes, the simulations were found to produce distinct differences in storm structure, precipitation, and cold pool strength. In particular, the Morrison scheme produced much higher surface precipitation rates and a stronger cold pool, especially in the early stages of storm development. A series of sensitivity experiments was conducted to identify the primary differences between the two schemes that resulted in the large discrepancies in the simulations. Different approaches in treating graupel and hail were found to be responsible for many of the key differences between the baseline simulations. The inclusion of hail in the baseline simulation using the Milbrant–Yau scheme with two rimed-ice categories (graupel and hail) had little impact, and therefore resulted in a much different storm than the baseline run with the single-category (hail) Morrison scheme. With graupel as the choice of the single rimed-ice category, the simulated storms had considerably more frozen condensate in the anvil region, a weaker cold pool, and reduced surface precipitation compared to the runs with only hail, whose higher terminal fall velocity inhibited lofting. The cold pool strength was also found to be sensitive to the parameterization of raindrop breakup, particularly for the Morrison scheme, because of the effects on the drop size distributions and the corresponding evaporative cooling rates. The use of a more aggressive implicit treatment of drop breakup in the baseline Morrison scheme, by limiting the mean–mass raindrop diameter to a maximum of 0.9 mm, opposed the tendency of this scheme to otherwise produce large mean drop sizes and a weaker cold pool compared to the hail-only run using the Milbrandt–Yau scheme.

scholarly journals A New Bulk Microphysical Scheme That Includes Riming Intensity and Temperature-Dependent Ice Characteristics

2011 ◽  
Vol 139 (3) ◽  
pp. 1013-1035 ◽  
Author(s):  
Yanluan Lin ◽  
Brian A. Colle
Keyword(s):  
Wrf Model ◽  
Computationally Efficient ◽  
Fall Velocity ◽  
Surface Precipitation ◽  
Ice Particles ◽  
Microphysical Processes ◽  
Empirical Coefficients ◽  
Oregon Cascades ◽  
Microphysical Parameterization ◽  
Ice Water

Abstract A new bulk microphysical parameterization (BMP) scheme is presented that includes a diagnosed riming intensity and its impact on ice characteristics. As a result, the new scheme represents a continuous spectrum from pristine ice particles to heavily rimed particles and graupel using one prognostic variable [precipitating ice (PI)] rather than two separate variables (snow and graupel). In contrast to most existing parameterization schemes that use fixed empirical relationships to describe ice particles, general formulations are proposed to consider the influences of riming intensity and temperature on the projected area, mass, and fall velocity of PI particles. The proposed formulations are able to cover the variations of empirical coefficients found in previous observational studies. The new scheme also reduces the number of parameterized microphysical processes by ∼50% as compared to conventional six-category BMPs and thus it is more computationally efficient. The new scheme (called SBU-YLIN) has been implemented in the Weather Research and Forecasting (WRF) model and compared with three other schemes for two events during the Improvement of Microphysical Parameterization through Observational Verification Experiment (IMPROVE-2) over the central Oregon Cascades. The new scheme produces surface precipitation forecasts comparable to more complicated BMPs. The new scheme reduces the snow amounts aloft as compared to other WRF schemes and compares better with observations, especially for an event with moderate riming aloft. Sensitivity tests suggest both reduced snow depositional growth rate and more efficient fallout due to the contribution of riming to the reduction of ice water content aloft in the new scheme, with a larger impact from the partially rimed snow and fallout.

Evaluation and Comparison of Microphysical Algorithms in ARW-WRF Model Simulations of Atmospheric River Events Affecting the California Coast

2009 ◽  
Vol 10 (4) ◽  
pp. 847-870 ◽  
Author(s):  
Isidora Jankov ◽  
Jian-Wen Bao ◽  
Paul J. Neiman ◽  
Paul J. Schultz ◽  
Huiling Yuan ◽  
...  
Keyword(s):  
Wrf Model ◽  
Weather Research And Forecasting ◽  
Test Bed ◽  
Cool Season ◽  
Model Simulations ◽  
Surface Precipitation ◽  
Low Level ◽  
Atmospheric River ◽  
Microphysical Parameterization ◽  
Precipitation Events

