National Report
Islamic Republic of Iran
10TH Meeting of Ozone Research Managers
28-30 Mars 2017, Geneva, Switzerland
1. Observational Activities
This report contains the updated information on the ozone and UV observation and research activities which have been pursued in Iran during past two years since the 9th meeting of the WMO/UNEP Ozone Research Managers.
For the past three decades, the Meteorological Organization (MO), Geophysics Institute of the University of Tehran and Tarbiat Modares University of Tehran (theDepartmentofPhysical Geography) with the encouragement and support of Iran’s NOU have been performing UV-B and ozone monitoring and research activities in Iran. However, there are some obstacles on this roadmap that have almost weakened the attainment of the specified goals.
Research and monitoring activities are based mainly on and through continuous cooperation and exchange of information between these centers and some other new research and executive entities. In addition, the Iran’s NOU through the communications and correspondences with different organizations and organizing successive meetings between members have now involved them to solve the capacity building problem of Ozone/UV monitoring system and public awareness. For example the Ministry of Health and Atomic Energy Organization have lunched the UV index Monitoring System in 18 stations of Iran during three past years. As a consequence, the mentioned UVI network in Iran is being tested and calibrated with international standard to be used in academic researches and for informing the public. It should be also noted that these new measuring instruments are result of efforts of the Department of Environment and other Institutes to improve and develop regional environmental information and reduce data gaps in order to better understand the global environment concerning UV radiation especially in the Middle East region (mentioned in the last report of UNEP in 2014).
In spite of fairly long history of the ozone atmospheric observation and research, Iran still lacks a sufficient capacity to form national network in the field of ozone observation limited to only two points of the country’s atmospheric research and monitoring platform.
Column measurements of ozone and other gases/variables relevant to ozone loss.
There are two stations where the ozone measurement facilities have been installed and are in use. The following stations are operating under the supervision of the Meteorological Organization (MO) and the Geophysics Institute of the University of Tehran. As shown in table 1, names, situation and other relevant information of three stations in Iran i.e. types and facilities have been included.
Two considered ground based stations of Isfahan and Geophysics of Tehran use two different kinds of Brewer and Dobson equipment respectively. The Firooz-kooh station which had been mentioned in the last national report of Iran had measured the tropospheric ozone not the stratospheric ozone. In fact, there are only two stations in Iran that have responsibility for measuring the Total Ozone Column (TOC). Nevertheless, the two mentioned stations are not permitted to arrange datasheet based on the annual and monthly timescales without long gaps, because so far, they have measured TOC with consecutive intervals.
The information of the above stations is provided in the Table 1, and the spatial distribution of them is also shown in the Figure 1. As it can be inferred from Fig 1, distance and distribution between three stations don’t well cover the all parts of country and there are many vacant and unknown areas from north-west to south –east and north east to south- west. Based on the last study performed by Iran’s NOU, no stations have been allocated for the regions of Iran where extreme UV radiation seen by the modified data of satellite instrument.
Table 1.stations active in the ozone and UV measurement and monitoring actives in Iran
Station / Type / Coordination / Measurement FacilitiesSynoptic / Upper Atmospheric / Latitude / Longitude / Altitude
(metric) / Surface / vertical / Total
Isfahan / Yes / Yes / 32° 37’N / 51° 40’ E / 1550 / Yes / Yes / Yes
Geophysics / Yes / No / 35° 44’N / 51° 33’ E / 1419 / Yes / No / Yes
Firooz-kooh / Yes / No / 35° 43’N / 52° 34’ E / 2986 / Yes / No / No
Figure 1. The spatial pattern of different stations in Iran with measurements of ozone column contents, (Isfahan measures UV and TOC, Geophysics measures TOC and Firooz-kooh measures surface Ozone).
