Topography, albedo-temperature feedback, and climate sensitivity

Numerical experiments with an energy balance model of the earth's climate suggest an enhancement of albedo-temperature feedback caused by the presence of a high middle-latitude plateau in the zonally averaged Northern Hemisphere topography. The increased climate sensitivity arises from the increased rate of change of snow cover produced by the advance or retreat of the winter snow line over the north slope of this topographic feature.     

A determination of the cloud feedback from climate variations over the past decade

Estimates of Earth's climate sensitivity are uncertain, largely because of uncertainty in the long-term cloud feedback. I estimated the magnitude of the cloud feedback in response to short-term climate variations by analyzing the top-of-atmosphere radiation budget from March 2000 to February 2010. Over this period, the short-term cloud feedback had a magnitude of 0.54 ± 0.74 (2σ) watts per square meter per kelvin, meaning that it is likely positive. A small negative feedback is possible, but one large enough to cancel the climate's positive feedbacks is not supported by these observations. Both long- and short-wave components of short-term cloud feedback are also likely positive. Calculations of short-term cloud feedback in climate models yield a similar feedback. I find no correlation in the models between the short- and long-term cloud feedbacks.     

Evidence for large decadal variability in the tropical mean radiative energy budget

It is widely assumed that variations in Earth's radiative energy budget at large time and space scales are small. We present new evidence from a compilation of over two decades of accurate satellite data that the top-of-atmosphere (TOA) tropical radiative energy budget is much more dynamic and variable than previously thought. Results indicate that the radiation budget changes are caused by changes in tropical mean cloudiness. The results of several current climate model simulations fail to predict this large observed variation in tropical energy budget. The missing variability in the models highlights the critical need to improve cloud modeling in the tropics so that prediction of tropical climate on interannual and decadal time scales can be improved.     

呼伦贝尔市2011年3月气候对农牧林业的影响

综合分析呼伦贝尔市2011年3月气候对于农牧林业生产的影响,利用降水、温度、大风与历年同期值的比较加以分析,认清雪灾、降温等灾害性天气事件造成的损失。     

积雪时空变化规律及其影响因素研究进展

积雪作为冰冻圈的重要组成部分,对气候变化的响应非常敏感。受局地气候和地形影响,积雪的分布和变化非常复杂,同时积雪对区域气候环境、植被生态系统、土壤性质及温室气体排放、工程基础设施等都会有一定的影响。通过文献综述北半球积雪的时间和空间变化规律、积雪的形成与维持与气象因子的关系、地形和植被对积雪的影响以及冻土区积雪与冻土的耦合关系。总之全球气候变暖使北半球积雪覆盖面积、最大积雪深度、积雪时长等都有减少的趋势。温度和降水量是影响小尺度积雪参数变化的主要气象因素,海拔是影响局地积雪分布的主要因子,植被的覆盖与冻土的存在一定程度上也会影响积雪的分布。未来气候变暖情景下,有关积雪地面台站监测数据与遥感监测数据的有效融合、进一步完善积雪参数的监测网络、厘清气候与积雪变化的关系,是未来该领域的研究重点。     

Human-induced changes in the hydrology of the western United States

Observations have shown that the hydrological cycle of the western United States changed significantly over the last half of the 20th century. We present a regional, multivariable climate change detection and attribution study, using a high-resolution hydrologic model forced by global climate models, focusing on the changes that have already affected this primarily arid region with a large and growing population. The results show that up to 60% of the climate-related trends of river flow, winter air temperature, and snow pack between 1950 and 1999 are human-induced. These results are robust to perturbation of study variates and methods. They portend, in conjunction with previous work, a coming crisis in water supply for the western United States.     

Global cooling after the eruption of Mount Pinatubo: a test of climate feedback by water vapor

The sensitivity of Earth's climate to an external radiative forcing depends critically on the response of water vapor. We use the global cooling and drying of the atmosphere that was observed after the eruption of Mount Pinatubo to test model predictions of the climate feedback from water vapor. Here, we first highlight the success of the model in reproducing the observed drying after the volcanic eruption. Then, by comparing model simulations with and without water vapor feedback, we demonstrate the importance of the atmospheric drying in amplifying the temperature change and show that, without the strong positive feedback from water vapor, the model is unable to reproduce the observed cooling. These results provide quantitative evidence of the reliability of water vapor feedback in current climate models, which is crucial to their use for global warming projections.     

