Measurement of the Reference Surface Air Temperature from Brightness Temperature of Atmospheric Radiation

Impact of radiation is unavoidable in surface air temperature measurement by thermometers. Although thermometer screens/shields are used to reduce it, they suffer from some impacts including influence of radiation by screens/shields itself. Their characteristics are different for each type of screens/shields. It is considered that the reference surface air temperature measurement which get little impact of radiation in principle is effective to evaluate to these characteristics. Very thin resistive wire (ISO 2007) and ultrasonic anemometer and thermometer (Lacombe et al. 2011) have been proposed as candidates for this measurement.

We suggest another method from a brightness temperature of atmospheric radiation. Yamamoto (2016) compared the surface air temperature estimated using a ground-based microwave radiometer with ones by shielded thermometers and got plausible results. In addition, we will introduce a new method from infrared radiation brightness.

We have started a field intercomparison of some candidates for measuring the reference surface air temperature including a very thin handmade thermocouple after Moriwaki et al. (2003) and Kurzeja (2010), ultrasonic anemometers and instruments which measure brightness temperature, and a shielded thermometer at Meteorological Instrument Centre, Japan Meteorological Agency, Tsukuba, Japan.

Acknowledgment: This work was supported by JSPS KAKENHI Grant Number JP17K20051.

References

International Organization for Standardization, 2007: ISO 17714:2007. 19 pp.

Kurzeja, R., 2010: Boundary-Layer Meteorol., 134, 181–193.

Lacombe, M., D. Bousri, M. Leroy, and M. Mezred, 2011: IOM Report,106, WMO/TD-No. 1579, World Meteorological Organization, ,106 pp.

Moriwaki, R., M. Kanda, and Y. Kimoto, 2003: Proc. Hydraul. Eng., 47, 1–6 (in Japanese).

Yamamoto, A. 2016: IOM Report, 125., World Meteorological Organization.