 Subjects -> METEOROLOGY (Total: 106 journals)
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- High-impact weather in Italy: a workshop to exchange the experience of
weather forecasters and researchers-
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Abstract: Abstract A workshop on high-impact meteorological events in Italy was jointly organized by the newly formed Italia Meteo Agency (AIM) and the Italian Association of Atmospheric Sciences and Meteorology (AISAM) on September 27, 2022. The aim of the workshop was to promote the sharing of the experiences that all operational and research meteorological centers in Italy have gained on specific types of high-impact events, favoring the establishment of a common know-how of Italian operational meteorology.
PubDate: 2023-02-15
- Effect of corrections for water vapor sensitivity of coumarin targets and
for density fluctuations (WPL) on O3 fluxes measured with the eddy
covariance technique-
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Abstract: Abstract Ozone vertical fluxes above land surfaces are commonly measured with the eddy covariance (EC) technique which requires non-conventional ozone fast analyzer mostly based on a chemiluminescence reaction of ozone with a reagent, either gaseous or solid. Currently, the most adopted reagent for this kind of O3 analyzers is a coumarin-47 solid dye absorbed on silica gel targets. However, ozone-induced chemiluminescence of coumarin-47 is enhanced by the presence of water vapor in the air sample. The aim of this paper is to evaluate the magnitude of the corrections to the ozone flux measurements due to coumarin-47 sensitivity to water vapor fluctuations, performed above a forest ecosystem from 2013 to 2020, and the combined effect with the WPL correction (Webb–Pearman–Leuning correction), another well-established correction for density fluctuations related to water vapor and sensible heat fluxes. Results confirm that water vapor sensitivity correction for the chemiluminescence reaction between coumarin-47 and ozone is quite small and negligible in most of the environmental conditions. On the contrary, WPL correction is almost one order of magnitude greater than the former correction. The combination of the two corrections results, on average, in a 6.6% reduction of the absolute value of the uncorrected ozone fluxes. Since the combined effect of the two corrections can be remarkable depending on the seasonal period of measurements, both corrections to the measured ozone fluxes are recommended, as well as the indication of their application in the published works.
PubDate: 2022-12-30
DOI: 10.1007/s42865-022-00053-0
- A new empirical method for correction of daytime air temperature
measurement errors in naturally ventilated radiation shields-
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Abstract: In the present study, a new empirical method is proposed for the correction of the daytime radiative temperature error of naturally ventilated radiation shields. The new regression-based method is an improvement of previous studies and was applied to seven different radiation shields. Two variants of the new method and a weighted technic for all methods were used in order to optimize the results. The robustness of the methods was also examined on two different sets of data. Results show that the root mean square radiative error (RMSE) between initial and corrected, by the new method, results were ranging from 22 to 70%. The new method was always more accurate and improves the average accuracy of all the tested shields of the present study from 3.22 to 4.13% with reference to existing empirical methods. Graphical 
PubDate: 2022-12-26
DOI: 10.1007/s42865-022-00051-2
- Trend analysis of annual and seasonal precipitation data in Arcadia region
(Greece)-
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Abstract: Abstract The purpose of the present study is to analyze the annual and seasonal precipitation trends in the prefecture of Arcadia, in Greece. Data series are based on records of 10 ground-based meteorological stations plus the available CRU TS 4.05 data series for Greece and for the geographic region of Peloponnese. The study contains a 30-year reference period from 1980 to 2009 and the last decade from 2010 to 2020. Homogeneity and serial correlation tests are considered in the analysis. Mostly negative trends are observed in annual and seasonal (except summer and irrigation period) series of reference period, with the majority of the significant trends to be in irrigation and autumn periods. The observed negative trends of the reference period tended to be transformed into positive trends over the last decade. Regarding the CRU TS 4.05 precipitation data, weak negative annual trends were observed during the reference period. However, significant positive trends were observed during autumn and irrigation periods. In the last decade, significant positive trends were detected during summer and irrigation periods.
