Journal of Geographical Sciences >
Spatiotemporal characteristics of seasonal precipitation and their relationships with ENSO in Central Asia during 1901-2013
Author: Chen Xi, Professor, specialized in hydrology and water resource, as well as environmental remote sensing. E-mail: chenxi@ms.xjb.ac.cn
Received date: 2018-01-05
Accepted date: 2018-03-20
Online published: 2018-09-25
Supported by
International Cooperation Fund of Ecological Effects of Climate Change and Land Use/Cover Change in Arid and Semiarid Regions of Central Asia in the Most Recent 500 Years, No.41361140361
The Western Scholars of the Chinese Academy of Sciences, No.2015-XBQN-B-20
National Natural Science Foundation of China, No.41471340, No.41605055
Hong Kong Baptist University Faculty Research, No.FRG2/17-18/030
Copyright
The vulnerable ecosystem of the arid and semiarid region in Central Asia is sensitive to precipitation variations. Long-term changes of the seasonal precipitation can reveal the evolution rules of the precipitation climate. Therefore, in this study, the changes of the seasonal precipitation over Central Asia have been analyzed during the last century (1901-2013) based on the latest global monthly precipitation dataset Global Precipitation Climatology Centre (GPCC) Full Data Reanalysis Version 7, as well as their relations with El Niño- Southern Oscillation (ENSO). Results show that the precipitation in Central Asia is mainly concentrated in spring and summer seasons, especially in spring. For the whole study period, increasing trends were found in spring and winter, while decreasing trends were detected in summer and fall. Inter-annual signals with 3-7 years multi-periods were derived to explain the dominant components for seasonal precipitation variability. In terms of the dominant spatial pattern, Empirical orthogonal function (EOF) results show that the spatial distribution of EOF-1 mode in summer is different from those of the other seasons during 1901-2013. Moreover, significant ENSO-associated changes in precipitation are evident during the fall, winter, spring, and absent during summer. The lagged associations between ENSO and seasonal precipitation are also obtained in Central Asia. The ENSO-based composite analyses show that these water vapor fluxes of spring, fall and winter precipitation are mainly generated in Indian and North Atlantic Oceans during El Niño. The enhanced westerlies strengthen the western water vapor path for Central Asia, thereby causing a rainy winter.
Key words: Central Asia; seasonal precipitation; spatiotemporal pattern; ENSO
CHEN Xi , WANG Shanshan , HU Zengyun , ZHOU Qiming , HU Qi . Spatiotemporal characteristics of seasonal precipitation and their relationships with ENSO in Central Asia during 1901-2013[J]. Journal of Geographical Sciences, 2018 , 28(9) : 1341 -1368 . DOI: 10.1007/s11442-018-1529-2
Figure 1 Study area and orographic features in Central Asia |
Table 1 Mean (mm), coefficient of variation (CV: %) and linear trend (K: mm/10a) of the seasonal precipitation over mountainous area, plain area and Central Asia during 1901-2013, 1951-2013 and 1979-2013 |
Study area | Season | 1901-2013 | 1951-2013 | 1979-2013 | ||||||
---|---|---|---|---|---|---|---|---|---|---|
Mean | CV | K | Mean | CV | K | Mean | CV | K | ||
Central Asia | MAM | 59 | 21 | 0.41 | 61 | 22 | 0.49 | 61 | 20 | 0.42 |
JJA | 57 | 20 | -0.09 | 57 | 19 | 0.4 | 58 | 19 | 1.62 | |
SON | 43 | 25 | -0.1 | 43 | 22 | 0.23 | 44 | 21 | -1.97 | |
DJF | 41 | 20 | 0.39 | 42 | 18 | 0.77 | 43 | 17 | 0.24 | |
Mountainous area | MAM | 79 | 21 | 0.22 | 81 | 20 | -0.62 | 80 | 20 | -1.47 |
JJA | 77 | 18 | -0.16 | 77 | 18 | 1.23 | 79 | 18 | 2.66 | |
SON | 46 | 29 | -0.16 | 45 | 25 | 0.68 | 47 | 25 | 0.3 | |
DJF | 42 | 22 | 0.31 | 43 | 23 | 0.78 | 43 | 22 | 2.54 | |
Plain area | MAM | 55 | 23 | 0.44 | 56 | 24 | 0.73 | 57 | 22 | 0.84 |
JJA | 53 | 23 | -0.09 | 53 | 22 | 0.21 | 53 | 22 | 1.37 | |
SON | 42 | 26 | -0.1 | 42 | 23 | 0.12 | 43 | 22 | -2.48 | |
