scholarly journals Influence of Parameterization of Some Physical Processes in Soils on Numerical Meteorological Forecasts of Surface Fields

2016 ◽  
Vol 20 (4) ◽  
pp. 48-58
Author(s):  
Andrzej Mazur ◽  
Grzegorz Duniec
Keyword(s):  
Boundary Layer ◽  
Numerical Models ◽  
Weather Prediction ◽  
Water System ◽  
Soil Processes ◽  
Plant Water ◽  
Physical Processes ◽  
High Quality ◽  
Nwp Model ◽  
Surface Fields

Abstract Physical processes in soil-plant-water system are very complicated. Complex physical processes in soil, in particular interaction between soil-plant-water system have significant influence on processes in Planetary Boundary Layer. Changes of soil state can significantly modify processes in the PBL and meteorological fields. Since numerical models are to determine the forecast of high quality, the physical processes occurring in soil should be properly described and then appropriately introduced into a model. Every process in soil occurs on a smaller scale than original model’s domain, so it should be described via adequate parameterization. Overall, soil parameterizations implemented in current numerical weather prediction (NWP) model(s) were prepared almost 40 years ago, when NWP models worked with very poor resolution mesh. Since nowadays NWP works over domains of high resolution, these “old” schemes parameterization must be adequately revised. In this paper preliminary results of changes of parameterization of soil processes will be presented.

scholarly journals An Overview of the Urban Boundary Layer Atmosphere Network in Helsinki

2013 ◽  
Vol 94 (11) ◽  
pp. 1675-1690 ◽  
Author(s):  
C. R. Wood ◽  
L. Järvi ◽  
R. D. Kouznetsov ◽  
A. Nordbo ◽  
S. Joffre ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Air Quality ◽  
Doppler Radar ◽  
Numerical Models ◽  
Weather Prediction ◽  
Urban Boundary Layer ◽  
Urban Surface ◽  
Physical Processes ◽  
Research Grade ◽  
Set Up

The Helsinki Urban Boundary-Layer Atmosphere Network (UrBAN: http://urban.fmi.fi) is a dedicated research-grade observational network where the physical processes in the atmosphere above the city are studied. Helsinki UrBAN is the most poleward intensive urban research observation network in the world and thus will allow studying some unique features such as strong seasonality. The network's key purpose is for the understanding of the physical processes in the urban boundary layer and associated fluxes of heat, momentum, moisture, and other gases. A further purpose is to secure a research-grade database, which can be used internationally to validate and develop numerical models of air quality and weather prediction. Scintillometers, a scanning Doppler lidar, ceilometers, a sodar, eddy-covariance stations, and radiometers are used. This equipment is supplemented by auxiliary measurements, which were primarily set up for general weather and/or air-quality mandatory purposes, such as vertical soundings and the operational Doppler radar network. Examples are presented as a testimony to the potential of the network for urban studies, such as (i) evidence of a stable boundary layer possibly coupled to an urban surface, (ii) the comparison of scintillometer data with sonic anemometry above an urban surface, (iii) the application of scanning lidar over a city, and (iv) combination of sodar and lidar to give a fuller range of sampling heights for boundary layer profiling.

scholarly journals A review of operational, regional-scale, chemical weather forecasting models in Europe

2012 ◽  
Vol 12 (1) ◽  
pp. 1-87 ◽  
Author(s):  
J. Kukkonen ◽  
T. Olsson ◽  
D. M. Schultz ◽  
A. Baklanov ◽  
T. Klein ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Weather Forecasting ◽  
Numerical Models ◽  
Weather Prediction ◽  
Regional Scale ◽  
Chemical Species ◽  
Future Research ◽  
Physical Processes ◽  
Forecasting Models ◽  
Air Chemistry