PubDate: 2022-12-15
DOI: 10.1007/s42865-022-00052-1
- Ice accretion panel model for cylinders at low Reynolds numbers
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Abstract: Abstract Small unmanned aircraft systems (sUAS) are becoming increasingly common in research and commercial operations and hazardous weather impacts, such as icing, are an important and complex problem for expanded operation of these vehicles. The hazards of icing on these smaller aircraft are significant and only beginning to be explored. In particular, greater understanding of accretion physics at low speeds and low altitudes is needed since icing models for manned aircraft are unsuited for small UAS. To improve operational capability and safety, a rapid ice accretion code was developed for this regime. In this study, a low Reynolds number formulation for cylinders is developed suitable for lifting surface leading edges and cylindrical system components in the range \(Re\sim 300,000 - 800,000\) . The 2D numerical icing model is designed using analytic methods suited for low Reynolds numbers and empirically derived heat flux relations. Experimental heat transfer tests were done to support the model. The experimental results adjust previously proven heat flux correlations for the current scale.
PubDate: 2022-12-01
DOI: 10.1007/s42865-022-00050-3
- A dataset of temperature, humidity, and liquid water path retrievals from
a network of ground-based microwave radiometers dedicated to fog
investigation-
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Abstract: Abstract The database presented in this study has been acquired during the SOuth west FOGs 3D (SOFOG3D) experiment for processes study. This international campaign led by Météo-France during the winter 2019–2020 aimed at deploying a unique network of both in situ and remote sensing measurements in order to document spatial and temporal variabilities of fog events. To support this scientific objective but also to conduct first data assimilation experiments within the French convective scale model AROME, an un-precedented network of 8 ground-based microwave radiometers (MWR) has been deployed in 7 different locations known to be prone to fog occurrences. The database gives access to vertical profiles of temperature and humidity (both absolute and relative) from the surface up to 10 km altitude as well as integrated water vapor and liquid water path estimates. The retrieved profiles offer a very large database that can be exploited for several scientific purposes: fog process studies at specific location, documentation on the variability of fog properties at the regional scale, better understanding of the atmospheric boundary layer (ABL) height and dynamics during wintertime conditions, development of nowcasting products dedicated to fog alerts, data assimilation experiments to improve fog forecasts, development of synergetical advanced products, and evaluation of new model configurations with advanced parameterization or resolutions.
PubDate: 2022-09-15
DOI: 10.1007/s42865-022-00049-w
- Short-term rainfall prediction using MLA based on commercial microwave
links of mobile telecommunication networks-
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Abstract: Abstract Rainfall prediction is a major problem with considerable socio-economic, industrial, and environmental impacts. The expansion of mobile telecommunication networks around the world is being used as an alternative to the declining number of rain gauges. Many researches, using those networks, have been carried out to solve water related issues in particular, and to propose hydro-meteorological applications in general. However, the possibility to use mobile telecommunications networks for rainfall prediction is still at its premises. Machine learning algorithms and techniques have been widely proven to be effective for rainfall prediction, using different geo-physical and environmental variables. In this paper, we propose to use machine learning algorithms, namely ensemble methods, to predict rainy events and their corresponding rainfall depths based on signal levels attenuations along microwave links of commercial mobile telecommunication networks. A sample of four microwave links, extracted from a dataset containing commercial microwave links data from the Netherlands, is considered. This dataset contains minimum and maximum powers received by base transceiver stations over 15-min intervals, i.e. four records per hour. A radar rainfall dataset with a spatial resolution of 1 km2, and a temporal resolution of 5 min, is used as rainfall observations. The predictions are done at two levels. First, the nature (wet or dry) of upcoming 15-min periods is predicted. Second, rainfall depths are estimated for upcoming 15-min wet periods. The results obtained show a prediction accuracy between 72% and 93% for the prediction of upcoming periods with a prediction horizon between 1 and 60 min. The correlation coefficient between predictions of rainfall depths and radar rainfall observations is between 0.70 and 0.98, and the coefficient of determination between 0.72 and 0.90. In addition, the prediction horizon can be extended up to 5 h with a prediction accuracy above 60%. These results reveal the potential of microwave links of mobile telecommunication for short-term warning systems in general, and flood prediction in particular, as our models tend to be very accurate for the prediction of heavy rainy events.
