scholarly journals Ensemble Forecasting Experiments Using the Breeding of Growing Modes with Perturbed Land Variables

Atmosphere ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1578
Author(s):  
Xin-Min Zeng ◽  
Yong-Jing Liang ◽  
Yang Wang ◽  
Yi-Qun Zheng
Keyword(s):  
Growth Rate ◽  
Land Surface ◽  
Heavy Rainfall ◽  
Mesoscale Model ◽  
Ensemble Forecasting ◽  
Probability Forecast ◽  
Ensemble Forecasts ◽  
Atmospheric Processes ◽  
Simulated Precipitation ◽  
Atmospheric Variables

Although land surface influences atmospheric processes significantly, insufficient studies have been conducted on the ensemble forecasts using the breeding of growing modes (BGM) with perturbed land surface variables. To investigate the practicability of perturbed land variables for ensemble forecasting, we used the ARWv3 mesoscale model to generate ensembles for an event of 24 h heavy rainfall with perturbed atmospheric and land variables by the BGM method. Results show that both atmospheric and land variables can generate initial perturbations with BGM, except that they differ in time and saturation characteristics, e.g., saturation is generally achieved in approximately 30 h with a growth rate of ~1.30 for atmospheric variables versus 102 h and growth rate of 1.02 for land variables. With the increase in precipitation, the importance of the perturbations of land variables also increases as compared to those of atmospheric variables. Moreover, the influence of the perturbations of land variables on simulated precipitation is still relatively large, although smaller than that of atmospheric variables, e.g., the spreads of perturbed atmospheric and land subsets were 7.3 and 3.8 mm, respectively. The benefits of perturbed initialisation can also be observed in terms of probability forecast. All findings indicate that the BGM method with perturbed land variables has the potential to ensemble forecasts for precipitation.

Intercomparison of Mesoscale Model Simulations of the Daytime Valley Wind System

2011 ◽  
Vol 139 (5) ◽  
pp. 1389-1409 ◽  
Author(s):  
Juerg Schmidli ◽  
Brian Billings ◽  
Fotini K. Chow ◽  
Stephan F. J. de Wekker ◽  
James Doyle ◽  
...  
Keyword(s):  
Land Surface ◽  
Mesoscale Model ◽  
Numerical Models ◽  
Surface Wind ◽  
Sensible Heat Flux ◽  
Surface Wind Speed ◽  
Time Shift ◽  
Wind System ◽  
Valley Wind ◽  
The Mean

Three-dimensional simulations of the daytime thermally induced valley wind system for an idealized valley–plain configuration, obtained from nine nonhydrostatic mesoscale models, are compared with special emphasis on the evolution of the along-valley wind. The models use the same initial and lateral boundary conditions, and standard parameterizations for turbulence, radiation, and land surface processes. The evolution of the mean along-valley wind (averaged over the valley cross section) is similar for all models, except for a time shift between individual models of up to 2 h and slight differences in the speed of the evolution. The analysis suggests that these differences are primarily due to differences in the simulated surface energy balance such as the dependence of the sensible heat flux on surface wind speed. Additional sensitivity experiments indicate that the evolution of the mean along-valley flow is largely independent of the choice of the dynamical core and of the turbulence parameterization scheme. The latter does, however, have a significant influence on the vertical structure of the boundary layer and of the along-valley wind. Thus, this ideal case may be useful for testing and evaluation of mesoscale numerical models with respect to land surface–atmosphere interactions and turbulence parameterizations.

