A Regional Scale Investigation of Climatological Tropical Convection and Precipitation in the Amazon Basin

This study constructs a regional scale climatology of tropical convection and precipitation from more than 15 years of monthly outgoing longwave radiation (OLR) and precipitation data on 2.5°× 2.5° latitude-longitude grid to examine the spatial and temporal patterns and variability of convection and precipitation in the Amazon Basin. A linear regression analysis also detects if any trends exist in the two datasets. The region of study extends from 15°N to 25°S and 30° to 80°W that encompass the Amazon Basin and surrounding fringe areas for the period from January 1979 through December 1995 for the OLR data and up to 1996 for the precipitation dataset. The basin-average mean monthly and seasonal climatology serve as a ‘baseline’ reference for comparison with the full time series of basin-average monthly OLR and precipitation to illustrate the interannual variability and identify anomalous periods of wet and dry conditions. A linear trend analysis of OLR data found small negative values across the Amazon Basin indicating a slight increase in convective activity over the period of study. The analysis of the precipitation time series, however, shows no coincidental increase in precipitation as would be expected with an increase in convective activity. Portions of Rondônia and Mato Grosso, areas that have undergone extensive deforestation, illustrate no trend in precipitation as suggested by GCM simulation results. The only area featuring any large change in precipitation occurs in a small area in the northwestern region of South America where a large positive trend in precipitation exists.     

Temporal and spatial trends of precipitation and river flow in the Yangtze River Basin, 1961–2000

The suspected impact of climate warming on precipitation distribution is examined in the Yangtze River Basin. Daily precipitation data for 147 meteorological stations from 1961–2000 and monthly discharge data for three stations in the basin have been analyzed for temporal and spatial trends. The methods used include the Mann–Kendall test and simple regression analysis. The results show (1) a significant positive trend in summer precipitation at many stations especially for June and July, with the summer precipitation maxima in the middle and lower Yangtze River basin in the 1990s; (2) a positive trend in rainstorm frequency that is the main contributor to increased summer precipitation in the basin; and (3) a significant positive trend in flood discharges in the middle and lower basin related to the spatial patterns and temporal trends of both precipitation and individual rainstorms in the last 40 years. The rainstorms have aggravated floods in the middle and lower Yangtze River Basin in recent decades. The observed trends in precipitation and rainstorms are possibly caused by variations of atmospheric circulation (weakened summer monsoon) under climate warming.     

黑河流域春季降水空间分异性特征及其与黑河流量的相关分析

利用黑河流域13个气象站建站至2012年3—5月降水量资料和黑河莺落峡水文站流量资料,分析了黑河流域春季降水的基本气候特征;通过EOF、REOF、Morlet小波变换等方法,对黑河流域春季降水的时空特性进行了研究;用Mann-Kendall检验法检验黑河流域春季降水序列是否存在突变现象.结果表明:黑河流域春季降水空间分布极不均匀,其空间分布特征是南部为多雨区、北部为少雨区.黑河流域春季降水在第一空间尺度上为全区一致,在第二空间尺度上可分为2个自然气候区,在第三空间尺度上可分为3个自然气候区.从年代际变化来看,21世纪最初10年是近半个世纪来降水最多的10年,20世纪70年代是降水最少的10年;黑河流域春季降水的年际变率十分显著,降水最多的年份是最少年份的6倍多.1961—2012年间河西走廊春季降水发生了明显的突变:2001年出现了一次趋于增多的突变.最显著的周期是4年的短周期、14年和22年的长周期.黑河流域春季各月降水与黑河流量均呈正相关,尤其是春季各月降水滞后1个月的相关和5月份降水的同期相关性显著;春季气温与黑河流量也均呈正相关,特别是春季各月气温的同期相关和3月气温滞后1个月的相关性显著,说明黑河流量的增加取决于前期降水量的增加和同期气候的明显变暖.     