Abstract. Numerical models that combine weather forecasting and atmospheric chemistry are here referred to as chemical weather forecasting models. Eighteen operational chemical weather forecasting models on regional and continental scales in Europe are described and compared in this article. Topics discussed in this article include how weather forecasting and atmospheric chemistry models are integrated into chemical weather forecasting systems, how physical processes are incorporated into the models through parameterization schemes, how the model architecture affects the predicted variables, and how air chemistry and aerosol processes are formulated. In addition, we discuss sensitivity analysis and evaluation of the models, user operational requirements, such as model availability and documentation, and output availability and dissemination. In this manner, this article allows for the evaluation of the relative strengths and weaknesses of the various modelling systems and modelling approaches. Finally, this article highlights the most prominent gaps of knowledge for chemical weather forecasting models and suggests potential priorities for future research directions, for the following selected focus areas: emission inventories, the integration of numerical weather prediction and atmospheric chemical transport models, boundary conditions and nesting of models, data assimilation of the various chemical species, improved understanding and parameterization of physical processes, better evaluation of models against data and the construction of model ensembles.

scholarly journals Low-level windshear associated with atmospheric boundary layer jets – Case studies

Atmósfera ◽  
2020 ◽  
Vol 34 (4) ◽  
pp. 461-490
Author(s):  
P. W. Chan ◽  
K. K. Hon ◽  
Q. S. Li
Keyword(s):  
Boundary Layer ◽  
Atmospheric Boundary Layer ◽  
Southern China ◽  
Weather Prediction ◽  
Northeast Monsoon ◽  
Jet Streams ◽  
Easterly Wind ◽  
Low Level ◽  
Reasonable Prediction ◽  
Nwp Model

Jet streams in the atmospheric boundary layer may lead to hazardous weather over southern China. In this paper, the jet-related low-level windshear to be encountered by an aircraft is documented. Two typical cases under the northeast monsoon regime are considered, namely, easterly jet disrupted by the mountains to the south of Hong Kong International Airport, and outbreak of monsoon surge that produces a low-level northeasterly jet. The Doppler Light Detection and Ranging (LIDAR) systems are found to capture the corresponding windshear features very well, e.g., consistent with pilot reports and flight data. They are useful in providing timely alert to the aircraft. In particular, the LIDAR captures a double jet structure in the atmospheric boundary layer for the easterly wind case, which has not been reported in the literature before. The physical mechanism for the occurrence of the double jet is yet to be revealed. Moreover, the performance of a high spatial resolution (200 m) numerical weather prediction (NWP) model in predicting the jet and the associated low-level windshear is studied. The model is found to provide reasonable prediction of the windshear features at a few hours ahead, and, for the cases studied, shows skills in providing timely alerts to the aircraft.

Submesoscale physical processes in the atmospheric boundary layer above fragmented sea ice.

2020 ◽  
Author(s):  
Marta Wenta ◽  
Agnieszka Herman
Keyword(s):  
Boundary Layer ◽  
Numerical Modelling ◽  
Sea Ice ◽  
Atmospheric Boundary Layer ◽  
Weather Prediction ◽  
Heat Fluxes ◽  
Physical Processes ◽  
Sea Ice Extent ◽  
Field Campaign ◽  
Modelling Studies

<p>In consequence of sea ice fragmentation in winter a range of physical processes take place between the sea/sea ice and the atmospheric boundary layer (ABL). Most of them occur on the level of individual ice floes and cracks and thus cannot be directly resolved by numerical weather prediction (NWP) models.  Parametrizations of those processes aim to describe their overall effect on grid scale values, given the grid scale variables. However, as many of the processes taking place during winter sea ice fragmentation remain largely unrecognized they cannot be incorporated into the NWP models. </p><p>The aim of the presented study is to determine whether the floe size distribution (FSD) has an effect on the ABL. Our previous research (Wenta, Herman 2018 and 2019) indicates that FSD might determine the intensity and spatial arrangement of convection and heat fluxes. A coefficient has been proposed for the correction of moisture heat flux, which can be incorporated into the NWP models. However, this research is based entirely on idealized model simulations and requires further modelling and observations based studies.</p><p>In order to address this shortcoming, a field campaign is going to take place in the Bay of Bothnia in March 2020. Our goal is to create a 3D view of the atmosphere above fragmented sea and verify whether the processes and effects we found in the modeling results take similar form in real situations. Measurements results will be useful in the validation of our numerical modelling studies and will provide a unique dataset about the sea-ice-atmosphere interactions in the Bay of Bothnia area. Considering a significant decreasing trend in winter sea ice extent in the Baltic Sea it might contribute to our understanding of the role of ice in the local weather patterns. The field campaign is going to be complemented by numerical modelling with full version of Weather Research and Forecasting (WRF) model adjusted to the conditions over the Bay of Bothnia. </p><p>Combined together - the results of our previous modelling studies and the results from the Bay of Bothnia field campaign, may considerably increase our knowledge about the surface-atmosphere coupling in the event of winter sea ice fragmentation.</p>

