Home > Guidance > Journal of the Aerological Observatory > Vol.67
| Title | Author | |
|---|---|---|
| Foreword | in Japanese | Norio Hayashi |
| (Frontispiece) Sudden Increase of Total Ozone during Dobson Regional Intercomparison Campaign for Asia in Tsukuba | in Japanese | Koji Miyagawa |
| Dobson Regional Intercomparison for Asia in Tsukuba, Japan (DIC-T2006) | [Abstract] | Koji MIYAGAWA and Kazuaki AKAGI |
| Characteristics of Aerological Data in Heavy Snowfalls during the 2005/2006 Winter in Japan | in Japanese | Satoshi ITO and Mariko KUMAMOTO |
| Reflected and Diffuse Spectral UV Observations using Brewer Spectrophotometers at Tsukuba | [Abstract] | Mahito ITO |
| Results of Calibration and Spectral UV/DS Ozone Observations using Brewer Spectrophotometer at Rikubetsu | [Abstract] | Mahito ITO, Masaji ONO and Yoshiyuki NOTO |
| Intercomparison of Brewer Spectrophotometers between MSC and JMA at Toronto, Canada in 2006, and Accuracy of MSC, IOS and JMA Systems for NIST Lamp Calibration | [Abstract] | Mahito ITO, Tom GRAJNAR, Michael BROHART, Vladimir SAVASTIOUK and Ken LAMB |
| Evaluation of the Influence of Obstacles on Downward Long-wave Radiation Measurement | [Abstract] | Yasuo HIROSE and Kohei HONDA |
| Verification and Evaluation of Cloud Screening Algorithm in Sunphotometer Observation | in Japanese | Osamu IJIMA |
| Method for Total Cloud Amount Measurement by Fish-eye Sky Camera and the Results | in Japanese | Matsumi TAKANO |
| Improvement of Ozone Measurement with RS2-KC96 Ozonesonde in the Lower Troposphere | in Japanese | Hirotsugu KAMATA,Ryodo SHIGEBAYASHI,Sonoki IWANO,Satoshi SASAKI,Satoshi ITO,Masami IWABUCHI,Yukihiro NOMURA and Shohei IWATSUBO |
| Upgrading of Automated Dobson Spectrophotometer Windows System -Transition to Compact-PCI Controlled System (WINDOBSON 2006)- |
[Abstract] | Koji MIYAGAWA |
| Improvement of Data Processing for Captive Balloon Observation System | in Japanese | Hirotoshi BABA and Mikako KUDO |
| Development of Combined System of Biodegradable Parachute and Unwinder for Radiosonde Observation | in Japanese | Tetsuji KANEKO, Koichi NAKASHIMA and Masami HINOHARA |
| Development of Combined System of Biodegradable Parachute and Unwinder for Radiosonde Observation | in Japanese | Aerological Observations Division, Aerological Observatory |
Worldwide ozone layer monitoring and trend detection are now being conducted by combining ozone observations from the ground surface, ozone sondes and satellites. Of these, total ozone observation with Dobson ozone spectrophotometers at surface stations has provided the most basic data for atmospheric ozone and environmental research. Long-term and quality total ozone records by Dobson spectrophotometers worldwide are utilized in the WMO/GAW program for the most reliable and accurate evaluation of the status of the ozone layer. For this reason, the WMO/GAW recommends regular comparison of Dobson instruments every four years to ensure the uniformity and consistency of global ozone measurements.
The Japan Meteorological Agency maintains the Regional Standard of Dobson instruments in Asia and held the Dobson Regional Intercomparison for Asia at the Aerological Observatory in Tsukuba from March 6 to March 24, 2006. This event was sponsored by the Ministry of Land, Infrastructure and Transport and funded by the Official Development Assistance (ODA) of the Japanese Government. Participants came from India, Iran, Pakistan, the Philippines and Thailand, and experts from the US National Oceanic and Atmospheric Administration (NOAA) and the Czech Hydro-Meteorological Institute (CHMI) attended. Participating instruments were inspected, cleaned, and adjusted to an accuracy of 1% as targeted by the WMO/GAW program. During the intercomparison, participants were provided with practical training in instrument maintenance and learned skills of various instrument adjustments to cope with minor hardware failures. Data processing software developed at the Aerological Observatory was offered as well and was expected to be a useful tool for helping the participants to avoid human error in data processing of measurements. In the workshop held during the last half of the intercomparison, each participant presented a country report, a NOAA expert lectured on the GAW ozone monitoring network and the calibrations structure, the importance of ozone monitoring was actively discussed, and participants exchanged information.