Characterisation and diachronous initiation of coarse clastic deposition in the Magallanes–Austral foreland basin,Patagonian Andes

Magallanes–Austral Basin (MAB) fill is preserved along a >1000 km north–south trending outcrop belt in the southern Patagonia region of Argentina and Chile. Although the stratigraphic evolution of the MAB has been well documented in the Chilean sector (referred to as the Magallanes Basin), its northern terminus in southern Argentina (Austral Basin) is poorly constrained. We present new stratigraphic and geochronologic analyses of the early basin fill (Aptian–Turonian) from the Argentine sector (49–51°S) of the MAB to document spatial variability in stratigraphy and timing of deposition during the initial stages of basin evolution. The initiation of the retroarc foreland basin fill is marked by the transition from mudstone to coarse‐clastic deposition, which is characterised by the consistent presence of sandstone beds > ca. 20 cm thick interpreted to represent sediment gravity flows deposited in a submarine fan system. Depositional environments within the early fill of the basin range from lower to upper deep‐water fan settings as well as previously undocumented slope deposits. These facies are present as far north as El Chalten, Argentina (ca. 49°S), indicating that facies‐equivalent rocks can be traced along‐strike for at least 5 degrees of latitude, based on correlation with strata as far south as the Cordillera Darwin (ca. 54°S). Eight new U‐Pb zircon ages from ash beds reveal an overall southward younging trend in the initiation of coarse clastic deposition. Inferred depositional ages range from ca. 115 ± 1.9 Ma in the northernmost study area to not older than 92 ± 1 Ma and 89 ± 1.5 Ma in the central and southern sectors respectively. The apparent diachronous delivery of coarse detritus into the basin may reflect (1) gradual southward progradation of a deep‐water fan system from a northerly point source and/or (2) orogen‐parallel variations in the timing and magnitude of thrust‐belt deformation and erosion that provided more local sources for sediment delivery.     

Observing climate impacts on tea yield in Assam,India

Tea is an important cash crop for the economy in northeast India. It also supports the livelihoods of a large proportion of the population. At the same time, tea growth is sensitive to climatic conditions making it vulnerable to climate change and variability. Identifying the tea yield response to climatic variability in operational plantations, and identifying the most important climatic variables that impact tea yield is critical to assessing the vulnerability of the industry and informing adaptation. Here, we developed a garden level panel dataset and estimated statistical models to identify the causal effect of monthly temperature, monthly precipitation, drought intensity, and precipitation variability on tea yield. We found decreasing tea yield returns to warmer monthly average temperatures, and when monthly temperatures were above 26.6 °C warming had a negative effect. We found that drought intensity did not affect tea yield and that precipitation variability, and in particular precipitation intensity, negatively affect tea yield. An increase in average temperatures as expected with global warming will reduce the productivity of tea plantations, all else held equal. Further, interventions to reduce the sensitivity of tea plantations to warming and precipitation variability will have immediate pay-offs as well as providing climate change adaptation benefits.     

1998—2012年黄河流域植被覆盖变化时空分析

利用黄河流域1998—2012年SPOT-NDVI数据及同期119个气象站的降水数据,计算每个像元的NDVI变化趋势,并结合植被降水利用效率来分析近15年来黄河流域植被覆盖的时空变化特征。结果表明：（1） 多年平均的植被指数有明显的空间差异性,随着纬度的增加,NDVI平均值呈降低趋势;（2） 从时间序列来看,黄河流域的植被覆盖呈逐年增加趋势,其中黄河上游NDVI值增长最为缓慢,中游保持稳定增长,下游增长最快;（3） 近15年来黄河流域植被覆盖的改善区域面积大于退化区域,植被恢复明显。最后,结合NDVI变化趋势和植被降水利用效率对上述结果进行了验证。     

