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  • 1
    Publication Date: 2020-12-18
    Description: The 2009 Arctic sudden stratospheric warming (SSW) was the most intense event of this kind ever observed. Unique ground-based measurements of middle atmospheric profiles for temperature, O3, CO, and N2O obtained at Thule (76.5°N, 68.8°W), Greenland, in the period January – early March are used to show the evolution of the 2009 SSW in the region of its maximum intensity. The first sign of the SSW was detected at θ~2000 K on January 19, when a rapid decrease in CO mixing ratio took place. The first evidence of a temperature increase was observed at the same level on 22 January, the earliest date on which lidar measurements reached above ~50 km. The warming propagated from the upper to the lower stratosphere in 7 days and the record maximum temperature of 289 K was observed between 1300 and 1500 K potential temperature on 22 January. A strong vortex splitting was associated with the SSW. Stratospheric backward trajectories indicate that airmasses arriving to Thule during the warming peak underwent a rapid compression and an intense adiabatic warming of up to 50 K. The rapid advection of air from the extra-tropics was also occasionally observed to produce elevated values of N2O mixing ratio. Starting from mid-February the temperature profile and the N2O mixing ratio returned to the pre-warming values in the mid and upper stratosphere, indicating the reformation of the vortex at these levels. In late winter, vertical descent from starting altitudes of ~60 km is estimated from CO profiles to be 0.25±0.05 km/day.
    Description: Published
    Description: D24315
    Description: 1.7. Osservazioni di alta e media atmosfera
    Description: 1.10. TTC - Telerilevamento
    Description: JCR Journal
    Description: open
    Keywords: sudden stratospheric warming ; winter polar stratosphere ; temperature ; O3 ; N2O ; CO ; 01. Atmosphere::01.01. Atmosphere::01.01.01. Composition and Structure ; 01. Atmosphere::01.01. Atmosphere::01.01.04. Processes and Dynamics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
    Publication Date: 2020-12-18
    Description: Ground-based measurements of atmospheric parameters have been carried out for more than 20 years at the Network for the Detection of Atmospheric Composition Change (NDACC) station at Thule Air Base (76.5°N, 68.8°W), on the north-western coast of Greenland. Various instruments dedicated to the study of the lower and middle polar atmosphere are installed at Thule in the framework of a long standing collaboration among Danish, Italian, and US research institutes and universities. This effort aims at monitoring the composition, structure and dynamics of the polar stratosphere, and at studying the Arctic energy budget and the role played by different factors, such as aerosols, water vapour, and surface albedo. During the International Polar Year (IPY), in winter 2008-2009, an intensive measurement campaign was conducted at Thule within the framework of the IPY project “Ozone layer and UV radiation in a changing climate evaluated during IPY” (ORACLE-O3) which sought to improve our understanding of the complex mechanisms that lead to the Arctic stratospheric O3 depletion. The campaign involved a lidar system, measuring aerosol backscatter and depolarization ratios up to 35 km and atmospheric temperature profiles from 25 to 70 km altitude, a ground-based millimeter-wave spectrometer (GBMS) used to derive stratospheric mixing ratio profiles of different chemical species involved in the stratospheric ozone depletion cycle, and then ground-based radiometers and a Cimel sunphotometer to study the Arctic radiative budget at the surface. The observations show that the surface radiation budget is mainly regulated by the longwave component throughout most of the year. Clouds have a significant impact contributing to enhance the role of longwave radiation. Besides clouds, water vapour seasonal changes produce the largest modification in the shortwave component at the surface, followed by changes in surface albedo and in aerosol amounts. For what concerns the middle atmosphere, during the first part of winter 2008-2009 the cold polar vortex allowed for the formation of polar stratospheric clouds (PSCs) which were observed above Thule by means of the lidar. This period was also characterized by GBMS measurements of low values of O3 due to the catalytic reactions prompted by the PSCs. In mid- January, as the most intense Sudden Stratospheric Warming event ever observed in the Arctic occurred, GBMS and lidar measurements of O3, N2O, CO and temperature described its evolution as it propagated from the upper atmosphere to the lower stratosphere.