PubDate: 2022-09-13
DOI: 10.1007/s42865-022-00047-y
- Improving precipitation ensemble forecasts of typhoon heavy rainfall over
East China with a modified probability-matching technique-
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Abstract: Abstract In this paper, four schemes involving the probability-matching technique were studied to obtain ensemble-based quantitative precipitation forecasts (QPFs) associated with Typhoon Lekima over East China. With the use of this technique, synthetic ensembles were created by blending low- and high-resolution rainfall forecasts. To effectively derive high-resolution ensemble forecasts, the neighborhood method was applied to mesoscale deterministic forecasts. Four schemes were explored based on the probability-matching technique. Two schemes resulted in ensemble forecasts, and the other two schemes yielded deterministic forecasts. By analyzing quantitative precipitation forecasts (QPFs) and ensemble forecasts, modified probability-matching-based schemes were determined to substantially reduce or eliminate the intrinsic model rainfall bias and to provide better QPF guidance. These encouraging results suggest that the modified probability-matching technique is a useful tool for QPFs of typhoon heavy rainfall over East China using dual-resolution ensemble forecasts.
PubDate: 2022-09-02
DOI: 10.1007/s42865-022-00048-x
- Observing temperature reliably using passively ventilated radiation
shields and a regression-based method to improve accuracy-
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Abstract: Abstract In the present study, a regression-based model of calculating the daytime radiative error is extended to be used easily in several commercial natural ventilated radiation shields. A low-cost homemade naturally ventilated radiation shield is also examined. Results show that the correction of the radiative error was significant for all the tested shields, and the model could be easily used to improve the temperature accuracy. The proposed homemade radiation shield can be an ideal alternative option with radiative error lower than the most of the tested commercial natural ventilated radiation shields.
PubDate: 2022-07-22
DOI: 10.1007/s42865-022-00046-z
- A 3D Lagrangian stochastic particle model for the concentration variance
dispersion-
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Abstract: Abstract A new scheme for the concentration variance calculation is assessed using field experiment data. The scheme is introduced in a Lagrangian stochastic particle model. The model provides run-time mean concentrations and concentrations’ variance 3D fields; thus, it does not need any off-line post-processing. The model is tested against the FFT-07 field experiment which involves a series of tracer releases. It is a short-range (500 m) highly instrumented experiment. In this work, measurement of tracer concentrations, emitted from a ground level point source is used to assess the ability of the new model in predicting the mean concentration, concentration variance, and the concentration fluctuation intensity at the ground level with a high spatial resolution. The results of the intercomparison are shown and discussed in terms of statistical plots and indices.
PubDate: 2022-06-28
DOI: 10.1007/s42865-022-00045-0
- The new pbl_met: an open-source library for building meteorological
processors and advanced data processing tools-
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Abstract: Abstract This paper presents the pbl_met, an open-source library for processing meteorological data collected in the planetary boundary layer (PBL) using conventional and modern sensors (examples of the latter include three-axial ultrasonic anemometers, SODAR/RASS, and wind-sensing LIDARs). The routines present in the pbl_met encompass the estimation of meteorological quantities (including global and net radiation and turbulence), the processing of ultrasonic anemometer raw data streams, the approximation of mixing height, and various facets of meteorological data management, summarization, and cleaning. The existence in pbl_met of estimation routines of diverse types allows to construct estimation paths of different depths, permitting the crafting of meteorological processors tailored to the data available. The overall quality of results obtained using estimation paths of differing depths has been investigated in a test case. Important differences have been observed, especially in mixing height, illustrating in the same time the wide range of processing options permitted by the pbl_met and the importance to select the best ones according to the data actually available; as some of the options allow the direct use of data from modern sensors, the pbl_met can be used as a platform for building next-generation meteorological processors for dispersion modeling applications.
