1,720,962 research outputs found
Middle-upper water vapour estimation from MSG/UTH products combined with NCEP/NCAR analysis
No full textAtmospheric water vapour is extremely variable on almostall scales, mainly in the troposphere Its distribution and variation knowledge is still incomplete and long term changes, mainly in the upper troposphere, are difficult to evaluateLong time satellite observations, collected since severalyears, could be useful for a better comprehension ofmoisture climatology.Objectives of our work is: • integrate tropospheric humidity satellite observations withanalysis dataset in order to estimate daily middle/upperprecipitable water (MUPW)• check its consistence with known moisture climatic field
Changes in temperature and precipitation extremes observed in Modena, Italy
No full textClimate changes has become one of the most analysed subjects from researchers community, mainly because of the numerous extreme events that hit the globe. To have a better view of climate changes and trends, long observations time series are needed.
During last decade a lot of Italian time series, concerning several surface meteorological variables, have been analysed and published. No one of them includes one of the longest record in Italy, the time series of the Geophysical Observatory of the University of Modena and Reggio
Emilia. Measurements, collected since early 19th century, always in the same position, except for some months during the second world war, embrace daily temperature, precipitation amount, relative humidity, pressure, cloudiness and other variables.
In this work we concentrated on the analysis of yearly and seasonal trends and climate extremes of temperature, both minimum and maximum, and precipitation time series, for the periods 1861–2010 and 1831–2010 respectively, in which continuous measurements are available.
In general, our results confirm quite well those reported by IPCC and in many other studies over
Mediterranean area. In particular, we found that minimum temperature has a non significant
positive trend of +0.1 °C per decade considering all the period, the value increases to 0.9 °C per
decade for 1981–2010. For maximum temperature we observed a non significant +0.1 °C trend
for all the period, while +0.8 °C for the last thirty years.
On the other hand precipitation is decreasing, -6.3 mm per decade, considering all the analysed
period, while the last thirty years are characterised by a great increment of 74.8 mm per decade.
For both variables several climate indices have been analysed and they confirm what has been
found for minimum and maximum temperatures and precipitation. In particular, during last
30 years frost days and ice days are decreasing, whereas summer days are increasing. During
the last 30-year tropical nights and warm spell duration indices are characterised by a
particular strong increment, if compared to the ones of the entire period.
Finally, a cursory comparison between winter precipitation and NAO index was done, showing
a high anti-correlation, especially since the second half of 20th century
Correlations between atmospheric water vapour content and outgoing longwave radiation from satellite observations
No full textDatasets of radiative fluxes at TOA and water vapour content observations, both obtained from space measurementsand for a period of several years (since 2004 till now), are available from CM-SAF. Despite being a fairlyshort time period to draw conclusions about climate changes, it is possible to perform a correlation analysis ontrends and on space-time variability between the radiation budget at TOA and water vapour content, based onexclusively polar and geostationary satellite datasets.In this work monthly data of thermal radiative fluxes at TOA and water vapour content from CM-SAF, coveringan area that comprises Europe, Africa and the Atlantic Ocean, are simultaneously analysed.A previous analysis of water vapour content, derived from CM-SAF dataset, have shown positive trends, withdifferent values for land and sea areas, with a good consistency with literature (e.g. IPCC reports). Because of thestrong effect of water vapour on the thermal emitted radiative flow, the correlation between them is confirmed.Moreover, by using some multivariate statistical techniques, the space variability between water vapour and OLRfields has been analysed. Results have confirmed their reciprocal coupling
Variability of middle-upper tropospheric precipitable water from satellite images
