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Asia Center of The Academy of Natural Sciences

Long-Term and Short-Term Climate Change in Northern Mongolia

Research Objectives

  • Define and describe short term climate conditions for each of the six Lake Hövsgöl study valleys
  • Define annual climate cycles for the region
  • Describe importance of wintertime thermal inversions
  • Define the long term climate change trends for the region.

Research activities

  • Design study of the macroclimate of the Hövsgöl Lake region and the microclimate of the study tributaries.
  • Perform graphical and statistical analysis of all data, following the guidance of specialists to analyze monitoring data, and relate to climate change data at Lake Hövsgöl and throughout Asia and Siberia.
  • Relate present day monitoring data with acceptable available meteorological records from prior years
  • Working with other researchers, help correlate all data with Ecosystem and Social studies of the Lake watershed.

Methods

  • Set up of Meteorological Equipments
    • CR10X Weather Stations (company Campbel Scientific Inc): Dalbay & Turag valleys
    • Hobo Pro Datalogger Series (temp and relative humidity): Noyon, Sevsuul, Shagnuul & Borsog
    • Standard Rain and Snow Gauge: each valley
    • MRC-vertical thermistors series for soil: Dalbay & Turag
  • Observations of meteorological parameters
    • Collect measured data from dataloggers by following special program
      • PC208W Campell Scientific, Inc.
      • Boxcar 3.2 Onset Comp Corporation
    • Meteorological Parameters
      • Air Temperature (Mean, Maximum and Minimum)
      • Solar Radiation
      • Wind Speed and Direction
      • Relative Humidity (Mean, Maximum and Minimum)
      • Soil Water Content
      • Soil Surface Temperature
      • Soil Depth Temperature (0, 0.02cm, 0.08cm, 0.15, 0.23cm, 0.30 cm, …100cm)
      • Precipitation (Rainfall and Snow)
      • Snow Depth
  • Data Processing
    • The meteorological data available to the Hövsgöl Project’s metadata database.
      • All data are from 6 valleys, situated Borsog, Dalbay, Sevsuul, Noyon, Shanguul and Turag.
      • In addition long-term meteorological data from 3 monitoring stations, situated around the Hovsgol Lake. (Hatgal, Hanh and Murun)
    • Quality Assurance/ Quality Control
      • We are using a series of data quality evaluation procedures used by WMO. We use special data control quality program FDP. (Vladimir E Romanobsky and Sergei S Marchenko, 2004). QC procedures include periodic instrument calibrations, site checks, data examination for reasonableness, and data validation. (Temporal Checking and Spatial Checking)
  • Data Analysis
    • Specific Tests and Basic statistics (JMP In, SAS 2000)
    • Time Series Analysis (“Instat” Climatic Statistical Software, Reading University, 1998 and JMP In. SAS 2000)
    • One & Two-way ANOVAs (JMP In. SAS 2000)
    • Trend Analysis
    • Calculation Climatic Parameters (Evapotranspiration, Growing Degree Days, Accumulated Precipitation, Date of air temperature passed 5oC,10oC and accumulated precipitation equal 50mm etc…)
    • Extreme Event Analyses

Initial Results

We are closely monitoring meteorological conditions in the study valleys, and reviewing longer term data sets collected at three meteorological stations located at Hanh (north end of lake), Hatgal (south end of lake) and Moron, the aimag center 80 kms south of Hövsgöl National Park.

Figure 1: Temperature change, Hatgal, 1963-2003

Climate conditions of northern Mongolia are changing as indicated by a long-term warming trend during the recent 30 to 40 years. During the last 30-40 years the annual mean air temperature has significantly increased 1.86°C and the air temperature trend increased 0.61°C from 1963 to 1989, but from 1990 to 2003 the trend increased 0.84°C in the Hövsgöl Basin area (Figure 1). Winter temperatures have increased more than during the other seasons. In general all season’s temperatures have increased over the last 40 years.

There appears to be a normal four-year cycle of one year’s heavy precipitation followed by three years of low precipitation. It is unclear at the present what this cycle is related to. There does not appear to be a change in precipitation associated with the warming trend, the pattern of precipitation closely follows a summer monsoonal pattern, though the origin of the rains is not a result of the monsoons, i.e., the summer monsoon rains of Asia do not extend to Mongolia. Land precipitation is slightly non-significantly (p>0.05) increased by about 27% and about 80mm from the 1963 to 2003 around Hövsgöl Basin.

Using high quality data from three stations around the Hovsgol Lake, significant increases were detected in the annual number of hot days and warm nights, with significant decreases in the annual number of cold days and cold nights. The number of precipitation days (with at least 2 mm of precipitation) has increased in Hovsgol basin area. The proportion of annual precipitation from extreme events has decreased and frequency of extreme precipitation events has declined at stations.

Figure 2: Growing Degree days above 5 degrees C, Hatgal, 1963-2003

Analysis of spatial and temporal long-term trends in climate in Hövsgöl Basin (Figure 2) shows increased seasonal variability due to an increase in the maximal and minimal temperatures (Tmax and Tmin, respectively) in the cool season, and an increase in Tmin and Tmax in the warm season.

Figure 3: Date Accumulate Precipation Equal 50 mm, Hatgal

Local herders have said that the rains have started later during the last 4 summers than historically. We, therefore, analyzed data to see if, in-fact, summer rains were later during last 4 years (Figure 3). I then assumed that 50 mm of rainfall was the quantity for beginning of the summer growth of plants based on personal observations. I also examined temperature data collected from 2 stations. Plant growth will begin soon after air temperature warms above 10°C. As a result of this analysis, At Hatgal and Hanh stations, however, the date air temperature passed 10°C has actually occurred earlier in the spring by almost 1 month (Figure 4).

Figure 4: Date Temperature Passed 10 degrees C, Hatgal, 1963-2004

This suggests what may be occurring is that evaporation has actually increased. As incipient global climate change is expressed, insignificant changes in precipitation are expected, while rising ambient temperature will increase evapotranspiration. The phenomenon could increase terrestrial dryness and reduce run-off. As global climate change is manifested in the long term, increased precipitation may offset water loss due to evapotranspiration and improve conditions for plant growth (Budyko et al.1991). Figure 5 (see below) shows a trend of increasing evapotranspiration rate at Hatgal during 1963 and 2003. We estimated the evapotranspiration rate by Busarova (Busarova, O.E., and E.M.Gusev, 1995) method. The evapotranspiration rate has significantly (p<0.05) increased by 18% and 72mm/per 41 year around the Hövsgöl Basin.

Figure 5: Evapotranspiration Change, mm/year, Hatgal, 1963-2003

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