PubDate: 2022-01-12
DOI: 10.1007/s42865-021-00042-9
- Surface albedo and spring snow melt variations at Ny-Ålesund,
Svalbard-
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Abstract: Abstract The monitoring of surface albedo using radiometric measurements is a simple but effective way to study variations in snow cover and melt timing in the high northern latitudes, where there is a clear indication of warming in response to the changing global climate. In this paper, we investigate these phenomena in the Northwest region of Svalbard using a 40-year record, combining previous data from 1981 to 1997, radiation measurements from the Baseline Surface Radiation Network (BSRN) station since 1993, and the Amundsen Nobile Climate Change Tower (CCT) since 2009. A methodology has been developed to estimate the start, duration, and end date of the spring snow melt. This has been applied to the integrated dataset for the period 1981 to 2019. Our results are in good agreement with qualitative information on snow persistence provided by webcam images archived since 2000. The date of snow melt has advanced at a rate of about 3 days per decade during the period of study, from Julian calendar date (doy) 180 in the early 1980s to 165–170 in the late 2010s. There is indication the trend has accelerated since 2010. The footprint of the radiation measurements is a crucial factor in the evaluation of surface albedo; the larger the area within the field of view of the instrument, the more representative is the measure. The assimilated 40-year dataset will provide a base for future monitoring of snow persistence at Ny-Ålesund as the climate continues to change in the region. Our work highlights the importance of technical improvements made in measurement systems and combining different techniques to monitor surface albedo. In particular, terrestrial photography, combined with broadband radiation measurements, will contribute to increased knowledge of underlying processes that determine the surface energy budget in the Arctic region. In addition, the combined ground-based measurements can be used to validate those derived from space-born platforms.
PubDate: 2021-12-23
DOI: 10.1007/s42865-021-00043-8
- Intercomparison of different state-of-the-art formulations of the mass
density of humid air-
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Abstract: Abstract The differences between one classical and three state-of-the-art formulations of the mass density of humid air were quantified. Here, we present both the calculi for direct determination of the humid-air mass density employing the virial form of the thermodynamic equation of state, and a sufficiently accurate look-up-table for the quick-look determination of the humid-air mass density, which is based on the advanced Thermodynamic Equation of Seawater 2010.
PubDate: 2021-12-17
DOI: 10.1007/s42865-021-00036-7
- Evaluation of rainfall and atmospheric parameters during afternoon summer
storms over Macaé city (Brazil) using WRF numerical model-
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Abstract: Abstract Forecasting summer storms requires addressing critical atmospheric conditions to determine the potential of their development and further evolution. However, due to the high degree of variability in the development of the storms, their early detection still represents a challenge to the operational forecasters and scientific community. In this context, this study endeavored to evaluate the rainfall and atmospheric parameters simulated by the Weather, Research, and Forecasting (WRF) numerical model using three grid domains (27 km, 09 km, and 03 km). This study proposed an evaluation of precipitation and atmospheric parameters for ten summer storm events over Macaé city during the austral summer of 2020 and 2021, as initially reported by local observers. The synoptic chart data showed that the local effects, the frontal systems passages, and the South Atlantic Convergence Zone (SACZ) were related to the storms observed. From the qualitative evaluation of the precipitation simulated by WRF, we found higher values over the mountainous region of Macaé city and lower values downstream. The quantitative assessment showed that the WRF model could reproduce the hourly rainfall development, although with a tendency of underestimation compared to the observations. The mean temporal evolution of atmospheric variables over Macaé city corroborated the importance of the joint analyses of thermodynamic and dynamic parameters and the increase of horizontal grid resolution to represent better the environment favorable to storm development.
PubDate: 2021-12-06
DOI: 10.1007/s42865-021-00044-7
- Vertical profile of the clear-sky aerosol direct radiative effect in an
Alpine valley, by the synergy of ground-based measurements and radiative
transfer simulations-
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Abstract: Abstract Atmospheric aerosols play an important role in Earth’s radiative balance, directly interacting with solar radiation or influencing cloud formation and properties. In order to assess their radiative impact, it is necessary to accurately characterise their optical properties, together with their spatial and vertical distribution. The information on aerosol vertical profile is often scarce, in particular in mountainous, complex terrains. This study presents the first attempt to evaluate the shortwave aerosol direct radiative effect in the Aosta Valley, a mountainous region in the Northwestern Italian Alps. Ground-based, remote sensing instruments (a sky radiometer and an Automated Lidar Ceilometer) are used to derive two descriptions of the aerosol properties and vertical distribution: a first, more accurate description, which includes the whole spectral information about the aerosol extinction coefficient, phase function and single scattering albedo; a second, more approximate one, which only relies on spectrally constant values of aerosol single scattering albedo and asymmetry factor. This information is used as input for radiative transfer simulations, which allow to estimate, in cloudless conditions, the shortwave aerosol direct radiative effect and the vertical profile of the instantaneous heating rates in the lower layers of the atmosphere. The simulations obtained with the two descriptions do not differ significantly: they highlight a strong surface dimming (between − 25 and − 50 W m− 2) due to the presence of aerosol, with a considerable radiative absorption inside the atmospheric column (around + 30 W m− 2), and an overall small cooling effect for the Earth-atmospheric system. The absorption of solar radiation within the atmospheric column due to aerosol leads to instantaneous heating rates up to 1.5 K day− 1 in the tropospheric layers below 6 km a.s.l. These results show that, in some conditions, the shortwave aerosol direct radiative effect can be considerable even in this Alpine environment, usually considered as relatively pristine (yearly average PM10 concentration about 20 μg m− 3).
