VESPA-22: a ground-based microwave spectrometer for long-term measurements of polar stratospheric water vapor
The new ground-based 22 GHz spectrometer, VESPA-22 (water Vapor Emission Spectrometer for Polar Atmosphere at 22 GHz ) measures the 22.23 GHz water vapor emission line with a bandwidth of 500 MHz and a frequency resolution of 31 kHz . The integration time for a measurement ranges from 6 to 24 h, dep...
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ftcopernicus:oai:publications.copernicus.org:amt60596 2023-05-15T15:18:06+02:00 VESPA-22: a ground-based microwave spectrometer for long-term measurements of polar stratospheric water vapor Mevi, Gabriele Muscari, Giovanni Bertagnolio, Pietro Paolo Fiorucci, Irene Pace, Giandomenico 2019-04-11 application/pdf https://doi.org/10.5194/amt-11-1099-2018 https://amt.copernicus.org/articles/11/1099/2018/ eng eng doi:10.5194/amt-11-1099-2018 https://amt.copernicus.org/articles/11/1099/2018/ eISSN: 1867-8548 Text 2019 ftcopernicus https://doi.org/10.5194/amt-11-1099-2018 2020-07-20T16:23:25Z The new ground-based 22 GHz spectrometer, VESPA-22 (water Vapor Emission Spectrometer for Polar Atmosphere at 22 GHz ) measures the 22.23 GHz water vapor emission line with a bandwidth of 500 MHz and a frequency resolution of 31 kHz . The integration time for a measurement ranges from 6 to 24 h, depending on season and weather conditions. Water vapor spectra are collected using the beam-switching technique. VESPA-22 is designed to operate automatically with little maintenance; it employs an uncooled front-end characterized by a receiver temperature of about 180 K and its quasi-optical system presents a full width at half maximum of 3.5 ∘ . Every 30 min VESPA-22 measures also the sky opacity using the tipping curve technique. The instrument calibration is performed automatically by a noise diode; the emission temperature of this element is estimated twice an hour by observing alternatively a black body at ambient temperature and the sky at an elevation of 60 ∘ . The retrieved profiles obtained inverting 24 h integration spectra present a sensitivity larger than 0.8 from about 25 to 75 km of altitude during winter and from about 30 to 65 km during summer, a vertical resolution from about 12 to 23 km (depending on altitude), and an overall 1 σ uncertainty lower than 7 % up to 60 km altitude and rapidly increasing to 20 % at 75 km . In July 2016, VESPA-22 was installed at the Thule High Arctic Atmospheric Observatory located at Thule Air Base (76.5 ∘ N, 68.8 ∘ W), Greenland, and it has been operating almost continuously since then. The VESPA-22 water vapor mixing ratio vertical profiles discussed in this work are obtained from 24 h averaged spectra and are compared with version 4.2 of concurrent Aura/Microwave Limb Sounder (MLS) water vapor vertical profiles. In the sensitivity range of VESPA-22 retrievals, the intercomparison from July 2016 to July 2017 between VESPA-22 dataset and Aura/MLS dataset convolved with VESPA-22 averaging kernels shows an average difference within 1.4 % up to 60 km altitude and increasing to about 6 % (0.2 ppmv ) at 72 km . Text Arctic Greenland Thule Air Thule Air Base Thule Copernicus Publications: E-Journals Arctic Greenland New Ground ENVELOPE(-55.215,-55.215,49.567,49.567) Thule Air Base ENVELOPE(-68.703,-68.703,76.531,76.531) Atmospheric Measurement Techniques 11 2 1099 1117 |
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Open Polar |
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Copernicus Publications: E-Journals |
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ftcopernicus |
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English |
description |
