1. Regional Radiation CENTER Tokyo in the WMO RA-II
Osamu Ijima
Radiation Section,
Atmospheric Environment Division,
Global Environment and Marine Department,
Japan Meteorological Agency (JMA)
I will present here RRC Tokyo in the WMO Regional Association II.
Oct. 2010, IPC-XI, Davos, Switzerland

2. RRC Regional Association (RA) II (Asia)
JMA (Tokyo) has been serving as RRC in the WMO Regional Association (RA) II (Asia) since 1965.
This is a map of Region II ASIA.
JMA (Tokyo) has been serving as RRC in the WMO Regional Association (RA) II (Asia) since 1965.
Region II ASIA MAP

3. Activities of RRC RA-II Tokyo No.1
- History and main activities -
1964 Pyrheliometer Intercomparison : India - Japan
(Pune, India)
1965 Regional Radiation Centre Establish
(RA II Res.20, CIMO IV Rec.1,3,9)
1968 Pyrheliometer Intercomparison : Thailand - Japan
(Tsukuba, Japan)
1970 Join in IPC-III (WRC/Davos, Switzerland)
1975 Join in IPC-IV (WRC/Davos, Switzerland)
Pyrheliometer Intercomparison : China - Japan
(Tsukuba, Japan) 
1980 Join in IPC-V (WRC/Davos, Switzerland)
1983 Pyrheliometer Intercomparison : Hong Kong - Japan
1985 Join in IPC-VI (WRC/Davos, Switzerland)
I report on the activity of RRC Tokyo.
RRC Tokyo participates in the intercomparison continuously from IPC-III. 3

4. Activities of RRC RA-II Tokyo No.2
- History and main activities -
1985 Join in IPC-VI (WRC/Davos, Switzerland)
1989 RPC-I : Regional Pyrheliometer Comparison of
RA II & RA V (Tsukuba, Japan) 
1990 Join in IPC-VII (WRC/Davos, Switzerland)
1994 Reference Pyranometer Calibration : Thailand
(Tsukuba, Japan)
1995 Pyrheliometer Intercomparison : China - Japan
Reference Pyranometer Calibration : Korea
Join in IPC-VIII (WRC/Davos, Switzerland)
1996 Training for Calibration of Pyrheliometers : Korea
RRC Tokyo holds Regional Pyrheliometer Comparison every five years. 4

5. Activities of RRC RA-II Tokyo No.3
- History and main activities -
1997 Pyrheliometer Intercomparison :
Hong Kong & Korea - Japan (Tsukuba, Japan)
Training for Reference Pyranometer Calibration :
Philippines (Tsukuba, Japan)
2000 Join in IPC-IX (WRC/Davos, Switzerland)
2002 Pyrheliometer Intercomparison :
Hong Kong, China & Korea - Japan
(Tsukuba, Japan) 
2005 Join in IPC-X (WRC/Davos, Switzerland)
2007 RPC-II : Regional Pyrheliometer Comparison
　　　　 　 of RA II (Tsukuba, Japan)
2010 Join in IPC-XI (WRC/Davos, Switzerland)
2012 RPC-III (planned)
　Next RPC is planned in 2012 at Mt. Tsukuba. 5

6. Calibration system within the framework of WMO
World Radiation Center
Solar Radiometry Section （WRC-SRS）
PMOD (Davos, Switzerland)
Regional Radiaton Centre（RRC）
RRC-Tokyo (Japan), RRC-Pune (India)
National Radiation Centre（NRC）
RIC-Beijing (China), RIC-Tsukuba (Japan)
World Standard Group (WSG)
Regional Standard Group
National Standard Group
Operational instruments
International Pyrheliometer Comparison (IPC)
Regional Pyrheliometer Comparison (RPC)
Calibration
traceability
traceability
This conceptual diagram shows the calibration of solar radiation instruments within the framework of WMO
I will report here on the RRC and NRC activity in the past five years.
traceability
Conceptual diagram of calibration of solar radiation instruments
within the framework of WMO 6

7. Regional Pyrheliometer Comparison (RPC)
RPCs are held once every 5 years, in principle in the next year of IPC.
Last RPC was held from Jan. to Jan at Tsukuba, Japan with 4 NRC in RAII and WRC.
The next RPC is planned in 2012.
RRC Tokyo holds RPCs once every 5 years, in principle in the next year of IPC.
Last RPC was held from Jan. to Feb at Tsukuba, Japan. Four NRCs and WRC participated in the RPC.
The next RPC is planned in 2012.
RPC at Mt.Tsukuba in 2007 7

