首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 593 毫秒
1.
Seven different tree-ring parameters (tree-ring width, earlywood width, latewood width, maximum density, minimum density, mean earlywood density, and mean latewood density) were obtained from Qinghai spruce (Picea crassifolia) at one chronology site in the Hexi Corridor, China. The chronologies were analyzed individually and then compared with each other. Growth–climate response analyses showed that the tree-ring width and maximum latewood density (MXD) are mainly influenced by warm season temperature variability. Based on the relationships derived from the climate response analysis, the MXD chronology was used to reconstruct the May–August maximum temperature for the period 1775–2008 A.D., and it explained the 38.1% of the total temperature variance. It shows cooling in the late 1700s to early 1800s and warming in the twentieth century. Spatial climate correlation analyses with gridded land surface data revealed that our warm season temperature reconstruction contains a strong large-scale temperature signal for north China. Comparison with regional and Northern Hemisphere reconstructions revealed similar low-frequency change to longer-term variability. Several cold years coincide with major volcanic eruptions.  相似文献   

2.
Long climate records are scarce on the Tibetan Plateau for understanding the climate variability on long-term context. Here we presented an early summer (May?CJune) temperature reconstruction since ad 1440 for Qamdo area using tree rings of Sabina tibetica. The reconstruction accounted for 64% of the variance in the instrumental record. It showed warm periods during 1501?C1514, 1528?C1538, 1598?C1609, 1624?C1636, 1650?C1668, 1695?C1705, 1752?C1762, 1794?C1804, 1878?C1890, 1909?C1921, 1938?C1949, and 1979?C1991. Cool early summer occurred during 1440?C1454, 1482?C1500, 1515?C1527, 1576?C1597, 1610?C1621, 1669?C1679, 1706?C1716, 1782?C1793, 1863?C1873, 1894?C1908, and 1922?C1937. Comparison with other proxy or meteorological records suggested that there is obvious spatial variability in the May?CJune temperature variations along the eastern margin of the Tibetan Plateau.  相似文献   

3.
We develop a summer temperature reconstruction for temperate East Asia based on a network of annual tree-ring chronologies covering the period 800–1989 C.E. The East Asia reconstruction is the regional average of 585 individual grid point summer temperature reconstructions produced using an ensemble version of point-by-point regression. Statistical calibration and validation tests indicate that the regional average possesses sufficient overall skill to allow it to be used to study the causes of temperature variability and change over the region. The reconstruction suggests a moderately warm early medieval epoch (ca. 850–1050 C.E.), followed by generally cooler ‘Little Ice Age’ conditions (ca. 1350–1880 C.E.) and 20th century warming up to the present time. Since 1990, average temperature has exceeded past warm epochs of comparable duration, but it is not statistically unprecedented. Superposed epoch analysis reveals a volcanic forcing signal in the East Asia summer temperature reconstruction, resulting in pulses of cooler summer conditions that may persist for several years. Substantial uncertainties remain, however, particularly at lower frequencies, thus requiring caution and scientific prudence in the interpretation of this record.  相似文献   

4.
Development of long tree-ring records is an important task in paleoclimate studies. Here we presented a five-century long reconstruction of summer (June to August) temperature based on a tree ring-width chronology of Picea brachytyla var. complanata originating from the Hengduan Mountains of China. Climate-growth response analysis showed that summer temperature was the main climatic factor limiting tree-ring growth in the study area. The reconstructed summer temperature accounted for 47.6% of the variance in actual temperature during their common period A.D. 1958–2002. Analysis of the temperature reconstruction showed that major warm periods occurred in the A.D. 1710s–1750s, 1850s, 1920s–1950s and 1990s to present, whereas cold intervals occurred in the A.D. 1630s–1680s, 1790s–1800s, 1860s–1880s and 1950s–1980s, respectively. The low-frequency variation of the reconstruction agreed fairly well with tree-ring reconstructed temperature from nearby regions and with records of glacier fluctuations in the surrounding high mountains, suggesting that our reconstructed summer temperature was reliable, and could aid in the evaluation of regional climate variability.  相似文献   

