WRF model

The impacts of the urban heat island (UHI) phenomenon on energy consumption, air quality, and human health have been widely studied and described. Mitigation strategies have been developed to fight the UHI and its detrimental consequences. A potential countermeasure is the increase of urban albedo by using cool materials. Cool materials are highly reflective materials that can maintain lower surface temperatures and thus can present an effective solution to mitigate the UHI. Terni's proven record of high temperatures along with related environmental and comfort issues in its urban areas have reflected the local consequences of global warming. On the other hand, it promoted integrated actions by the government and research institutes to investigate solutions to mitigate the UHI effects. In this study, the main goal is to investigate the effectiveness of albedo increase as a strategy to tackle the UHI, by using the Weather Research and Forecasting (WRF) mesoscale model to simulate the urban climate of Terni (Italy). Three different scenarios through a summer heat wave in the summer of 2015 are analyzed. The Base Scenario, which simulates the actual conditions of the urban area, is the control case. In the Albedo Scenario (ALB Scenario), the albedo of the roof, walls and road of the whole urban area is increased. In the Albedo-Industrial Scenario (ALB-IND Scenario), the albedo of the roof, walls and road of the area occupied by the main industrial site of Terni, located in close proximity to the city center, is increased. The simulation results show that the UHI is decreased up to 2 • C both at daytime and at nighttime in the ALB and in ALB-IND Scenarios. Peak temperatures in the urban area can be decreased by 1 • C at daytime, and by about 2 • C at nighttime. Albedo increase in the area of interest might thus represent an opportunity to decrease the UHI effect and its consequences.

MEGASAINS

MEGASAINS merupakan bulletin yang diterbitkan oleh Stasiun Pemantau Atmosfer Global (GAW) Bukit kototabang sebagai media penuangan Karya Tulis Ilmiah (KTI) yang bersumber dari kegiatan penelitian berbasis ilmu-ilmu Meteorologi, Klimatologi, Kualitas udara, dan Geofisika (MKKuG), serta lingkungan. Dewan Redaksi membuka kesempatan bari para pakar ataupun praktisi untuk dapat mengirimkan naskah KTI, terutama yang berkaitan dengan fokus utama dari Buletin MEGASAINS. Naskah KTI yang dikirimkan hendaknya asli dan belum pernah dipublikasikan. Naskah diketik dengan menggunakan aplikasi MicrosoftTM Word dengan ketentuan panjang naskah maksimal 20 halaman pada kertas ukuran A4; batas kiri 4 cm, kanan 3,17 cm, atas dan bawah 2,54 cm; satu kolom; font Arial; judul ditulis menggunakan font 12 pts, rata tengah, spasi tunggal, huruf capital, dan cetak tebal; isi ditulis menggunakan font 10 pts, rata kiri-kanan, dan spasi tunggal; tulisan disertai dengan abstrak sepanjang satu alinea, dicetak dengan font 10, spasi tunggal, dan disertai dengan 2-5 kata kunci. Dewan Redaksi berhak mengubah isi naskah sepanjang tidak mengubah substansinya. Isi naskah adalah sepenuhnya tanggung jawab penulis. Pemilihan naskah yang laik cetak adalah sepenuhnya hak Dewan Redaksi.

Solar energy applications need reliable forecasting of solar irradiance. In this study, we present an assessment of a short-term global horizontal irradiance forecasting system based on Advanced Research Weather Research and Forecasting (WRF-ARW) meteorological model and neural networks as a post-processing method to improve the skill of the system in a highly favorable location for the utilization of solar power in Turkey. The WRF model was used to produce 1 month of 3 days ahead solar irradiance forecasts covering Southeastern Anatolia of Turkey with a horizontal resolution of 4 km. Single-input single-output (SISO) and multi-input single-output (MISO) artificial neural networks (ANN) were used. Furthermore, the overall results of the forecasting system were evaluated by means of statistical indicators: mean bias error, relative mean bias error, root mean square error, and relative root mean square error. The MISO ANN gives better results than the SISO ANN in terms of improving the model predictions, provided by WRF-ARW simulations for August 2011.