Isfahan Ozone Station:
This station is recognized by an international 336 code and is connected to the global networking system. Total ozone is being measured using Dobson system since January 2000. Since April 2000, Brewer equipment was installed and has been operating at Isfahan station. This system measures total ozone in vertical column in an area of 1 cm2 by attracting solar and sky radiation. In addition, the system measures UV-B, SO2, and NO2.The Isfahan station is recognized by an OIFM code and measures on a daily basis the upper atmospheric conditions between 11 to 12 GMT. This station is also equipped with Radiosonde (RS80) and Hydrogen balloon (totex 600gr) in order to study the Upper Atmosphere. Unfortunately during recent years, due to the lack of calibration at its deadline (from May 2013), the Brewer spectrophotometer located in Isfahan station was stopped measuring the Total Ozone along with other parameters. So far, Iran’s NOU and MO have frequently requested WMO/UNEP and other relevant universities and institutes to assist to solve this routine and simple problem (calibration) , but the Brewer instrument of Isfahan station has been still remained undecided in the technical warehouse of MO and is waiting to receive permission of calibration in a reliable and responsible country.
Geophysics institute station:
The institute is mainly responsible for total ozone monitoring, data recording and processing, networking with World Ozone and Ultraviolet Radiation Data Center (WOUDC) and conducts networking, training and public awareness campaigns on stratospheric and surface ozone. The center is equipped with a Dobson photo-spectrometer and ancillary data processing and analysis hardware and software systems. The institute has been cooperating with the Municipality of Tehran for the air pollution monitoring activities through the established network of pollutants monitoring stations. As of 2000, total ozone has been measured using Dobson system for 30 minutes (from 8am to 7pm). Results of the measurements are regularly calibrated using satellite data. The data recorded at the above stations is being reported to the WOUDC and are available through the center’s web pages.
Dobson photo-spectrometer in Geophysics institute station had been idle up to September 2016. Iran’s NOU has been following up this issue and coordinated so that Geophysics Institute could eventually calibrate Dobson instrument through an equipped center in Europe. The calibration of the equipment was delayed because they could hardly find a responsible organization to perform calibration. Finally, as of October 2016, after about 5 years delay in calibration, this instrument in Geophysics institute station has been operating while suffering from many technical issues.
Firooz-Kooh Station:
Of the above station, Firooz-kooh has not reportedly been active to measure stratospheric ozone for about past 10 years. Surface ozone outside urban area has been measured at Firooz- Kooh. The station is a reference station and official connected to the World Meteorological Organization’s (WMO) Global Atmospheric Watch (GAW).
Isfahan and Geophysics stations are mainly involved in the ozone and UV observation in the world network measurement activities.
1.2 Profile measurements of ozone and other gases/variables relevant to ozone loss
(e.g. ozonesondes, ozone lidar)
Profile measurement of ozone needs employment of special equipment which are not available at the existing station. In order to study the Upper Atmosphere, radiosonde (RS80) and hydrogen balloon (Totex 600gr) were in use at Isfahan station. Data recorded by these instruments then is transmitted to the global telecommunication system using a switching system. Isfahan station is connected to the global network of ozone observation and reports the data back to the WOUDC on a regular basis.
1.3 UV measurements
Until a few years ago, the UV-B measurement in Iran was only being recorded at Isfahan by Brewer instrument at the wavelengths between 303.2 and 320.1 nm (which has been currently out of work) but with continuous effort by Iran’s NOU and through cooperation with other organizations, the UV-B network was developed in 18 provinces of Iran. It is projected during next two years, the number of stations expand to 32 points. The solar UV radiation under this project measures the wavelengths between 280 and 400 nm including UV B-A.
There are several other locations reported as high risk spots in terms of exposure to UV. UV monitoring in these high risk spots are of utmost importance and need establishment and use of new UV measurement equipment and facilities beside the other native devices.