5.
 During the Younger Dryas (YD) the climate in NW Europe returned to near-glacial conditions. To improve our understanding of climate variability during this cold interval, we compare an AGCM simulation of this climate, performed with the ECHAM model, with temperature reconstructions for NW Europe based on geological and paleoecological records. Maps for the mean winter, summer and annual temperature are presented. The simulated winters are consistent with reconstructions in the northern part of the study area. A strong deviation is noted in Ireland and England, where the simulation is too warm by at least 10 °C. It appears that the N Atlantic was cooler than prescribed in the YD simulation, including a southward expansion of the sea-ice margin. The comparison for the summer shows a too warm continental Europe in the simulation. Supposedly, these anomalously warm conditions are caused by the AGCM’s response to the prescribed increased summer insolation. The region of maximum summer cooling is similar in both the simulation and reconstruction, i.e., S Sweden. We suggest that this is due to the local cooling effect of the Scandinavian ice sheet. Compared to the present climate a considerable increase of the annual temperature range is inferred, especially for regions close to the Atlantic Ocean. Received: 20 November 1996 / Accepted: 8 July 1997  相似文献   

6.
The Mediterranean has been identified as particularly vulnerable to climate change, yet a high-resolution temperature reconstruction extending back into the Medieval Warm Period is still lacking. Here we present such a record from a high-elevation site on Mt. Smolikas in northern Greece, where some of Europe’s oldest trees provide evidence of warm season temperature variability back to 730 CE. The reconstruction is derived from 192 annually resolved, latewood density series from ancient living and relict Pinus heldreichii trees calibrating at r1911–2015 = 0.73 against regional July–September (JAS) temperatures. Although the recent 1985–2014 period was the warmest 30-year interval (JAS Twrt.1961–1990 = + 0.71 °C) since the eleventh century, temperatures during the ninth to tenth centuries were even warmer, including the warmest reconstructed 30-year period from 876–905 (+ 0.78 °C). These differences between warm periods are statistically insignificant though. Several distinct cold episodes punctuate the Little Ice Age, albeit the coldest 30-year period is centered during high medieval times from 997–1026 (− 1.63 °C). Comparison with reconstructions from the Alps and Scandinavia shows that a similar cold episode occurred in central Europe but was absent at northern latitudes. The reconstructions also reveal different millennial-scale temperature trends (NEur = − 0.73 °C/1000 years, CEur = − 0.13 °C, SEur = + 0.23 °C) potentially triggered by latitudinal changes in summer insolation due to orbital forcing. These features, the opposing millennial-scale temperature trends and the medieval multi-decadal cooling recorded in Central Europe and the Mediterranean, are not well captured in state-of-the-art climate model simulations.  相似文献   

7.
基于华东399个气象站点逐日最高、最低气温数据，利用极端气候指数软件RClimdex和线性倾向估计、Mann-Kendall突变检验、概率密度函数等气候统计诊断方法，分析了华东极端气候的时空变化特征。结果表明，1961-2015年期间，华东最低气温极大值和极小值分别以0.2℃/10a和0.6℃/10a的趋势显著增加，最高气温极小值以0.3℃/10a的趋势显著增加，结冰、霜冻、冷夜和冷昼日数分别以0.5d/10a、3.7d/10a、2.0%/10a和0.7%/10a显著减少，夏天日数、热夜日数、暖夜和暖昼日数分别以2.9d/10a、2.8d/10a、1.8%/10a和0.8%/10a显著增加。期间华东最低和最高气温极值均发生升高突变，霜冻和结冰日数、冷夜和冷昼日数分别在20世纪80年代中后期和90年代发生减少突变，夏天日数、热夜日数、暖夜和暖昼日数则在2000年发生增多突变。与1961-1990年期间相比，1991-2015年间华东最低和最高气温极值的概率密度函数分布均右移，峰值多增大；霜冻、结冰、冷夜和冷昼日数的分布函数左移，峰值升高，形状变窄，而夏天日数、热夜日数、暖夜和暖昼日数恰好相反。  相似文献   

