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Vladimir and Elena Aizen, Arzhan Surazakov

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1 Vladimir and Elena Aizen, Arzhan Surazakov
Is Central Asia really exsiccated? Vladimir and Elena Aizen, Arzhan Surazakov University of Idaho People of central Asia totally depend on seasonal snow and glacier melt water. Without snow and glaciers, central Asia will dry out. The glacier changes over central Asia have been historically defined and are anticipated to be more significant than in Polar regions

2 From ancient to modern irrigation systems
Agricultural and industrial expansion Population grows

3 Objective: What is the past century climate and water resources changes in
central Asia? Data: Long-term observational data and assimilated remote sensing information. Aerial (1943), remote sensing data (Corona, Hexagon KH-9, Landsat, Aster, SRTM and MODIS – collection 4-5) Methods: Thiessen’s spatial averaging/polygon method to interpolate gaps in meteorological data. - differences in averages for two thirty-year periods & T-test at 20% for precipitation and 10 % for air temperature level - linear trends for the same periods. Coefficients of determination, F tests at 80% for precipitation and 90% for air temperature level of significant - acceleration in changes for the last thirty years is difference in trends - differences in standard deviations and coefficient variations two thirty-year periods. Geographically weighted regression (GWR) method for spatial interpolation of precipitation (P) and temperature (T) data. The optimal size of the kernel is 30 neighbors Imagery processing

4 Recent research on climate changes over the Central Asia
Region area № of stat. Period Resol. Conclusion Authors (Tien Shan 200 to > 4000 m 110 monthly Temp C/yr Prec.+1.2 mm /yr l<2000m Aizen, et al., 1997 Central Asia 35-50N E 32 summer At SE Mongolia & N China negative trend Yatagai & Yasunari, 1995 Tajikistan m 4 year Temp C /60 yr and +0.4C HE Preci to 0.25 mm/yr <1000 m +1.82to +5/37 >2000 m Finaev, 1995 Central A sia plains and foothills 26 +50 Steady positive trend in air temperature. Decrease of total river runoff and increase in its variability for comparing for Konovalov, 2003; Konovalov &Williams, 2005 m 39- 45N E 21 Temp C /yr Giese et al., 2007 Northern China 9 1979–1999 Winter Successive droughts for 3 summers ( ) at northern China Xu, 2001

5 Main periods of observations 1942-1972 and 1973-2003
264 Central Asian hydro-meteorological stations used for analysis Central Asia by climatic zones Number of stations by elevations Main periods of observations and

6 Differences in 30-year averages of annual (A) and summer (B) air temperature
(Δ = AVE – AVE ) A B Average weighted differences between annual, annual-maximum & summer means temperatures ( and ) for climatic regions Average weighted differences annual, annual-maximum and summer means of air temperatures ( and ) for altitudinal belts

7 Acceleration in changes of annual (A) and summer (B) air temperature for the last 30 years
(Δ = SLOPE – SLOPE ) A B

8 Differences in 30-year averages of annual precipitation (Δ = AVE1973-2003 – AVE1942-1972)
(A) altitudinal distribution of central Asia areas (S, km2), (B) average weighted differences in annual precipitation for the periods from and (Δ, km3 )

9 Altitudinal distribution of average weighted differences of annual precipitation for the periods from and (b) (Δ, km3) by climatic regions

10 Differences in 30-year averages of winter (A) and summer (B) precipitation
(Δ = AVE – AVE ) A B

11 Acceleration in changes of annual precipitation Δ = SLOPE1972-2002 – SLOPE1942-1972)
Accelerating altitudinal changes of precipitation for the last 30 years compared to the previous 30 years , Acc = Sl Sl , mm Accelerating changes by region of precipitation for the last 30 years compared to the previous 30 years , Acc = Sl Sl , mm

12 Overall decadal trends show the high dust loading for the 1960’s and 70’s, with maximum dust loading apparent for the 30’s and that is in accordance with results from 154 Chinese stations on maximum frequency of dust weather for the mid-1960’s (Qian et al; Sun et al., 2002) and the lowest in the 90’s to be one-fifth that of the 60’s.

13 The seasonal snow covered area in Tien Shan decreased by 15%
Tien Shan, number of days with snow The seasonal snow covered area in Tien Shan decreased by 15% approximately km2 Tien Shan, number of days with snow

14 Snow covered areas by 1,000m isohyps over the Tien Shan for the last twenty years reconstructed by surface observational, AVHRR and MODIS data Duration of snow melt from the date of maximum snow cover to date of it’s disappearance reduced on 30 days during the last twenty years, equal 138 days in Snow melt 30 days faster then 20 years ago. The decrease of snow cover is not linear process. ten days AVHRR data calibrated with surface observational data eight days MODIS data Twenty years mean of snow cover areas from the date of maximum cover to it’s disappearing approximated by 2 order polynomial function. Duration of snow melt from the date of maximum snow cover to date of it’s disappearance reduced on 30 days during the last twenty years, equal 138 days in Snow melt 30 days faster then 20 years ago. There is a tendency in decrease of snow covered area during 20 years equal -0.11% for each day of snow cover (15% in average for the whole period) with maximum degrease in June -1.1% yr-1. At high elevations, maximum snowmelt occurs during the last ten days of snow cover existence. The decrease of snow cover is not linear process. Further decrease of snow covered areas may be accelerated due to reduced snow covered area and consequently lesser of heat input necessary to melt it . Due to increase in air temperature more proportion of liquid precipitation rather then snow in spring time, which also accelerate snow melt and impact river runoff regime.

15 1,617 km2 (-10.1%) glacier area reduction during the last thirty years in Tien Shan
K A Z A K H S T A N C H I N A 50 150 km

16 Inner Tien Shan area Aksiirak glacierized massif 2003 1977 1943
182 glaciers; 427 km2 glacierized area (aerial photogrammetry 1943) 2003 1977 1943 182 glaciers; km2 glacierized area; 4.2% area reduction (aerial photogrammetry 1943/1977) 178 glaciers; km2 glacierized area; 8.7% area reduction (aerial photogrammetry 1977/ASTER ) Petrov Glacier 2003 2002 1995 1977 1956 1943 1869 1800 Описание обработки убрать. Green, olive and lightseagreen. True hardware-enabled stereo viewing with nadir 3N and backward-looking 3B bands was applied to delineate glaciers in problem areas (debris-covered termini and shadows).

17 Conclusion Statistically significant difference in means of annual and seasonal precipitation and air temperature for two 30-year periods was observed at more than 73 (precipitation) and /93% (air temperature) of 264 stations The last 30-years average precipitation has decreased on 0.1% of average compared with previous 30-years The last thirty year deficit of precipitation income was -62 km3 that is about 6 % from total 1,048 km3 volume Tien Shan glaciers The most significant deficit in precipitation income observed at the alpine regions and Kazakhstan steppes during summer season Acceleration in decrease of precipitation for the last 30 years for all central Asia Increased precipitation in winter at low altitudes, at Aral-Caspian and Tarim basin deserts, western and even Eastern Pamir Increased annual air temperatures for the last 30 years on 0.68°C by increased summer air temperatures Total central river runoff have decreased on 4% in all central Asia Snow covered areas shrunk by 15% and glacier covered area by 10% over the last 30 years


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