Comments on “Impacts of CO2-Induced Warming on Simulated Hurricane Intensity and Precipitation: Sensitivity to the Choice of Climate Model and Convective Scheme”

2005 ◽  
Vol 18 (23) ◽  
pp. 5179-5182 ◽  
Author(s):  
Patrick J. Michaels ◽  
Paul C. Knappenberger ◽  
Christopher Landsea
Keyword(s):  
Carbon Dioxide ◽  
Growth Rate ◽  
Tropical Cyclones ◽  
Real World ◽  
Climate Model ◽  
Mesoscale Model ◽  
Strong Relationship ◽  
Sea Surface ◽  
Hurricane Intensity ◽  
Convective Scheme

Abstract In a simulation of enhanced tropical cyclones in a warmer world, Knutson and Tuleya make several assumptions that are not borne out in the real world. They include an unrealistically large carbon dioxide growth rate, an overly strong relationship between sea surface temperature and hurricane intensity, and the use of a mesoscale model that has shown little to no useful skill in predicting current-day hurricane intensity. After accounting for these inaccuracies, a detectable increase in Atlantic hurricane intensity in response to growing atmospheric greenhouse gas levels during this century becomes unlikely.

scholarly journals Role of land state in a high resolution mesoscale model for simulating the Uttarakhand heavy rainfall event over India

2016 ◽  
Vol 125 (3) ◽  
pp. 475-498 ◽  
Author(s):  
P V Rajesh ◽  
S Pattnaik ◽  
D Rai ◽  
K K Osuri ◽  
U C Mohanty ◽  
...  
Keyword(s):  
High Resolution ◽  
Heavy Rainfall ◽  
Mesoscale Model ◽  
Rainfall Event ◽  
Heavy Rainfall Event

scholarly journals Validation and Sensitivities of Dynamic Precipitation Simulation for Winter Events over the Folsom Lake Watershed: 1964–99

2005 ◽  
Vol 133 (1) ◽  
pp. 3-19 ◽  
Author(s):  
Jianzhong Wang ◽  
Konstantine P. Georgakakos
Keyword(s):  
Sierra Nevada ◽  
Mesoscale Model ◽  
Pilot Project ◽  
Storm Events ◽  
Bias Score ◽  
Warm Start ◽  
Precipitation Simulation ◽  
Simulated Precipitation ◽  
Precipitation Gauge ◽  
Folsom Lake

Abstract A total of 62 winter-storm events in the period 1964–99 over the Folsom Lake watershed located at the windward slope of the Sierra Nevada were simulated with a 9-km resolution using the fifth-generation Pennsylvania State University–NCAR Mesoscale Model (MM5). Mean areal precipitation (MAP) over the entire watershed and each of four subbasins was estimated based on gridded simulated precipitation. The simulated MAP was verified with MAP estimated (a) by the California Nevada River Forecast Center (CNRFC) for the four subbasins based on eight operational precipitation stations, and (b) for the period from 1980 to 1986, on the basis of a denser precipitation observing network deployed by the Sierra Cooperative Pilot Project (SCPP). A number of sensitivity runs were performed to understand the dependence of model precipitation on boundary and initial fields, cold versus warm start, and microphysical parameterization. The principal findings of the validation analysis are that (a) MM5 achieves a good percentage bias score of 103% in simulating Folsom basin MAP when compared to MAP derived from dense precipitation gauge networks; (b) spatial grid resolution higher than 9 km is necessary to reproduce the spatial MAP pattern among subbasins of the Folsom basin; and (c) the model performs better for heavy than for light and moderate precipitation. The analysis also showed significant simulation dependence on the spatial resolution of the boundary and initial fields and on the microphysical scheme used.

scholarly journals Advantages of using a fast urban canopy model as compared to a full mesoscale model to simulate the urban heat island of Barcelona

2016 ◽  
Author(s):  
M. García-Díez ◽  
D. Lauwaet ◽  
H. Hooyberghs ◽  
J. Ballester ◽  
K. De Ridder ◽  
...  
Keyword(s):  
Simple Model ◽  
Land Surface ◽  
Climate Model ◽  
Mesoscale Model ◽  
Urban Climate ◽  
Urban Canopy ◽  
Forecast Model ◽  
Reanalysis Data ◽  
Urban Canopy Model ◽  
Canopy Model