scholarly journals A Hybrid NWP–Analog Ensemble

2016 ◽  
Vol 144 (3) ◽  
pp. 897-911 ◽  
Author(s):  
F. Anthony Eckel ◽  
Luca Delle Monache
Keyword(s):  
Real Time ◽  
Weather Prediction ◽  
Ensemble Member ◽  
Initial Condition ◽  
Error Growth ◽  
High Quality ◽  
Time Model ◽  
Probabilistic Forecasts ◽  
Nwp Model ◽  
Dependent Error

Abstract An analog ensemble (AnEn) is constructed by first matching up the current forecast from a numerical weather prediction (NWP) model with similar past forecasts. The verifying observation from each match is then used as an ensemble member. For at least some applications, the advantages of AnEn over an NWP ensemble (multiple real-time model runs) may include higher efficiency, avoidance of initial condition and model perturbation challenges, and little or no need for postprocessing calibration. While AnEn can capture flow-dependent error growth, it may miss aspects of error growth that can be represented dynamically by the multiple real-time model runs of an NWP ensemble. To combine the strengths of the AnEn and NWP ensemble approaches, a hybrid ensemble (HyEn) is constructed by finding m analogs for each member of a small n-member NWP ensemble, to produce a total of m × n members. Forecast skill is compared between the AnEn, HyEn, and an NWP ensemble calibrated using logistic regression. The HyEn outperforms the other approaches for probabilistic 2-m temperature forecasts yet underperforms for 10-m wind speed. The mixed results reveal a dependence on the intrinsic skill of the NWP members employed. In this study, the NWP ensemble is underspread for both 2-m temperature and 10-m winds, yet displays some ability to represent flow-dependent error for the former and not the latter. Thus, the HyEn is a promising approach for efficient generation of high-quality probabilistic forecasts, but requires use of a small, and at least partially functional, NWP ensemble.

scholarly journals Study of the Vertical Structure of the Coastal Boundary Layer Integrating Surface Measurements and Ground-Based Remote Sensing

Sensors ◽  
2020 ◽  
Vol 20 (22) ◽  
pp. 6516
Author(s):  
Teresa Lo Feudo ◽  
Claudia Roberta Calidonna ◽  
Elenio Avolio ◽  
Anna Maria Sempreviva
Keyword(s):  
Remote Sensing ◽  
Boundary Layer ◽  
Vertical Structure ◽  
Weather Prediction ◽  
Internal Boundary Layer ◽  
Internal Boundary ◽  
Maximum Height ◽  
Coastal Boundary Layer ◽  
Wind Profiles ◽  
Nwp Model

The understanding of the atmospheric processes in coastal areas requires the availability of quality datasets describing the vertical and horizontal spatial structure of the Atmospheric Boundary Layer (ABL) on either side of the coastline. High-resolution Numerical Weather Prediction (NWP) models can provide this information and the main ingredients for good simulations are: an accurate description of the coastline and a correct subgrid process parametrization permitting coastline discontinuities to be caught. To provide an as comprehensive as possible dataset on Mediterranean coastal area, an intensive experimental campaign was realized at a near-shore Italian site, using optical and acoustic ground-based remote sensing and surface instruments, under different weather characteristic and stability conditions; the campaign is also fully simulated by a NWP model. Integrating information from instruments responding to different atmospheric properties allowed for an explanation of the development of various patterns in the vertical structure of the atmosphere. Wind LiDAR measurements provided information of the internal boundary layer from the value of maximum height reached by the wind profile; a height between 80 and 130 m is often detected as an interface between two different layers. The NWP model was able to simulate the vertical wind profiles and the eight of the ABL.