The greenhouse theory of climate change: a test by an inadvertent global experiment

Since the dawn of the industrial era, the atmospheric concentrations of several radiatively active gases have been increasing as a result of human activities. The radiative heating from this inadvertent experiment has driven the climate system out of equilibrium with the incoming solar energy. According to the greenhouse theory of climate change, the climate system will be restored to equilibrium by a warming of the surfacetroposphere system and a cooling of the stratosphere. The predicted changes, during the next few decades, could far exceed natural climate variations in historical times. Hence, the greenhouse theory of climate change has reached the crucial stage of verification. Surface warming as large as that predicted by models would be unprecedented during an interglacial period such as the present. The theory, its scope for verification, and the emerging complexities of the climate feedback mechanisms are discussed.     

2013年春季抚顺市异常气象条件对农业生产的影响分析

分析了2013年春季异常气候条件对抚顺市农业生产的影响,结果表明,2013年春季全市平均气温为6．3℃,比常年偏低1.4℃;降水量为118．9mm,比常年偏少10％;日照时数为643h,比常年偏少30h。春季前期低温春湿,大田整地和春播推迟。不利气象条件对农业生产带来影响,使地温回暖缓慢,春播期延迟,低温寡照食用菌段发菌缓慢。大棚蔬菜生长受到影响,病虫害较重,使节气延后。形成异常气候环流形势特征为：初春极涡中心偏向东北部,4月东亚大槽偏西偏强,我国东北地区存在显著的负距平,造成抚顺市初仲春气温异常偏低,雨雪天气频繁。     

Modelling of maize production in Croatia: present and future climate

Maize is one of the most important agricultural crops in Croatia, and was selected for research of the effect of climate warming on yields. The Decision Support System for the Agrotechnology Transfer model (DSSAT) is one of the most utilized crop-weather models in the world, and was used in this paper for the investigation of maize growth and production in the present and future climate. The impact of present climate on maize yield was studied using DSSAT 4.0 with meteorological data from the Zagreb-Maksimir station covering the period 1949-2004. Pedological, physiological and genetic data from a 1999 field maize experiment at the same location were added. The location is representative of the continental climate in central Croatia. The linear trends of model outputs and the non-parametric Mann-Kendall test indicate that the beginning of silking has advanced significantly by 1·4 days/decade since the mid-1990s, and maturity by 4·5 days/decade. It also shows a decrease in biomass by 122 kg/ha and in maize yield by 216 kg/ha in 10 years.Estimates of the sensitivity of maize growth and yield in future climates were made by changing the initial weather and CO(2) conditions of the DSSAT 4.0 model according to the different climatic scenarios for Croatia at the end of the 21st century. Changed climate suggests increases in global solar radiation, minimal temperature and maximal temperature (×1·07, 2 and 4°C, respectively), but a decrease in the amount of precipitation (×0·92), compared with weather data from the period 1949-2004. The reduction of maize yield was caused by the increase in minimal and maximal temperature and the decrease in precipitation amount, related to the present climate, is 6, 12 and 3%, respectively. A doubling of CO(2) concentration stimulates leaf assimilation, but maize yield is only 1% higher, while global solar radiation growth by 7% increases evapotranspiration by 3%. Simultaneous application of all these climate changes suggested that the maize growth period would shorten by c. 1 month and maize yield would decrease by 9%, with the main reason for maize yield reduction in Croatia being due to extremely warm conditions in the future climate.     

Environmental change and Antarctic seabird populations

Recent changes in Antarctic seabird populations may reflect direct and indirect responses to regional climate change. The best long-term data for high-latitude Antarctic seabirds (Adélie and Emperor penguins and snow petrels) indicate that winter sea-ice has a profound influence. However, some effects are inconsistent between species and areas, some in opposite directions at different stages of breeding and life cycles, and others remain paradoxical. The combination of recent harvest driven changes and those caused by global warming may produce rapid shifts rather than gradual changes.     