Abstract Numerical prediction of precipitation associated with five cool-season atmospheric river events in northern California was analyzed and compared to observations. The model simulations were performed by using the Advanced Research Weather Research and Forecasting Model (ARW-WRF) with four different microphysical parameterizations. This was done as a part of the 2005–06 field phase of the Hydrometeorological Test Bed project, for which special profilers, soundings, and surface observations were implemented. Using these unique datasets, the meteorology of atmospheric river events was described in terms of dynamical processes and the microphysical structure of the cloud systems that produced most of the surface precipitation. Events were categorized as “bright band” (BB) or “nonbright band” (NBB), the differences being the presence of significant amounts of ice aloft (or lack thereof) and a signature of higher reflectivity collocated with the melting layer produced by frozen precipitating particles descending through the 0°C isotherm. The model was reasonably successful at predicting the timing of surface fronts, the development and evolution of low-level jets associated with latent heating processes and terrain interaction, and wind flow signatures consistent with deep-layer thermal advection. However, the model showed the tendency to overestimate the duration and intensity of the impinging low-level winds. In general, all model configurations overestimated precipitation, especially in the case of BB events. Nonetheless, large differences in precipitation distribution and cloud structure among model runs using various microphysical parameterization schemes were noted.

scholarly journals Evaluation of the Simulation of Typhoon Lekima (2019) Based on Different Physical Parameterization Schemes and FY-3D Satellite’s MWHS-2 Data Assimilation

2021 ◽  
Vol 13 (22) ◽  
pp. 4556
Author(s):  
Dongmei Xu ◽  
Xuewei Zhang ◽  
Hong Li ◽  
Haiying Wu ◽  
Feifei Shen ◽  
...  
Keyword(s):  
Data Assimilation ◽  
Three Dimensional ◽  
Wrf Model ◽  
Background Field ◽  
Weather Research And Forecasting ◽  
Initial Field ◽  
Parameterization Schemes ◽  
Microwave Humidity Sounder ◽  
Radiance Data ◽  
Physical Parameterization

In this study, the case of super typhoon Lekima, which landed in Jiangsu and Zhejiang Province on 4 August 2019, is numerically simulated. Based on the Weather Research and Forecasting (WRF) model, the sensitivity experiments are carried out with different combinations of physical parameterization schemes. The results show that microphysical schemes have obvious impacts on the simulation of the typhoon’s track, while the intensity of the simulated typhoon is more sensitive to surface physical schemes. Based on the results of the typhoon’s track and intensity simulation, one parameterization scheme was further selected to provide the background field for the following data assimilation experiments. Using the three-dimensional variational (3DVar) data assimilation method, the Microwave Humidity Sounder-2 (MWHS-2) radiance data onboard the Fengyun-3D satellite (FY-3D) were assimilated for this case. It was found that the assimilation of the FY-3D MWHS-2 radiance data was able to optimize the initial field of the numerical model in terms of the model variables, especially for the humidity. Finally, by the inspection of the typhoon’s track and intensity forecast, it was found that the assimilation of FY-3D MWHS-2 radiance data improved the skill of the prediction for both the typhoon’s track and intensity.

scholarly journals Three-Dimensional Modelling of Precipitation Enhancement by Cloud Seeding in Three Different Climate Zones

Atmosphere ◽  
2019 ◽  
Vol 10 (6) ◽  
pp. 294 ◽  
Author(s):  
Mladjen Ćurić ◽  
Miloš Lompar ◽  
Djordje Romanic ◽  
Linda Zou ◽  
Haoran Liang
Keyword(s):  
United Arab Emirates ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Arid Climate ◽  
Weather Research And Forecasting ◽  
Effective Precipitation ◽  
Surface Precipitation ◽  
Low Humidity ◽  
Seeding Agent ◽  
Precipitation Enhancement

This study numerically investigates precipitation enhancement from cumuliform clouds in three different climate regions: (1) Arid climate of the United Arab Emirates (UAE); (2) maritime climate of Thailand; and (3) continental climate of Serbia. Recently developed core/shell sodium chloride (NaCl)/titanium dioxide (TiO2) nanostructure (CSNT) aerosol was tested as a precipitation enhancer in all three climate regions. Previous experimental studies in cloud chambers and idealized numerical simulations demonstrated that CSNT is a significantly more effective precipitation enhancer than the traditional NaCl. Here, CSNT and NaCl seeding agents are incorporated into the WRF (Weather Research and Forecasting) model microphysics with explicate treatment of aerosol. Our results show that CSNT is a profoundly more effective precipitation enhancer in the case of arid climate characterized with low humidity. The accumulated surface precipitation in the arid test was 1.4 times larger if CSNT seeding agent was used instead of NaCl. The smallest difference in the effectiveness between CSNT and NaCl was observed in the maritime case due to their similar activation properties at high values of relative humidity.

