Development of a Peltier-based chilled-mirror hygrometer, SKYDEW, for tropospheric and lower-stratospheric water vapor measurements
<p>We have developed a Peltier-based non-cryogenic chilled-mirror hygrometer named SKYDEW to measure water vapor from the surface to the stratosphere. Several chamber experiments were conducted to investigate the characteristics and performance of the instrument under various conditions. The s...
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Copernicus Publications
2025-01-01
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| Series: | Atmospheric Measurement Techniques |
| Online Access: | https://amt.copernicus.org/articles/18/509/2025/amt-18-509-2025.pdf |
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| author | T. Sugidachi M. Fujiwara K. Shimizu S.-Y. Ogino J. Suzuki R. J. Dirksen |
| author_facet | T. Sugidachi M. Fujiwara K. Shimizu S.-Y. Ogino J. Suzuki R. J. Dirksen |
| author_sort | T. Sugidachi |
| collection | DOAJ |
| description | <p>We have developed a Peltier-based non-cryogenic chilled-mirror hygrometer named SKYDEW to measure water vapor from the surface to the stratosphere. Several chamber experiments were conducted to investigate the characteristics and performance of the instrument under various conditions. The stability of the feedback controller that maintains the condensate on the mirror depends on the controller setting, the condensate condition, and the frost point in ambient air. The results of condensate observation by a microscope and proportional-integral-derivative (PID) tuning in a chamber were used to determine the PID parameters of the controller such that slight oscillations of the scattered light signal from the mirror and mirror temperature are retained. This allows for the detection of steep gradients in the humidity profile, which are otherwise not detected because of the slower response. The oscillation of the raw mirror temperature is smoothed with a golden point method that selects the equilibrium point of the frost layer. We further describe the details of the data processing and the uncertainty estimation for SKYDEW measurements in terms of the Global Climate Observing System (GCOS) Reference Upper-Air Network (GRUAN) requirements. The calibration uncertainty of the mirror temperature measurement is <span class="inline-formula"><</span> 0.1 K for the entire temperature range from <span class="inline-formula">−</span>95 to 40 °C. The total measurement uncertainty of SKYDEW measurements can exceed 0.5 K in regions where large oscillations of the mirror temperature remain.</p>
<p>Intercomparisons with relative humidity (RH) sensors on radiosondes, the cryogenic frost point hygrometer (CFH), and the Aura Microwave Limb Sounder (MLS) were performed at various latitudes in the Northern Hemisphere to evaluate the performance of SKYDEW. These results show that SKYDEW can reliably measure atmospheric water vapor up to 25 km altitude. Data from several SKYDEW and CFH measurements predominantly agree within their respective uncertainties, although a systematic difference of <span class="inline-formula">∼</span> 0.5 K between SKYDEW and CFH was found in the stratosphere, the reason for which is unknown. SKYDEW shows good agreement with Aura MLS for profiles that are not affected by contamination.</p> |
| format | Article |
| id | doaj-art-8783b495ddf24c5aad32ee72bde8899a |
| institution | Kabale University |
| issn | 1867-1381 1867-8548 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | Copernicus Publications |
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| series | Atmospheric Measurement Techniques |
