A Review of Decadal/Interdecadal Climate Variation Studies in China

Decadal/interdecadal climate variability is an important element in the CLIVAR (Climate Variability and Predictability) and has received much attention in the world. Many studies in relation to interdecadal variation have also been completed by Chinese scientists in recent years. In this paper, an introduction in outline for interdecadal climate variation research in China is presented. The content includes the features of interdecadal climate variability in China, global warming and interdecadal temperature variability, the NAO (the North Atlantic Oscillation)/NPO (the North Pacific Oscillation) and interdecadal climate variation in China, the interdecadal variation of the East Asian monsoon, the interdecadal mode of SSTA (Sea Surface Temperature Anomaly) in the North Pacific and its climate impact, and abrupt change feature of the climate.

The NPO/ NAO and Interdecadal Climate Variation in China

This article discusses the interannual variation of the North Atlantic Oscillation (NAO) and North Pacific Oscillation (NPO), its relationship with the interdecadal climate variation in China which is associated with the climate jump in the Northern Hemisphere in the 1960’s, using the data analyses. It is clearly shown that both the amplitudes of the NAO and NPO increase obviously in the 1960’s and the main period of the oscillations changes from 3-4 years before the 1960’s to 8–15 years after the 1960’s. Therefore, interdecadal climate variation in China or the climate jump in the 1960’s is closely related to the anomalies of the NAO and NPO. Key words North Atlantic Oscillation (NAO) - North Pacific Oscillation (NPO) - Climate Jump - Interdecadal climate variation This work was supported by National Key Basic Science Program in China (G1998040903), Chinese Academy of Science and the National Natural Science Fundation of China (Grant No.49823002).The authors are also grateful to Ms. Wang Xuan for typing the manuscript.

Effect of Aspect on Climate Variation in Mountain Ranges of Shennongjia Massif, Central China

The aim of this study was to better understand the mechanisms of regional climate variation in mountain ranges with contrasting aspects as mediated by changes in global climate. It may help predict trends of vegetation variations in native ecosystems in natural reserves. As measures of climate response, temperature and precipitation data from the north, east, and south-facing mountain ranges of Shennongjia Massif in the coldest and hottest months(January and July), different seasons(spring, summer, autumn, and winter) and each year were analyzed from a long-term dataset(1960 to 2003) to tested variations characteristics, temporal and spatial quantitative relationships of climates. The results showed that the average seasonal temperatures and precipitation in the north, east, and south aspects of the mountain ranges changed at different rates. The average seasonal temperatures change rate ranges in the north, east, and south-facing mountain ranges were from –0.0210℃/yr to 0.0143℃/yr, –0.0166℃/yr to 0.0311℃/yr, and –0.0290 ℃/yr to 0.0084℃/yr, respectively, and seasonal precipitation variation magnitude were from –1.4940 mm/yr to 0.6217 mm/yr, –1.6833 mm/yr to 2.6182 mm/yr, and –0.8567 mm/yr to 1.4077 mm/yr, respectively. The climates variation trend among the three mountain ranges were different in magnitude and direction, showing a complicated change of the climates in mountain ranges and some inconsistency with general trends in global climate change. The climate variations were significantly different and positively correlated cross mountain ranges, revealing that aspects significantly affected on climate variations and these variations resulted from a larger air circulation system, which were sensitive to global climate change. We conclude that location and terrain of aspect are the main factors affecting differences in climate variation among the mountain ranges with contrasting aspects.

Analysis on the Climate Variation Characteristics of Frost in Shandong Province

[Objective] The research aimed to study the climate variation characteristics of frost in Shandong Province. [Method] The daily minimum surface temperature ≤ 0 ℃ in autumn or spring was as the frost index. Based on the daily minimum surface temperature data in 67 meteorological observatories of Shandong Province during 1961-2008, the variation characteristics of first, last frost dates and frost-free period in Shandong Province were analyzed by using the climate diagnosis analysis method. [Result] The climate characteristics of first, last frost dates and frost-free period had the obvious geographical differences in Shandong Province in recent 48 years. The extreme differences of first, last frost dates and frost-free period were all above the three times of their standard deviations. It illustrated that the dispersion degrees of first, last dates and frost-free period were all very big. The average first frost date postponed with 1.99 d/10 a velocity in Shandong Province in recent 48 years, and the last frost date advanced with 1.46 d/10 a velocity. The postponing range of first frost date was bigger than the advancing range of last frost date, and the frost-free period prolonged with 3.42 d/10 a velocity. Seen from the interdecadal variations, the first frost date started to obviously postpone, and the last frost date obviously advanced since the 1990s. The frost-free period also started to obviously prolong since the 1990s. [Conclusion] The research provided the certain reference for the predication, prevention of frost disaster and the structure adjustment of crops.