8.
Winter-spring cold extreme is a kind of serious natural disaster for southeastern China. As such events are recorded in discrete documents, long and continuous records are required to understand their characteristics and driving forces. Here we report a regional-scale winter-spring (January–April) temperature reconstruction based on a tree-ring network of pine trees (Pinus massoniana) from five sampling sites over a large spatial scale (25–29°N, 111–115°E) in southeastern China. The regional tree-ring chronology explains 48.6% of the instrumental temperature variance during the period 1957–2008. The reconstruction shows six relatively warm intervals (i.e., ~1849–1855, ~1871–1888, ~1909–1920, ~1939–1944, ~1958–1968, 1997–2007) and five cold intervals (i.e., ~1860–1870, ~1893–1908, ~1925–1934, ~1945–1957, ~1982–1996) during 1849–2008. The last decade and the 1930s were the warmest and coldest decades, respectively, in the past 160 years. The composite analysis of 500-hPa geopotential height fields reveals that distinctly different circulation patterns occurred in the instrumental and pre-instrumental periods. The winter-spring cold extremes in southeastern China are associated with Ural-High ridge pattern for the instrumental period (1957–2008), whereas the cold extremes in pre-instrumental period (1871–1956) are associated with North circulation pattern.  相似文献   

9.
Changes in maximum spring and summer temperature are expected to have impacts on plant phenology and the occurrence of forest fires. Homogenised instrumental records of maximum spring and summer temperature are available in northern France for the past century, as well as documentary records of grape harvest dates and forest fire frequencies. Here we provide a new proxy of seasonal climate obtained by the analysis of latewood tree ring cellulose isotopic composition (δ18O, δ13C and δD), from 15 living oak trees (Quercus petraea) sampled in the Fontainebleau forest, near Paris. For the past 30 years, we have conducted a study on the inter-tree (for oxygen isotopes) and inter-station (for oxygen and hydrogen) isotopic variability. Multiple linear regression statistical analyses are used to assess the response function of documentary and tree-ring isotopic records to a variety of climatic and hydrological parameters. This calibration study highlights the correlation between latewood tree-ring δ18O and δ13C, grape harvest dates and numbers of forest fire starts with maximum growing season (April to September) temperature, showing the potential of multiple proxy reconstructions to assess the past fluctuations of this parameter prior to the instrumental period.  相似文献   

10.
The aim of this study is to determine the influence of atmospheric circulation on the recently observed changes in the number of warm days and cold days in Europe. The temperature series for stations in the European Climate Assessment and Data set project and the Grosswetterlagen (GWL) were used here. The temperature series were first adjusted for global warming before determining the indices for cold and warm extremes. The 29 GWLs were grouped in ten circulation types. Then, the number of days a certain circulation type occurred was determined for each winter (December, January and February) and summer (June, July and August). The relation between the circulation type frequencies and the temperature indices was modelled with a multi-regression fit over the period 1947–1974 and tested for the period 1974–2000. The difference between the observed indices and the calculated indices in the second period (using the fit coefficients for the first period) shows a warming effect for both winter and summer and for at least the warm day index, which is unaccounted for by the global warming trend. A simple snow model shows that variations in the European snow cover extent are likely influencing the cold and warm day indices in winter: there is a correlation between the decreasing trend of the snow cover extent in Europe and the increasing (decreasing) trend of the number of warm (cold) days for stations throughout Europe.  相似文献   

11.
The Yangtze River Delta Economic Belt is one of the most active and developed areas in China and has experienced quick urbanization with fast economic development. The weather research and forecasting model (WRF), with a single-layer urban canopy parameterization scheme, is used to simulate the influence of urbanization on climate at local and regional scales in this area. The months January and July, over a 5-year period (2003–2007), were selected to represent the winter and summer climate. Two simulation scenarios were designed to investigate the impacts of urbanization: (1) no urban areas and (2) urban land cover determined by MODIS satellite observations in 2005. Simulated near-surface temperature, wind speed and specific humidity agree well with the corresponding measurements. By comparing the simulations of the two scenarios, differences in near-surface temperature, wind speed and precipitation were quantified. The conversion of rural land (mostly irrigation cropland) to urban land cover results in significant changes to near-surface temperature, humidity, wind speed and precipitation. The mean near-surface temperature in urbanized areas increases on average by 0.45?±?0.43°C in winter and 1.9?±?0.55°C in summer; the diurnal temperature range in urbanized areas decreases on average by 0.13?±?0.73°C in winter and 0.55?±?0.84°C in summer. Precipitation increases about 15% over urban or leeward areas in summer and changes slightly in winter. The urbanization impact in summer is stronger and covers a larger area than that in winter due to the regional east-Asian monsoon climate characterized by warm, wet summers and cool, dry winters.  相似文献   