DJF | 40 | 22 | 0.4 | 42 | 18 | 0.75 | 43 | 17 | -0.29 |
Figure 2 Seasonal precipitation anomalies (a: MAM; b: JJA; c: SON and d: DJF) averaged over Central Asia during 1901-2013, where the reference period is 1961-1990. The thick curve line is the 11-year moving average result. |
Figure 3 The decomposition results of annual precipitation time series over Central Asia, (a): MAM; (b): JJA; (c): SON and (d): DJF during the period of 1901-2013. The IMF1-IMF5 indicate the different periods of the annual precipitation time series, and the residue term r is the nonlinear trend obtained by the EEMD method. |
Table 2 Hurst Index (H) of the seasonal precipitation over mountainous area, plain area and Central Asia during 1901-2013, 1951-2013 and 1979-2013 |
Study area | Season | 1901-2013 | 1951-2013 | 1979-2013 |
---|---|---|---|---|
Central Asia | MAM | 0.56 | 0.62 | 0.66 |
JJA | 0.68 | 0.81 | 0.75 | |
SON | 0.63 | 0.76 | 0.82 | |
DJF | 0.86 | 0.82 | 0.92 | |
Mountainous area | MAM | 0.58 | 0.60 | 0.72 |
JJA | 0.75 | 0.86 | 0.79 | |
SON | 0.55 | 0.66 | 0.80 | |
DJF | 0.59 | 0.74 | 0.82 | |
Plain area | MAM | 0.56 | 0.63 | 0.69 |
JJA | 0.66 | 0.77 | 0.73 | |
SON | 0.65 | 0.78 | 0.81 | |
DJF | 0.89 | 0.81 | 0.98 |
Figure 4 Spatial distributions of the linear trends of the seasonal precipitation over Central Asia during the period of 1901-2013. Statistically significant linear trends at the 95% confidence level are indicated by cross (p<0.05). |
Table 3 Percentage areas (%) with the increasing trend, decreasing trend, significant increasing trend (SIT) and significant decreasing trend (SDT) at 95% confidence level of the four seasonal precipitation during 1901-2013, 1951-2013 and 1979-2013 |
Period | Season | Increase | Decrease | SI | SD |
---|---|---|---|---|---|
1901-2013 | MAM | 69.00 | 31.00 | 18.78 | 11.83 |
JJA | 50.37 | 49.63 | 3.01 | 9.06 | |
SON | 57.40 | 42.60 | 6.60 | 16.48 | |
DJF | 60.99 | 39.01 | 26.67 | 20.34 | |
1951-2013 | MAM | 66.50 | 33.50 | 17.22 | 3.71 |
JJA | 57.75 | 42.25 | 9.25 | 1.72 | |
SON | 60.95 | 39.05 | 9.57 | 1.87 | |
DJF | 71.26 | 28.74 | 16.56 | 1.95 | |
1979-2013 | MAM | 61.07 | 38.93 | 4.22 | 1.87 |
JJA | 63.30 | 36.70 | 3.44 | 0.86 | |
SON | 32.57 | 67.43 | 4.49 | 10.39 | |
DJF | 58.53 | 41.47 | 17.77 | 6.21 |
Figure 5 Same as Figure 4, but for the period of 1951-2013 |
Figure 6 Same as Figure 4, but for the period of 1979-2013 |
Figure 7 EOF-1 (left panel) of the seasonal precipitation anomalies (mm) and the corresponding time coefficients (right panel) over Central Asia during 1901-2013 |
Figure 8 Inter-annual signals of the seasonal precipitation and Niño 3.4 index obtained by EEMD method during 1951-2013 |
Figure 9 CC results of the inter-annual signals between seasonal precipitation and Niño 3.4 index during 1951-2013, (a) CC of the periods from year i to 2013 (i = 1951, …, 1984) and (b) 30-yr moving CC, where the vertical blue line is in the year 1966 |
Table 4 CC results of the seasonal lags time series between the precipitation and Niño 3.4 index during 1951-2013, lag-i (i=0, 1, 2, 3, 4) means lag i seasons |
Seasonal lag | MAM | JJA | SON | DJF |
---|---|---|---|---|
lag-0 | 0.35* | 0.03 | 0.27* | 0.5** |
lag-1 | 0.31* | 0.27* | 0.47** | 0.42** |
lag-2 | 0.12 | 0.44** | 0.38** | 0.32* |
lag-3 | 0.11 | 0.44** | 0.32* | -0.12 |
lag-4 | 0.22 | 0.36** | -0.21 | 0.11 |
Figure 10 Spatial distributions of the correlation coefficients of the inter-annual signals between the seasonal precipitation and Niño 3.4 during 1951-2013, where the cross symbols are the correlation coefficient values significantly at 95% confidence level |
Table 5 El Niño and La Niña years used in the composite analyses |
Season | El Niño | La Niña |
---|---|---|
MAM | 1958, 1969, 1983, 1987, 1992, 1993, 1998, 2005, 2010 | 1955, 1956, 1967, 1968, 1971, 1974, 1975, 1985, 1989, 1999, 2000, 2008 |
JJA | 1957, 1965, 1972, 1982, 1987, 1991, 1992, 1997, 2002, 2004, 2009 | 1954, 1955, 1956, 1964, 1970, 1973, 1974, 1975, 1988, 1999, 2010 |
