Meteorological observations

were obtained by standard meteorological instruments based on standard methods in all meteorological network stations of former Soviet Union approved by WMO. Until 1936 the main meteorological observations in the former Soviet Union were carried out three times each day 07.00, 13.00 and 21.00 of local solar time. During 1936 - 1966 in Soviet Union, the observations occurred four times each day 01.00, 07.00, 13.00 and 19.00 of local solar time and beginning in 1966 the observations were carried out eight times, 00.00, 03.00, 06.00, 09.00, 12.00, 15.00, 18.00 and 21.00 Moscow time. Meteorological observations are obtained in an open area not lesser than 676 m2, i.e. 26 X 26 m in size.

There are several factors influencing the homogeneity of meteorological characteristics. In the 30-th years, most stations in the former USSR were moved to open places which is more favorable for most meteorological characteristics except precipitation, because precipitation vary with different wind influence on equipment. All data have been checked and corrected. We have additionally, thoroughly checked the initial data for homogeneity of observational series, representativeness, and presence of random errors. Analysis of data homogeneity have estimated all statistically significant jump and implement the nature of its parent.

Solar Radiation

There are four actinometric stations in the Tien Shan. Observations of solar radiation are carried out in the 0.3-4.0 mm (300 - 4000 nm) range. The measurements of direct solar radiation on perpendicular surface are occurred by actinometer during sunshine, when sun ray can be fixed on the sight of actinometer. The measurements of total, diffuse, and reflected solar radiation are occurred by piranometer based on thermoelectric principle. Horizontal surface of piranometer is covered by glass for protection from long wave radiation, precipitation and wind. To measure a diffuse radiation, receiving surface is shadowed by screen from direct solar radiation. Measurements of total radiation balance including long-wave radiation is occurred by pergiometer. Receiving part is composed by two horizontal thick metallic plates faced by blacked surfaces upward and other down. Magnitude of current which proportionate to intensity of solar radiation is measured by galvanometer. Measurements of solar radiation characteristics occur at 1.5 m above surface. Errors of total radiation measurements associated with wind speed is 2 - 12% and moistening of measured equipment 7 - 10%. Observations were carried out at 00.30, 06.30, 09.30, 12.30, 15.30, 18.30 of average solar time. Duration of solar radiance is measured at the 20 meteorological stations in the Northern Tien Shan. Heliograph with glass ball used as lens measures a duration of solar radiance. From north side on a focus distance there is a paper film with hourly division. Information about real and possible (i.e. under cloudless weather) duration of solar radiance and number of days without sun is represented in (Reference book of climate USSR). Calculations were carried out for day, decade, month and year. Except the fixed-time measurements several stations have continuous observational records of actinometric characteristics.

Air Temperature

is measured by the dry-bulb mercury thermometer of Augustus's aspiration psychrometer, by maximum mercury and minimum spirit thermometers placed in meteorological box with 525 mm of height, 460 mm of width and 290 mm of depth. Maximum temperatures are measured by maximum mercurial thermometer, and minimum temperatures are measured by minimum spirit thermometer. These thermometers are placed in meteorological box and their reservoirs are at the 2 m above surface. The measurement error is plus/minus 0.05oC. There are continuous observations of air temperature with a thermograph (i.e automatic self recording instrument) placed in meteorological box at the 2 m above surface. Data include: (1) means of daily, monthly, annual air temperatures; (2) absolute and average monthly maximum and minimum temperatures; (3) average daily and monthly amplitudes of air temperatures.

Wind measurements

until 1970s were measured mainly by Vild's weathercock. It was placed in a meteorological ground at 8 - 10 m over surface. In present the wind measurements are made by anemometers that are more sensible to small wind speed. The anemometer averages wind speed for ten minutes when Vild's weathercock averages speed for two minutes. Based on simultaneous measurements, the correction of observed data was done. Errors of wind speed measurements are plus/minus 0.25 m/sec during wind speed up to 20 m/sec, plus/minus1.0 m/sec during wind speed from 20 to 28 m/sec, and 1.5 m/sec during wind speed from 28 to 40 m/sec. Observations of wind directions at eight compass points are made. The main climatic characteristics of wind speed are maximum speed and frequency of different ranges of wind speed per day, month, year.

Cloudiness

Amount of low and total cloud and their form are observed visually. A cloud base recorder measures the height by reflection of light beam. Vertical thickness of cloudiness is calculated on the basis of aerological (balloon) data. The measurement errors of cloudiness amount are enough high (plus/minus1, plus/minus 2). The main calculated characteristics of cloudiness are frequency of different ranges in cloudiness, average number days without and with cloudiness. There are three ranges in the calculations of cloudiness frequency: 0 - 2 is clear (without cloudiness), 3 - 7 is half clear, 8-10 is cloudiness weather. Frequency of cloudiness, number of days with and without cloudiness are calculated for every month including total and low cloudiness.

Air humidity

is measured by dry-bulb and wet-bulb mercury thermometers of Augustus's aspiration psychrometer, measurements of relative humidity are made by "hair" hygrometer, continuous observations of air humidity is carried out with hygrographer placed in meteorological boxes at the 2 m.

Precipitation

is measured by rain gauges placed in meteorological stations on the wooden post of 2 m of height with special protection. Until 1952-1954 area of the funnel mouth was 500 cm2, after change of equipment it's area became 200 cm2. Type of protection was changed too. Correction of measurement has been done by Shver’s (Shver, C.A. Atmospheric Precipitation on the USSR Territory. Hydrometeo Publishing, Leningrad, 302 p. 1976, in Russ.) method. There are no discrepancies between two types of measurements in summer precipitation, the biggest differences were established in winter precipitation amount. Errors of precipitation measurements associated with evaporation is 2 - 20 %, moistening of measured equipment 4 - 15% and with wind influence 5 - 10% of average (Shver, 1976). The main calculated characteristics of the precipitation are: their amount during different periods of time (day, month, season, and year), extreme values, duration, intensity type of precipitation (solid, liquid, mixed) and their share in total.

Snow Cover

measurements include observations at meteorological stations and surveys. Snow thickness, density and snow water equivalent are measured every day in meteorological stations and at points along the snow route. A snow survey was carried out along transect, at the end of every winter month. The extent of the route can be from two kilometers to several tens kilometers, including several altitudinal zones in a basin. Error of snow thickness measurements is plus/minus 0.5 cm, plus/minus 0.5 g cm3. Aircraft (helicopter) observations of snow thickness by remote metal rods, and position of snow boundary on slopes of basins are carried out in the end of each month. The characteristics of snow cover are: (1) average (monthly, ten days) and maximum (monthly) thickness, (2) dates of appearance and disappearance, (3) number days with snow cover per ten days, (4) date of monthly maximum snow thickness, (5) monthly, decadal (ten days) density, 6. average and maximum monthly and decadal (ten days) snow water equivalent.

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