12.
Effects of global warming on radial growth were examined for the subalpine tree species Abies veitchii (1600–2200 m?a.s.l.), A. mariesii (2000–2500 m?a.s.l.) and Betula ermanii (1600–2500 m?a.s.l.) in central Japan, by using dendrochronological techniques. Chronologies of tree-ring widths were examined for the three species and of maximum latewood densities for the two Abies species at their upper and lower distribution limits (total 10 chronologies). We developed multiple regression models to reproduce these chronologies from the monthly mean temperature and sum of precipitation. Of the 10 chronologies, growth-climate relations could not be modeled for tree-ring width chronologies of the three species at their lower distribution limits because of low correlation. Annual mean temperature and annual sum of precipitation will increase about 3 °C and 100 mm, respectively, by 2100 in central Japan, according to 18 climatic change scenarios (6 general circulation models ×3 greenhouse gasses emission scenarios). We predicted tree-ring widths and maximum latewood densities by substituting 18 climatic change scenarios into the growth-climate models. Maximum latewood densities and tree-ring widths of A. mariesii at the upper and lower distribution limits increased by 2100. The rates of the increase tended to be greater for scenarios with more greenhouse gas emission. By contrast, maximum latewood densities of A. veitchii and tree-ring widths of B. ermanii were unchanged by 2100, irrespective of the three greenhouse gas emission scenarios. This study showed that radial growth of the three species responds differently to global warming and their responses are predictable by dendrochronological models.  相似文献   

13.
For the first time we present a multi-proxy data set for the Russian Altai, consisting of Siberian larch tree-ring width (TRW), latewood density (MXD), δ13C and δ18O in cellulose chronologies obtained for the period 1779–2007 and cell wall thickness (CWT) for 1900–2008. All of these parameters agree well between each other in the high-frequency variability, while the low-frequency climate information shows systematic differences. The correlation analysis with temperature and precipitation data from the closest weather station and gridded data revealed that annual TRW, MXD, CWT, and δ13C data contain a strong summer temperature signal, while δ18O in cellulose represents a mixed summer and winter temperature and precipitation signal. The temperature and precipitation reconstructions from the Belukha ice core and Teletskoe lake sediments were used to investigate the correspondence of different independent proxies. Low frequency patterns in TRW and δ13C chronologies are consistent with temperature reconstructions from nearby Belukha ice core and Teletskoe lake sediments showing a pronounced warming trend in the last century. Their combination could be used for the regional temperature reconstruction. The long-term δ18O trend agrees with the precipitation reconstruction from the Teletskoe lake sediment indicating more humid conditions during the twentieth century. Therefore, these two proxies could be combined for the precipitation reconstruction.  相似文献   

14.
This paper investigates monthly and seasonal precipitation–temperature relationships (PTRs) over Northeast China using a method proposed in this study. The PTRs are influenced by clouds, latent and sensible heat conversion, precipitation type, etc. In summer, the influences of these factors on temperature decrease are different for various altitudes, latitudes, longitudes, and climate types. Stronger negative PTRs ranging from ?0.049 to ?0.075 °C/mm mostly occur in the semi-arid region, where the cold frontal-type precipitation dominates. In contrast, weaker negative PTRs ranging from ?0.004 to ?0.014 °C/mm mainly distribute in Liaoning Province, where rain is mainly orographic rain controlled by the warm and humid air of East Asian summer monsoon. In winter, surface temperature increases owing to the release of latent heat and sensible heat when precipitation occurs. The stronger positive PTRs ranging from 0.963 to 3.786 °C/mm mostly occur at high altitudes and latitudes due to more release of sensible heat. The enhanced atmospheric counter radiation by clouds is the major factor affecting increases of surface temperature in winter and decreases of surface temperature in summer when precipitation occurs.  相似文献   

15.
We present two tree-ring chronologies for the southeastern Tibetan Plateau (TP), established by applying the signal-free regional curve standardization and standard dendrochronological methodologies to a set of ring-width series of Tibetan juniper. The relationship between tree growth and climate shows that temperature variability in the previous year is the primary factor controlling tree growth at the upper portion of the forest belt. Accordingly, we developed a mean annual temperature reconstruction covering the period A.D. 984–2009 and explaining 50 % of the instrumental variance. The spatial correlation patterns suggest that our temperature reconstruction is a reasonable proxy for temperature change over the TP. At long time scales, the temperature reconstruction shows similar warm-cold patterns to those in temperature records from other regions of the TP, indicating that decadal and multidecadal temperature variations were generally synchronous across the TP during the past millennium. The periods 1140–1350 and 1600–1800 were common warm and cold episodes over the TP, respectively. Comparison of our reconstruction with four Northern Hemisphere (NH) temperature series indicates that temperature changes on the southeastern TP have generally followed the NH temperature patterns during the past millennium. Our results also suggest that temperature variability over the TP is affected by the Atlantic Multidecadal Oscillation (AMO), with the warm (cool) phases of the AMO associated with above-average (below-average) temperatures over the TP.  相似文献   