The 4–5 December 2001 IMPROVE-2 Event: Observed Microphysics and Comparisons with the Weather Research and Forecasting Model

2009 ◽  
Vol 137 (4) ◽  
pp. 1372-1392 ◽  
Author(s):  
Yanluan Lin ◽  
Brian A. Colle
Keyword(s):  
Water Conservation ◽  
Wrf Model ◽  
Spherical Particles ◽  
Weather Research And Forecasting ◽  
Coast Range ◽  
Surface Precipitation ◽  
Orographic Rainfall ◽  
Convective Cells ◽  
Weather Research

Abstract This paper highlights the observed and simulated microphysical evolution of a moderate orographic rainfall event over the central Oregon Cascade Range during 4–5 December 2001 of the Second Improvement of Microphysical Parameterization through Observational Verification Experiment (IMPROVE-2). Airborne in situ measurements illustrate the spatial variations in ice crystal distributions and amounts over the windward Cascades and within some convective cells. The in situ microphysical observations, ground radars, and surface observations are compared with four bulk microphysical parameterizations (BMPs) within the Weather Research and Forecasting (WRF) model. Those WRF BMP schemes that overpredict surface precipitation along the Cascade windward slopes are shown to have too rapid graupel (rimed snow) fallout. Most BMP schemes overpredict snow in the maximum snow depositional growth region aloft, which results in excessive precipitation spillover into the immediate lee of the Cascades. Meanwhile, there is underprediction to the east of the Cascades in all BMP schemes. Those BMPs that produce more graupel than snow generate nearly twice as much precipitation over the Oregon Coast Range as the other BMPs given the cellular convection in this region. Sensitivity runs suggest that the graupel accretion of snow generates too much graupel within select WRF BMPs. Those BMPs that generate more graupel than snow have shorter cloud residence times and larger removal of available water vapor. Snow depositional growth may be overestimated by 2 times within the BMPs when a capacitance for spherical particles is used rather than for snow aggregates. Snow mass–diameter relationships also have a large impact on the snow and cloud liquid water generation. The positive definite advection scheme for moisture and hydrometeors in the WRF reduces the surface precipitation by 20%–30% over the Coast Range and improves water conservation, especially where there are convective cells.

scholarly journals The Impact of Assimilating Atmospheric Infrared Sounder Observation on the Forecast of Typhoon Tracks

2011 ◽  
Vol 2011 ◽  
pp. 1-10 ◽  
Author(s):  
Chien-Ben Chou ◽  
Huei-Ping Huang
Keyword(s):  
Data Assimilation ◽  
Three Dimensional ◽  
Wrf Model ◽  
Weather Research And Forecasting ◽  
Atmospheric Infrared Sounder ◽  
Background Error ◽  
Forecasting System ◽  
Typhoon Tracks ◽  
The Impact ◽  
Decorrelation Scale

This work assesses the effects of assimilating atmospheric infrared sounder (AIRS) observations on typhoon prediction using the three-dimensional variational data assimilation (3DVAR) and forecasting system of the weather research and forecasting (WRF) model. Two major parameters in the data assimilation scheme, the spatial decorrelation scale and the magnitude of the covariance matrix of the background error, are varied in forecast experiments for the track of typhoon Sinlaku over the Western Pacific. The results show that within a wide parameter range, the inclusion of the AIRS observation improves the prediction. Outside this range, notably when the decorrelation scale of the background error is set to a large value, forcing the assimilation of AIRS data leads to degradation of the forecast. This illustrates how the impact of satellite data on the forecast depends on the adjustable parameters for data assimilation. The parameter-sweeping framework is potentially useful for improving operational typhoon prediction.

scholarly journals Inclusion of ash and SO<sub>2</sub> emissions from volcanic eruptions in WRF-Chem: development and some applications

2013 ◽  
Vol 6 (2) ◽  
pp. 457-468 ◽  
Author(s):  
M. Stuefer ◽  
S. R. Freitas ◽  
G. Grell ◽  
P. Webley ◽  
S. Peckham ◽  
...  
Keyword(s):  
Transport Model ◽  
Three Dimensional ◽  
Wrf Model ◽  
Volcanic Eruptions ◽  
Weather Research And Forecasting ◽  
Tephra Fall ◽  
Additional Information ◽  
Volcanic Emission ◽  
Good Coincidence ◽  
Fall Deposits