1.4 Calibration Activities
Data recorded by the stations was being regularly checked for their validation and consistency. In the case of data inconsistency the equipment were sent to the WMO for calibration. But during 5 years ago, Islamic Republic of Iran has encountered with many obstacles for calibrating their instruments which have had international codes in WOUDC. NOU of Iran wishes that International Organizations would carry out their professional duties and also consider a solution that every four years the Dobson and Brewer instruments in developing countries are regularly calibrated regardless of the international political controversies. However, only the Dobson instrument was hardly calibrated by the intervention of Iran’s NOU. But despite many efforts, Brewer spectrophotometer which is well known in the WOUDC and supported by WMO still has not been calibrated.
Equipment installed at the Firooz-kooh station was damaged and not in use since about 10 years ago. In order to maintain the continuity of ozone data series, the station will need to fix the damaged apparatus and to improve its measurement system. This station only records surface ozone data. A strategy was in place to change the station’ systems to European standards.
As mentioned above, calibration of equipment in Geophysics station had been last made in February 2006 in Japan. In an agreement with the Japanese atmospheric research center, the Dobson apparatus at Geophysics station should be calibrated, which was refused for unknown reason during 5 years ago. Eventually, this Dobson spectrophotometer with many troubles has been calibrated through an equipped center in Europe and it has been operated from October 2016, after about 5 years delay in calibration. According to the previous information, the data collected by the Geophysics equipment had 3% deviation from the satellite data recorded for the same period which is considerably acceptable.
Regarding to previous statement of Brewer instrument, the ozone and UV-B radiation measurement equipment at Isfahan station has not been still calibrated. Since May 2013, the machine is not working and needs to be calibrated. Up to now, in spite of the correspondences with the respective international organizations, unfortunately no required movement or action has been performed for this instrument yet.
1. Results from Observations and analysis using data of Isfahan station.
Figure 2 is shown variability of Ozone over Isfahan station with two measuring instruments of ground-based station and satellite data. As seen in this figure, the first half of year, the curve of satellite data has exceeded the ground-based data (until May) but in the second half of year it is approximately lower or equal than ground observation. In the following, figure 3 is shown that this proportion of difference between the ground based and satellite UV Index data is significant especially during months with the high solar UV radiation (Apr- Sep). However, these two study periods do not completely overlap each other, but with balancing and assimilating the periods would not been seen significant difference between them again. For this reason, one of the importance issues which can
Figure 2. Monthly variation of total ozone for two periods of 1979-2011 (TOMS-OMI instrument) and 1997-2011 (Brewer spectrophotometer) over Isfahan station.
Figure 3. Monthly variation of UV-B radiation for two periods of 1979-2011 (TOMS-OMI instrument) and 1997-2011 (Brewer spectrophotometer) over Isfahan station.
consider for developing and expanding the ground based UV and ozone observational network in each country, is the reality of ground-based data in comparison with satellite data which does not well compute aerosol and cloudiness in lower atmosphere. As a consequence, however satellite data is providing the global coverage of Ozone and UV observation even with high resolution, because their instruments does not well calculate other atmospheric elements into the lower tropospheric, they could not been used for important and executive decisions.
Figure 4 shows the TOC time series in two separate periods of 1979–1994 and 1996–2011. This is because of negative trend in NH extratropical ozone existed up to the mid-1990s that corresponded with an increase in the concentration of the ozone depletion chemicals in the stratosphere. Afterwards, a kind of the ozone recovery has been observed. The annual mean of TOC reveals high inter variability as well as a decreasing trend in the first period. Although, the mean level of TOC over the 1996–2011 period (in comparison with the 1979-1994 period) reduced by about 8 DU, the anomaly amplitude and the downward linear trend have considerably weakened in this duration. It is reported that in the mid-latitude lower stratosphere (15–25 km) after long-term decreasing of TOC for the 1980–1995 period, the total ozone has approximately remained stable at this altitudes since 2000. On the longer time scale (1979–2011), the linear regression analysis of ozone mean levels indicated a decrease of 4 DU (1.4 %) per decade over central plateau of Iran, which strongly depends on the seasons with a maximum (minimum) decrease of about 2.2 % in spring/winter months (0.5 % per decade in the summer/ autumn months).