Monitoring middle-atmospheric water vapor over Seoul by using a 22 GHz ground-based radiometer SWARA

Soohyun Ka; Evelyn de Wachter; Niklaus Kaempfer; Jung Jin Oh

doi:10.1117/12.869501

28 October 2010 Monitoring middle-atmospheric water vapor over Seoul by using a 22 GHz ground-based radiometer SWARA

Soohyun Ka, Evelyn de Wachter, Niklaus Kaempfer, Jung Jin Oh

Proceedings Volume 7859, Remote Sensing of the Atmosphere and Clouds III; 78590K (2010) https://doi.org/10.1117/12.869501
Event: SPIE Asia-Pacific Remote Sensing, 2010, Incheon, Korea, Republic of

Abstract

Water vapor is the strongest natural greenhouse gas in the atmosphere. It is most abundant in the troposphere at low altitudes, due to evaporation at the ocean surface, with maximum values of around 6 g/kg. The amount of water vapor reaches a minimum at tropopause level and increases again in the middle atmosphere through oxidation of methane and vertical transport. Water vapor has both positive and negative effects on global warming, and we need to study how it works on climate change by monitoring water vapor concentration in the middle atmosphere. In this paper, we focus on the 22 GHz ground-based radiometer called SWARA (Seoul Water vapor Radiometer) which has been operated at Sookmyung women's university in Seoul, Korea since Oct. 2006. It is a joint project of the University of Bern, Switzerland, and the Sookmyung Women's University of Seoul, South Korea. The SWARA receives 22.235 GHz emitted from water vapor spontaneously and converts down to 1.5 GHz with +/- 0.5 GHz band width in 61 kHz resolution. To represent 22.235 GHz water vapor spectrum precisely, we need some calibration methods because the signal shows very weak intensity in ~0.1 K on the ground. For SWARA, we have used the balancing and the tipping curve methods for a calibration. To retrieve the water vapor profile, we have applied ARTS and Qpack software. In this paper, we will present the calibration methods and water vapor variation over Seoul for the last 4 years.

Citation Download Citation

Soohyun Ka, Evelyn de Wachter, Niklaus Kaempfer, and Jung Jin Oh "Monitoring middle-atmospheric water vapor over Seoul by using a 22 GHz ground-based radiometer SWARA", Proc. SPIE 7859, Remote Sensing of the Atmosphere and Clouds III, 78590K (28 October 2010); https://doi.org/10.1117/12.869501

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KEYWORDS

Calibration

Antennas

Radiometry

Microwave radiation

Atmospheric monitoring

Climate change

Sensors

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