Study on Temporal and Spatial Characteristics of Climate Variation in Hebei Area during 1956-2007

[Objective] The research aimed to study temporal and spatial characteristics of climate variation in Hebei area during 1956-2007. [Method] Based on the data from 23 weather stations evenly distributed over Hebei area (included Beijing and Tianjin) during 1956-2007, by using statistical analytic method, the temporal and spatial variation characteristics of main meteorological factors (temperature and precipitation, etc.) in the area were analyzed. The variation fact and evolution rule of climate in the area in 52 years were discussed. [Result] In Hebei area during 1956-2007, the annual and four-season temperatures both presented wavy rise trends. The temperature increment in winter was the maximum, contributing the most to the annual temperature elevation in this area. The temperatures in the whole district all presented rise trends, and the variation difference had regularity. The annual and four-season rainfalls both had large fluctuation amplitudes, following different linear variation trends. The annual rainfall overall presented wavy decrease trends. The spatial difference of rainfall variation was significant. The rainfalls in the whole district all presented decrease trends. The decrease amplitude presented low-high-low pattern from the northeast to the southwest. The potential evaporation capacity over the whole district was the highest in the 1960s, and decreased ever since instead of increasing with the temperature. The potential evaporation capacities of each season also presented decline trends. Except in Fengning and Yuxian, the evaporation capacities of other stations in the whole district all presented decline trends. The relative humidity slightly decreased as time, with the exception of Chengde, Qinhuangdao and Nangong. The sunshine hours had a clear decrease trends. [Conclusion] The research provided scientific basis for realizing regional sustainable development, improving ecological environment and people’s life quality.

ANALYSIS OF THE RELATIONSHIP BETWEEN THE CHINA ANOMALOUS CLIMATE VARIATION AND ENSO CYCLE ON THE QUASI-FOUR-YEAR SCALE

The relationship between the ENSO and abnormal variation of precipitation and temperature in China is investigated based on the monthly data. Firstly, interannual variability of precipitation and temperature are discussed in different sub-areas using Rotational EOF (REOF). Then, the variation of precipitation and temperature in different phases of ENSO cycle is each investigated with Complex Singular Value Decomposition (CSVD). Results show that, during the period of El Nio, precipitation in the eastern China, especially in the northeastern China and Yangtze River valley, is much more than normal and is apt to flood. Precipitation in northern China and Huanghe River valley, especially in the middle reach of Huanghe River, is less than normal and is apt to be less. Precipitation in the Yangtze River valley is closely related to the SSTA in the central and eastern tropical Pacific on the QFO scale, and the precipitation variation lags behind SSTA by about 3 months. For the variation of surface temperature, during the period of El Nio, it is usually colder than normal in northeastern China, and in other regions, especially in the region of Great Bend of the Yellow River and southwestern China, is warmer than normal. The temperature in northeast China is closely associated with SSTA in eastern Pacific on the QFO scale and the surface temperature variation in the northeast China lags behind that of SSTA about 2 months.

Climate Disasters and Climate Variation of Little Ice Age in East Asia

In this paper, climate variation is reconstructed on the basis of the chronicles of weather disasters in Japan and China. There remain many rainstorm records in southern coast of Japan, and south-eastern coast of China. Both in Japan and China, many rainstorm disasters appeared in summer. But, they usually appeared one or two months later in Japan. The period of frequent windstorm damage occurrence in Little Ice Age differs among Japan and China, and it was caused by the change of atmospheric circulation. Cool summer period appeared around 1705, 1740, 1765, 1785, 1830, and 1845. It was generally cool before 1855, but it became warm after 1855. It corresponds with the sudden retreat of glaciers of European Alps.