16.
Temperature trends in Libya over the second half of the 20th century   总被引：1，自引：0，他引：1  
This paper investigates spatial variability of temperature trends over Libya in the second half of the 20th century. The study is based on complete and homogeneous time series of minimum, maximum, and mean temperature for ten observatories. During the investigated period (1951–1999), temperature trend analyses have experienced a downward trend in the maximum surface temperature (about –0.06°C decade–1) and an upward trend in the minimum surface temperature (about 0.23°C decade–1). Cooling tendency in maximum temperature is spatially more pronounced in inland stations compared to coastal stations. At the seasonal scale, maximum temperature cooling is more obvious in winter and spring, meanwhile minimum temperature warming is more pronounced in summer and fall. In accordance with global trends, the surface mean temperature has moderately risen at an average rate of 0.09°C decade–1. However, this trend has shown considerable temporal variability considering a more pronounced upward trend in summer and fall. In conjunction with other regional and global investigations, clear trends towards smaller diurnal range are presented (–0.28°C decade–1).  相似文献   

17.
亚洲夏季风建立前后对流层温度场演变特征及其热力成因   总被引：5，自引：1，他引：4  
对１９９６年亚洲夏季风爆发前后（３～６月）印度及南海季风区对流层温度演变特征及其热力成因作了比较分析。结果表明：印度和南海夏季风的爆发与各季风区对流层中上层南北温差逆转密切相关,而南北温差逆转是由１０～３０°Ｎ之间纬度带对流层的季节性增暖引起的。夏季风爆发前期,南海季风区的增温主要由暖平流及非绝热加热过程（主要为凝结潜热）共同作用所致。春季在印度季风区大陆上空存在显著的下沉绝热增温,使得对流层中上层的增温率比华南大陆及邻近地区上空的增温率显著得多。但印度季风区冬末春初的南北温差（南暖北冷）也非常明显,以至该地区对流层中上层增暖到引起南北温差发生逆转的时间较迟,而南海季风区对流层中层南北温差发生逆转的时间相对要早,因而印度夏季风比南海夏季风迟爆发。  相似文献   

18.
Glaciers around the world retreated as the climate warmed substantially. For the majority of alpine and arctic areas, however, the lack of meteorological data over a long period makes it difficult to build long-term climate and glacial fluctuation relationships, emphasizing the importance of natural proxy archives. Here we use the 230-year record of stem radial growth of birch trees (Betula ermanii) from the treeline forests above the receding glaciers in eastern maritime Kamchatka to analyse temporal variations of climate as well as glacial advance and retreat. Glaciers in Kamchatka Peninsula represent the southern limit of glaciation in far eastern Eurasia, which makes them prone to global warming. Using instrumental climate data (1930–1996) from local meteorological stations, we find that the July temperature had most prominent positive impact on birch growth. On the contrary, smaller ring increments are associated with the positive summer and net annual ice mass balance of Koryto Glacier. The prevailing trend of higher summer temperatures and lower snowfall over the past 70 years has enhanced tree growth while causing the glacier’s surface to lower by about 35 m and its front to retreat by about 490 m. Assuming these same relationships between climate, tree growth, and glacier mass balance also existed in the past, we use tree rings as a proxy record of climatically induced temporary halts in the glacier’s retreat over the past two centuries, which in total was over 1,000 m. Both direct observations and tree ring proxies indicate several prolonged warm periods (1990s, 1960s, 1930–1940s, 1880–1900s) interspersed with cooler periods (1984–1985, 1970–1976, 1953–1957, 1912–1926, 1855–1875, 1830–1845, 1805–1820 and 1770–1780) when the glacier re-advanced, creating several consecutive terminal moraine ridges. We conclude that birch tree-rings are suitable for assessing tree growth/climate/glacial relationships over a longer timescale in maritime Kamchatka.  相似文献   

