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Evaluation of the Water Vapor Radiometer Stability with a Modified Protective Shield in Precipitation Conditions

V. U. Bykov, G. N. Ilin, A. M. Shishikin

Transactions of IAA RAS, issue 72, 14–19 (2025)

Keywords: radiometer, water vapor, precipitation, stability

Abstract

A water film on the surface of the water vapor radiometer antenna system and especially water droplets on the heatinsulating screen, which appear under conditions of liquid precipitation, lead to incorrect values of the tropospheric parameters measured by the WVR. To minimize the impact of precipitation on the measurement results, a blowing system is provided in the WVR design. The practice of operating the WVRs in the VLBI observatories of the Kvazar-KVO complex have shown that the existing blowing system requires significant revision, since low blowing intensity in some cases leads to many hours of delay in drying the blown surfaces and, as a consequence, a significant time interval for recording incorrect data after the end of the precipitation period. Statistical data processing has shown that losses due to prolonged drying after the end of precipitation account for up to half of the data losses caused by precipitation. The existing blowing system was redesigned to concentrate the air flow on the aperture of the horn-lens feeds, as well as to enhance the flow by using more powerful fans. A special design of air ducts was developed and manufactured using 3D printing to implement the task. The efficiency of the blowing system was assessed using the example of the WVR operation at the Zelenchukskaya Observatory. The assessment was carried out by comparing the results of measuring the humidity tropospheric delay by a radiometer and the delay obtained from GNSS data, which are known to be invariant to precipitation. The developed blowing system has shown high efficiency. In order to assess the efficiency of the Zelenchukskaya Observatory WVR blowing system, the available data were compared with similar data for the period 2023-2024, during which similar meteorological conditions were observed. Calculations showed a decrease in the relative drying time from 1.5 to 0.6%, and in data losses from 2.8 to 0.9%. A more accurate assessment of the blowing system efficiency will be obtained upon completion of its annual operation cycle. Further reduction in WVR data losses in precipitation conditions is possible when the system is operated in combination with specialized data processing software.

Citation

Text

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RIS

V. U. Bykov, G. N. Ilin, A. M. Shishikin. Evaluation of the Water Vapor Radiometer Stability with a Modified Protective Shield in Precipitation Conditions // Transactions of IAA RAS. — 2025. — Issue 72. — P. 14–19.

@article{bykov2025,
  abstract = {A water film on the surface of the water vapor radiometer antenna system and especially water droplets on the heatinsulating screen, which appear under conditions of liquid precipitation, lead to incorrect values of the tropospheric parameters measured by the WVR. To minimize the impact of precipitation on the measurement results, a blowing system is provided in the WVR design. The practice of operating the WVRs in the VLBI observatories of the Kvazar-KVO complex have shown that the existing blowing system requires significant revision, since low blowing intensity in some cases leads to many hours of delay in drying the blown surfaces and, as a consequence, a significant time interval for recording incorrect data after the end of the precipitation period. Statistical data processing has shown that losses due to prolonged drying after the end of precipitation account for up to half of the data losses caused by precipitation.
The existing blowing system was redesigned to concentrate the air flow on the aperture of the horn-lens feeds, as
well as to enhance the flow by using more powerful fans. A special design of air ducts was developed and manufactured using 3D printing to implement the task. The efficiency of the blowing system was assessed using the example of the WVR operation at the Zelenchukskaya Observatory. The assessment was carried out by comparing the results of measuring the humidity tropospheric delay by a radiometer and the delay obtained from GNSS data, which are known to be invariant to precipitation.
The developed blowing system has shown high efficiency. In order to assess the efficiency of the Zelenchukskaya Observatory WVR blowing system, the available data were compared with similar data for the period 2023-2024, during which similar meteorological conditions were observed. Calculations showed a decrease in the relative drying time from 1.5 to 0.6%, and in data losses from 2.8 to 0.9%. A more accurate assessment of the blowing system efficiency will be obtained upon completion of its annual operation cycle. Further reduction in WVR data losses in precipitation conditions is possible when the system is operated in combination with specialized data processing software.},
  author = {V.~U. Bykov and G.~N. Ilin and A.~M. Shishikin},
  doi = {10.32876/ApplAstron.72.14-19},
  issue = {72},
  journal = {Transactions of IAA RAS},
  keyword = {radiometer, water vapor, precipitation, stability},
  pages = {14--19},
  title = {Evaluation of the Water Vapor Radiometer Stability with a Modified Protective Shield in Precipitation Conditions},
  url = {http://iaaras.ru/en/library/paper/2207/},
  year = {2025}
}

TY  - JOUR
TI  - Evaluation of the Water Vapor Radiometer Stability with a Modified Protective Shield in Precipitation Conditions
AU  - Bykov, V. U.
AU  - Ilin, G. N.
AU  - Shishikin, A. M.
PY  - 2025
T2  - Transactions of IAA RAS
IS  - 72
SP  - 14
AB  - A water film on the surface of the water vapor radiometer antenna
system and especially water droplets on the heatinsulating screen,
which appear under conditions of liquid precipitation, lead to
incorrect values of the tropospheric parameters measured by the WVR.
To minimize the impact of precipitation on the measurement results, a
blowing system is provided in the WVR design. The practice of
operating the WVRs in the VLBI observatories of the Kvazar-KVO
complex have shown that the existing blowing system requires
significant revision, since low blowing intensity in some cases leads
to many hours of delay in drying the blown surfaces and, as a
consequence, a significant time interval for recording incorrect data
after the end of the precipitation period. Statistical data
processing has shown that losses due to prolonged drying after the
end of precipitation account for up to half of the data losses caused
by precipitation.  The existing blowing system was redesigned to
concentrate the air flow on the aperture of the horn-lens feeds, as
well as to enhance the flow by using more powerful fans. A special
design of air ducts was developed and manufactured using 3D printing
to implement the task. The efficiency of the blowing system was
assessed using the example of the WVR operation at the Zelenchukskaya
Observatory. The assessment was carried out by comparing the results
of measuring the humidity tropospheric delay by a radiometer and the
delay obtained from GNSS data, which are known to be invariant to
precipitation.  The developed blowing system has shown high
efficiency. In order to assess the efficiency of the Zelenchukskaya
Observatory WVR blowing system, the available data were compared with
similar data for the period 2023-2024, during which similar
meteorological conditions were observed. Calculations showed a
decrease in the relative drying time from 1.5 to 0.6%, and in data
losses from 2.8 to 0.9%. A more accurate assessment of the blowing
system efficiency will be obtained upon completion of its annual
operation cycle. Further reduction in WVR data losses in
precipitation conditions is possible when the system is operated in
combination with specialized data processing software.
DO  - 10.32876/ApplAstron.72.14-19
UR  - http://iaaras.ru/en/library/paper/2207/
ER  -