Physical Processes

1998 ◽  
Author(s):  
T. N. Krishnamurti ◽  
H. S. Bedi ◽  
V. M. Hardiker
Keyword(s):  
Boundary Layer ◽  
Energy Balance ◽  
Surface Energy ◽  
Surface Energy Balance ◽  
Weather Prediction ◽  
Surface Fluxes ◽  
Physical Processes ◽  
Numerical Weather ◽  
Spectral Models ◽  
Heat And Moisture

In this chapter we present some of the physical processes that are used in numerical weather prediction modeling. Grid-point models, based on finite differences, and spectral models both generally treat the physical processes in the same manner. The vertical columns above the horizontal grid points (the transform grid for the spectral models) are the ones along which estimates of the effects of the physical processes are made. In this chapter we present a treatment of the planetary boundary layer, including a discussion on the surface similarity theory. Also covered is the cumulus parameterization problem in terms of the Kuo scheme and the Arakawa- Schubert sheme. Large-scale condensation and radiative transfer in clear and cloudy skies are the final topics reviewed. There are at least three types of fluxes that one deals with, namely momentum, sensible heat, and moisture. Furthermore, one needs to examine separately the land and ocean regions. In this section we present the socalled bulk aerodynamic methods as well as the similarity analysis approach for the estimation of the surface fluxes. The radiation code in a numerical weather prediction model is usually coupled to the calculation of the surface energy balance. This will be covered later in Section 8.5.6. This surface energy balance is usually carried out over land areas, where one balances the net radiation against the surface fluxes of heat and moisture for the determination of soil temperature. Over oceans, the sea-surface temperatures are prescribed where the surface energy balance is implicit. Thus it is quite apparent that what one does in the parameterization of the planetary boundary layer has to be integrated with the radiative parameterization in a consistent manner.

scholarly journals On the Representation of High-Latitude Boundary Layer Mixed-Phase Cloud in the ECMWF Global Model

2014 ◽  
Vol 142 (9) ◽  
pp. 3425-3445 ◽  
Author(s):  
Richard M. Forbes ◽  
Maike Ahlgrimm
Keyword(s):  
Boundary Layer ◽  
Liquid Water ◽  
Large Scale ◽  
Weather Prediction ◽  
Supercooled Liquid ◽  
Mixed Phase ◽  
Radiative Properties ◽  
Small Scale ◽  
Physical Processes ◽  
Boundary Layer Clouds

Supercooled liquid water (SLW) layers in boundary layer clouds are abundantly observed in the atmosphere at high latitudes, but remain a challenge to represent in numerical weather prediction (NWP) and climate models. Unresolved processes such as small-scale turbulence and mixed-phase microphysics act to maintain the liquid layer at cloud top, directly affecting cloud radiative properties and prolonging cloud lifetimes. This paper describes the representation of supercooled liquid water in boundary layer clouds in the European Centre for Medium-Range Weather Forecasts (ECMWF) global NWP model and in particular the change from a diagnostic temperature-dependent mixed phase to a prognostic representation with separate cloud liquid and ice variables. Data from the Atmospheric Radiation Measurement site in Alaska and from the CloudSat/Cloud–Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite missions are used to evaluate the model parameterizations. The prognostic scheme shows a more realistic cloud structure, with an SLW layer at cloud top and ice falling out below. However, because of the limited vertical and horizontal resolution and uncertainties in the parameterization of physical processes near cloud top, the change leads to an overall reduction in SLW water with a detrimental impact on shortwave and longwave radiative fluxes, and increased 2-m temperature errors over land. A reduction in the ice deposition rate at cloud top significantly improves the SLW occurrence and radiative impacts, and highlights the need for improved understanding and parameterization of physical processes for mixed-phase cloud in large-scale models.

