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