The aim of this work is to simulate the Urban Heat Island (UHI) in a medium size Mediterranean city (Lecce, IT) and to analyze its consequences for thermal comfort. We use the Weather Research and Forecasting (WRF) model (version 3.2), that accounts for the urban structure with a multilayer urban parameterization (BEP+BEM i.e. the Building Effect Parameterization (BEP) combined with the Building Energy Model (BEM)). Three hot and cloudless summer days have been simulated and results have been compared with field data collected during an experimental campaign performed over the whole summer in the city of Lecce, Italy. In the model, the structure and shape of the city are reproduced using detailed data related to different urban classes, urban fraction and building morphometry. For the residential urban classes, different thermal parameters that are representative of building materials in the oldest and the newer part of the city, are used. Results show that UHI reaches, on average, its maximum intensity (4-5 °C) just before sunrise, and its minimum (2 °C) occurs during the day. Model validation inferred through statistical analysis shows overall a better model performance for the historical city centre than for the suburban area. This suggests that further refinement of the building representation in the outskirts might still be required. Consequences of the increased urban temperature are evaluated in terms of thermal comfort. The maximum thermal stress occurs during the central hours of the day, while, the minimum thermal stress occurs during the twilight hours.

Mesoscale Convective System (MCS) banyak aktif Di Benua Maritim seperti Asia Tenggara khususnya Indonesia. Fenomena ini mampu menghasilkan area awan Cumulonimbus yang luas (ratusan hingga ribuan km) dengan masa hidup yang lebih panjang (lebih dari tiga jam). Identifikasi dan pelacakan MCS dengan menggunakan Radar cuaca dilakukan dengan melihat parameter yaitu, daerah mininum minimal (luasan) 1250km², untuk reflektivitas threshold >20 DBZ, setidaknya memiliki masa hidup 1 jam.
Model WRF masih belum mampu merepresentasikan kondisi Mesoscale Convective System dengan baik. Dari analisis dinamika MCS yang terjadi di Makassar menggunakan model WRF diketahui proses terjadinya MCS sangat dipengaruhi dengan besarnya nilai CAPE yang terjadi sekitar Laut Jawa, proses terjadinya MCS diperlukan sebuah kolam dingin (cold pool) yang luas dan juga aktif dalam waktu yang lama, serta pola angin seringkali terjadi downdraft pada lapisan bawah dan juga pada beberapa lokasi terdapat arus siklonik pada lapisan ±500mb.

The stable stratified atmospheric boundary layer continues to pose challenges for Numerical Weather
Prediction and Climate models. Existing parameterizations cannot adequately capture the depth of the Planetary
Boundary Layer (PBL), low-level jets and nocturnal near surface temperature because of their poor representation of
turbulent fluxes, especially in mountainous terrain. In addition, small scale processes such as collisions between
katabatic and valley flows which produce intense mixing, strong vertical velocities and a rapid drop in temperature
are distributed in space and time and are unable to be captured. These interactions between flows of different scales,
in general, can contribute significantly to sub-grid, short-lived, intense turbulence events, spasmodically producing
high fluxes over short periods. Such vigorous mixing episodes need to be included in meso-scale models in order to
improve their performance, especially in dealing with near surface flows.
High-resolution numerical calculations were performed using the Weather Research and Forecasting (WRF) model to
test its ability to predict mountain weather. Data from two comprehensive field experiments conducted under the
aegis of Mountain Terrain Atmospheric Modelling and Observations (MATERHORN) Program
(www.nd.edu/~dynamics/materhorn) were used in this study. Different PBL options available in the WRF model
were tested and evaluated for stable conditions. The Yonsei University (YSU) PBL scheme was modified and
implemented in WRF. The performance of the modified and original YSU scheme, were compared. Preliminary
results show that the modified version is more capable of predicting the velocity of the observed low-level jet, which
was consistently over-predicted by the original version.
Further data processing and analysis is under way. The objective is to develop better parameterizations for turbulent
fluxes in the complex terrain leading to improved predictability of local scale air flow. This work is a contribution in
this direction and numerous applications follow from this research including air quality modelling and aviation