Impact of climate variation on fog in China

Using foggy days and mean temperature and relative humidity data of 602 stations from January to December in the period 1961-2003 in China, the relationship between variations of foggy days and temperature and its possible reason for the 43 years were analyzed by regression, correlation and contrastive analysis methods. The results show that the higher （lower） the mean temperature and the lower （higher） the relative humidity correspond to less （more） foggy days, the relationship is the best in the western, northern and eastern Sichuan, Yunnan-Guizhon Plateau, and southeast highland in China. This induces a decrease in relative humidity when the climate becomes warmer, and eventually brings about a decrease in foggy days in China.

Glacier Variation in Response to Climate Change in Chinese Tianshan Mountains from 1989 to 2012

Based on the 1990, 2000 and 2011 Landsat TM/ETM+ remote sensing data, glacier information of three periods in the Chinese Tianshan Mountains were extracted by using ratio threshold method(TM3/TM5) and visual interpretation, combined with digital processing of satellite images and analysis in GIS. The climate data in the surrounding area were analyzed by using linear regression, Mann-Kendall abrupt test, and Morlet wavelet analysis. Study results showed that: over the 23 years investigation, the glacier areas have markedly decreased. In the last 12 years(2000 to 2011), the rate of retreat has begun to accelerate. The most dramatic glacier shrinkage occurred in the central region, the lowest in the eastern region. The mean summer temperature and warm precipitation in Chinese Tianshan Mountains had an increasing trend, with rates of 0.22°C /10 a and 5.1mm/10 a from 1960 to 2011, respectively. Mean summer temperature have experienced a strong increase in 1998. The analysis of the results showed that the rise of mean summer temperature was the main factor that contributed to glacier shrinkage. Regional differences of glacier area changes were investigated by analyzing glacier behavior in five study sub-regions; regional differences are related to local climate, to the relative proportion of glaciers in different size classes, altitudinal and aspect distribution of glaciated areas. In addition, the lag theory indicated that glaciers may accelerate the retreat in the next decade, considering climate trends recognized for the period 2000-2011.

Vegetation and Climate Variations at Taibai, Qinling Mountains in Central China for the Last 3 500 cal BP

Pollen records of two swamp sections, located at Taibai Mountain, the highest peak in the Qinling Mountains of central China, show variations of vegetation and climate for the last 3 500 cal BP. The pollen assemblage at the Foyechi and Sanqingchi sections and the surface soil pollen allowed us to reconstruct a high-altitude vegetation history at Taibai Mountain for the first time. The data indicated that there was a cold-dry climate interval between 3 500 and 3 080 cal BP and a relatively warm and wet period compared with the present from 3 080 to 1 860 cal BE The warmest period in the late Holocene on Taibai Mountain was from 1 430 to 730 cal BP, with an approximate 2 ~C increase in mean annual temperature compared with today. There was a relatively cool-dry climate interval from 730 to 310 cal BE After 310 cal BE a mountain tundra vegetation developed again and the position of the modern tree line was established.

IMPACT OF CLIMATE VARIATIONS ON SOC-ECONOMY IN CHINA

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Analysis on the Climate Characteristics of Relative Humidity in Recent 40 Years in Urumqi City

By using the daily average relative humidity data in Urumqi during 1961-2000,the basic climate characteristics and the variation trend of relative humidity in Urumqi in recent 40 years were analyzed.The results showed that the yearly average relative humidity in Urumqi was 57.5%.The relative humidity in winter was 77.5% which was the biggest all the year round,and the relative humidity in summer was 41.2% which was the smallest.The relative humidity in spring,summer,autumn,winter and the yearly relative humidity all displayed the increase trend.The yearly mean relative humidity had the periods of mainly 2,3-4 and quasi-7 years.The periodic oscillation of quasi-7 years was the strongest.