    Description: Published
    Description: S0323
    Description: 2A. Fisica dell'alta atmosfera
    Description: 7A. Geofisica di esplorazione
    Description: JCR Journal
    Description: open
    Keywords: polar atmosphere ; NDACC ; radiative budget ; stratospheric ozone ; 01. Atmosphere::01.01. Atmosphere::01.01.01. Composition and Structure ; 01. Atmosphere::01.01. Atmosphere::01.01.04. Processes and Dynamics ; 01. Atmosphere::01.01. Atmosphere::01.01.05. Radiation ; 01. Atmosphere::01.01. Atmosphere::01.01.08. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 3
    Publication Date: 2020-12-18
    Description: The Arctic region plays a central role in the global climate system. Modifications in the Arctic radiative budget may strongly influence large scale atmospheric and oceanic circulation. The evaluation of the surface energy balance sensitivity to variations in several parameters, such as surface temperature, water vapour content, surface albedo, and atmospheric aerosols, is one of the main issues in assessing how the Arctic will respond to future climate changes. The NDACC station at Thule Air Base (76.5°N, 68.8°W) is equipped with a variety of instruments for the measurement of the radiative fluxes at the surface, aerosol optical properties, water vapour atmospheric content, and meteorological parameters. A Yankee Environmental System Total Solar Pyranometer (YES-TSP) and an Eppley pyrgeometer (PIR) are installed at Thule for the measurement of the global shortwave and longwave downward irradiances at the surface. The TSP was installed in 2002, while the PIR in 2009. A Cimel Sunphotometer measures aerosol optical properties and water vapour columnar content; the Cimel is part of the Aerosol Robotic Network and was installed in 2007. In winter, the water vapour columnar content is also measured at Thule with a millimeter-wave spectrometer (GBMS) operating in the 230-280 GHz range. GBMS measurements have been carried out during several winters between 2002 and 2011. A meteorological station, which measures surface temperature and pressure, relative humidity, wind speed and direction is also continuously operational at Thule. Satellite observations of the surface shortwave albedo obtained from MODIS have been used together with ground-based measurements. Four years (2007 to 2010) of surface shortwave irradiance at the surface, aerosol optical properties, and water vapour have been combined with satellite observations of the surface albedo. Radiative transfer model calculations are used to reproduce the observed shortwave fluxes and to separate the effects of the different parameters in modulating the cloud-free downward shortwave radiation at the ground. Water vapour is the main factor affecting the cloud-free shortwave irradiance at the surface. Its column value varies between 0.1 and 1.4 cm during the period spring to early autumn. Water vapour produces a reduction of the surface shortwave flux by -(212%). The surface albedo varies between 0.05 and 0.66 in the period March to September, with values larger than 0.5 in spring and smaller than 0.1 in summer. In spring the surface albedo induces an increase by +(2-4.5%) in the downward shortwave radiation. The aerosol optical depth at 500 nm is generally lower than 0.2; atmospheric aerosols produce a reduction in the shortwave radiation down to -5%. On annual base, the mean effects of water vapour and surface albedo are estimated to be –(10-11) Wm-2 and +(2-3) Wm-2, respectively. The temperature and humidity profiles in the troposphere have the strongest influence on the cloud-free downwelling longwave irradiance. In wintertime, in absence of solar radiation, the longwave fluxes dominate the surface radiation budget. GBMS water vapour measurements from winters 2009 to 2011 have been used, together with surface humidity and temperature, to investigate the relative influence of these factors in affecting the downwelling longwave irradiance.
    Description: Unpublished
    Description: Réunion Island, Francia
    Description: 1.8. Osservazioni di geofisica ambientale
    Description: 1.10. TTC - Telerilevamento
    Description: open
    Keywords: shortwave infrared ; longwave infrared ; radiation budget ; aerosols ; water vapour ; Greenland ; Arctic ; 01. Atmosphere::01.01. Atmosphere::01.01.05. Radiation
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Conference paper
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  • 4
    Publication Date: 2020-12-18
    Description: This study is based on ground-based measurements of downward surface shortwave irradiance (SW), columnar water vapour (wv), and aerosol optical depth (s) obtained at Thule Air Base (Greenland) in 2007–2010, together with MODIS observations of the surface shortwave albedo (A). Radiative transfer model calculations are used in combination with measurements to separate the radiative effect of A (∆SWA), wv (DSWwv), and aerosols (∆SWs) in modulating SW in cloud-free conditions. The shortwave radiation at the surface is mainly affected by water vapour absorption, which produces a reduction of SW as low as -100 Wm-2 (-18%). The seasonal change of A produces an increase of SW by up to +25 Wm-2 (+4.5%). The annual mean radiative effect is estimated to be -(21–22) Wm-2 for wv, and +(2–3) Wm-2 for A. An increase by +0.065 cm in the annual mean wv, to which corresponds an absolute increase in ∆SWwv by 0.93 Wm-2 (4.3%), has been observed to occur between 2007 and 2010. In the same period, the annual mean A has decreased by -0.027, with a corresponding decrease in ∆SWA by 0.41 Wm-2 (-14.9%). Atmospheric aerosols produce a reduction of SW as low as -32 Wm-2 (-6.7%). The instantaneous aerosol radiative forcing (RFs) reaches values of -28 Wm-2 and shows a strong dependency on surface albedo. The derived radiative forcing efficiency (FEs) for solar zenith angles between 55 and 70 is estimated to be (-120.6 ± 4.3) for 0.1〈A〈0.2, and (-41.2 ± 1.6) Wm-2 for 0.5〈A〈0.6.