PubDate: 2021-10-12
DOI: 10.1007/s42865-021-00041-w
- A network of water vapor Raman lidars for improving heavy precipitation
forecasting in southern France: introducing the WaLiNeAs initiative-
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Abstract: Abstract Extreme heavy precipitation events (HPEs) pose a threat to human life but remain difficult to predict because of the lack of adequate high frequency and high-resolution water vapor (WV) observations in the low troposphere (below 3 km). To fill this observational gap, we aim at implementing an integrated prediction tool, coupling network measurements of WV profiles, and a numerical weather prediction model to precisely estimate the amount, timing, and location of rainfall associated with HPEs in southern France (struck by ~ 7 HPEs per year on average during the fall). The Water vapor Lidar Network Assimilation (WaLiNeAs) project will deploy a network of 6 autonomous Raman WV lidars around the Western Mediterranean to provide measurements with high vertical resolution and accuracy to be assimilated in the French Application of Research to Operations at Mesoscale (AROME-France) model, using a four-dimensional ensemble-variational approach with 15-min updates. This integrated prediction tool is expected to enhance the model capability for kilometer-scale prediction of HPEs over southern France up to 48 h in advance. The field campaign is scheduled to start early September 2022, to cover the period most propitious to heavy precipitation events in southern France. The Raman WV lidar network will be operated by a consortium of French, German, Italian, and Spanish research groups. This project will lead to recommendations on the lidar data processing for future operational exploitation in numerical weather prediction (NWP) systems.
PubDate: 2021-09-24
DOI: 10.1007/s42865-021-00037-6
- Time-lapse photography and its teaching usefulness in planetary boundary
layer meteorology-
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Abstract: Abstract In this paper, the author shares her experiences in producing time-lapse movies dedicated to teaching introductory level meteorology and micro-meteorology, intended as dynamical phenomena unfolding in time. In this work, the process of producing teaching-grade meteorological time lapses is discussed, along with indications based on literature and the author’s experience to obtain evocative results using easily accessible, low-cost off-the-shelf equipment. Ideas on use of time-lapse meteorological and micro-meteorological movies to build teaching presentations are also given, with practical suggestions on improving students learning experience, to allow them developing their own scientific voice, and hopefully to spark enduring passions on a subject often considered dry and cold.
PubDate: 2021-09-01
DOI: 10.1007/s42865-021-00039-4
- The 2020 Arctic ozone depletion and signs of its effect on the ozone
column at lower latitudes-
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Abstract: Abstract The present study discusses the effect of the ozone depletion that occurred over the Arctic in 2020 on the ozone column in central and southern Europe by analysing a data set obtained from ground-based measurements at six stations placed from 79 to 42°N. Over the northernmost site (Ny-Ålesund), the ozone column decreased by about 45% compared to the climatological average at the beginning of April, and its values returned to the normal levels at the end of the month. Southwards, the anomaly gradually reduced to nearly 15% at 42°N (Rome) and the ozone minimum was detected with a delay from about 6 days at 65°N to 20 days at 42°N. At the same time, the evolution of the ozone column at the considered stations placed below the polar circle corresponded to that observed at Ny-Ålesund, but at 42°–46°N, the ozone column turned back to the typical values at the end of May. This similarity in the ozone evolutional patterns at different latitudes and the gradually increasing delay of the minimum occurrences towards the south allows the assumption that the ozone columns at lower latitudes were affected by the phenomenon in the Arctic. The ozone decrease observed at Aosta (46°N) combined with predominantly cloud-free conditions resulted in about an 18% increase in the erythemally weighted solar ultraviolet irradiance reaching the Earth’s surface in May.