塔里木河流域径流变化趋势及其对气候变化的响应

This paper has studied the change of streamflow and the impact of climatic variability conditions on regional hydrological cycle in the headwater of the Tarim River Basin. This study investigates possible causes of observed trends in streamflow in an environment which is highly variable in terms of atmospheric conditions, and where snow and ice melt play an important role in the natural hydrological regime. The discharge trends of three head streams have a significant increase trend from 1957 to 2002 with the Mann-Kendall test. Complex time-frequency distributions in the streamflow regime are demonstrated especially by Morlet wavelet analysis over 40 years. The purpose is to ascertain the nature of climatic factors spatial and temporal distribution, involved the use of EOF （Empirical Orthogonal Function） to compare the dominant temperature, precipitation and evaporation patterns from normally climatic records over the Tarim＇s headwater basin. It shows that the first principal component was dominated since the 1990s for temperature and precipitation, which identifies the significant ascending trend of spatial and temporal pattern characteristics under the condition of the global warming. An exponential correlation is highlighted between surface air temperature and mean river discharge monthly, so the regional runoff increases by 10%-16% when surface air temperature rises by 1 ℃. Results suggest that headwater basins are the most vulnerable environments from the point of view of climate change, because their watershed properties promote runoff feeding by glacier and snow melt water and their fundamental vulnerability to temperature changes affects rainfall, snowfall, and glacier and ice melt.     

不同源降水数据在天山南坡阿克苏河流域适用性分析

降水是水热循环以及气候变化研究的重要环节,降水资料的准确与否直接影响流域尺度的水文过程研究。本文基于2000-2015年天山南坡阿克苏河流域气象站点观测降水数据,对比分析了Tropical Rainfall Measuring Mission（TRMM）降水数据集和Global Land Data Assimilation System（GLDAS）两种具有代表性的降水格网数据集在阿克苏河流域的适用性。结果表明：TRMM3B43数据在阿克苏河流域的整体表现优于GLDAS-2数据。两种数据的精度在月尺度上表现最优,相关系数分别为0.938和0.901,通过了0.01的显著性检验;在季节尺度,TRMM3B43数据各季节与站点插值的拟合度要优于GLDAS-2数据,但二者均呈现出高估冷季降水而低估暖季降水的趋势;在年尺度上,两种数据表现较差。在空间分布上,两种数据类型均能够反映出阿克苏河流域降水自西北向东南递减的空间分布趋势。并且两种数据在平原区的表现均优于山区,低估高海拔地区降水而高估低海拔地区的降水。     

吐鲁番盆地人工增水作业区域与作业时机选择

利用吐哈盆地2011-2015年逐时FY-2E静止气象卫星红外云图资料,吐鲁番市1976-2015年5个国家气象站和2013-2015年26个区域气象站降水资料,采用卫星资料反演和统计分析方法,首次定义T_K（地面气温与云顶亮温的差值）来规避地面辐射对卫星接收辐射的影响,分析吐鲁番盆地各级别TBB（-10~-20℃、-20~-30℃、-30~-40℃、-40~-50℃）云的分布状况及其与降水的关系、降水的时空分布特征和变化趋势。结果表明,吐鲁番盆地TBB各级别云覆盖度与海拔高度显著正相关,云量从盆地平原区向山区递增;T_K的月变化同月降水具有较好的正相关性,TK正值时段4~8月与盆地汛期相对应,T_K极大值对应月降水量最大的6月;降水与海拔高度显著正相关,降水先随海拔高度增加而增多,1 400~1 900 m区域是降水量和降水垂直变率最大的区域,之后降水随海拔高度增加而减少;降水高度集中在夏季与秋季,6月降水最多（占3~4成）;降水集中出现在白天,平原地区集中在早晨至中午,山区集中在下午至傍晚。综合分析得出吐鲁番盆地人工增水作业区域、作业月份、作业"时间窗"选择的参考依据,其中最佳作业区域在1 400~1 900 m,最佳作业月份为6月,最佳作业"时间窗"为上午的06~10时与下午的14~18时。     

吐鲁番盆地气候变化及其对水资源的可能影响

目前全球和大尺度区域的气候变化研究成果较多,而中小尺度区域的研究,由于资料的缺乏及模拟模型精度不够等原因,进展较慢。吐鲁番盆地是极端干旱的山间盆地,对于全球气候变化十分敏感。本文收集了有关新疆东部气候变化的历史、树轮、仪器测量等资料,对吐鲁番盆地气候变化的历史及未来趋势进行了研究,并探讨了气候变化对区域水资源的可能影响,以及应采取的对策。     

