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  • 1
    Publication Date: 2020-12-14
    Description: Observations of very low amounts of precipitable water vapor (PWV) by means of the Ground-Based Millimeter wave Spectrometer (GBMS) are discussed. Low amounts of column water vapor (between 0.5 and 4 mm) are typical of high mountain sites and polar regions, especially during winter, and are difficult to measure accurately because of the lack of sensitivity of conventional instruments to such low PWV contents. The technique used involves the measurement of atmospheric opacity in the range between 230 and 280 GHz with a spectral resolution of 4 GHz, followed by the conversion to precipitable water vapor using a linear relationship. We present the intercomparison of this data set with simultaneous PWV observations obtained with Vaisala RS92k radiosondes, a Raman lidar, and an IR Fourier transform spectrometer. These sets of measurements were carried out during the primary field campaign of the Earth Cooling by Water vapor Radiation (ECOWAR) project which took place at Breuil-Cervinia (45.9N, 7.6E, elevation 1990 m) and Plateau Rosa (45.9N, 7.7E, elevation 3490 m), Italy, from 3 to 16 March 2007. GBMS PWV measurements show a good agreement with the other three data sets exhibiting a mean difference between observations of 9%. The considerable number of data points available for the GBMS versus lidar PWV correlation allows an additional analysis which indicates negligible systematic differences between the two data sets.
    Description: Published
    Description: D14314
    Description: 1.8. Osservazioni di geofisica ambientale
    Description: JCR Journal
    Description: reserved
    Keywords: millimeter wave spectroscopy ; column water vapor ; 01. Atmosphere::01.01. Atmosphere::01.01.01. Composition and Structure
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
    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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  • 3
    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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  • 4
    Publication Date: 2020-12-14
    Description: In this study we present an intercomparison of measurements of very low water vapor column content obtained with a Ground-Based Millimeter-wave Spectrometer (GBMS), Vaisala RS92k radiosondes, a Raman Lidar, and an IR Fourier Transform Spectrometer. These sets of measurements were carried out during the primary field campaign of the ECOWAR (Earth COoling by WAter vapor Radiation) project which took place on the Western Italian Alps from 3 to 16 March, 2007.
    Description: Published
    Description: 135-138
    Description: 1.8. Osservazioni di geofisica ambientale
    Description: N/A or not JCR
    Description: open
    Keywords: Precipitable Water Vapor ; ECOWAR ; IR and Millimeter-Wave Spectroscopy ; 01. Atmosphere::01.01. Atmosphere::01.01.01. Composition and Structure ; 01. Atmosphere::01.01. Atmosphere::01.01.02. Climate
    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: 2017-04-03
    Description: We assess the quality of the version 2.2 (v2.2) HNO3 measurements from the Microwave Limb Sounder (MLS) on the Earth Observing System Aura satellite. The MLS HNO3 product has been greatly improved over that in the previous version (v1.5), with smoother profiles, much more realistic behavior at the lowest retrieval levels, and correction of a high bias caused by an error in one of the spectroscopy files used in v1.5 processing. The v2.2 HNO3 data are scientifically useful over the range 215 to 3.2 hPa, with single-profile precision of 0.7 ppbv throughout. Vertical resolution is 3–4 km in the upper troposphere and lower stratosphere, degrading to 5 km in the middle and upper stratosphere. The impact of various sources of systematic uncertainty has been quantified through a comprehensive set of retrieval simulations. In aggregate, systematic uncertainties are estimated to induce in the v2.2 HNO3 measurements biases that vary with altitude between ±0.5 and ±2 ppbv and multiplicative errors of ±5–15% throughout the stratosphere, rising to ±30% at 215 hPa. Consistent with this uncertainty analysis, comparisons with correlative data sets show that relative to HNO3 measurements from ground-based, balloon-borne, and satellite instruments operating in both the infrared and microwave regions of the spectrum, MLS v2.2 HNO3 mixing ratios are uniformly low by 10–30% throughout most of the stratosphere. Comparisons with in situ measurements made from the DC-8 and WB-57 aircraft in the upper troposphere and lowermost stratosphere indicate that the MLS HNO3 values are low in this region as well, but are useful for scientific studies (with appropriate averaging).
    Description: Published
    Description: D24S40
    Description: 1.7. Osservazioni di alta e media atmosfera
    Description: JCR Journal
    Description: reserved
    Keywords: satellite validation ; stratospheric HNO3 ; 01. Atmosphere::01.01. Atmosphere::01.01.01. Composition and Structure
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 8
    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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  • 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 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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  • 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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