Dynamics and Responses of Vegetation to Climatic Variations in Ziya- Daqing Basins, China

Examining the direct and indirect effects of climatic factors on vegetation growth is critical to understand the complex linkage between climate change and vegetation dynamics. Based on the Moderate Resolution Imaging Spectroradiometer(MODIS) Normalized Difference Vegetation Index(NDVI) data and meteorological data(temperature and precipitation) from 2001 to 2012, the trend of vegetation dynamics were examined in the Ziya-Daqing basins, China. The path analysis was used to obtain the information on the relationships among climatic factors and their effects on vegetation growth. It was found that the trends of growing season NDVI were insignificant in most plain dry land, while the upward trends were significant in forest, grass and dry land in Taihang Mountains. According to the path analysis, in 23% of the basins the inter-annual NDVI variation was dominated by the direct effect of precipitation, in 5% by the direct effects of precipitation and temperature, and in less than 1% by the direct effect of temperature or indirect effects of these two climatic factors. It indicated that precipitation significantly affected the vegetation growth in the whole basins, and this effect was not regulated by temperature. Precipitation increase(especially in July, August and September) was favorable to greenness enhancement. Summer temperature rising showed negative effect on plant productivity enhancement, but temperature rise in April was beneficial for the vegetation growth. When April temperature increases by 1℃, the onset date of greenness for natural vegetation will be 2 days in advance. There was a lag-time effect of precipitation or temperature on monthly NDVI for all land use types except grass.

Analysis on the Change Characteristics of Climate in Suizhong in Recent 55 Years

[Objective] The research aimed to study the variation characteristics of climate in Suizhong in recent 55 years.[Method] Based on the meteorological observation data (temperature,sunshine,precipitation,etc.) in Suizhong County during 1956-2010,the variation trend,the time and stability which stably passed one threshold of meteorological factors were analyzed by using the linear regression,five-day sliding average and deviation coefficient.The change characteristics of climate in Suizhong County in recent 55 years were grasped.[Result] In recent 55 years,the temperature in Suizhong presented the rise trend.In recent 25 years (1986-2010),the temperature rise was obvious.The rise ranges of winter average temperature and average minimum temperature were big.Moreover,the variation range was big,and the stability was bad.The variation trends of frost-free period and ≥10 ℃ accumulated temperature were basically consistent with that of temperature.The sunshine hours overall presented the decline trend,which wasn’t obvious.It presented the rise trend in winter half year and the decline trend in summer half year.The decline trend in summer was obvious.The rainfall overall presented the decline trend.Spring precipitation presented the rise trend.The precipitation in summer and autumn presented the decline trend.The variation range of precipitation in winter was big,and the stability was bad.The variation range of precipitation in summer was small,and the stability was good.[Conclusion] The research provided the basis for management department understanding and grasping the variation characteristics of local climate,disaster prevention and reduction.

Evidence of Climate Variability in Imo State of Southeastern Nigeria

Climate variation generally occurs at local scale, regional scale, national scale and global scale. Having established that the global climate has varied slowly over the past millennia, centuries, and decades and it is expected to continue to vary in future. Like the climate change, variability may be due to, national internal processes within the climate （internal variability）, or variations in natural or anthropogenic external forces （external variability）. Evidence of climate variations is now well documented, and the implications are becoming increasingly clear as data accumulates and data and climate models become increasingly sophisticated. The fluctuations in rainfall and temperature regimes are the atmospheric driving forces that are responsible for the climate variations over the southeastern Nigeria including Imo State as the case in other parts of the world. It is on this premise that this study examined the evidence of climate variability in Imo State of the southeastern Nigeria. The study employed the holistic use of real meteorological data from Nigerian Meteorological Department on two weather parameters （temperature and rainfall）, for 30 years （1980-2009）. Results indicated fluctuations in temperature and rainfall regimes within the period under study, which were the reasons for the variations in climate of the region. Apparently, evidence of climate variability are indicated by increasing surface air temperature, increasing heat waves which enhances disease vectors, communicable diseases and epidemics, sea level rise and associated coastal erosion, flooding, increased evaporation that dry up streams and rivers etc..

Characteristics of Spatial and Temporal Variations of Monthly Mean Surface Air Temperature over Qinghai-Tibet Plateau

The recorded meteorological data of monthly mean surface air temperature from 72 meteorological stations over the Qinghal-Tibet Plateau in the period of 1960-2003 have been analyzed by using Empirical Orthogonal Function （EOF） method, to understand the detailed features of its temporal and spatial variations. The results show that there was a high consistency of the monthly mean surface air temperature, with a secondarily different variation between the north and the south of the plateau. Warming trend has existed at all stations since the 1960s, while the warming rates were different in various zones. The source regions of big rivers had intense warming tendency. June, November and December were the top three fast-warming months since the 1960s; while April, July and September presented dramatic warming tendency during the last decade.