No full textAim of this work is the investigation of middle-upper tropospheric (above 850 hPa) precipitable water space-time distribution obtained from satellite images, in order to look for typical patterns related to tropical and extra-tropical teleconnections.Precipitable water data are calculated from daily tropospheric humidity product derived from two water vapour channels of meteorological geostationary satellites Meteosat-8/-9. Tropospheric humidity provides a layer-mean relative humidity for two tropospheric layers (between 600 and 850 hPa and between 850 and 600 hPa).Monthly analysis of precipitable water has been realized for the period February 2004 - January 2009, over a circular area covered by satellites Meteosat-8/-9 (the satellite radiometer has a resolution of 3 km), included between 63 degree north and south of latitude and between 63 degree west and east of longitude. This area comprises all African continent and Middle East, Atlantic Ocean, the east part of Brazil and the major part of Europe.The time-space analysis of monthly middle-upper tropospheric precipitable water fields has been obtained by using different explorative and statistical analysis methods (e.g. extended EOF). It has revealed a weak and a moderate El Niño phenomena (between JJA 2004 and JFM 2005 and between JAS 2006 and DJF 2007) and a moderate La Niña event (between ASO 2007 and AMJ 2008)
Upper and middle precipitable water calculated from METEOSAT-8/-9 tropospheric humidity and NCEP/NCAR temperatures
No full textThe aim of this work is the estimation and the analysis of precipitable water in the middle-upper troposphere (850 hPa–300 hPa), obtained through Meteosat-8/-9 tropospheric humidity products, together with air temperature data, from NCEP/NCAR daily global reanalysis 1. The period of observation goes from 1st February 2004 to 30th November 2008, on a regular grid of 2.5° × 2.5° resolution, over Meteosat-8/-9 area, included between about 63°N–63°S of latitude and between about 63°W–63°E of longitude.Daily averages of tropospheric humidity products have been checked with two data sets: the first one was vertically averaged relative humidity from 97 Integrated Global Radiosonde Archive (IGRA) stations, the second one was relative humidity averaged from NCEP/NCAR daily global reanalysis 1. These comparisons have shown an underestimation of Meteosat relative humidity data respect the radiosounding data, in particular in the middle layer (850–600 hPa).Estimated middle-upper tropospheric precipitable water has shown a general coherence with typical climatological values representing about 30–45% of whole precipitable water in the same area. Linear trends for middle-upper troposphere shows values comprised between − 1.0 kg m− 2 yr− 1 and 0.2 kg m− 2 yr− 1, with bigger values (up to − 1.6 kg m− 2 yr− 1) mainly in the equatorial area, over South America. Hovmöller analysis underline mainly the middle-upper precipitable water seasonality with maximum values oscillating around the equator, following ITCZ migration, more marked over land than over the Ocean, from North to South
Observed tropical and extratropical modes of variability in moisture fields from climate satellite dataset
No full textGlobal and high resolution climate dataset taken from satellite images represents one of the most interestingsources for the monitoring and the investigation of present climate and, for short time periods (decadal), analternative to NWP reanalysis datasets. The Satellite Application Facility on Climate Monitoring (CM-SAF)archive represents a complete global dataset since January 2004 of several daily and monthly averaged atmosphericvariables such as radiative flows at surface and TOA, clouds parameters, precipitable water, surface albedo and soon.In this study CM-SAF daily data of layered precipitable water and relative humidity for a period of six years,all over the globe (with the exception of polar regions), have been analyzed. Applying teleconnectivity mapsboth in horizontal and in vertical, and multivariate statistics methods (EOF) to moisture fields, the appearanceof principal modes of general circulation variability patterns over the tropical band (Indian peninsula, southernAfrica, Australia and West Pacific Ocean) seems to have been revealed. Moreover, comparisons of precipitablewater fields with surface albedo and clouds data, yet collected from CM-SAF archive, have been evaluated
Confronto di Acqua Precipitabile ottenuta da osservazioni GPS al suolo con/senza misure meteorologiche in loco
No full textI sistemi di navigazione satellitare (GNSS) rappresentano, da diversi anni, un confermato e valido strumento per le osservazioni meteorologiche (diagnostica in tempo quasi reale e miglioramento dei modelli di previsione numerica) e per il monitoraggio del clima. In particolare, l’osservazione GPS al suolo permette, attraverso la combinazione dei ritardi zenitali troposferici totali dei segnali GPS con misure di pressione e temperatura alla superficie, la stima del contenuto colonnare totale del vapor acqueo (acqua precipitabile) in atmosfera. La maggior parte delle stazioni permanenti GPS non colleziona misure meteorologiche in corrispondenza effettiva alle rispettive antenne, per cui la valutazione dell’acqua precipitabile necessita l’utilizzo di altri dataset meteorologici. Obiettivo di questo lavoro è stato quello di confrontare, per ogni stazione presa in considerazione, i valori di acqua precipitabile ottenuti dai ritardi GPS, sia utilizzando misure meteorologiche in loco sia utilizzando analisi NCEP/NCAR (risoluzione 2.5° x 2.5°). Le stazioni GPS, da cui sono stati collezionati ritardi zenitali troposferici totali giornalieri prodotti dal Bundesamt für Kartographie und Geodäsie (BKG), appartengono alla rete permanente europea EUREF. Le stazioni analizzate sono state dieci per un periodo di sei anni (2001-2006). I confronti dei dati di acqua precipitabile ottenuti con i due metodi hanno mostrato, per il periodo complessivo e per tutte le stazioni, bias ed RMSE inferiori a 2 kg/m2. Questi risultati suggeriscono un impiego estensivo delle osservazioni GPS (inclusione delle stazioni permanenti prive di misure meteorologiche in loco) per un monitoraggio globale del vapor acqueo in atmosfera