Abstract. We describe a new functionality within the Weather Research and Forecasting (WRF) model with coupled Chemistry (WRF-Chem) that allows simulating emission, transport, dispersion, transformation and sedimentation of pollutants released during volcanic activities. Emissions from both an explosive eruption case and a relatively calm degassing situation are considered using the most recent volcanic emission databases. A preprocessor tool provides emission fields and additional information needed to establish the initial three-dimensional cloud umbrella/vertical distribution within the transport model grid, as well as the timing and duration of an eruption. From this source condition, the transport, dispersion and sedimentation of the ash cloud can be realistically simulated by WRF-Chem using its own dynamics and physical parameterization as well as data assimilation. Examples of model applications include a comparison of tephra fall deposits from the 1989 eruption of Mount Redoubt (Alaska) and the dispersion of ash from the 2010 Eyjafjallajökull eruption in Iceland. Both model applications show good coincidence between WRF-Chem and observations.

scholarly journals Evaluating Warm and Cold Rain Processes in Cloud Microphysical Schemes Using OLYMPEX Field Measurements

2020 ◽  
Vol 148 (5) ◽  
pp. 2163-2190
Author(s):  
Aaron R. Naeger ◽  
Brian A. Colle ◽  
Na Zhou ◽  
Andrew Molthan
Keyword(s):  
Wrf Model ◽  
Field Measurements ◽  
Weather Research And Forecasting ◽  
Flow Conditions ◽  
Surface Precipitation ◽  
Particle Properties ◽  
Warm Rain ◽  
Simulated Precipitation ◽  
Rain Fall ◽  
Western Washington

Abstract Field observations from the Olympic Mountain Experiment (OLYMPEX) around western Washington State during two atmospheric river (AR) events in November 2015 were used to evaluate several bulk microphysical parameterizations (BMPs) within the Weather Research and Forecasting (WRF) Model. These AR events were characterized by a prefrontal period of stable, terrain-blocked flow with an abundance of cold rain over the lowland region followed by less stable, unblocked flow with more warm rain, and a shift in the largest precipitation amounts to over the windward Olympic slopes. Our WRF simulations underpredicted the precipitation by 19%–36% in the Morrison (MORR) and Thompson (THOM) BMPs and 10%–23% in the predicted particle properties (P3) BMP, with the largest underpredictions over the windward slopes during the more convective, unblocked flow conditions. Several important processes related to the BMPs led to the differences in simulated precipitation. First, the prognostic single ice category parameterization in the P3 scheme promoted a more realistic evolution of rimed particles and larger cold rain production, which led to the lowest underpredictions in precipitation among the schemes. Second, efficient melting processes associated with the production of nonspherical ice and snow in the P3 and THOM BMPs, respectively, promoted a more realistic transition to rain fall speeds within the warm layer compared to the spherical snow assumption in MORR. Last, all BMPs underpredict the contribution of warm rain processes to the surface precipitation, particularly during the unblocked flow period, which may be partly explained by too weak condensational and collisional growth processes due to the neglect of turbulence parameterizations within the schemes.

scholarly journals An Experiment for Assimilating Different Type of Data Observations in Forecasting Heavy Rainfall over Central Highlands Region Due to the Impact of Hurricane Damrey

2019 ◽  
Vol 35 (4) ◽  
Author(s):  
Le Lan Phuong ◽  
Pham Quang Nam ◽  
Tran Quang Duc ◽  
Phan Van Tan
Keyword(s):  
Lead Time ◽  
Heavy Rainfall ◽  
Three Dimensional ◽  
Wrf Model ◽  
Weather Research And Forecasting ◽  
Data Types ◽  
Warm Start ◽  
Central Highlands ◽  
Atmospheric Motion Vectors ◽  
The Impact