Investigation of the thermal history of the Delaware Basin (West Texas,USA) using carbonate clumped isotope thermometry

We utilized carbonate clumped isotope thermometry to explore the thermal history of the Delaware Basin, West Texas, USA. Carbonate wellbore cuttings from five oil/gas wells across the basin yielded clumped isotope temperatures (T(Δ₄₇)) ranging from 27°C to 307°C, interpreted to reflect a combination of initial precipitation/recrystallization temperature and solid-state C-O bond reordering during burial. Dolomite samples generally record lower apparent T(Δ₄₇)s than calcite, reflecting greater resistance to reordering in dolomite. In all five wells, clumped isotope temperatures exceed modern downhole temperature measurements, indicating higher heat flow in the past. Using modelled burial curves based on sedimentological history, we created unique time-temperature histories by linearly applying a geothermal gradient. Applying two different thermal history reordering models, we modelled the extent of solid-state C–O bond reordering to iteratively find the time-averaged best-fit geothermal gradients for each of the five wells. Results of this modelling suggest that the shallower, southwestern portion of the study area experienced higher geothermal gradients throughout the sediment history (~45°C/km) than did the deeper, southeastern portion (~32°C/km), with the northern portion experiencing intermediate geothermal gradients (~35–38°C/km). This trend is in agreement with the observed gas/oil ratios of the Delaware Basin, increasing from east to west. Furthermore, our clumped isotope temperatures agree well with previously published vitrinite reflectance data, confirming previous observations and demonstrating the utility of carbonate clumped isotope thermometry to reconstruct basin thermal histories.     

四川省近50年降水的变化特征及影响

利用1961-2008 年四川省133 个气象站逐日降水资料,研究分析了四川省近50 年大气降水的变化特征及影响。研究发现：四川省年均暴雨日数从西到东呈现“增-减-增”的总体变化趋势：甘孜州、凉山州南部、攀枝花等地区年均暴雨日数主要呈弱增加趋势,四川盆地西部、中部呈明显减少趋势,盆地东北部地区则呈较强增加趋势;除了盆地中部、南部部分地区外,四川省其余地区的暴雨强度主要呈增强趋势,其中盆地东北部加强趋势明显。四川盆地西部、中部地区各量级雨日均主要呈减少趋势,无雨日明显增加,年降水减少明显;盆地东北部地区年均暴雨、大雨日数及强度都呈明显增加、增强趋势,此区域年降水量的增加主要是由于大雨、暴雨量的增加导致。近50 年来四川省大气降水的变化形势给不同的区域带来了不同影响：四川盆地西部和中部地区大气降水明显减少,影响到地表径流以及地下水位,导致水资源紧张;川西高原北部阿坝州降水也明显减少,在一定程度上促进了生态环境恶化;而盆地东北部、甘孜州、攀枝花和凉山州等地区暴雨日数和强度的增多、增强导致部分地区洪涝、地质灾害频发。     

新疆北部夏季降水与海温异常的关系

利用1960—2004年新疆北部36个气象站月降水资料和美国国家气候数据中心重建的1960—2004年全球2°×2°月平均海洋表面温度资料,研究了新疆北部夏季降水与海温异常的关系。研究表明,新疆北部夏季降水变化与ENSO事件关系不密切,而与前期冬末—春季的5个海温敏感区密切联系,这5个海温敏感区分别为北印度洋、西太平洋暖池及黑潮区、热带中东太平洋、北大西洋和热带大西洋。前期春季海温异常与新疆北部夏季降水变化联系最显著,表现为显著正相关关系。研究为预测新疆北部夏季降水提供了有益的因子。     

Neotectonic basin and landscape evolution in the Eastern Cordillera of NW Argentina,Humahuaca Basin (~24°S)