PubDate: 2021-08-31
DOI: 10.1007/s42865-021-00040-x
- High-resolution climatic characterization of air temperature in the urban
canopy layer-
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Abstract: Abstract Urbanized environments are of greater relevance because of the high and still rapidly increasing percentage of the world population living in and around cities and as the preferred location of human activities of every type. For this reason, much attention is paid to the urban climate worldwide. Among the UN 2030 17 Sustainable Development Goals, at least one concerns resilient cities and climate action. The WMO supports these goals promoting safe, healthy, and resilient cities by developing specially tailored integrated urban weather, climate, and environmental services. An unavoidable basis for that is an improved observational capability of urban weather and climate, as well as high-resolution modeling. For both the former and the latter, and of primary importance for the latter, urban meteorological surface networks are undoubtedly a very useful basis. Nevertheless, they are often unfit for detailed urban climatological studies and they are generally unable to describe the air temperature field in the urban canopy layer (UCL) with a spatial resolution which is sufficient to satisfy the requirements set by several professional activities and especially for local adaptation measures to climate change. On the other hand, remote sensing data from space offer a much higher spatial resolution of the surface characteristics, although the frequency is still relatively lower. A useful climatological variable from space is, for instance, the land surface temperature (LST), one of the WMO Essential Climate Variables (ECV). So often used to describe the Surface Urban Heat Islands (S-UHI), LST has no simple correlation with UCL air temperature, which is the most crucial variable for planning and management purposes in cities. In this work, after a review of correlation and interpolation methods and some experimentation, the cokriging methodology to obtain surface air temperature is proposed. The implemented methodology uses high quality but under-sampled in situ measurements of air temperature at the top of UCL, obtained by using a dedicated urban network, and satellite-derived LST. The satellite data used are taken at medium (1 × 1 km2) resolution from Copernicus Sentinel 3 and at high resolution (30 × 30 m2) from NASA-USGS Landsat 8. This fully exportable cokriging-based methodology, which also provides a quantitative measure of the related uncertainties, was tested and used to obtain medium to high spatial resolution air temperature maps of Milan (Italy) and the larger, much populated, but also partly rural, surrounding area of about 6000 km2. Instantaneous as well as long period mean fields of fine spatially resolved air temperature obtained by this method for selected weather types and different Urban Heat Island configurations represent an important knowledge improvement for the climatology of the urban and peri-urban area of Milan. It finds application not only in more detailed urban climate studies but also in monitoring the effects of urban activities and for the assessment of adaptation and mitigation measures in the urban environment. Finally, the first set of interactive maps of medium–high resolution UCL air temperature was produced in the framework of the locally funded ClimaMi project and made freely available to urban authorities and professionals as an improved climatological basis for present and future plans and projects to be developed in the framework of the national and international adaptation and mitigation measures.
PubDate: 2021-08-24
DOI: 10.1007/s42865-021-00038-5
- On the computation of ISO amplitude and frequency indices using a discrete
wavelet transform model and application to the study of the annual cycle
of ISO activity in Central Africa-
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Abstract: Abstract The role of the intraseasonal oscillations (ISOs) in the tropical climate system has been widely investigated by researchers around the world. However for the better representation of ISOs in climate models, one of the greatest challenges remains the definition of suitable ISO-related metrics. As attempt to the definition of these ISO-related metrics, we proposed in this paper an algorithm for the computation of ISO intensity (ISOI) and ISO periods (ISOP) indices using a discrete wavelet transform (DWT) model. Then we used these indices to investigate the annual cycle of ISO activity in Central Africa (CA). The plots of spatial distribution of ISOI and ISOP show that both quantities exhibit strong month-to-month variations throughout the year. In fact, the high values of ISOI are observed during December–May and lower values during June–November, while the ISOP values are high December–February and June–August and lower values during March–May and September–December. We also accessed the large-scale dynamics associated with the ISO activity and found that over the land, the incursions of the moisture flux from Atlantic and Indian basins are of great contribution in the annual variations of ISOI. Finally, we studied the impact of ISO on rainfall and showed that the influence of ISO on rainfall strongly varies throughout the year, with maximum impact during June and minimum impact during November.
PubDate: 2021-08-09
DOI: 10.1007/s42865-021-00035-8
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