A modified Brewer spectrophotometer for observing reflected UV radiation on the ground surface and an automated shadow unit controlled by computer to observe diffuse UV radiation in the sky, together with the calibration and the monitoring methods of instrument responsivity, were completed at the Aerological Observatory in Tsukuba (Ito:2004, 2006). In this paper, the results of reflected and diffuse spectral UV measurements carried out from December 2003 to December 2006 and from August 2005 to December 2006, respectively, are compared with global UV and solar radiation data. The results using the named symbols (RF uv, reflected UV ; DF uv, diffuse UV ; GL uv, global UV ; RF solar, reflected solar irradiance ; DF solar, diffuse solar ; GL solar, global solar ; RRF uv, reflectivity of RF uv/GL uv ; RDF uv, diffusibility (diffuse solar irradiance ratio) of DF uv/GL uv ; RRF solar, reflectivity of RF solar/GL solar ; and RDF, diffusibility of solar DF solar/GL solar) are summarized below.
1) Monthly mean of daily total RF uv excluding snow cover days was maximum from March to April, minimum from December to January, and a weak maximum from July to August. The monthly mean of daily RRF uv had a maximum from January to April and a minimum from June to September. The three-year average of monthly means of daily total RF uv (UVB) was 214J/m2 compared with 2,582kJ/m2 for RF solar. The three-year average of monthly mean of RRF uv (UVB) was 1.6% compared with 18.8% for RRF solar.
2) The monthly mean of daily total DF uv was the maximum from May to August (peak in August) and minimum from December to January in 2006. The monthly mean of daily RDF uv was maximum from June to July and from January to February (peak in October 2005) and a minimum in March and September. The annual mean for the monthly mean of daily total DF uv (UVB) was 10,747J/m2 compared with 6,899kJ/m2 for DF solar. The annual mean for the monthly mean of RDF uv (UVB) was 87.0% compared with 66.9% for RDF solar in 2006.
3)Daily total RF uv was maximum at around 110JD (early April) and minimum at around 360JD (late December). Daily RRF uv was about 2.7% in the maximum period from 65 to 95JDs (late March to early April), and about 1.2 % in the longer minimum period from 180 to 270JDs (early June to late September) due to the UVB absorbing effect of vegetation.
4) Daily RDF uv was maximum from 200 to 210JDs (late June) and minimum around 360JD (late December). For daily RDF uv, the minima of the lower limit envelope appeared as about 60% at around 120JD (from late April to early May) and around 270JD (late September to early October), and the maxima of the envelope were about 88% and appeared at around 170JD (middle June) and around 350JD (middle December).
5) Annual relative amplitudes of RF uv, DF uv and GL uv (as total irradiance of TUV, UVB, DUV and CIE) were larger than that of solar irradiances. The total UV irradiances at shorter wavelengths indicated larger amplitudes in the order of DUV > CIE > UVB > TUV.
6) Daily spectral RRF uv from winter to spring exhibited linear wavelength dependence with higher reflectivity at longer wavelengths, but no significant wavelength dependence in summer due to the UVB absorbing effect of vegetation. Daily spectral RDF uv from autumn to winter exhibited linear wavelength dependence with lower diffusibility at longer wavelengths, but no significant wavelength dependence in other seasons.
7) Relations between UV (RF uv, DF uv and GL uv) and solar (RF solar, DF solar and GL solar) irradiances were examined. The maximum correlation factor was found in GL, and the order was GL > RF > DF. The correlation factors depended on month.
8) The annual mean of direct UV irradiance DR uv was calculated from GL uv and DF uv. The ratios of DR uv, DF uv, and RF uv to GL uv were about 17% (13%), 83% (87%) and 1.8% (1.6%) respectively in 2006 (the percentage values are the ratios of monthly mean of daily total irradiances (values in parentheses represent the monthly mean of daily irradiance ratios)). In case of solar irradiance, the ratios were 44 % (33%), 56 % (67%) and 20% (19%) respectively.
Seasonal data of global UV radiation, diffuse UV radiation and reflected UV radiation were obtained by using carefully maintained Brewers. They revealed remarkable differences of UV radiation components from solar radiation in the atmosphere. The accuracy of ss data using ss.rtn can be evaluated by comparing with the value of DR uv calculated from DF uv and GL uv.
Brewer spectrophotometer #057 of the National Institute for Environmental Studies, Japan (NIES) was repaired and calibrated in the laboratory of Aerological Observatory, JMA, in 2005. It subsequently produced UV data and O3/SO2 data at NIES' Rikubetsu station from Nov. 2005 to Dec. 2006. These activities are summarized as follows. 1) Instrument constants for UV observation were calibrated by NIST lamp tests and compared to Brewer MKIII #173 and for O3/SO2 by comparisons to Dobson spectrophotometer #125 (#116) and Brewer MKIII #174, after optical adjustment. 2) An instrument monitoring system with the same high accuracy as JMA's system was established at Rikubetsu. 3) The high accurate daily instrument responsivities from Nov. 2005 to Dec. 2006 could be produced, now that the difference of calculated responsivities between the method by NIST lamp tests and that by external lamp tests was within 1% at Rikubetsu in Dec. 2006. 4) The annual mean of UVB irradiance at Rikubetsu in 2006 was about 10.8kJ/m2 compared with 11.6kJ/m2 at Sapporo station, and the seasonal change in a year was almost the same as for Sapporo. 5) The annual mean of O3 at Rikubetsu in 2006 was about 360m atm-cm compared with 353m atm-cm at Sapporo, and the seasonal change in a year was almost the same as at Sapporo. 6) Lower intensity annual SO2 was observed at Rikubetsu.