19.
The Mediterranean region has been identified as a global warming hotspot, where future climate impacts are expected to have significant consequences on societal and ecosystem well-being. To put ongoing trends of summer climate into the context of past natural variability, we reconstructed climate from maximum latewood density (MXD) measurements of Pinus heldreichii (1521–2010) and latewood width (LWW) of Pinus nigra (1617–2010) on Mt. Olympus, Greece. Previous research in the northeastern Mediterranean has primarily focused on inter-annual variability, omitting any low-frequency trends. The present study utilizes methods capable of retaining climatically driven long-term behavior of tree growth. The LWW chronology corresponds closely to early summer moisture variability (May–July, r = 0.65, p < 0.001, 1950–2010), whereas the MXD-chronology relates mainly to late summer warmth (July–September, r = 0.64, p < 0.001; 1899–2010). The chronologies show opposing patterns of decadal variability over the twentieth century (r = ?0.68, p < 0.001) and confirm the importance of the summer North Atlantic Oscillation (sNAO) for summer climate in the northeastern Mediterranean, with positive sNAO phases inducing cold anomalies and enhanced cloudiness and precipitation. The combined reconstructions document the late twentieth—early twenty-first century warming and drying trend, but indicate generally drier early summer and cooler late summer conditions in the period ~1700–1900 CE. Our findings suggest a potential decoupling between twentieth century atmospheric circulation patterns and pre-industrial climate variability. Furthermore, the range of natural climate variability stretches beyond summer moisture availability observed in recent decades and thus lends credibility to the significant drying trends projected for this region in current Earth System Model simulations.  相似文献   

20.
A diagnostic study of 80 yrs(1901–80) of surface temperatures collected at West Lafayette, Indiana, has been found to be in tune with the global trend and that for the eastern two-thirds of the United States, namely, cold at the turn of the century, warming up to about 1940, and then cooling to present. The study was divided into two cold periods (1901–18, 1947–80) and a warm period (1919–46), based on the distribution of annual mean temperature. Decadal mean annual temperatures ranged from 10 °C in period I to 12.2 °C in period II, to 9.4 °C during the present cold period. Themean annual temperature for the 80 yr ranged from the coldest of 8.7 °C in 1979 to the warmest of 13.6 °C in 1939. Thedaily mean temperature for the entire 80-yr ranged from -4.7 °C on 31 January to 25.1 °C on 27 July. Thecoldest daily mean was -26.7 °C on 17 January, 1977, and thewarmest daily mean was 35 °C on 14 July, 1936. The range of values for thedaily mean maximum temperatures was -.2 °C on 31 January to 31.4 °C on 27 July. Corresponding values for thedaily mean minimum are -9.2 °C on 31 January and 18.7 °C on 27 July. The all-time extreme temperatures are -30.6 °C on 26 February, 1963 and 43.9 °C on 14 July, 1936. Climatic variability has been considered by computing the standard deviations of a) the daily mean maximum and minimum temperature per year, and b) the daily mean maximum and minimum temperatures for each day of the year for the 80-yr period. These results have shown that there is more variability in the daily mean maximum per year than in the daily mean minimum, for each year of the 80-yr period. Also the variability for both extremes has been greater in each of the two cold periods than in the warm period. Particularly noticeable has been theincrease in the variability of the daily mean minima per year during the current cooling trend. Further, it has been determined that the variability in the daily mean maxima and minima for each day of the year (based on the entire 80 yrs is a) two times greater in the winter than in the summer for both extremes, and b) about the same for each in the summer, greater for daily maximum in the spring and fall, but greater for the daily minimum during the winter. The latter result is undoubtedly related to the effect of snow cover on daily minimum temperatures. An examination of daily record maximum and minimum temperatures has been made to help establish climatic trends this century. For the warm period, 175 record maxima and 68 record minima were set, compared to 213 record minima and 105 record maxima during the recent cold period. For West Lafayette, the present climatic trend is definitely one of extreme record-breaking cold. Evidence has also been presented to show the substantial increases in snowfall amounts in the lee regions of the Great Lakes during the present cold period, due to the lake-induced snow squalls associated with cold air mass intrusions. The possible impact of the cooling trend on agricultural activities has also been noted, due to a reduced growing season.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号