    Description: Published
    Description: 953-969
    Description: 1.10. TTC - Telerilevamento
    Description: 3.7. Dinamica del clima e dell'oceano
    Description: JCR Journal
    Description: restricted
    Keywords: Arctic radiative balance ; Surface albedo ; Atmospheric aerosols ; Water vapour ; Direct radiative forcing ; Arctic amplification ; 01. Atmosphere::01.01. Atmosphere::01.01.02. Climate ; 01. Atmosphere::01.01. Atmosphere::01.01.05. Radiation
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 5
    Publication Date: 2020-12-18
    Description: Several instruments are operational at Thule Air Base (76.5oN, 68.8oW) as part of the Network for Detection of Atmospheric Composition Change. A lidar was installed in 1990 and has been operational particularly during the winter season. Lidar measurements are used to derive the aerosol backscatter ratio between about 10 and 35 km, and the atmospheric temperature (T) profile from 25 up to 70 km, with a resolution of 150 m. A ground-based millimeter-wave spectrometer (GBMS) was installed at Thule in 2001, and has been operational during the winter seasons of 2001-2003 and 2009-2011. The GBMS permits to derive the atmospheric concentration profiles of different chemical species, such as O3, CO, N2O, and HNO3, between about 15 and 80 km at a resolution of 6-8 km. The Arctic winter stratosphere is characterized by a high variability, and detection of trends is particularly difficult. The evolution of the vortex and the temperatures in the lower stratosphere has a large impact on formation of Polar Stratospheric Clouds (PSC) and on the stratosphere chemical evolution. Coldest winters occurred in 1999-2000, and 2004-2005. Intensive measurement campaigns were conducted at Thule Air Base during winters 2008-2009 and 2010-2011. These two winters have been deeply different in their thermal, dynamical and chemical evolution. The 2008-2009 Arctic winter has been characterized by the most intense Sudden Stratospheric Warming (SSW) event ever observed, and the maximum of this warming was detected over Greenland. Thus, ground-based observations of the thermal structure and chemical composition of the middle atmosphere from the station at Thule Air Base have permitted to show the evolution of the phenomenon and its interactions with the dynamical structure of the polar vortex in the region of maximum warming. On the contrary, the 2010-2011 has been a very cold winter, and polar stratospheric clouds have been detected by lidar from mid-February to mid-March at Thule Air Base. This very cold winter, together with the massive formation of PSCs, has caused the record stratospheric ozone loss that is occurring in spring 2011 in the Arctic. In this study, we will present a summary of the measurements of the thermal and chemical stratospheric structure obtained at Thule Air Base between 1990 and 2011, with special attention to the two winters of 2008-2009 and 2010-2011.
    Description: Unpublished
    Description: Sheraton Denver Downtown Hotel, Denver, CO, USA
    Description: 1.8. Osservazioni di geofisica ambientale
    Description: 1.10. TTC - Telerilevamento
    Description: 3.7. Dinamica del clima e dell'oceano
    Description: open
    Keywords: stratospheric composition ; ozone ; nitric acid ; sudden stratospheric warming ; Greenland ; Arctic ozone loss ; lidar observations ; microwave remote sensing ; 01. Atmosphere::01.01. Atmosphere::01.01.99. General or miscellaneous ; 01. Atmosphere::01.01. Atmosphere::01.01.01. Composition and Structure
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Abstract
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  • 6
    Publication Date: 2012-02-03
    Description: The Radiation Explorer in the Far InfraRed-Prototype for Applications and Development (REFIR-PAD) spectroradiometer was operated from the Testa Grigia Italian-Alps station in March 2007 during the Earth Cooling by Water Vapour Radiation (ECOWAR) measurement campaign, obtaining downwelling radiance spectra in the 100–1100 cm−1 range, under clear-sky conditions and in the presence of cirrus clouds. The analysis of these measurements has proven that the instrument is capable of determining precipitable water vapor with a total uncertainty of 5–7% by using the far-infrared rotational band of water. The measurement is unaffected by the presence of cirri, whose optical depth can be instead retrieved as an additional parameter. Information on the vertical profiles of water vapor volume mixing ratio and temperature can also be retrieved for three altitude levels. The ability to measure the water vapor column with a simple, uncooled instrument, capable of operating continuously and with a time resolution of about 10 min, makes REFIR-PAD a very valuable instrument for meteorological and climatological studies for the characterization of the water vapor distribution.
