The Climatological Bulletin is published annually and contains summaries of meteorological observations gathered at the Institute of Environmental Research and Sustainable Development of the National Observatory of Athens (NOA) on the Hill of Nymphs at Thissio (latitude 37° 58' N, longitude 23° 43' E, height of 107 m above MSL) near the center of Athens. Continuous observations of standard meteorological parameters have been carried out at this location, the close surroundings of which remain unaltered, since 1858.

The Bulletin includes tables with values of the following meteorological parameters:

• Air temperature (°C) (hourly, daily and monthly means, maximum and minimum values).
• Soil temperature at a depth of 0.15 m (°C) (hourly, daily and monthly mean values).
• Relative humidity (%) (hourly, daily and monthly mean values).
• Atmospheric pressure (hPa) (hourly, daily and monthly mean values).
• Wind speed m/s) (hourly, daily and monthly mean values).
• Wind direction (deg) (hourly values, wind rose).
• Rainfall amount and duration (mm, hrs).
• Evaporation (mm).
• Dew-point (°C).
• Saturation deficit (mm Hg).
• Vapour pressure (mm Hg).
• Sunshine duration (hrs).
• Cloudiness and cloud type (octals).
• Degree days (°C).
• Total solar radiation on horizontal surface (W/m2) (hourly, daily and monthly values with Eppley pyranometer).
• Diffuse solar radiation on horizontal surface (W/m2) (hourly, daily and monthly values with Eppley pyranometer and shadow ring,
  not corrected for shadow-ring effect).
• Total illuminance on horizontal surface (kLux) (hourly, daily and monthly values)
• Diffuse illuminance on horizontal surface (kLux) (hourly, daily and monthly values, corrected for shadow-ring effect).
• Visibility.
• Miscellaneous phenomena.
• Climatological Means (normal values).

Measurements of additional parameters on a routine basis but not published in the Climatological Bulletin include ground surface temperatures and temperatures at depths: 0.02m, 0.05m, 0.10m, 0.15m, 0.20m, 0.30m, 0.40m, and 0.50m and in cups at depths: 0.30m, 0.60m, 0.90m and 1.20m.

Information on instruments and observing practice:
All meteorological parameters refer to Local Standard Time (LST = GMT+2hr).
Air temperature (dry and wet) is measured with electronic thermometers (Pt-100) housed in a Stevenson screen 1.50 m above ground level.
Relative humidity is derived from the readings of dry- and wet-bulb thermometers (August psychrometer).
Evaporation is measured with Wild and Piche evaporimeters, which are also housed in the Stevenson screen.
Mercury barometers and barographs are used for the pressure readings.
Total precipitation is measured with standard raingauges. The total amount as well as the highest recorded value is obtained for a nominal 24 hours day that starts and ends at 0800 LST.
Visibility and cloud observations are made at 0800, 1400 and 2000 LST. The latter observations are also made at 0820, 1120, 1420 and 1720 LST at the NOA actinometric station. An empirical scale from 0 to 9 is used for the visibility observation.
Calms are considered in the range 0-0.3 m/sec, while the symbol (-) indicates missing data.
Since January 1992, a JOULE class Daylight Measurement Station has been operating along with the NOA radiometric station.
Diffuse Illuminance data are submitted to shadow band correction according to the method proposed by P.J. Littlefair.

Along with the annual Climatological Bulletin, a Monthly Bulletin is published on the WEB by IERSD at the end of each month.

Photos from the IERSD's Meteorological-Actinometric Station at Thissio Site are available here.

The station of the Meteorological Instruments Calibration Laboratory of IERSD is established at Penteli (Lofos Koufou). The geographical position of the station is: latitude 38° 2.94' N, longitude 23° 51.78' E and altitude 495 m above MSL.

The Bulletin includes tables with values of the following meteorological parameters:

• Air temperature (°C) (hourly, daily and monthly means, maximum and minimum values).
• Relative humidity (%) (hourly, daily and monthly mean values).
• Atmospheric pressure (hPa) (hourly, daily and monthly mean values).
• Wind speed m/s) (hourly, daily and monthly mean values).
• Wind direction (deg) (hourly values, wind rose).
• Rainfall amount and duration (mm, hrs).
• Total solar radiation on horizontal surface (W/m2) (hourly, daily and monthly values with Kipp & Zonen CM11 pyranometer).
• Diffuse solar radiation on horizontal surface (W/m2) (hourly, daily and monthly values with Kipp & Zonen CM11 pyranometer and Kipp & Zonen CM121 shadow ring, not corrected for shadow-ring effect).
• Total illuminance on horizontal surface (kLux) (hourly, daily and monthly values).

Information on instruments and observing practice:
All meteorological parameters refer to Local Standard Time (LST = GMT+2hr).

All data are acquired at a sampling rate of 30 sec except wind data where the sampling rate is 10 sec. Data are recorded every 1 min.

Hourly values of air temperature, relative humidity and atmospheric pressure correspond to the 1min measurements of these parameters at each integral hour. Mean daily values for each hour of the day, calcualted from the N respective hourly values, where N is the number of the month's days, and, mean monthly values, are presented. Also, daily and monthly maximum/minimum values are also presented. Atmosperic pressure refers to sea level.
Hourly values of solar radiation are calculated as average from 60 1min values. Mean daily values, mean monthly value for each hour of the day, calcualted from the N respective hourly values, where N is the number of the month's days, and mean monthly values are also presented. Data of diffuse solar radiation are not submitted to shadow ring correction.
Total precipitation is presented as daily sums, calculated from 1min measurements, along with daily rainfall duration, expressed in full hours.
The wind parameters are calculated as mean hourly values of wind vector deduced from the 60 1min values. Arithmetic mean daily values mean monthly value for each hour of the day, calcualted from the N respective hourly values, where N is the number of the month's days, and, mean monthly values.

Photos from the IERSD's Meteorological-Actinometric Station at Penteli Site are available here.