8. RPC at Mt. Tsukuba Mt. Tsukuba
Aerological Observatory (BSRN Site: Tateno
　　　 at Tsukuba City)
50km
Mt. Tsukuba
▲ 877m
Tsukuba City
●Narita
●Tokyo
The RPC is held on the roof of the Keisei Hotel on the mountainside of Mt. Tsukuba.
Mt. Tsukuba is located about 20km north of the Aerological Observatory.
Keisei Hotel (560m)
Mt. Tsukuba (877m)

9. National Radiation Centre（NRC）
Intercomparisons are held once a year among the regional and national standard groups to maintain their accuracy.
The NRC holds intercomparisons once a year among the regional and national standard groups
to maintain their accuracy.
Moreover, we are calibrating pyrheliometers and pyranometers.
Annual internal pyrheliometer comparison at Mt.Tsukuba in 2010
Left: Regional standard group (pyrheliometers)
Right: National standard group (pyranometers with collimation tubes) 9

10. Collimation tube method Sun and shade method (ISO9846）
Pyranometer Calibration Result
Collimation tube method
Sun and shade method (ISO9846)
Reference
(Standard Instrument,
Absolute Pyrheliometer)
calibration
calibration
calibration
(AHF: 32446)
Reference
(Pyrheliometer
CH1: PKT10359)
Pyranometer
(CM21:970409
CMP21:070107)
Pyranometer
(CM21:970409
CMP21:070107)
Pyrheliometer
(CH1 : PKT10359)
Method
Date
Reference
Light source
Pyranometer CM
CMP
Collimation tube method
2009/1/25 ～ 2009/1/28
Absolute Pyrheliometer
AHF　32446
Outdoor
12.20
8.79
Sun and shade method (ISO9846）
2009/2/6
Pyrheliometer CH1　PKT10359 －
8.77
2009/2/12
12.19
8.76
Coefficient (mV/W/m^2)
I’d like to show you pyranometer calibration results by different two methods,
the collimation tube method and the sun and shade method.
JMA adopts the collimation tube method for operational calibration of national standard pyranometers.
On the other hand, the sun and shade method is treated in ISO9846 as a standard calibration method.
We used an absolute pyrheliometer and a pyrheliometer that are traceable to WRR as a reference instruments in each method.
This table shows the results by the two methods.
It shows that the pyranometer sensitivities obtained by the two methods agree well each other,
and we confirmed the validity of the collimation method.

11. A B Structure of the Collimation tube Target
（Opening full-angle　5°　Slope angle　1°）
Diaphragm
The scattered light is effectively suppressed
by the diaphragms.
Pyranometer A B
The Pyranometer is set at the bottom of the tube, so it has the same structure as the Pyrheliometer.
I’d like to show you the brief outline of JMA’s pyranometer calibration method, called Collimation Tube method.
This slide shows the structure of the Collimation Tube. It is designed to have five degree opening full-angle
and one degree slope angle.
The diaphragms are placed to prevent scattering lights by the wall.
The pyranometer to be calibrated is set at the bottom of the tube.
As a result, the pyranometer has the same structure as the pyrheliometer.
The Sun and shade method is the calibration method of Pyranomer that registered as ISO9846.
We compared with these method.
Comparison between the Sun and shade method （A）
and the Collimation tube method （B）
Mt.Tsukuba in 2009

12. Calibration of infrared radiation instruments within the framework of WMO
The world infrared irradiance standard developed at PMOD based on the World Infrared Standard Group (WISG) in 2004.
RRCs are recommended to have a regional standard group of pyrgeometers and send them every three years to the WRC-IRS for calibration.
World Radiation Centre
Infrared Radiometry Section (WRC-IRS)
PMOD (Davos, Switzerland)
Regional Radiaton Centre（RRC）
RRC-Tokyo (Japan), RRC-Pune (India)
Calibration Service
World Infrared Standard Group (WISG)
traceability
This conceptual diagram shows the calibration of infrared radiation instruments within the framework of WMO
RRCs are recommended to have a regional standard group of pyrgeometers and send them every three years
to the WRC-IRS(Infrared Radiometry Section) for calibration.
Regional Standard Group
Current state of calibration of infrared radiation instruments
within the framework of WMO 12

