Inversion skill for limited-area shelf modeling. Part I: An OSSE case study

2001 ◽  
Vol 21 (11-12) ◽  
pp. 1121-1137 ◽  
Author(s):  
Christopher E. Naimie ◽  
Daniel R. Lynch
Keyword(s):  
Limited Area

scholarly journals Numerical simulations of June 7, 2020 convective precipitation over Slovakia using deterministic, probabilistic, and convection-permitting approaches

Időjárás ◽  
2021 ◽  
Vol 125 (4) ◽  
pp. 571-607
Author(s):  
André Simon ◽  
Martin Belluš ◽  
Katarína Čatlošová ◽  
Mária Derková ◽  
Martin Dian ◽  
...  
Keyword(s):  
Satellite Imagery ◽  
Weather Prediction ◽  
Severe Weather ◽  
Precipitation Forecast ◽  
Convective Precipitation ◽  
Small Scale ◽  
Limited Area ◽  
Systematic Effect ◽  
The Impact

The paper presented is dedicated to the evaluation of the influence of various improvements to the numerical weather prediction (NWP) systems exploited at the Slovak Hydrometeorological Institute (SHMÚ). The impact was illustrated in a case study with multicell thunderstorms and the results were confronted with the reference analyses from the INCA nowcasting system, regional radar reflectivity data, and METEOSAT satellite imagery. The convective cells evolution was diagnosed in non-hydrostatic dynamics experiments to study weak mesoscale vortices and updrafts. The growth of simulated clouds and evolution of the temperature at their top were compared with the brightness temperature analyzed from satellite imagery. The results obtained indicated the potential for modeling and diagnostics of small-scale structures within the convective cloudiness, which could be related to severe weather. Furthermore, the non-hydrostatic dynamics experiments related to the stability and performance improvement of the time scheme led to the formulation of a new approach to linear operator definition for semi-implicit scheme (in text referred as NHHY). We demonstrate that the execution efficiency has improved by more than 20%. The exploitation of several high resolution measurement types in data assimilation contributed to more precise position of predicted patterns and precipitation representation in the case study. The non-hydrostatic dynamics provided more detailed structures. On the other hand, the potential of a single deterministic forecast of prefrontal heavy precipitation was not as high as provided by the ensemble system. The prediction of a regional ensemble system A-LAEF (ALARO Limited Area Ensemble Forecast) enhanced the localization of precipitation patterns. Though, this was rather due to the simulation of uncertainty in the initial conditions and also because of the stochastic perturbation of physics tendencies. The various physical parameterization setups of A-LAEF members did not exhibit a systematic effect on precipitation forecast in the evaluated case. Moreover, the ensemble system allowed an estimation of uncertainty in a rapidly developing severe weather case, which was high even at very short range.

scholarly journals Effects of temperature on flood forecasting: analysis of an operative case study in Alpine basins

2013 ◽  
Vol 13 (4) ◽  
pp. 1051-1062 ◽  
Author(s):  
A. Ceppi ◽  
G. Ravazzani ◽  
A. Salandin ◽  
D. Rabuffetti ◽  
A. Montani ◽  
...  
Keyword(s):  
Limited Area ◽  
Ensemble Forecasts ◽  
Meteorological Forcing ◽  
Snow Line ◽  
Operative Case ◽  
Hydrostatic Model ◽  
Forecasting Analysis ◽  
Time Systems

Abstract. In recent years the interest in the forecast and prevention of natural hazards related to hydro-meteorological events has increased the challenge for numerical weather modelling, in particular for limited area models, to improve the quantitative precipitation forecasts (QPF) for hydrological purposes. After the encouraging results obtained in the MAP D-PHASE Project, we decided to devote further analyses to show recent improvements in the operational use of hydro-meteorological chains, and above all to better investigate the key role played by temperature during snowy precipitation. In this study we present a reanalysis simulation of one meteorological event, which occurred in November 2008 in the Piedmont Region. The attention is focused on the key role of air temperature, which is a crucial feature in determining the partitioning of precipitation in solid and liquid phase, influencing the quantitative discharge forecast (QDF) into the Alpine region. This is linked to the basin ipsographic curve and therefore by the total contributing area related to the snow line of the event. In order to assess hydrological predictions affected by meteorological forcing, a sensitivity analysis of the model output was carried out to evaluate different simulation scenarios, considering the forecast effects which can radically modify the discharge forecast. Results show how in real-time systems hydrological forecasters have to consider also the temperature uncertainty in forecasts in order to better understand the snow dynamics and its effect on runoff during a meteorological warning with a crucial snow line over the basin. The hydrological ensemble forecasts are based on the 16 members of the meteorological ensemble system COSMO-LEPS (developed by ARPA-SIMC) based on the non-hydrostatic model COSMO, while the hydrological model used to generate the runoff simulations is the rainfall–runoff distributed FEST-WB model, developed at Politecnico di Milano.