油蒿光系统II光化学参数在生长季早期对降雪事件的响应

目的研究生长季早期降雪事件对于典型沙生灌木光合生理状态的影响,以及胁迫发生后植物适应胁迫的光合生理机制。方法在降雪前后,使用多通道连续监测荧光仪,通过原位连续监测当地建群种油蒿的叶绿素荧光参数和能量分配参数的变化,确定胁迫恢复期,并分析恢复期各参数与环境因子的关系。结果实际光化学量子效率（Φ_PSII）在降雪当天达到最低值,且Φ_PSII的日间均值比降雪前后分别下降了约40%和33%。调节性能量耗散（Φ_NPQ）和非光化学淬灭（NPQ）均在降雪当天达到最高值,其中降雪当天Φ_NPQ的日间均值比降雪前后分别升高了95%和48%,NPQ分别升高了94%和76%。降雪当天的最大光化学量子效率（F_v/F_m）降到了最低（0.69）,比降雪前降低了约12%,并且低于了0.73的胁迫线。F_v/F_m经过3 d恢复到了降雪前的水平。在恢复过程中油蒿伴随着光照900 μmol/（m2·s）和温度10 ℃的阈值拥有不同的响应关系,可能是在阈值前后拥有不同的环境主导因子。土壤水分始终是油蒿恢复过程中的限制性因素。结论本次降雪对于油蒿产生了胁迫,胁迫的原因主要是由于融雪产生的低温和高光强的协同作用导致的。油蒿通过动态调节自身光系统II反应中心的能量分配机制,增大调节性热能耗散比重来适应低温胁迫。油蒿从一次胁迫中恢复约需3 ~ 4 d,低光照、较高温度和较高水分有利于植物恢复过程。      

辽西北霜期气候变化及气象服务对策

为了霜期设施农业充分利用气候资源适应气候变化,规避气象灾害风险,利用辽宁西北部气象资料分析霜期气候资源变化,并探讨霜期设施农业气象服务对策。结果表明：辽西北地区霜期气温升高而不稳,极端最低气温天气更显突出,霜期降雪增加,阴天日数增加,日照时间减少,太阳总辐射减弱,大风强度增加,霜期极端天气现象对霜期设施农业影响显著。霜期设施农业气象服务势在必行,为了推动霜期设施农业的发展,应从设施农业工程、环境控制、利用气候资源节约能源、适应气候变化等方面入手,建立评估、监测、预警气象服务一体化服务系统,通过网络平台,搭建专业化、动态化、多元化、精细化的霜期设施农业气象服务预警平台,提高防灾减灾能力,确保霜期设施农业可持续发展。     

抚顺暴雪天气特征及其农业影响

统计抚顺1976～2008年33年暴雪天气,分析了暴雪气候规律、暴雪出现环流形势特征,总结暴雪对农业影响。结果表明,抚顺地区33年暴雪总趋势增加,年平均暴雪日数为1d,出现暴雪最多年份为1976和2000年,年暴雪日为4日。暴雪月分布特点是出现在每年1~4月和11~12月份。11月份出现次数最多,2月份出现次数最少。地理分布特点新宾站最多,清原站最少。暴雪环流特征500hPa为两槽一脊型、一槽一脊型和冷涡型。过程前一天850hPa抚顺地区位于暖温度脊控制,地面影响系统为黄河倒槽。暴雪天气对农业及各行各业带来严重影响。对农业的影响主要有设施农业、水库蓄水、土壤墒情、水果、蔬菜、森林防火、作物病虫害、家禽饲养。     

全球变暖对四川气候旅游资源的影响探析

利用四川省139个站点1961～2004年月平均气温和降水资料,并选取九寨沟、海螺沟、峨眉山、蜀南竹海4个旅游景区的气象站点,统计分析了其在全球变暖的背景下的气候变化趋势,进而研究了气候变暖对四川旅游气候资源的影响。结果表明,20世纪90年代以来,与全球变暖相对应,四川地区年均气温呈上升趋势、年降水量呈下降趋势,6个景点的气候变化趋势也基本有类似的响应,这对于以水为景、以气为景的旅游景区(如九寨)的可持续发展提出了挑战。但是冬暖气候在导致降水量减少、冰川面积减少、积雪量减少、雪线上升的同时,也提供了开展冬季旅游、重构现有旅游格局、挖掘新的旅游资源、拓展新的特色旅游空间的机遇。在此基础上,研究提出了主动适应全球变暖的气候响应,大力开展冬季旅游的建议。     