GPS, NCEP Data and METEOSAT Precipitable Water Comparison for Balkan Area
No full textIntegrated Precipitable Water Vapor (IPWV) studies are an important mode for the hydrological regime evaluation with respect to the vertical structure of the atmosphere. The aim of this work is to integrate different observation systems (for instance Global Positioning System and METEOSAT-8) and data sources in order to study IPWV spatial and temporal distribution for Balkans region, sparsely covered with atmospheric vertical observations, as the helpful aid in the analysis of weather and synoptic processes.Global Positioning System (GPS) represents an enormous ongoing three-dimensional atmospheric observation system since the wet component of the tropospheric delay in GPS signals is nearly proportional to the quantity of integrated precipitable water vapor (IPWV). Tropospheric solutions for Balkans GPS sites of Sarajevo, Osjek, Dubrovnik and Ohrid are studied and presented in comparison to METEOSAT-8 and NCEP data.Tropospheric humidity product derived from the two water vapor channels of meteorological satellite METEOSAT-8 provides a layer-mean relative humidity for two tropospheric layers (between about 500 and 200hPa and between 850 and 300 hPa) with the resolution of 3 km, subsequently a biased estimation of IPWV can be obtained.Daily global analysis precipitable water data since 1980 available at 2.5 degrees resolution from the National Centres for Environmental Prediction (NCEP) is a helpful climate data source to evaluate humidity observations
SAF-CM water vapor products and their relationship to large and intense precipitation over Europe during 2005
No full textClimate data available by Satellite Application Facility (SAF) on Climate Monitoring (CM) represent a new important data source to investigate on climate changes, hydrology, and environmental sciences.The behavior of some atmospheric parameters like Cloud water liquid path (CWLP) and Humidity Composite Products (HCP) can be essential to understand the generation of intense and large events of precipitation.In this work temporal and spatial evolution of CWLP and HCP fields patterns over the CM-SAF baseline area during the year 2005 are analysed in connection to flooding episodes and extreme rainfall events.Furthermore, CLWP connections to North Atlantic Oscillation and Mediterranean Oscillation are shown.The area of analysis includes the European continent, the Mediterranean sea, and parts of North Atlantic and Middle East, ranging from 30° N up to 80° N and from 60° W to 60° E.CLWP product is derived from data obtained by instruments on-board of polar orbiting NOAA satellites (AVHRR) and the Meteosat Second Generation (SEVIRI) geostationary satellite. The products have a spatial resolution of 15 Km
Comparison between Precipitable Water Vapor data, obtained from METEOSAT products and NCEP Data
No full textWater vapor in atmosphere plays an important role in the mechanisms to the base of meteorology and climatology. Precipitable water vapor trends study is an usefulmethod in order to analyse and observe climate and its changes, both on a regional and global scale.The aim of this work is to study precipitable water vapor spatial and temporal distribution obtained from satellite observations.Precipitable water vapor values are calculated from tropospheric humidity data, a product derived from two water vapor channels of meteorological satellite Meteosat-8. The tropospheric humidity product provides a layer-mean relative humidity for twotropospheric layers (between 600 and 850 hPa and between 850 and 600 hPa). In this work the integrated precipitable water vapor between 300 and 850 hPa isobaric layers is analyzed, for the period from February to December 2004. The geographicalarea studied in this work coincides with the one that satellite Meteosat - 8 analyses (the satellite instrument has a resolution of 3 km), a circular area included between 63 degree north and south of latitude and between 63 degree west and east of longitude.Analyzing precipitable water vapor trends, a connection between its temporal variation and the North Atlantic Oscillation (NAO) is noted. Seen the lack of phenomena of El Nino or La Nina in year 2004, eventually connections between precipitable watervapor temporal trends and the Southern Oscillation (SO) couldn’t be observed and therefore analysed.In order to evaluate the results consistence, daily global analysis of precipitable water vapor data from National Centers for Environmental Prediction (NCEP), with a 2.5 degree resolution, is done
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