Abstract. As most of the population lives in urban environments, the simulation of the urban climate has become a key problem in the framework of the climate change impact assessment. However, the high computational power required by these simulations is a severe limitation. Here we present a study on the performance of a Urban Climate Model (UrbClim), designed to be several orders of magnitude faster than a full-fledge mesoscale model. The simulations are validated with station data and with land surface temperature observations retrieved by satellites. To explore the advantages of using a simple model like UrbClim, the results are compared with a simulation carried out with a state-of-the-art mesoscale model, the Weather Research and Forecasting model, using an Urban Canopy model. The effect of using different driving data is explored too, by using both relatively low resolution reanalysis data (70 km) and a higher resolution forecast model (15 km). The results show that, generally, the performance of the simple model is comparable to or better than the mesoscale model. The exception are the winds and the day-to-day correlation in the reanalysis driven run, but these problems disappear when taking the boundary conditions from the higher resolution forecast model.

scholarly journals Initiation and Maintenance Mechanisms for Heavy Precipitation System over a Mountainous Island under a Prevailing Monsoon Current

2016 ◽  
Vol 5 (2) ◽  
pp. 90
Author(s):  
Y.-L. Lin ◽  
K.-Y. Lee ◽  
C.-S. Chen ◽  
F.-Y. Cheng ◽  
P.-L. Lin ◽  
...  
Keyword(s):  
Heavy Rainfall ◽  
Mesoscale Model ◽  
Convective Available Potential Energy ◽  
Leading Edge ◽  
Western Slope ◽  
Mountain Range ◽  
Unstable Flow ◽  
Near Surface ◽  
Precipitation System ◽  
Early Afternoon

In this study, the initiation and maintenance mechanisms of two long-lived, summer heavy rainfall systems over Taiwan are investigated by performing observational data analyses and numerical simulations using a mesoscale model. For both cases of 9-10 July 2008 (Case A) and 18-19 August 2006 (Case B), the heavy rainfall system developed over the western slope of the Central Mountain Range (CMR) under low-level prevailing southwesterly and westerly flows in early afternoon, respectively. These heavy rainfall systems were moving westward toward Taiwan Strait from CMR, while the embedded individual cells were moving in the opposite direction, behaving like a multicell storm. It was also found these individual cells were initiated, enhanced, and then maintained at the leading edge of the near-surface cool outflow and merged with the heavy rainfall systems which became long-lived. These heavy rainfall systems were classified as an upstream propagating precipitation system in a low Froude-number, conditionally unstable flow with high convective available potential energy (CAPE) or Regime I as proposed in a previous study.

scholarly journals Continuous high-resolution midlatitude-belt simulations for July–August 2013 with WRF

2017 ◽  
Vol 10 (5) ◽  
pp. 2031-2055 ◽  
Author(s):  
Thomas Schwitalla ◽  
Hans-Stefan Bauer ◽  
Volker Wulfmeyer ◽  
Kirsten Warrach-Sagi
Keyword(s):  
High Resolution ◽  
Land Surface ◽  
Large Scale ◽  
Temperature Fields ◽  
Surface Model ◽  
Limited Area ◽  
Data Set ◽  
Latitude Belt ◽  
Simulated Precipitation ◽  
The Impact

Abstract. Increasing computational resources and the demands of impact modelers, stake holders, and society envision seasonal and climate simulations with the convection-permitting resolution. So far such a resolution is only achieved with a limited-area model whose results are impacted by zonal and meridional boundaries. Here, we present the setup of a latitude-belt domain that reduces disturbances originating from the western and eastern boundaries and therefore allows for studying the impact of model resolution and physical parameterization. The Weather Research and Forecasting (WRF) model coupled to the NOAH land–surface model was operated during July and August 2013 at two different horizontal resolutions, namely 0.03 (HIRES) and 0.12° (LOWRES). Both simulations were forced by the European Centre for Medium-Range Weather Forecasts (ECMWF) operational analysis data at the northern and southern domain boundaries, and the high-resolution Operational Sea Surface Temperature and Sea Ice Analysis (OSTIA) data at the sea surface.The simulations are compared to the operational ECMWF analysis for the representation of large-scale features. To analyze the simulated precipitation, the operational ECMWF forecast, the CPC MORPHing (CMORPH), and the ENSEMBLES gridded observation precipitation data set (E-OBS) were used as references.Analyzing pressure, geopotential height, wind, and temperature fields as well as precipitation revealed (1) a benefit from the higher resolution concerning the reduction of monthly biases, root mean square error, and an improved Pearson skill score, and (2) deficiencies in the physical parameterizations leading to notable biases in distinct regions like the polar Atlantic for the LOWRES simulation, the North Pacific, and Inner Mongolia for both resolutions.In summary, the application of a latitude belt on a convection-permitting resolution shows promising results that are beneficial for future seasonal forecasting.