This study investigates and assesses the impact of assimilating data types (observed data surface, sounding, and satellite-derived atmospheric motion vectors – AMVs) for the Weather Research and Forecasting (WRF) in forecasting heavy rainfall over Central Highlands region, due to the impact of hurricane Damrey. The WRF model combined with the Gridpoint Statistical Interpolation (GSI) system, was started running at 12Z 03/11/2017, and 84h forecasts in advance, with two kinds for running assimilation "cold start" and "warm start", and with the three-dimensional variational data assimilation (3D-Var) method. The results showed that assimilated cases have improved forecasting about spatial distribution and amount of rainfall at a 24-hour lead time, in which, the "warm start" for better forecasting. Notably, the assimilation of AMVs data with the "warm start" run has improved forecasting quality of heavy rainfall, the POD, FAR, and CSI indicators are the best at the 24-hour lead time, for rainfall thresholds greater than 80mm.    

scholarly journals Investigasi Pengaruh Skenario Modifikasi Urbanisasi pada Perubahan Hujan di Kota Makassar

2020 ◽  
Vol 5 ◽  
Author(s):  
Fitria Puspita Sari ◽  
Satriawan Nadhrotal Atsidiqi
Keyword(s):  
Urban Areas ◽  
Three Dimensional ◽  
Wrf Model ◽  
Heavy Rain ◽  
Urban Heat Islands ◽  
Weather Research And Forecasting ◽  
Rain Event ◽  
Monsoon Period ◽  
Urban Heat ◽  
Weather Research

<p class="AbstractEnglish"><strong>Abstract:</strong> Urbanization affects the atmosphere through the urban heat island (UHI) process, resulting in the change of rain patterns over urban areas. Makassar as the one of big cities in Indonesia is assumed to be suffering from this effect, thus an investigation related to the issue needs to be done.  This study contains a simulation of urbanization scenarios using a three-dimensional non-hydrostatic Weather Research and Forecasting (WRF) Model during the transition monsoon period: September-October-November (SON) 2014-2018. The study covers 5 selected heavy-rain-event during the SON period: 24 September 2016, 9 October 2016, 24 October 2016, 22 November 2016, and 23 September 2017. Result shows that the model is able to simulate some weather parameters with relatively small root-mean-square-error (RMSE) and high correlation on three rain event cases. Afterwards, scenarios of 25% and 50% increasing urban area towards Makassar coastal line (as reclamation plan) and existing urban areas have been done.  The results show that urbanization increases daily average temperature over urban areas, so does UHI maximum reach number of 1.5°C for both scenarios on 24 September 2016 rain event. Also, it increases rain accumulation up to 50% over reclamation areas and relativeky decreases rainfall over existing urban areas. </p><p class="AbstrakIndonesia"><strong>Abstrak:</strong> Peningkatan jumlah penduduk dan kegiatan urbanisasi dapat mengubah interaksi atmosfer melalui penambahan pelepasan panas yang menyebabkan terjadinya efek <em>urban heat islands </em>(UHI) serta perubahan hujan di wilayah perkotaan. Sebagai salah satu kota metropolitan di Indonesia, Makassar dimungkinkan terdampak oleh efek UHI tersebut. Sehingga penelitian ini dilakukan untuk mengetahui dampak urbanisasi terhadap perubahan akumulasi dan/atau pola hujan di wilayah Makassar sesuai skenario jumlah penduduk tahun 2045. Investigasi dilakukan dengan memanfaatkan model non-hidrostatik tiga dimensi <em>Weather Research and Forecasting (</em>WRF) pada musim transisi September-Oktober-November (SON) 2014-2018. Kejadian hujan lebat terpilih sebanyak 5 hari yakni tanggal 24 September 2016, 9 Oktober 2016, 24 Oktober 2016, 22 November 2016, dan 23 September 2017. Verifikasi model dilakukan dengan menggunakan metode statistik. Hasilnya, model mampu digunakan untuk mensimulasikan tiga dari lima kejadian hujan lebat dengan nilai RMSE relatif rendah dan korelasi tinggi. Selanjutnya, skenario modifikasi dilakukan dengan menambahkan wilayah urban sebesar 25% dan 50% untuk masing-masing area di bagian pantai (sesuai rencana reklamasi) dan taman kota. Dari hasil simulasi hujan lebat tanggal 24 September 2016 diketahui bahwa urbanisasi meningkatkan rataan suhu harian wilayah perkotaan yang menyebabakan UHI maksimum meningkat antara 0.1° hingga 1.5°C pada dua skenario modifikasi. Selain itu skenario modifikasi urbanisasi menyebabkan peningkatan hujan sebesar 50% di area reklamasi dan cenderung normal bahkan mengalami penurunan di wilayah taman kota sekitar Universitas Hasanuddin.</p>

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