Impact of soil surface moisture initialization on rainfall in a limited area model: a case study of the 1995 South Ticino flash flood

2002 ◽  
Vol 16 (6) ◽  
pp. 1301-1317 ◽  
Author(s):  
C. Cassardo ◽  
G. P. Balsamo ◽  
C. Cacciamani ◽  
D. Cesari ◽  
T. Paccagnella ◽  
...  
Keyword(s):  
Flash Flood ◽  
Soil Surface ◽  
Limited Area ◽  
Limited Area Model ◽  
Area Model ◽  
Surface Moisture

scholarly journals Multisensor Comparison and Numerical Modeling of Atmospheric Water Fields: A VOLTAIRE Case Study over Cyprus

2008 ◽  
Vol 23 (4) ◽  
pp. 674-701 ◽  
Author(s):  
Stefano Mariani ◽  
Christophe Accadia ◽  
Nazario Tartaglione ◽  
Marco Casaioli ◽  
Marco Gabella ◽  
...  
Keyword(s):  
Water Vapor ◽  
Mediterranean Sea ◽  
Rain Gauge ◽  
Limited Area ◽  
Atmospheric Water ◽  
Limited Area Model ◽  
Trmm Pr ◽  
Rain Gauge Network ◽  
Total Column

Abstract This paper presents a study performed within the framework of the European Union’s (EU) VOLTAIRE project (Fifth Framework Programme). Among other tasks, the project aimed at the integration of the Tropical Rainfall Measuring Mission (TRMM) data with ground-based observations and at the comparison between water fields (precipitation and total column water vapor) as estimated by multisensor observations and predicted by NWP models. In particular, the VOLTAIRE project had as one of its main objectives the goal of assessing the application of satellite-borne instrument measures to model verification. The island of Cyprus was chosen as the main “test bed,” because it is one of the few European territories covered by the passage of the TRMM Precipitation Radar (PR) and it has a dense rain gauge network and an operational weather radar. TRMM PR provides, until now, the most reliable space-borne spatial high-resolution precipitation measurements. Attention is focused on the attempt to define a methodology, using state-of-the-art diagnostic methods, for a comprehensive evaluation of water fields as forecast by a limited area model (LAM). An event that occurred on 5 March 2003, associated with a slow cyclone moving eastward over the Mediterranean Sea, is presented as a case study. The atmospheric water fields were forecast over the eastern Mediterranean Sea using the Bologna Limited Area Model (BOLAM). Data from the Cyprus ground-based radar, the Cyprus rain gauge network, the Special Sensor Microwave Imager (SSM/I), and the TRMM PR were used in the comparison. Ground-based radar and rain gauge data were merged together in order to obtain a better representation of the rainfall event over the island. TRMM PR measurements were employed to range-adjust the ground-based radar data using a linear regression algorithm. The observed total column water vapor has been employed to assess the forecast quality of large-scale atmospheric patterns; such an assessment has been performed by means of the Hoffman diagnostic method applied to the entire total column water vapor field. Subsequently, in order to quantify the spatial forecast error at the finer BOLAM scale (0.09°), the object-oriented contiguous rain area (CRA) analysis was chosen as a comparison method for precipitation. An assessment of the main difficulties in employing CRA in an operational framework, especially over such a small verification domain, is also discussed in the paper.

The Diurnal and Seasonal Variation of the Northern Australian Dryline

2007 ◽  
Vol 135 (8) ◽  
pp. 2995-3008 ◽  
Author(s):  
Sarah J. Arnup ◽  
Michael J. Reeder
Keyword(s):  
Great Plains ◽  
Sea Breeze ◽  
The United States ◽  
Moisture Gradient ◽  
Limited Area ◽  
Mixing Ratio ◽  
Prediction Scheme ◽  
Thermodynamic Variables ◽  
Good Agreement

Abstract The diurnal and seasonal variations of the northern Australian dryline are examined by constructing climatologies of low-level dynamic and thermodynamic variables taken from the high-resolution Australian Bureau of Meteorology’s Limited Area Prediction Scheme (LAPS) forecasts from 2000 to 2003. The development of the dryline is analyzed within the framework of the frontogenesis function applied to the mixing ratio and the airstream diagnostics of Cohen and Schultz. A case study of 12–13 October 2002 illustrating the airmass boundaries over the Australian region is also examined. Daytime surface heating produces sea-breeze circulations around the coast and a large inland heat trough that extends east–west along northern Australia. At night, air parcels accelerate toward low pressure, increasing convergence and deformation within the heat trough. This sharpens the moisture gradient across the tropical and continental airmass boundary into a dryline. This is different than the dryline of the Great Plains in the United States, which generally weakens overnight. The Australian dryline is strongest in spring just poleward of the Gulf of Carpentaria, where the moisture gradient across the heat trough is enhanced by the coast, and the axis of dilatation is closely aligned with mixing ratio isopleths. The dryline is weakest in winter, when the heat trough is weak. The LAPS 3-h forecasts are in good agreement with observations obtained from the Automatic Weather Station network. The 3-h forecasts capture the observed diurnal and seasonal cycle of the airmass boundaries. However, the sea-breeze circulation and ageostrophic flow into the surface heat trough is limited by the model resolution. The LAPS 3-h forecasts may therefore underestimate the nocturnal intensification of the dryline, especially since the inland moisture content is overestimated.

