Kipp & Zonen Radiometers

CM21 Pyranometer CG4 Pyrgeometer

Introduction

ISFF uses CM21s and CG4s to measure broadband visible and infrared radiation, respectively. Our short-term goal is to obtain enough sensors to be able to instrument 9 sites with 4-component radiation measurement systems, using our complement of Epply PSP and PIR sensors for 5 of the sites. As of Oct 2006, we can instrument another 3 sites using Kipp & Zonen sensors.

These sensors are lighter than Epply PSP and PIRs and thus are preferred where weight is critical (such as on Arctic ice deployments). This also permits a lighter mounting structure to be used. Furthermore, results from EBEX suggest that the Kipp & Zonen sensors are more accurate than the Epplys and the CG4 has a smaller dome temperature correction than the PIR. Thus, we plan to utilize these sensors more in future deployments. Our CG4s do not have a Tdome sensor, so it is not possible to implement a dome heating correction. The CG4 manual states that the dome-case temperature difference is no more than 0.3C and would produce an error of less than 4 W/m^2. The manual also says that the CG4 does not need to be shaded from direct sun (the shortwave radiation correction). Data shown by H. Naganuuma (http://www.gewex.org/BSRN/BSRNagendafinal.htm) show the CG4 reading lower by 5 W/m^2 when shaded from full sun (f=~0.5%).

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