scholarly journals Impact of Parameterization of Physical Processes on Simulation of Track and Intensity of Tropical Cyclone Nargis (2008) with WRF-NMM Model

2012 ◽  
Vol 2012 ◽  
pp. 1-18 ◽  
Author(s):  
Sujata Pattanayak ◽  
U. C. Mohanty ◽  
Krishna K. Osuri
Keyword(s):  
Land Surface ◽  
Mesoscale Model ◽  
Initial Conditions ◽  
Surface Wind ◽  
India Meteorological Department ◽  
Heat Fluxes ◽  
Cumulus Convection ◽  
Cyclonic Storm ◽  
Parameterization Schemes ◽  
Cyclone Nargis

The present study is carried out to investigate the performance of different cumulus convection, planetary boundary layer, land surface processes, and microphysics parameterization schemes in the simulation of a very severe cyclonic storm (VSCS) Nargis (2008), developed in the central Bay of Bengal on 27 April 2008. For this purpose, the nonhydrostatic mesoscale model (NMM) dynamic core of weather research and forecasting (WRF) system is used. Model-simulated track positions and intensity in terms of minimum central mean sea level pressure (MSLP), maximum surface wind (10 m), and precipitation are verified with observations as provided by the India Meteorological Department (IMD) and Tropical Rainfall Measurement Mission (TRMM). The estimated optimum combination is reinvestigated with six different initial conditions of the same case to have better conclusion on the performance of WRF-NMM. A few more diagnostic fields like vertical velocity, vorticity, and heat fluxes are also evaluated. The results indicate that cumulus convection play an important role in the movement of the cyclone, and PBL has a crucial role in the intensification of the storm. The combination of Simplified Arakawa Schubert (SAS) convection, Yonsei University (YSU) PBL, NMM land surface, and Ferrier microphysics parameterization schemes in WRF-NMM give better track and intensity forecast with minimum vector displacement error.

scholarly journals An investigation of ozone and planetary boundary layer dynamics over the complex topography of Grenoble combining measurements and modeling

2003 ◽  
Vol 3 (1) ◽  
pp. 797-825 ◽  
Author(s):  
O. Couach ◽  
I Balin ◽  
R. Jiménez ◽  
P. Ristori ◽  
S. Perego ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Planetary Boundary Layer ◽  
Land Surface ◽  
Mesoscale Model ◽  
Ozone Production ◽  
Horizontal Wind ◽  
Maximum Height ◽  
Complex Topography ◽  
Atmospheric Measurements ◽  
Model Calculations

Abstract. This paper concerns an evaluation of ozone (O3) and planetary boundary layer (PBL) dynamics over the complex topography of the Grenoble region through a combination of measurements and mesoscale model (METPHOMOD) predictions for three days, during July 1999. The measurements of O3 and PBL structure were obtained with a Differential Absorption Lidar (DIAL) system, situated 20 km south of Grenoble at Vif (310 m a.s.l.). The combined lidar observations and model calculations are in good agreement with atmospheric measurements obtained with an instrumented aircraft (METAIR). Ozone fluxes were calculated using lidar measurements of ozone vertical profiles concentrations and the horizontal wind speeds measured with a Radar Doppler wind profiler (DEGREANE). The ozone flux patterns indicate that the diurnal cycle of ozone production is controlled by local thermal winds. The convective PBL maximum height was some 2700 m above the land surface while the nighttime residual ozone layer was generally found between 1200 and 2200 m. Finally we evaluate the magnitude of the ozone processes at different altitudes in order to estimate the photochemical ozone production due to the primary pollutants emissions of Grenoble city and the regional network of automobile traffic.

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