This study investigates the impact of reactive halo-gen species (RHS, containing chlorine (Cl), bromine (Br) or iodine (I)) on atmospheric chemistry in the tropical tro-posphere and explores the sensitivity to uncertainties in the fluxes of RHS to the atmosphere and their chemical processing. To do this, the regional chemistry transport model WRF-Chem has been extended to include Br and I, as well as Cl chemistry for the first time, including heterogeneous recycling reactions involving sea-salt aerosol and other particles , reactions of Br and Cl with volatile organic compounds (VOCs), along with oceanic emissions of halocar-bons, VOCs and inorganic iodine. The study focuses on the tropical east Pacific using field observations from the Tropical Ocean tRoposphere Exchange of Reactive halo-gen species and Oxygenated VOC (TORERO) campaign (January-February 2012) to evaluate the model performance. Including all the new processes, the model does a reasonable job reproducing the observed mixing ratios of bromine oxide (BrO) and iodine oxide (IO), albeit with some discrepancies , some of which can be attributed to difficulties in the model's ability to reproduce the observed halocarbons. This is somewhat expected given the large uncertainties in the air-sea fluxes of the halocarbons in a region where there are few observations of their seawater concentrations. We see a considerable impact on the inorganic bromine (Br y) partitioning when heterogeneous chemistry is included , with a greater proportion of the Br y in active forms such as BrO, HOBr and dihalogens. Including debromination of sea salt increases BrO slightly throughout the free tropo-sphere, but in the tropical marine boundary layer, where the sea-salt particles are plentiful and relatively acidic, debromi-nation leads to overestimation of the observed BrO. However , it should be noted that the modelled BrO was extremely sensitive to the inclusion of reactions between Br and the oxygenated VOCs (OVOCs), which convert Br to HBr, a far less reactive form of Br y. Excluding these reactions leads to modelled BrO mixing ratios greater than observed. The reactions between Br and aldehydes were found to be particularly important, despite the model underestimating the amount of aldehydes observed in the atmosphere. There are only small changes to the inorganic iodine (I y) partitioning and IO when Published by Copernicus Publications on behalf of the European Geosciences Union. 3162 A. Badia et al.: Importance of reactive halogens in the tropical marine atmosphere the heterogeneous reactions, primarily on sea salt, are included. Our model results show that tropospheric O x loss due to halogens ranges between 25 % and 60 %. Uncertainties in the heterogeneous chemistry accounted for a small proportion of this range (25 % to 31 %). This range is in good agreement with other estimates from state-of-the-art atmospheric chemistry models. The upper bound is found when reactions between Br and Cl with VOCs are not included and, consequently , O x loss by BrO x , ClO x and IO x cycles is high (60 %). With the inclusion of halogens in the troposphere, O 3 is reduced by 7 ppbv on average. However, when reactions between Br and Cl with VOCs are not included, O 3 is much lower than observed. Therefore, the tropospheric O x budget is highly sensitive to the inclusion of halogen reactions with VOCs and to the uncertainties in current understanding of these reactions and the abundance of VOCs in the remote marine atmosphere.

The accuracy of air pollutants dispersion modelling results depends on the quality of the input data, including the representativeness of the meteorological data. The paper presents the results of the AERMOD model validation using data from Tracy Power Plant experiment (Nevada, USA) with various meteorological data sources, including WRF modelling system outputs. The highest efficiency of the AERMOD model performance was found using site-specific meteorological data and the results from the WRF model. In general, the AERMOD modelling system inadequately represents the concentration levels of tracer gas (SF6) at receptors situated below the emitter height in areas of complex topography.

In a data-poor, hazard-prone country like the Philippines, interpolating distant data points and computer modelling have become the go-to methods for determining the hazards that may affect an area. The absence of monitoring stations and gauges necessitates the application of modelling techniques to build on the little data available and generate reliable hazard maps. In this study-the devastating Sep 2009 Tropical Cyclone Ketsana (local name: Ondoy) event, its atmospheric characteristics, and its effects near Mt. Makiling, Laguna-is analyzed utilizing two modelling software: the Weather Research and Forecasting (WRF) model to assess the amount of rainfall, and FLO-2D to map the flood hazard areas around the volcano using the output of the WRF. A lone meteorological observation station on Mt. Makiling provided rainfall data for comparison with the results of the meteorological and hydrological models. The WRF model yielded a mean rainfall amount in the study area of 129.92 mm over 24 h for the storm against the observed rainfall amount for the same duration at 182.3 mm from the meteorological station. The flood model using the WRF data yielded minimal inundated areas, while the flood model of the observed rainfall data showed several low-lying urban areas inundated by up to 1.5 m of floodwaters. Comparison with flood data collected by responding agencies and groups after the event shows good correlation of affected areas and flood heights, with discrepancies being attributed to the swelling of Laguna de Bay because of excess runoff from other surrounding provinces-a factor that the models could not consider. Despite this, the WRF model generated from global atmospheric data and the flood model using the WRF product appears as a feasible substitute in the absence of on-site observation points and monitoring stations.

Using Bayesian Model Averaging (BMA), an attempt was made to obtain calibrated probabilistic numerical forecasts of 2-meter temperature over Iran. The ensemble makes use of three limited area models (WRF, MM5 and HRM), with WRF used five times with different configurations. The resulting ensemble of eight members was run for a period of 6 months (from December 2008 to May 2009) over Iran.