The intermontane Quebrada de Humahuaca Basin (Humahuaca Basin) in the Eastern Cordillera of the southern Central Andes of NW Argentina (23°–24°S) records the evolution of a formerly contiguous foreland‐basin setting to an intermontane depositional environment during the late stages of Cenozoic Andean mountain building. This basin has been and continues to be subject to shortening and surface uplift, which has resulted in the establishment of an orographic barrier for easterly sourced moisture‐bearing winds along its eastern margin, followed by leeward aridification. We present new U–Pb zircon ages and palaeocurrent reconstructions suggesting that from at least 6 Ma until 4.2 Ma, the Humahuaca Basin was an integral part of a largely contiguous depositional system that became progressively decoupled from the foreland as deformation migrated eastward. The Humahuaca Basin experienced multiple cycles of severed hydrological conditions and subsequent re‐captured drainage, fluvial connectivity with the foreland and sediment evacuation. Depositional and structural relationships among faults, regional unconformities and deformed landforms reveal a general pattern of intrabasin deformation that appears to be associated with different cycles of alluviation and basin excavation in which deformation is focused on basin‐internal structures during or subsequent to phases of large‐scale sediment removal.     

洞庭湖流域植被动态变化的小波多分辨率分析

将离散小波多分辨率分析（MRA）应用于归一化植被指数（NDVI）时间序列研究,分解NDVI原数据序列成不同时间尺度的子序列,从而进行植被动态变化分析。针对洞庭湖流域的NDVI时间序列进行多尺度分解,挖掘这些数据中潜在的植被季节性和年际变化,对其进行评估,并结合土地覆盖变化与降水趋势变化分析引起该变化的可能原因。结果表明：小波多分辨率分析能提取洞庭湖流域植被动态的相关信息,如NDVI的年际成分均值、最低值、植被年内变化的振幅、NDVI最大值出现的月份和土地覆盖变化的趋势及幅度,这些信息有效刻画了流域植被动态变化特征。此外,将土地覆盖变化分析结果与降水数据相结合进行分析,发现流域植被覆盖的变化与降水变化有明显的关联性,其中西部地区和西北部地区植被动态变化对降水响应最为明显。但是有些地区降水没有明显减少趋势,而植被覆盖却存在减少趋势,则可能与该地地势较高、城镇化建设等其他因素相关。     

新疆伊犁河流域气候变化(英文)

In this paper, the monthly precipitation and temperature data collected at 7 stations in the Ili River Basin from 1961 to 2007 were analyzed by means of simple regression analysis, running mean, db6 wavelet function and Mann-Kendall test. This study revealed the characteristics of climate change and abrupt change points of precipitation and temperature during different time scales in the Ili River Basin within the past 50 years. The results showed that the precipitation increased from the mid-1980s until 2000 and has continued to increase at a smaller magnitude since 2000. Over the studied period, the precipitation increased significantly during the summer and winter months. The temperature increased greatly in the late 1980s, and has continued to show an increasing trend from the year 2000 to present. The temperature increases were most significant during the summer, autumn and winter months. In terms of different geographies, the temperature increase was significant during the winter in the plains and hilly regions; the increase was also significant during autumn in the intermontane basins. The climate change trends in the Ili River Basin were consistent with the changing trends of the North Atlantic Oscillation and the plateau monsoon.     

Variation and abrupt change of climate in Ili River Basin, Xinjiang

In this paper, the monthly precipitation and temperature data collected at 7 stations in the Ili River Basin from 1961 to 2007 were analyzed by means of simple regression analysis, running mean, db6 wavelet function and Mann-Kendall test. This study revealed the characteristics of climate change and abrupt change points of precipitation and temperature during different time scales in the Ili River Basin within the past 50 years. The results showed that the precipitation increased from the mid-1980s until 2000 and has continued to increase at a smaller magnitude since 2000. Over the studied period, the precipitation increased significantly during the summer and winter months. The temperature increased greatly in the late 1980s, and has continued to show an increasing trend from the year 2000 to present. The temperature increases were most significant during the summer, autumn and winter months. In terms of different geographies, the temperature increase was significant during the winter in the plains and hilly regions; the increase was also significant during autumn in the intermontane basins. The climate change trends in the Ili River Basin were consistent with the changing trends of the North Atlantic Oscillation and the plateau monsoon.     

