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- WRF data assimilation of weather stations and lightning data for a
convective event in northern Italy-
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Abstract: Abstract The present work shows the relevance of assimilating mesoscale observations and lightning data in the Weather Research and Forecasting (WRF) model, to simulate a strong convective event in northern Italy, poorly forecasted by available weather models even a few hours before the event itself. The data assimilation was conducted by testing the 3D-VAR and 4D-VAR assimilation algorithms implemented in the WRF data assimilation (WRFDA) suite, with different configurations and different assimilation windows. An extensive sensibility test has been operated to properly analyze the effect that the assimilation of a single station has on the model outcomes. Input data were taken from two networks of more than 1000 citizen-science meteorological stations, available in northern Italy, and from lightning flashes derived from Earth Networks Total Lightning Network, assimilated using the atmospheric water vapor as a proxy variable. Rain forecasts over an area in the north of Milan were compared to the station’s measurements in the same area; POD, FAR, and CSI categorical statistics have been calculated. Results showed a positive improvement in the forecasted rain amounts with the ingestion of mesoscale weather data into 3D-VAR and 4D-VAR algorithms, more pronounced using 4D-VAR with a more frequent input data integration. A few improvements were reported by the 3D-VAR, with the lightning data assimilation, probably caused by the absence of the model’s spin-up time with this configuration. An ideal simulation, which increased the water vapor of the air mass 2 h before the convective event, reported a positive enhancement of the rain amounts. The tests conducted on a single convective event are nevertheless encouraging, because they show a positive improvement of forecast with the assimilation of near-ground weather data and tropospheric water vapor 1 or 2 h before the beginning of the convection activity.
PubDate: 2023-09-14
DOI: 10.1007/s42865-023-00061-8
- Evaluation of the performance of the World Wide Lightning Location Network
(WWLLN) using the lightning detection network (LINET) as a truth-
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Abstract: Abstract Observations from lightning detection networks are useful for forecasting or monitoring several phenomena or parameters such as bushfires or nitrogen oxide production. As networks are constantly expanding and their detection capabilities are improving, it is essential to understand their performance. A systematic evaluation of the performance of the World Wide Lightning Location Network (WWLLN) in northern Benin is carried out using data from the lightning detection network (LINET) data as ground truth. The study runs from 18 June to 18 November 2006. The detection efficiency of the WWLLN is found to be strongly dependent on the peak current. It is low and reveals the distance of the sensors from the area. This same sensitivity to peak current explains the bias between the spatial and temporal localisation of the two networks. The peak of the period, in terms of the number of events observed, is obtained in July for the LINET and in September for the WWLLN. The diurnal variation indicates an overall peak of activity in the evening for both networks but with a slight time lag for WWLLN. However, taking into account the flashes with peak current greater than or equal to 30 kA, it is noted that the two networks are almost identically located. The results also show that the WWLLN is capable of locating both cloud-to-ground (CG) and inter-cloud (IC) lightning. Additional receiving stations are continuously added to the network, which improves detection efficiency.
PubDate: 2023-07-31
DOI: 10.1007/s42865-023-00060-9
- Development of an airfoil-based passive volumetric air sampling and flow
control system for fixed-wing UAS-
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Abstract: Abstract This study aims to develop a concept of a passive volumetric flow control system for gas sampling applications onboard fixed-wing UAS based on the pressure field around airfoils. The passive flow control system utilizes the aerodynamics of a UAS to create a vacuum pump effect that ensures constant gas sampling, which can be used to facilitate airborne aerosol and gas measurements. The pump effect is achieved by short-circuiting the pressure field’s minima and maxima points around an airfoil through pipes and 3D printed structures that could function both as a pump system and a gas measurement chamber. The design of this structurally integrated functionality brings many advantages for scientific applications, especially onboard small research UAS, which would dispense entirely with complex active pump systems, thus reducing weight and ensuring gas sampling at a constant volumetric flow rate independent of altitude and atmospheric variance. In favor of developing further applications, this paper outlines the development steps of the passive pump concept starting from the theory and numerical modeling of the effect to the implementation on board a fixed-wing UAS. Finally, possible improvements based on numerical models and flight measurements are discussed.