scholarly journals Winter atmospheric boundary layer observations over sea ice in the coastal zone of the Bay of Bothnia (Baltic Sea)

2021 ◽  
Vol 13 (1) ◽  
pp. 33-42
Author(s):  
Marta Wenta ◽  
David Brus ◽  
Konstantinos Doulgeris ◽  
Ville Vakkari ◽  
Agnieszka Herman
Keyword(s):  
Boundary Layer ◽  
Sea Ice ◽  
Atmospheric Boundary Layer ◽  
Weather Prediction ◽  
Sonic Anemometer ◽  
Aerial Photographs ◽  
Physical Processes ◽  
Ice Surface ◽  
Atmospheric Observations ◽  
Meteorological Observations

Abstract. The Hailuoto Atmospheric Observations over Sea ice (HAOS) campaign took place at the westernmost point of Hailuoto island (Finland) between 27 February and 2 March 2020. The aim of the campaign was to obtain atmospheric boundary layer (ABL) observations over seasonal sea ice in the Bay of Bothnia. Throughout 4 d, both fixed-wing and quad-propeller rotorcraft unmanned aerial vehicles (UAVs) were deployed over the sea ice to measure the properties of the lower ABL and to obtain accompanying high-resolution aerial photographs of the underlying ice surface. Additionally, a 3D sonic anemometer, an automatic weather station, and a Halo Doppler lidar were installed on the shore to collect meteorological observations. During the UAV flights, measurements of temperature, relative humidity, and atmospheric pressure were collected at four different altitudes between 25 and 100 m over an area of ∼ 1.5 km2 of sea ice, located 1.1–1.3 km off the shore of Hailuoto's Marjaniemi pier, together with orthomosaic maps of the ice surface below. Altogether the obtained dataset consists of 27 meteorological flights, four photogrammetry missions, and continuous measurements of atmospheric properties from ground-based stations located at the coast. The acquired observations have been quality controlled and post-processed and are available through the PANGAEA repository (https://doi.org/10.1594/PANGAEA.918823, Wenta et al., 2020). The obtained dataset provides us with valuable information about ABL properties over thin, newly formed sea ice cover and about physical processes at the interface of sea ice and atmosphere which may be used for the validation and further improvement of numerical weather prediction (NWP) models.

scholarly journals Role of Atmospheric Boundary Layer (ABL) Height and Ventilation Coefficient on Urban Air Quality- A study based on Observations and NWP Model

2019 ◽  
Vol 2 (3) ◽  
Author(s):  
Aditi Singh
Keyword(s):  
Boundary Layer ◽  
Air Quality ◽  
Atmospheric Boundary Layer ◽  
Air Pollutants ◽  
Weather Prediction ◽  
Urban Region ◽  
Maximum Height ◽  
Nwp Model ◽  
Ventilation Coefficient

Air pollution is an issue of great concern in any urban region due to its serious health implications. The capital of India, New Delhi continues to be in the list of most polluted cities since 2014. The air quality of any region depends on the ability of dispersion of air pollutants. The height or depth of the atmospheric boundary layer (ABL) is one measure of dispersion of air pollutants. Ventilation coefficient is another crucial parameter in determining the air quality of any region. Both of these parameters are obtained over Delhi from the operational global numerical weather prediction (NWP) model of National Centre for Medium Range Weather forecasting (NCMRWF) known as NCMRWF Unified Model (NCUM). The height of ABL over Delhi, is also obtained from radiosonde observations using the parcel method. A good agreement is found between the observed and predicted values of ABL height. The maximum height of ABL is obtained during summer season and minimum is obtained in winter season. High values of air pollutants are found when the values of ABL height and ventilation coefficient are low. 

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