SON | 1965, 1972, 1982, 1987, 1991, 2002, 2004, 2006, 2009 | 1954, 1955, 1964, 1970, 1973, 1975, 1988, 1998, 1999, 2010 |
DJF | 1957, 1965, 1972, 1982, 1986, 1991, 1994, 1997, 2002, 2009 | 1955, 1970, 1973, 1975, 1988, 1998, 1999, 2007, 2010 |
Figure 11 The El Niño minus La Niña composite difference in seasonal precipitation: (a) MAM, (b) SON and (c) DJF during 1951-2013, where the cross symbols are the different values significantly at 95% confidence level |
Figure 12 The El Niño minus La Niña composite difference in moisture flux: (a) MAM, (b) SON and (c) DJF during 1951-2010 |
Figure 13 ENSO-based composites of divergences of the total moisture fluxes for MAM, SON and DJF during 1950-2013. The contour interval is 5×10-6 kg/m2/s and the gray areas denote regions significant at the 95% level (p<0.05) by the student’s t-test. The zero contour is omitted and dashed lines are negative. |
Figure 14 ENSO-based composites of geopotential height (HGT) (left column) and wind for MAM, SON and DJF at 850 hPa during 1950-2013. The contour interval is 5 m for HGT and the gray areas denote regions significant at the 95% level (p<0.05) by the student’s t-test. The zero contour is omitted and dashed lines are negative. |
Figure 15 Same as Figure 14 but for 200 hPa |
Table 6 Comparison of decadal seasonal precipitation change rate (mm/10a or %/10a) of Central Asia from 1901 to 2013 from this study to rates reported in other studies, where + means increasing trend, - means decreasing trend, CMIP5 (Coupled Model Intercomparison Project, phase 5), MOPREDAS (Monthly Precipitation Database of Spain), USHCN v2.5 (U.S. Historical Climate Network, version 2.5), Climatic Research Unit (CRU) TS3.21 dataset, NH (Northern Hemispheres) |
Studies | Study area | Study period | Data | MAM | JJA | SON | DJF |
---|---|---|---|---|---|---|---|
Abatzoglou et al. (2014) | Pacific Northwest of the United States | 1901-2012 | USHCN v2.5, PRISM, CRU TS3.21 and U.S. climate division dataset | 1.8%/10a | 1.3%/10a | 0 | 0.2%/10a |
Noake et al. (2012) | Globe | 1952-1999 | VASClimO, Zhang, CRU and CMIP3 | +mid to high latitude of NH | + mid to high latitude of NH | + mid to high latitude of NH | +mid to high latitude of NH |
Sarojini et al. (2012) | Globe | 1951-2005 | Zhang and CMIP5 | + high latitude of NH | + high latitude of NH | + high latitude of NH | + high latitude of NH |
Yao et al. (2008) | Asia | 1978-2002 | Gridded dataset from Xie et al. (2007) | + southeastern and northwestern China | |||
Wang and Yan (2009) | China | 1961-2007 | 587 stations | + northwestern China | + northwestern China | + northwestern China | + north- western China |
De Luis et al. (2010) | Iberian Peninsula | 1946-2005 | MOPREDA | - | + | - | |
De Luis et al. (2009) | Mediter- ranean Iberian Peninsula | 1951-2000 | MOPREDA | -5.5 mm/10a | -4.4 mm/10a | -1.8 mm/10a | -2.2 mm/10a |
Li et al.(2011) | Xinjiang | 1961-2005 | 65 stations | -1.08 mm/10a | 1.8 mm/10a | 2.1 mm/10a | |
Our study | Central Asia | 1901-2013 | GPCC V7 | 0.41 mm/10a | -0.09 mm/10a | -0.1 mm/10a | 0.39 mm/10a |
1951-2013 | 0.49 mm/10a | 0.4 mm/10a | 0.23 mm/10a | 0.77 mm/10a | |||
1979-2013 | 0.42 mm/10a | 1.62 mm/10a | -1.97 mm/10a | 0.24 mm/10a |
Table 7 Correlation coefficient (CC) results between the seasonal precipitation and temperature during the three periods, and between the seasonal precipitation and the normalized difference vegetation index (NDVI) during 1982-2012, where the CC values are obtained by the linear least square method and ** significant at a 99% confidence level by student’s t test |
Variable | Period | MAM | JJA | SON | DJF |
---|---|---|---|---|---|
Temperature | 1901-2013 | -0.06 | -0.24 | 0.15 | 0.27 |
1951-2013 | -0.13 | -0.15 | 0.01 | 0.1 | |
1979-2013 | -0.05 | -0.13 | -0.17 | 0.14 | |
NDVI | 1982-2012 | 0.18 | 0.57** | -0.32 | -0.01 |
The authors have declared that no competing interests exist.
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