The new ground-based 22 GHz spectrometer, VESPA-22 (water Vapor Emission Spectrometer for Polar Atmosphere at 22 GHz ) measures the 22.23 GHz water vapor emission line with a bandwidth of 500 MHz and a frequency resolution of 31 kHz . The integration time for a measurement ranges from 6 to 24 h, depending on season and weather conditions. Water vapor spectra are collected using the beam-switching technique. VESPA-22 is designed to operate automatically with little maintenance; it employs an uncooled front-end characterized by a receiver temperature of about 180 K and its quasi-optical system presents a full width at half maximum of 3.5 ∘ . Every 30 min VESPA-22 measures also the sky opacity using the tipping curve technique. The instrument calibration is performed automatically by a noise diode; the emission temperature of this element is estimated twice an hour by observing alternatively a black body at ambient temperature and the sky at an elevation of 60 ∘ . The retrieved profiles obtained inverting 24 h integration spectra present a sensitivity larger than 0.8 from about 25 to 75 km of altitude during winter and from about 30 to 65 km during summer, a vertical resolution from about 12 to 23 km (depending on altitude), and an overall 1 σ uncertainty lower than 7 % up to 60 km altitude and rapidly increasing to 20 % at 75 km . In July 2016, VESPA-22 was installed at the Thule High Arctic Atmospheric Observatory located at Thule Air Base (76.5 ∘ N, 68.8 ∘ W), Greenland, and it has been operating almost continuously since then. The VESPA-22 water vapor mixing ratio vertical profiles discussed in this work are obtained from 24 h averaged spectra and are compared with version 4.2 of concurrent Aura/Microwave Limb Sounder (MLS) water vapor vertical profiles. In the sensitivity range of VESPA-22 retrievals, the intercomparison from July 2016 to July 2017 between VESPA-22 dataset and Aura/MLS dataset convolved with VESPA-22 averaging kernels shows an average difference within 1.4 % up to 60 km altitude and increasing to about 6 % (0.2 ppmv ) at 72 km . |
format |
Text |
author |
Mevi, Gabriele Muscari, Giovanni Bertagnolio, Pietro Paolo Fiorucci, Irene Pace, Giandomenico |
spellingShingle |
Mevi, Gabriele Muscari, Giovanni Bertagnolio, Pietro Paolo Fiorucci, Irene Pace, Giandomenico VESPA-22: a ground-based microwave spectrometer for long-term measurements of polar stratospheric water vapor |
author_facet |
Mevi, Gabriele Muscari, Giovanni Bertagnolio, Pietro Paolo Fiorucci, Irene Pace, Giandomenico |
author_sort |
Mevi, Gabriele |
title |
VESPA-22: a ground-based microwave spectrometer for long-term measurements of polar stratospheric water vapor |
title_short |
VESPA-22: a ground-based microwave spectrometer for long-term measurements of polar stratospheric water vapor |
title_full |
VESPA-22: a ground-based microwave spectrometer for long-term measurements of polar stratospheric water vapor |
title_fullStr |
VESPA-22: a ground-based microwave spectrometer for long-term measurements of polar stratospheric water vapor |
title_full_unstemmed |
VESPA-22: a ground-based microwave spectrometer for long-term measurements of polar stratospheric water vapor |
title_sort |
vespa-22: a ground-based microwave spectrometer for long-term measurements of polar stratospheric water vapor |
publishDate |
2019 |
url |
https://doi.org/10.5194/amt-11-1099-2018 https://amt.copernicus.org/articles/11/1099/2018/ |
long_lat |
ENVELOPE(-55.215,-55.215,49.567,49.567) ENVELOPE(-68.703,-68.703,76.531,76.531) |
geographic |
Arctic Greenland New Ground Thule Air Base |
geographic_facet |
Arctic Greenland New Ground Thule Air Base |
genre |
Arctic Greenland Thule Air Thule Air Base Thule |
genre_facet |
Arctic Greenland Thule Air Thule Air Base Thule |
op_source |
eISSN: 1867-8548 |
op_relation |
doi:10.5194/amt-11-1099-2018 https://amt.copernicus.org/articles/11/1099/2018/ |
op_doi |
https://doi.org/10.5194/amt-11-1099-2018 |
container_title |
Atmospheric Measurement Techniques |
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11 |
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2 |
container_start_page |
1099 |
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1117 |
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1766348323528114176 |