    Description: Published
    Description: D02310
    Description: 1.7. Osservazioni di alta e media atmosfera
    Description: 1.10. TTC - Telerilevamento
    Description: JCR Journal
    Description: reserved
    Keywords: tropospheric water vapor ; IR spectroscopy ; REFIR-PAD ; ECOWAR ; 01. Atmosphere::01.01. Atmosphere::01.01.01. Composition and Structure ; 01. Atmosphere::01.01. Atmosphere::01.01.08. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 7
    Publication Date: 2017-04-04
    Description: The REFIR-PAD spectroradiometer was operated from the Testa Grigia Italian-Alps station in March 2007 during the Earth COoling by WAter vapouR emission (ECOWAR) measurement campaign, obtaining downwelling radiance spectra in the 100-1100 cm−1 range, under clear-sky condition and in the presence of cirrus clouds. The analysis of these mea surements has proven that the instrument is capable of determining precipitable water vapor with a total uncertainty of 5–7% by using the far-infrared rotational band of water. The measurement is unaffected by the presence of cirri, whose optical depth can be instead retrieved as an additional parameter. Information on the vertical profiles of water vapor volume mixing ratio and temperature can also be retrieved for three altitude levels. The ability to measure the water vapor column with a simple, uncooled instrument, capable of operating continuously and with a time resolution of about 10 minutes makes REFIR-PAD a very valuable instrument for meteorological and climatological studies for the characterization of the water vapor distribution.
    Description: In press
    Description: 1.7. Osservazioni di alta e media atmosfera
    Description: 1.10. TTC - Telerilevamento
    Description: JCR Journal
    Description: restricted
    Keywords: tropospheric water vapor ; IR spectroscopy ; REFIR-PAD ; ECOWAR ; 01. Atmosphere::01.01. Atmosphere::01.01.01. Composition and Structure ; 01. Atmosphere::01.01. Atmosphere::01.01.08. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 8
    Publication Date: 2017-04-04
    Description: Water vapour is a crucial element of the climate system. Accurate observations of stratospheric humidity are needed in the equatorial belt, where most water vapour crosses the tropopause, and in the polar regions, that are most affected by climate change trends. Satellite-based observations provide atmospheric composition data with extensive spatial and temporal coverage, but these need to be validated and integrated by ground-based networks like GAW (Global Atmospheric Watch) and NDACC (Network for Detection of Atmospheric Composition Change). This contribution presents a new ground-based spectrometer for the observation of middle atmospheric humidity profiles being currently developed at INGV - Istituto Nazionale di Geofisica e Vulcanologia. The instrument will detect the water vapour spectral line at 22.235 GHz by using the balanced beam-switching observation technique. The receiver antenna system has a parabolic mirror and a corrugated horn with an overall HPBW of 3.5°. Preliminary tests of the horn performed at the Table Mountain Facility of the Jet Propulsion Laboratory, California are presented. An uncooled GaAsFET low-noise amplifier was custom-assembled for the receiver front-end. The back-end will be a FFT spectrometer with a 1 GHz bandwidth and a 63 kHz resolution which, given the pressure broadening coefficient of the H2O line, will allow to retrieve concentration profiles from about 15 to 80 km altitude. Since the retrieval altitude range is also limited by the spectral signal-to-noise ratio and baseline artifacts, special care is taken in minimizing receiver noise temperature. Low noise temperatures will imply integration times short enough to be able to observe diurnal changes in the lower stratosphere. In order to extend unmanned operation time and limit LN2 supplies at remote stations, calibrated noise sources will be used as cold load reference on a daily basis. The control interface, which is also under development at INGV, will be based on reconfigurable hardware (USB-CPLD). Several different sites are proposed for permanent installation. Among these the GAW sites of Thule Airbase, Greenland for polar monitoring, or Mount Chacaltaya, Bolivia, for tropical tropopause observations.
