Search results for "water vapou"
showing 10 items of 21 documents
Extreme precipitation events over northern Italy. Part II : Dynamical precursors
2021
The connection between weather extremes and Rossby wave packets (RWP) has been increasingly documented in recent years. RWP propagation and characteristics can modulate the midlatitude weather, setting the scene for temperature and precipitation extremes and controlling the geographical area affected. Several studies on extreme precipitation events (EPEs) in the Alpine area reported, as the main triggering factor, a meridionally elongated upper‐level trough as part of an incoming Rossby wave packet. In this work, we investigate a wide number of EPEs occurring between 1979 and 2015 in northern‐central Italy. The EPEs are subdivided into three categories (Cat1, Cat2, Cat3) according to thermo…
Atmospheric water vapour content retrieval from visible and thermal data in the framework of the DAISEX campaigns
2005
In this paper three methods are presented that retrieve the atmospheric water vapour from DAIS (digital airborne imaging spectrometer) data in the framework of the DAISEX (DAIS Experiment) campaigns carried out by ESA (European Space Agency). The three methodologies analysed in the paper are: (i) the ratio technique, in which the water vapour is obtained from visible and near‐infrared bands; (ii) the split‐window technique; and (iii) the split‐window covariance‐variance ratio technique, in which the water vapour content is retrieved from thermal infrared bands. A comparison between the atmospheric water vapour content extracted from the DAIS images using these techniques and that obtained f…
Mountain waves modulate the water vapor distribution in the UTLS
2017
Abstract. The water vapor distribution in the upper troposphere–lower stratosphere (UTLS) region has a strong impact on the atmospheric radiation budget. Transport and mixing processes on different scales mainly determine the water vapor concentration in the UTLS. Here, we investigate the effect of mountain waves on the vertical transport and mixing of water vapor. For this purpose we analyze measurements of water vapor and meteorological parameters recorded by the DLR Falcon and NSF/NCAR Gulfstream V research aircraft taken during the Deep Propagating Gravity Wave Experiment (DEEPWAVE) in New Zealand. By combining different methods, we develop a new approach to quantify location, direction…
Optimal use of the Prede POM sky radiometer for aerosol, water vapor, and ozone retrievals
2021
The Prede POM sky radiometer is a filter radiometer deployed worldwide in the SKYNET international network. A new method, called Skyrad pack MRI version 2 (MRI v2), is presented here to retrieve aerosol properties (size distribution, real and imaginary parts of the refractive index, single-scattering albedo, asymmetry factor, lidar ratio, and linear depolarization ratio), water vapor, and ozone column concentrations from the sky radiometer measurements. MRI v2 overcomes two limitations of previous methods (Skyrad pack versions 4.2 and 5, MRI version 1). One is the use of all the wavelengths of 315, 340, 380, 400, 500, 675, 870, 940, 1020, 1627, and 2200 nm if available from the sky radiomet…
Measurement of low-ppm mixing ratios of water vapor in the upper troposphere and lower stratosphere using chemical ionization mass spectrometry
2018
A chemical ionization mass spectrometer (CIMS) instrument has been developed for the fast, precise, and accurate measurement of water vapor (H2O) at low mixing ratios in the upper troposphere and lower stratosphere (UT/LS). A low-pressure flow of sample air passes through an ionization volume containing an α-particle radiation source, resulting in a cascade of ion-molecule reactions that produce hydronium ions (H3O+) from ambient H2O. The production of H3O+ ions from ambient H2O depends on pressure and flow through the ion source, which were tightly controlled in order to maintain the measurement sensitivity independent of changes in the airborne sampling environment. The instrument w…
Trends in column integrated water vapour over Europe from 1973 to 2003
2010
The spatial and temporal variations of atmospheric precipitable water (PW) content anomalies were analysed over Europe from 1973 to 2003 using daily data (0000 and 1200 UTC) from National Center of Environmental Prediction and National Center of Atmospheric Research Reanalysis project (NCEP-1) and in situ radiosonde data. Mann–Kendall trend tests were applied to long-term PW time series. Technology changes influence PW radiosonde trends, although these are in agreement with NCEP-1 trends. Over the south of the Iberian Peninsula, trends are negative and statistically significant ( 0.04 mm year−1; p < 0.05). Seasonal trends revealed negative and significant trends over the Iberian Peninsula f…
Metallic interconnects for solid oxide fuel cell: Effect of water vapour on oxidation resistance of differently coated alloys
2009
International audience; The need of interconnect to separate fuel and oxidant gasses and connect individual cells into electrical series in a SOFC stack appears as one of the most important point in fuel cell technology. Due to their high electrical and thermal conductivities, thermal expansion compatibility with the other cell components and lowcost, ferritic stainless steels (FSS) are nowconsidered to be among the most promising candidate materials as interconnects in SOFC stacks. Despite the formation at 800 ◦C of a protective chromia Cr2O3 scale, it can transform in volatile chromium species, leading to the lost of its protectiveness and then the degradation of the fuel cell. A previous…
Sensitivity of extreme rainfall to temperature in semi-arid Mediterranean regions
2019
Abstract Warmer air has the potential to hold more water vapour and, therefore, to provide more water to rainfall events. Studying the relationship between rainfall and temperature represents an emerging issue in hydrology and meteorology, since it can be considered fundamental for evaluating the effects of global warming on future precipitation. Various approaches have been tested across different parts of the world, in many cases observing an intensification of extreme precipitation at higher temperatures consistent with the well-known thermodynamic Clausius-Clapeyron relation (CC-scaling rate of 6–7%°C−1). However, at different locations for hourly time-scales, the temperature-extreme ra…
Precipitable water vapour content from ESR/SKYNET sun-sky radiometers: validation against GNSS/GPS and AERONET over three different sites in Europe
2018
The estimation of the precipitable water vapour content (W) with high temporal and spatial resolution is of great interest to both meteorological and climatological studies. Several methodologies based on remote sensing techniques have been recently developed in order to obtain accurate and frequent measurements of this atmospheric parameter. Among them, the relative low cost and easy deployment of sun–sky radiometers, or sun photometers, operating in several international networks, allowed the development of automatic estimations of W from these instruments with high temporal resolution. However, the great problem of this methodology is the estimation of the sun-photometric calibration par…
Thermal and hygrometric properties of traditional calcarenite stones in the area of Palermo
2017
Il contributo espone le misure di conducibilità termica svolte su tre conci di calcarenite conchiliare e la caratterizzazione igrometrica di uno di essi. I risultati sono confrontati con i dati termici e igrometrici riportati dalle norme tecniche esistenti (UNI 10351, UNI EN ISO 10456, UNI EN 1745). The energy improvement of historic buildings requires detailed knowledge of the thermal and hygrometric properties of traditional materials and components. These data should be collected for specific local contexts, where the features of historic constructions are comparable. For the purpose of developing this tool for the architectural heritage of Palermo, this research focuses on calcarenite s…