scholarly journals The isotopic composition of precipitation from a winter storm – a case study with the limited-area model COSMO<sub>iso</sub>

2011 ◽  
Vol 11 (9) ◽  
pp. 26521-26570
Author(s):  
S. Pfahl ◽  
H. Wernli ◽  
K. Yoshimura
Keyword(s):  
Isotopic Composition ◽  
Spatial Pattern ◽  
Water Vapour ◽  
Water Isotopes ◽  
Limited Area ◽  
Synoptic Scale ◽  
Winter Storm ◽  
Limited Area Model ◽  
Area Model

Abstract. Stable water isotopes are valuable tracers of the atmospheric water cycle, and potentially provide useful information also on weather-related processes. In order to further explore this potential, the water isotopes H218O and HDO are incorporated into the limited-area model COSMO. In a first case study, the new COSMOiso model is used for simulating a winter storm event in January 1986 over the eastern United States associated with intense frontal precipitation. The modelled isotope ratios in precipitation and water vapour are compared to spatially distributed δ18O observations. COSMOiso very accurately reproduces the statistical distribution of δ18O in precipitation, and also the synoptic-scale spatial pattern and temporal evolution agree well with the measurements. Perpendicular to the front that triggers most of the rainfall during the event, the model simulates a gradient in the isotopic composition of the precipitation, with high δ18O values in the warm air and lower values in the cold sector behind the front. This spatial pattern is created through an interplay of large scale air mass advection, removal of heavy isotopes by precipitation at the front and microphysical interactions between rain drops and water vapour beneath the cloud base. This investigation illustrates the usefulness of high resolution, event-based model simulations for understanding the complex processes that cause synoptic-scale variability of the isotopic composition of atmospheric waters. In future research, this will be particularly beneficial in combination with laser spectrometric isotope observations with high temporal resolution.

scholarly journals Case study of a moisture intrusion over the Arctic with the ICOsahedral Non-hydrostatic (ICON) model: resolution dependence of its representation

2022 ◽  
Vol 22 (1) ◽  
pp. 173-196
Author(s):  
Hélène Bresson ◽  
Annette Rinke ◽  
Mario Mech ◽  
Daniel Reinert ◽  
Vera Schemann ◽  
...  
Keyword(s):  
High Resolution ◽  
Temporal Structure ◽  
Specific Humidity ◽  
The Arctic ◽  
Limited Area ◽  
Turbulent Heat ◽  
Strong Impact ◽  
Downward Longwave Radiation ◽  
Spatio Temporal

Abstract. The Arctic is warming faster than the global average and any other region of a similar size. One important factor in this is the poleward atmospheric transport of heat and moisture, which contributes directly to the surface and air warming. In this case study, the atmospheric circulation and spatio-temporal structure of a moisture intrusion event is assessed, which occurred from 5 to 7 June 2017 over the Nordic seas during an intensive measurement campaign over Svalbard. This analysis focuses on high-spatial-resolution simulations with the ICON (ICOsahedral Non-hydrostatic) model which is put in context with coarser-resolution runs as well the ERA5 reanalysis. A variety of observations including passive microwave satellite measurements is used for evaluation. The global operational ICON forecasts from the Deutscher Wetterdienst (DWD) at 13 km horizontal resolution are used to drive high-resolution Limited-Area Mode (LAM) ICON simulations over the Arctic with 6 and 3 km horizontal resolutions. The results show the skilful capacity of the ICON-LAM model to represent the observed spatio-temporal structure of the selected moisture intrusion event and its signature in the temperature, humidity and wind profiles, and surface radiation. In several aspects, the high-resolution simulations offer a higher accuracy than the global simulations and the ERA5 reanalysis when evaluated against observations. One feature where the high-resolution simulations demonstrated an advanced skill is the representation of the changing vertical structure of specific humidity and wind associated with the moisture intrusion passing Ny-Ålesund (western Svalbard); the humidity increase at 1–2 km height topped by a dry layer and the development of a low-level wind jet are best represented by the 3 km simulation. The study also demonstrates that such moisture intrusions can have a strong impact on the radiative and turbulent heat fluxes at the surface. A drastic decrease in downward shortwave radiation by ca. 500 W m−2 as well as an increase in downward longwave radiation by ca. 100 W m−2 within 3 h have been determined. These results highlight the importance of both moisture and clouds associated with this event for the surface energy budget.

Sign in / Sign up

Export Citation Format

Share Document