13. The regional standard group at RRC-Tokyoc
List of pyrgeometers making up
the regional standard group (calibration date)
Eppley PIR/32205F3 (Dec, 2006)
Kipp&Zonen CG4/ (Jan, 2007)
Kipp&Zonen CGR4/ (Dec, 2008)
Kipp&Zonen CGR4/ (Dec, 2009)
Kipp&Zonen CGR4/070039
(in calibration at PMOD, Now)
Each reference pyrgeometer is sent to WRC-IRS every 3 years for calibration.
There are currently five pyrgeometers calibrated at PMOD.
Each reference pyrgeometer is sent to WRC-IRS every 3 years for calibration.
the regional standard
group in a desiccator 13

14. The pyrgeometer calibration procedure at RRC
Adopt the same procedure as the WRC-IRS’s
The pyrgeometers are calibrated outdoors by comparisng with the standard group.  traceable to the WISG
inspected pyrgeometers
the standard group
The Aerological Observatory adopts the same procedure as that of the WRC-IRS.
The pyrgeometers are calibrated outdoors by comparing with the standard group.
Outdoor comparisons with the pyrgeometer standard group 14

15. difference with BB calibration (W/m2)
contribution for improvements of pyrgeometer calibration within the framework of WMO.
cavity temp. controller
(bath vessel)
pyrgeometer body
temp.　controller
data logger
black body cavity
dry air temp. controller
(pyrgeometer dome temp.)
Performance of JMA’s Black body (BB) cavity
Comparisons of mean difference from reference longwave radiation by class of pyrgeometer body temperature (for K&Z CG4 s/n:050798).
Temp. class (deg.C)
difference without
BB calibration (W/m2)
difference with BB calibration (W/m2)
0 - 10
-0.58
0.13
0.02
-0.06
0.40
-0.30
pyrgeometer
conical cavity
desiccant
bath vessel P
pump
thermocontroller
Pertier PC
data logger
(cavity temp.)
(body temp.)
(dome temp.)
heat transfer liquid
dry air
signal
Calibration coefficients for Eppley/PIR (s/n:32205F3) by WMO/World Radiation Center(WRC) and JMA
Temperature-dependent calibration coefficients are determined by using JMA’s black body cavity.
The results of the calibration by JMA is almost comparable to that by PMOD.
Coefficient
WRC
(Dec. 2006)
JMA
(Jun. 2004)
(Jan. 2007) C
3.91
3.9647
3.9328 k1
0.01
0.0146
0.0143 k2
1.0024
1.0025
1.0028 k3
3.2
2.8752
2.9012
Picture and schematic figure of JMA’s BB cavity

16. Summary RRC-Tokyo has been serving as RRC in RA II since 1965.
In January 2007, the RRC of Tokyo organized a regional intercomparison at Mt Tsukuba, attended by experts from China including Hong Kong, the Republic of Korea, Japan and the WRC. The report of the regional intercomparison has been published from WMO as WMO/TD-No
Next RPC is planned in 2012 at Mt. Tsukuba. The details of the RRC will be announced to participants in due course.
RRC-Tokyo has established a pyrgeometer calibration procedure for Eppley PIR and Kipp&Zonen CG4/CGR4 pyrgeometers.
RRC-Tokyo would like to cooperate in calibration of radiation instruments for the improvements of surface radiation measurements.
RRC-Tokyo has been serving as RRC in RA II since 1965.
In January 2007, the RRC of Tokyo organized a regional intercomparison at Mt Tsukuba, attended by experts
from China including Hong Kong, the Republic of Korea, Japan and the WRC.
The report of the regional intercomparison has been published from WMO as WMO/TD-No
Next RPC is planned in 2012 at Mt. Tsukuba. The details of the RRC will be announced to participants in due course.
RRC-Tokyo has established a pyrgeometer calibration procedure for Eppley PIR and Kipp&Zonen CG4/CGR4 pyrgeometers.
RRC-Tokyo would like to cooperate in calibration of radiation instruments for the improvements
of surface radiation measurements. 16

17. Thank you !!
at Tateno 17