PubDate: 2023-07-18
DOI: 10.1007/s42865-023-00057-4
- Professional LoRaWAN IoT Decentlab sensors: 1 year of data and analysis
within the experimental project of meteorological monitoring in the
Regional Forest of Pian Cansiglio (north-east region of Italy)-
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Abstract: Abstract Within the experimental project of meteorological monitoring in the Regional Forest of Pian Cansiglio (mountain Regions of Veneto and Friuli Venezia Giulia, Italy—https://www.piancansigliometeowebcam.it), three professional sensors with LoRaWAN technology have been installed in 2020 and 2021, in three specific experimental locations, chosen for their peculiar climatic conditions (I Bech, 983 m a.s.l.; Valmenera, 903 m a.s.l.; and Rif. Carlo e Massimo Semenza, 2.020 m a.s.l.). After 1 year of data and detailed analysis, Decentlab professional sensors (Decentlab GmbH n.d.), operating in the severe environmental context of the Pian Cansiglio Regional Forest, were found suitable for such monitoring purposes, ensuring accurate measurements in sites where minimum values can drop below − 30 °C and moisture is constant, with big ice accumulations on all surfaces which can completely cover the transmitters. As a further level of development in the IoT segment, a self-built electronic board (called “LoRa Weather board”) was implemented by Dr. Mauro Girotto, based on LoRaWAN technology (Environmental monitoring using LoRaWAN technology: experimental measurements and data analytics platform– Dr. Luigi Laricchia – MSc Informatics (University of Bologna – Italy) n.d.) and The Things Network (The Things Network n.d.). The board has been designed for battery-powered applications and, at the hardware level, is ready for mounting various sensors, depending on the application, including thermo-hygrometers, rain gauges, and barometers. Data are collected since January 2022, and the hardware will be tested in coming winters to achieve the necessary robustness for harsh environmental conditions.
PubDate: 2023-06-01
DOI: 10.1007/s42865-023-00059-2
- Extreme convective precipitation in Liguria (Italy): a brief description
and analysis of the event occurred on October 4, 2021-
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Abstract: Abstract An extreme precipitation episode, occurred in Liguria region on October 4, 2021, is presented and discussed in the present paper. In particular, a series of V-shaped quasi-stationary convective systems repeatedly affected central and western Liguria producing impressive and, in some cases, unprecedented rainfall amounts (up to 378 mm in 3 h, 496 mm in 6 h, and 741 mm in 12 h). A peculiar feature of this case study is its occurrence and propagation downwind the Apennines Mountain range. The main characteristics of the event, in terms of synoptic and mesoscale triggering processes as well as its dynamics, are discussed. It is found that the larger moisture contribution seems to have a Mediterranean origin and a possible role of a cold pool generated in the first phase of the event in the evolution of the convective system is hypothesized. This paper follows a workshop on high-impact weather jointly organized by the newly formed Italia Meteo Agency and the Italian Association of Atmospheric Sciences and Meteorology (AISAM) in September 2022, to promote the sharing of the experiences among operational and research meteorological centers in Italy. The preliminary results presented here are intended to stimulate further work on the topic to gain a better understanding of the dynamics of such extreme precipitation events and to improve the predicting capability.
PubDate: 2023-05-17
DOI: 10.1007/s42865-023-00058-3
- On the parametrizations for the dissipation rate of the turbulence kinetic
energy in stable conditions-
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Abstract: Abstract Observations acquired in the stable surface layer during two field experiments (The Mountain Terrain Atmospheric Modeling and Observations Program and the Climate Change Tower Integrated Project) are considered to test different parametrizations of the dissipation rate of turbulence kinetic energy (TKE). Particular attention is dedicated to the effect of the submeso motions on these parametrizations. The analysis shows that TKE-based formulations are particularly prone to the submeso effect, while better results are obtained if the vertical velocity variance is considered. In the latter case, stability must be taken into account explicitly in Mellor-Yamada type parametrizations but not in shear-based formulations.
PubDate: 2023-05-09
DOI: 10.1007/s42865-023-00055-6
- Solid precipitation and its relationship with the Hess and Brezowsky
classification: case in the French department of the Alpes-Maritimes-
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Abstract: Abstract The study combined the observations of the 24-h solid precipitation (SP) measured by 5 weather stations located in the French department of the Alpes-Maritimes and the daily atmospheric circulation types (ACT), based on the classification of Hess and Brezowsky, and made available by the German Meteorological Service. The results show that the seasonal frequency (1985–2019 DJFMA) of the 24-h SP followed three trends at the weather station of Isola 2000 (1910 m above sea level): from 1985 to 1999, they decreased significantly; from 2000 to 2015, they increased; since 2016, a decline seems to be in progress. The variations between the negative and positive phases of the North Atlantic Oscillation (NAO) index would partly explain the modifications in the occurrences of the SP. Moreover, it is noted a reduction in the number of the SP for the months of December, January, and April (significantly validated by the Mann–Kendall test only for April). This situation is quite worrying because it could show the impact of rising temperatures even at 1910 m above sea level, bringing more precipitation in liquid form at the beginning and end of the season. The south atmospheric circulations (SC) are those that produce the greatest number of SP for the period 1997–2019, and they generate a majority of the extreme events. Thus, the talweg on western Europe (TRW) is the subclass of ACTs that causes the largest number of events. However, behind these results, it is also noted that the classification of Hess and Brezowsky is not sufficiently discriminating to establish one or more types of circulations very specific to the SP; to go further, it will be necessary to compute a synoptic classification composed of correlated variables with SP.
PubDate: 2023-04-03
DOI: 10.1007/s42865-023-00056-5
- 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
DOI: 10.1007/s42865-023-00054-7
- 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
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