CLIMATIC VARIATIONS IN CHINA OVER THE LAST 2000 YEARS

A compilation of paleoclimate records from ice core, tree-rings, lake sediments and historical documents provides a view of temperature change in China over the recent 2000 years. For all-China temperature reconstruction, six sub-stages are identified for the last two millennia. Around AD 0－240, AD 800－1100, AD 1320－1400 and the period from AD 1880 on were warm while around AD 240－800, AD 1100－1320, AD 1400－1880 were cold. Also, temperature varied from region to region in each of the warm or cold periods. The Eastern Han warm period (0－AD 240), the cold period covering the span of Wei, Jin, and the Southern and Northern Dynasties, the MWP (AD 800－1100) and succeeding LIA occurred in eastern China and the Qilian Mountains. Only the first two climatic events were recorded in Guliya ice core while the so-called MWP and LIA was far weaker. Also, the warming between AD 800 and 1100 didn′t occur in the south of Xizang (Tibet) Plateau. Instead, the southern Xizang Plateau experienced warming in AD 1150－1400. The aggregated China temperature agrees well with North-hemisphere temperature in the past millennia, indicating close relationship of temperature changes between China and North-hemisphere.

Preliminary Analysis of Climatic Variation during the Last 39 Years in China

The preliminary analysis of climatic variation in China during the last 39 years has been made in this paper. The results show that although the global climate is getting warmer, some parts of China are cooling. The warming only occurs in Northeast, North and the west part of Northwest China while the areas between about 35°N and Nanling Mountain, east of the Tibetan Plateau in China are getting cooler. The cooling centers are located in Sichuan, the south part of Shaanxi and the north part of Yunnan respectively. According to the theory of greenhouse effect, there are much precipitation at low and high latitudes and less precipitation in middle latitude. However, the precipitation in the most parts of China has been decreased, especially in North and Northwest China.

Global sea level variations from altimetry,GRACE and Argo data over 2005-2014

Total sea level variations（SLVs） are caused by two major components：steric variations due to thermal expansion of seawater,and mass-induced variations due to mass exchange between ocean and land.In this study,the global SLV and its steric and mass components were estimated by satellite altimetry,Argo float data and the Gravity Recovery and Climate Experiment（GRACE） data over 2005-2014.Space gravimetry observations from GRACE suggested that two-thirds of the global mean sea level rise rate observed by altimetry（i.e.,3.1 ± 0.3 mm/a from 2005 to 2014） could be explained by an increase in ocean mass.Furthermore,the global mean sea level was observed to drop significantly during the2010/2011 La Nina event,which may be attributed to the decline of ocean mass and steric SLV.Since early 2011,the global mean sea level began to rise rapidly,which was attributed to an increase in ocean mass.The findings in this study suggested that the global mean sea-level budget was closed from 2005 to 2014 based on altimetry,GRACE,and Argo data.

Water storage variations in the Poyang Lake Basin estimated from GRACE and satellite altimetry

The Gravity Recovery and Climate Experiment（GRACE） satellite mission provides a unique opportunity to quantitatively study terrestrial water storage（TWS） variations. In this paper,the terrestrial water storage variations in the Poyang Lake Basin are recovered from the GRACE gravity data from January 2003 to March 2014 and compared with the Global Land Data Assimilation System（GLDAS） hydrological models and satellite altimetry. Furthermore, the impact of soil moisture content from GLDAS and rainfall from the Tropical Rainfall Measuring Mission（TRMM） on TWS variations are investigated. Our results indicate that the TWS variations from GRACE, GLDAS and satellite altimetry have a general consistency. The TWS trends in the Poyang Lake Basin determined from GRACE, GLDAS and satellite altimetry are increasing at 0.0141 km^3/a, 0.0328 km^3/a and 0.0238 km^3/a,respectively during the investigated time period. The TWS is governed mainly by the soil moisture content and dominated primarily by the precipitation but also modulated by the flood season of the Yangtze River as well as the lake and river exchange water.