基于多源降水数据的洞庭湖流域夏季降水与西太平洋副热带高压的关系

基于中国气象科学数据共享服务网提供的1979~2012年夏季6~8月降水实测数据（CMD）和3种不同来源的再分析降水数据,研究和比较副高特征指数与洞庭湖流域夏季降水的关系及空间差异。结果表明：① 6、7月副热带高压（副高）脊线位置偏北,洞庭湖流域大部分区域降水偏多,8月偏少;6、7月北界位置偏北使流域东南降水偏少、西北降水偏多,8月大部分地区降水偏多;6~8月西伸脊点位置东移使降水偏多范围自东向西增大;6月份副高强度增强使东部和南部降水偏多、西部和北部降水偏少,7和8月大部分地区降水减少。② 再分析降水数据大体上能反映出7月份脊线指数、6和7月北界指数、6~8月西伸脊点指数和副高强度指数对相应月份CMD降水的影响。③ 副高特征指数对CMD降水的拟合能力存在区域差异。     

1981-2010 年柴达木盆地气候要素变化特征及湖泊和植被响应

以1981-2010 年柴达木盆地及其周边气象站点逐月气温和降水量资料为基础, 通过气候趋势分析、气候突变分析等方法, 研究了柴达木盆地气候要素的变化特征, 并结合Landsat TM/ETM+影像、NOAA/AVHRR-NDVI和EOS/MODIS-NDVI 数据, 研究了近30 年来柴达木盆地湖泊面积和植被生长的动态变化及其对气候要素的响应。结果表明:① 1981-2010 年, 柴达木盆地气温整体升高, 秋冬增幅最为明显, 年平均气温在1997 年发生暖突变, 1998 年以后升温趋势显著。② 1981-2010 年, 柴达木盆地年可利用降水量经历了“减少—增加—减少—增加”的变化, 但整体呈增加趋势, 1980-1985 年、1990-2001 年, 年可利用降水量呈减少趋势;1985-1990 年、2001-2010 年, 年可利用降水量呈增加趋势。③ 柴达木盆地湖泊面积受夏季可利用降水量影响显著, 1985-2010 年, 托素和冬给措纳湖泊面积呈“扩张—萎缩—扩张”变化;1985-1990 年, 湖面轻微扩张;1990-2001 年, 湖面明显萎缩;2001 年以后, 湖面显著扩张。④ 柴达木盆地植被生长受生长季可利用降水量影响显著, 1982-2010 年柴达木盆地植被生长呈“退化—改善—退化—改善”变化, 但整体呈改善趋势;1982-1985 年植被轻微退化, 1985-1990 年植被轻微改善, 1990-2001 年植被显著退化, 2001 年以后植被显著改善。     

WATERSHED HETEROGENEITY AND THE RESPONSE TO 2 × CO2 CLIMATE: A CASE STUDY FROM THE UPPER DESCHUTES BASIN,OREGON

A fully allocated surface water supply in the Upper Deschutes Basin, Oregon, intensifies concern for the watershed's response to climate change. Such concern provides the impetus for this case study of the basin under a potential doubling of atmospheric trace gas concentrations (2 × CO₂). Modeling the watershed as four sectors incorporates climate and landscape heterogeneity and defines a control climate that closely simulates adjusted gaged runoff. Monthly temperature and precipitation from a limited area model nested in a global circulation model define changes for modeling the watershed 2 × CO₂ climate. Precipitation increases are greatest in the Wickiup sector and least in the Little Deschutes sector for a 2 × CO₂ climate, but snow-water equivalent decreases substantially in all sectors. Summer water deficits are extended and magnified in all sectors and increase by 175% in the Wickiup sector. Water surplus increases range from 34% for Wickiup to 5% for Benham Falls. Average monthly runoff for the Upper Deschutes Basin increases by 7 mm or 24% in the 2 × CO₂ climate, but the greatest monthly runoff differences are for the Crescent Lake sector, where February and March runoff increase by 68% and May runoff decreases by 10%. The earlier occurrence of maximum and minimum 2 × CO₂ climate runoff of one to five months significantly alters the Upper Deschutes Basin runoff regime. [Key words: mesoscale hydroclimate model, climate change, Deschutes River Basin.]