High natural aerosol loading over boreal forests

Aerosols play a key role in the radiation balance of the atmosphere. Here, we present evidence that the European boreal region is a substantial source of both aerosol mass and aerosol number. The investigation supplies a straightforward relation between emissions of monoterpenes and gas-to-particle formation over regions substantially lacking in anthropogenic aerosol sources. Our results show that the forest provides an aerosol population of 1000 to 2000 particles of climatically active sizes per cubic centimeter during the late spring to early fall period. This has important implications for radiation budget estimates and relevancy for the evaluation of feedback loops believed to determine our future climate.     

西双版纳热带季节雨林辐射长期变化特征

[目的]太阳辐射是森林生态系统最主要的能量来源,同时是影响森林生态系统区域气候与环境的最重要因素之一.探讨森林辐射长期变化特征,以期为气候变化、热带地区森林生产力、辐射能量平衡的研究以及辐射模型的建立和验证等建立研究基础.[方法]利用西双版纳热带季节雨林14年(2003-2016)辐射实测数据,对不同时间尺度的辐射各分...     

近50年宿州积雪日数的气候变化特征及其影响因子分析

[目的]研究近50年宿州积雪日数的气候变化特征及其影响因子。[方法]根据1961～2010年宿州年积雪日数及相关资料,运用线性趋势法、累积距平及完全相关系数法等数理统计方法,对宿州积雪日数的气候变化特征及其影响因子进行分析。[结果]50年来宿州积雪期呈现出缩短趋势。除≥20 cm厚度的积雪日数外,各级厚度积雪的年积雪日数呈现出不同程度的减少趋势;年积雪日数呈波动下降趋势,下降幅度为0.84 d/10a;年积雪日数20世纪60年代～70年代前期呈现由少到多的态势,70年代中后期～80年代中期步入少积雪的时期,80年代后期～90年代初逐渐增加,90年代中期～2003年又进入少雪期,2004年至今呈现出多雪、少雪交替的振荡。影响宿州年积雪日数变化的主要气候因子为平均气温,其次为平均地表温度。[结论]该研究为全球气候变暖背景下宿州的气候变化分析提供理论依据。     

大兴安岭地区近31年积雪与冻土变化分析

利用1975～2005年大兴安岭地区6个气象台站的常规观测资料,分析了大兴安岭冬春积雪日数和最大冻土深度的变化及其与气候变化的关系。结果表明,大兴安岭冬春积雪日数在20世纪80年代略有增加,90年代减少;而近31年总体趋势呈减少趋势。近31年大兴安岭的最大冻土深度呈递减趋势。冬春积雪日数变化与冬春气温变化呈负相关,但与冬春降水之间没有明显的相关关系。最大冻土深度的变化与冬春气温和冬春降水的变化均呈负相关。     

地形与林型影响春季融雪过程的定量化研究

春季融雪是北方寒冷地区春季径流的主要来源,对缓解春旱具有重要意义。森林能够延缓春季融雪径流已成为共识,但流域内地形与植被等因素的不同使得森林对融雪速率的影响具有时空异质性,定量估算地形因素与植被因素对融雪过程的影响有助于提高流域水文模型的精度。本文采用山地小气候模型(MTCLIM)的方法计算了地形对太阳辐射的分配以及雪蒸发的模拟,采用经地形与植被修正的气温日数法计算融雪量,从而定量探讨了地形与植被因素对融雪的综合影响效果。结果表明:流域内融雪的模拟计算能够较好地反映地形与植被对融雪的影响,计算值与观测值之间的相关系数为0.90。流域内植被对融雪过程的影响要远大于地形的影响,仅考虑地形的影响时,平均融雪速率为1.91 mm/d,与空旷平地融雪速率1.95 mm/d相近,而仅考虑植被影响情境下,融雪速率为1.26 mm/d,仅为空旷平地融雪速率的64.6%。但具体到坡面某点,模拟的准确性还有待提高。雪蒸发的模拟结果较差,说明仅考虑地形与植被的Priestly-Taylor方法无法正确模拟雪蒸发的时空分布。