| spelling | doaj-art-8783b495ddf24c5aad32ee72bde8899a2025-01-28T15:37:19ZengCopernicus PublicationsAtmospheric Measurement Techniques1867-13811867-85482025-01-011850953110.5194/amt-18-509-2025Development of a Peltier-based chilled-mirror hygrometer, SKYDEW, for tropospheric and lower-stratospheric water vapor measurementsT. Sugidachi0M. Fujiwara1K. Shimizu2S.-Y. Ogino3J. Suzuki4R. J. Dirksen5Meisei Electric Co., Ltd., 2223 Naganumamachi, Isesaki-shi, Gunma, 372-8585, JapanFaculty of Environmental Earth Science, Hokkaido University, Kita 10 Nishi 5, Kita-ku, Sapporo, Hokkaido, 060-0810, JapanMeisei Electric Co., Ltd., 2223 Naganumamachi, Isesaki-shi, Gunma, 372-8585, JapanJapan Agency for Marine-Earth Science and Technology, Yokohama, Kanagawa, 236-0001, JapanJapan Agency for Marine-Earth Science and Technology, Yokohama, Kanagawa, 236-0001, JapanGRUAN Lead Centre, Meteorologisches Observatorium Lindenberg, Deutscher Wetterdienst, Am Observatorium 12, 15848 Tauche, Germany<p>We have developed a Peltier-based non-cryogenic chilled-mirror hygrometer named SKYDEW to measure water vapor from the surface to the stratosphere. Several chamber experiments were conducted to investigate the characteristics and performance of the instrument under various conditions. The stability of the feedback controller that maintains the condensate on the mirror depends on the controller setting, the condensate condition, and the frost point in ambient air. The results of condensate observation by a microscope and proportional-integral-derivative (PID) tuning in a chamber were used to determine the PID parameters of the controller such that slight oscillations of the scattered light signal from the mirror and mirror temperature are retained. This allows for the detection of steep gradients in the humidity profile, which are otherwise not detected because of the slower response. The oscillation of the raw mirror temperature is smoothed with a golden point method that selects the equilibrium point of the frost layer. We further describe the details of the data processing and the uncertainty estimation for SKYDEW measurements in terms of the Global Climate Observing System (GCOS) Reference Upper-Air Network (GRUAN) requirements. The calibration uncertainty of the mirror temperature measurement is <span class="inline-formula"><</span> 0.1 K for the entire temperature range from <span class="inline-formula">−</span>95 to 40 °C. The total measurement uncertainty of SKYDEW measurements can exceed 0.5 K in regions where large oscillations of the mirror temperature remain.</p> <p>Intercomparisons with relative humidity (RH) sensors on radiosondes, the cryogenic frost point hygrometer (CFH), and the Aura Microwave Limb Sounder (MLS) were performed at various latitudes in the Northern Hemisphere to evaluate the performance of SKYDEW. These results show that SKYDEW can reliably measure atmospheric water vapor up to 25 km altitude. Data from several SKYDEW and CFH measurements predominantly agree within their respective uncertainties, although a systematic difference of <span class="inline-formula">∼</span> 0.5 K between SKYDEW and CFH was found in the stratosphere, the reason for which is unknown. SKYDEW shows good agreement with Aura MLS for profiles that are not affected by contamination.</p>https://amt.copernicus.org/articles/18/509/2025/amt-18-509-2025.pdf |
| spellingShingle | T. Sugidachi M. Fujiwara K. Shimizu S.-Y. Ogino J. Suzuki R. J. Dirksen Development of a Peltier-based chilled-mirror hygrometer, SKYDEW, for tropospheric and lower-stratospheric water vapor measurements Atmospheric Measurement Techniques |
| title | Development of a Peltier-based chilled-mirror hygrometer, SKYDEW, for tropospheric and lower-stratospheric water vapor measurements |
| title_full | Development of a Peltier-based chilled-mirror hygrometer, SKYDEW, for tropospheric and lower-stratospheric water vapor measurements |
| title_fullStr | Development of a Peltier-based chilled-mirror hygrometer, SKYDEW, for tropospheric and lower-stratospheric water vapor measurements |
| title_full_unstemmed | Development of a Peltier-based chilled-mirror hygrometer, SKYDEW, for tropospheric and lower-stratospheric water vapor measurements |
| title_short | Development of a Peltier-based chilled-mirror hygrometer, SKYDEW, for tropospheric and lower-stratospheric water vapor measurements |
| title_sort | development of a peltier based chilled mirror hygrometer skydew for tropospheric and lower stratospheric water vapor measurements |
| url | https://amt.copernicus.org/articles/18/509/2025/amt-18-509-2025.pdf |
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