    Description: Unpublished
    Description: Florence, Italy
    Description: restricted
    Keywords: millimeter wave spectroscopy ; stratospheric water vapour ; climate change ; 01. Atmosphere::01.01. Atmosphere::01.01.01. Composition and Structure ; 01. Atmosphere::01.01. Atmosphere::01.01.04. Processes and Dynamics ; 01. Atmosphere::01.01. Atmosphere::01.01.08. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Poster session
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  • 9
    Publication Date: 2017-04-04
    Description: Water vapour is a crucial element of the climate system. Accurate observations of stratospheric humidity are needed in the equatorial belt, where water vapour crosses the tropopause, and in the Polar regions, that are affected the most by climate change trends [IPCC, 2007; Solomon et al., 2010]. Satellite-based observations provide atmospheric composition data with extensive spatial and temporal coverage, but these need to be validated and integrated by ground-based networks like GAW and NDACC Changes in middle atmospheric water vapour on time scales longer than the a satellite mission have been successfully observed by ground-based instruments [Nedoluha et al., 2009]. Several ground-based spectrometers have been developed in the last decades to detect the water vapour rotational emission line at 22.235 GHz with heterodyne microwave receivers [e.g., Nedoluha et al., 2009; Straub et al., 2011, Forkman et al., 2003, De Wachter et al., 2011] (see map on the left). The proposed sites for long-term installation of the new spectrometer are Concordia Station, Antarctica (3233 m asl 75.10°S, 123.3°E, NDACC site) or Thule Air Base, Greenland (76.5°N, 68.8°W; NDACC site) for polar monitoring, or Mount Chacaltaya, Bolivia (5.320 m asl, 16.2ºS, 68.1ºW, GAW site) for tropical observations.
    Description: Unpublished
    Description: Saint Paul, Reunion Island, France
    Description: 1.7. Osservazioni di alta e media atmosfera
    Description: 1.10. TTC - Telerilevamento
    Description: open
    Keywords: microwave remote sensing ; water vapour ; stratosphere ; Antarctica ; 01. Atmosphere::01.01. Atmosphere::01.01.99. General or miscellaneous ; 01. Atmosphere::01.01. Atmosphere::01.01.08. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Poster session
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  • 10
    Publication Date: 2017-04-04
    Description: The Ground-Based Millimeter-wave Spectrometer (GBMS) was designed and built at the State University of New York at Stony Brook in the early 1990s and since then has carried out many measurement campaigns of stratospheric O3, HNO3, CO and N2O at polar and mid-latitudes. Its HNO3 data set shed light on HNO3 annual cycles over the Antarctic continent and contributed to the validation of both generations of the satellite-based JPL Microwave Limb Sounder (MLS). Following the increasing need for long-term data sets of stratospheric constituents, we resolved to establish a long-term GMBS observation site at the Arctic station of Thule (76.5 N, 68.8 W), Greenland, beginning in January 2009, in order to track the long- and short-term interactions between the changing climate and the seasonal processes tied to the ozone depletion phenomenon. Furthermore, we updated the retrieval algorithm adapting the Optimal Estimation (OE) method to GBMS spectral data in order to conform to the standard of the Network for the Detection of Atmospheric Composition Change (NDACC) microwave group, and to provide our retrievals with a set of averaging kernels that allow more straightforward comparisons with other data sets. The new OE algorithm was applied to GBMS HNO3 data sets from 1993 South Pole observations to date, in order to produce HNO3 version 2 (v2) profiles. A sample of results obtained at Antarctic latitudes in fall and winter and at mid-latitudes is shown here. In most conditions, v2 inversions show a sensitivity (i.e., sum of column elements of the averaging kernel matrix) of 100±20% from 20 to 45 km altitude, with somewhat worse (better) sensitivity in the Antarctic winter lower (upper) stratosphere. The 1 uncertainty on HNO3 v2 mixing ratio vertical profiles depends on altitude and is estimated at 15% or 0.3 ppbv, whichever is larger. Comparisons of v2 with former (v1) GBMS HNO3 vertical profiles, obtained employing the constrained matrix inversion method, show that v1 and v2 profiles are overall consistent. The main difference is at the HNO3 mixing ratio maximum in the 20–25 km altitude range, which is smaller in v2 than v1 profiles by up to 2 ppbv at mid-latitudes and during the Antarctic fall. This difference suggests a better agreement of GBMS HNO3 v2 profiles with both UARS/ and EOS Aura/MLS HNO3 data than previous v1 profiles.
    Description: Published
    Description: 1317-1330
    Description: 1.7. Osservazioni di alta e media atmosfera
    Description: JCR Journal
    Description: open
    Keywords: Atmospheric composition and structure ; Instruments and techniques ; 01. Atmosphere::01.01. Atmosphere::01.01.01. Composition and Structure ; 01. Atmosphere::01.01. Atmosphere::01.01.04. Processes and Dynamics ; 01. Atmosphere::01.01. Atmosphere::01.01.08. Instruments and techniques ; 05. General::05.05. Mathematical geophysics::05.05.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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