Experiment studies using NIST standard lamps and the intercomparison of Brewer spectrophotometers for UVB observation between the Canadian standard (MKIII BR#145) and Japanese standards (MKIII BR#174 and MKII BR#113) were conducted March 7 to 28, 2006, at the Meteorological Service of Canada (MSC). These studies and intercomparisons were carried out as the MSC-JMA joint project "Cooperation on the Advanced System for Hazardous Solar Ultraviolet Radiation Spectrum Monitoring with Brewer Spectrophotometer" in the framework of the Canada-Japan Cooperative Agreement on Science and Technology.
The results were as follows.
1)The difference of instrument responsivity ratios determined by several NIST lamp calibration methods using three systems (MSC, new IOS and JMA) exhibited the following various ratios as "S_D(L/H)" (S system, D distance, L normal or reverse lamp direction, H normal or open lamp housing installation). (a) JMA_50(N/N)/MSC_40(N/N)=1.033. (b)IOS_40(N/N)/MSC_40(N/N)=1.000. (c) IOS_50(N/N)/MSC_40(N/N)=1.005. (d) JMA_50(N/N)/JMA_50(N/O)=1.020. (e) IOS_50(N/N)/JMA_50(N/O)=0.993. (f) MSC_40(N/N)/JMA_50(N/O)=0.988. The difference of 3.3% between MSC and JMA systems proved an estimated difference of 2 to 3% from the last comparison and test at MSC in 2002. The difference of responsivity between the new IOS and MSC systems at D (distance)=40cm agreed within 0.0%. The irradiance by the new IOS system at D=50cm indicated almost the same irradiance (0.7%) as the ideal calibration without lamp housing in a darkroom.
2) Comparison between BR#145 and BR#174(BR#113) for eight days revealed the following ratios of measured solar UV irradiances. (a) Ir#174/Ir#145: from 0.956 to 0.966. (b) Ir#113/Ir#145: from 0.961 to 0.981. After correction considering the difference of 3.3% between MSC and JMA NIST lamp calibration systems, their ratios changed as follows. (a) Ir#174/Ir#145: from 0.987 to 0.998. (b) Ir#113/Ir#145: from 0.993 to 1.006. The irradiance ratios between BR#145 and BR#174(BR#113) after the correction agreed within about 1%. Based on the fact that these comparison results were almost the same as the results by previous comparisons in 1994, 1998 and 2002, and that the JMA system was not changed from 1989, we concluded that the irradiance level of the NIST lamp calibration of the Brewer Spectrophotometer at Aerological Observatory, JMA, has been kept 3.3% higher than MSC's lamp calibration for 17 years.
This paper describes a trial method for evaluating measurement error induced by surrounding surface obstacles such as buildings or vegetation in downward long-wave radiation measurement utilizing the Moderate-Resolution Transmittance Code (MODTRAN) for four standard model atmospheres. The geometrical distance distribution of the obstacles viewed from the sensor is an important factor in estimating the influence of obstacles on DL measurement. Diagrams were constructed for this purpose. A series of evaluating procedures was applied to an existing urban sky, providing a good reference relation between the obstacle condition and the influence.
An advanced system of automated Dobson ozone spectrophotometers utilizing compact PCI successively began routine operation in the GAW ozone observation network (Tsukuba, Seoul, Sapporo, and Naha) in June 2006. The first domestic version of an automated Dobson system in the DOS environment was developed at JMA's Aerological Observatory in 1994. This was followed by an upgraded Windows version in 2000, which realized high adaptability to the latest Windows PC and a flexible data handling system by taking full advantage of the Windows interface. The newly developed current version of an automated Dobson system (WINDOBSON 2006) was designed to be universal and has been converted into an international version by adopting a compact PCI for hardware control on Windows XP and language-independent programs in data processing, display and output. In March 2006, the Japan Meteorological Agency began providing the data processing programs of the new system to the GAW ozone community at the request of WMO. These programs are expected to be useful tools for ozone data processing even at manual operating Dobson stations. The whole automated system was installed on the Dobson site at Yonsei University in response to a request from the Korean Meteorological Administration (KMA) in August 2006.