1981—2009年辽宁省河流封冻期特征及对气候变暖的响应

利用辽宁省1981—2009年主要河流冻结和解冻日期观测资料,分析河流冻结日期、解冻日期、封冻期的变化特征及其对气候变暖的响应。结果表明,辽宁省各流域河流平均冻结日期最早出现在11月3日,最晚在11月15日;河流平均解冻日期最早出现在3月15日,最晚在3月30日;平均封冻期为120～146 d。1981—2009年河流冻结和解冻日期分别呈显著的推迟和提前趋势,封冻期呈显著减少趋势;冻结日期的早晚受11月最低气温的影响较大,同年3月地面温度的升高对解冻日期的提前影响最大,封冻期的长短对11月至次年3月平均气温的变化最为敏感。     

大同市冻土气候变化初探

利用大同市所辖8个站1962—2012年地面气象观测记录中的冻土资料,采用线性倾向估计、累积距平等方法,分析大同市土壤开始冻结期、完全解冻期、冻结期及最大冻土深度的变化特征及其影响因素。结果发现：51年中大同市冻土主要表现为最大冻土深度减小, 开始冻结期推迟,解冻期提前, 冻结持续期缩短的总体变化趋势,冻土除了受气温的影响外,局地因素对最大冻土深度的影响较大。     

湖泊和上风向地形对纳木错地区秋季降水影响

首先利用中国区域地面气象要素数据集(CMFD)分析了1992-2015年纳木错地区月平均降水分布,发现湖泊效应导致的下风向降水在10-11月较为明显。其次根据中国科学院纳木错多圈层综合观测研究站自动气象站2 m的风速和气温的数据,分析了2005-2015年焚风累积发生次数的月分布特征,发现12月焚风发生几率最大,且10月是秋季中发生焚风现象次数最多的月份的结果。再者,运用WRF模型对纳木错地区10月份降水进行了模拟,发现在已有大气环流背景条件下,纳木错地区秋季降水受到湖泊存在的影响比上游地形影响显著。有、无湖模拟试验表明,纳木错地区湖泊的存在会使周边地区尤其是湖泊下风向降水增多,影响范围可达100 km。上风向较高地形会使整个区域降水小幅增加,上风向地形导致的焚风效应对纳木错地区降水的影响较弱。     

2005年渤海海冰冰厚热力增长特征实验的个例研究

认识渤海海冰冰厚热力增长特征,是开发利用海冰资源的理论基础.本文通过2005年1月12日-27日在辽东湾鲅鱼圈和渤海湾黄骅海冰现场实验个例研究得出:鲅鱼圈的累积冰厚平均日增量1.33 em/d,平均冰厚日变化为3 cm;黄骅的累计冰厚平均日增量为0.54 cm/d,平均冰厚变化22.3 cm;冰厚从0 cm增长到10 cm所需的时间为鲅鱼圈5 d左右,黄骅10 d左右;冰厚日变化与日平均气温和日平均冰温与之间相关性显著,但冰厚对气温和冰温降低的反应有一定的滞后性;当环境温度持续下降时,累积冰厚与累积气温之间有显著的正相关,当环境温度上升时,累积冰厚与累积气温之间相关性逆转.     

纳木错湖夏季典型大气边界层特征的数值模拟

为了进一步检验分析纳木错湖对当地地方性环流、湖气能量交换及大气边界层的影响,在本文中使用美国NCAR新版MM5V3.7非静力中尺度模式,设计了有湖面、3/4湖面、1/2湖面及无湖四组试验,以NCEP再分析资料做初、边值条件,做了48 h三重嵌套模拟试验,对比中国科学院"纳木错圈层相互作用"综合观测站实测资料,说明该模式模拟性能良好。白天在纳木错湖风与念青唐古拉山北坡谷风共同作用下,在念青唐古拉山脊处汇合,形成一强水平切变及辐合上升运动,造成了该地夏季白天复杂多变的天气;夜间由于南岸湖风与山风叠加,使得整个区域为强大南风气流控制,这也补给了水汽和热量,也为白天不稳定运动提供了能量。对大气边界层特征的模拟结果表明:由于白天(夜晚)纳木错湖的存在有很好的降温(保温)作用,该湖表现出了明显的冷(暖)湖效应;纳木错湖对感热和潜热的影响有很强的日变化,白天湖面感热、潜热均小于周围陆地,夜间湖面有强潜热通量;纳木错湖使得白天湖区边界层顶低,陆区边界层顶高,夜间相反。这样的地方性环流和大气边界层特征的配合,是该地中小尺度天气剧烈变化的重要原因。     

平安地区自建站以来冻土变化规律分析

利用1989—2013年平安区气象局冻土资料,分析了25a平安地区季节性冻土变化情况。平安区冻土开始日期逐渐延后,1989—2000年,平均开始日期为11月1日,2001—2013年,平均开始日期为11月8日,平均开始时间推迟了7d。冻土结束日期提前,2000年以前的平均解冻日期是3月21日,2000年以后的平均解冻日期是3月8日,解冻时间提前了13d。冻土持续时间缩短了21d。平均冻土深度和最大冻土深度均减小,其中平均冻土深度从2000年以前的93.5cm减少至2000年以后的88.5cm。平均深度减小了5cm。     

新疆乌兰乌苏物候变化规律及其对气候变化的响应

分析新疆乌兰乌苏农业气象试验站1980—2002年物候与相应气候因子资料,得出乌兰乌苏23a来气温增高,降水增多,气候增暖增湿;候鸟停留时间增长,与积温、日照时数和降水量的年变化趋势一致,除降水外,其他均存在显著正相关关系;木本植物生育期延长,与4—10月平均气温、平均相对湿度、总日照时数和总降水量趋势一致;初霜和终霜均推迟,无霜期缩短;初雪和初次积雪提前,终雪推迟,冬季雪日增长;积雪开始融化提前,完全融化推迟,融化时间增长;土壤表面开始解冻日期趋势提前,而土壤表面开始冻结日期趋势推迟。另外,通过物候与气象因子建立的最优回归方程,获得物候对气候响应的定量关系,为生态环境研究提供一定的理论依据。     

基于MODIS影像的色林错湖面积变化及成因

利用2002—2009年EOS／MODIS卫星遥感资料和气温、地表温度气象资料,对色林错湖面积变化进行分析,并探讨了其成因。结果表明：西藏那曲地区色林错湖（包括雅根错湖）面积在近8a呈显著的扩大趋势,从2002年的1955．49km^2增至2009年的2197．46km^2,8a内增长了241．97km^2,现已超过纳木错湖面积,成为西藏第一大咸水湖。气温、地表温度升高导致冰雪融化和冻土层变浅是湖泊上涨的主要原因。通过研究证明了EOS/MODIS资料在研究湖泊变化中具有较好的指示作用。     

一种简易恒温加热防冻结装置在三穗国家基准气候站的实践应用

低海拔地区冬季由于凝冻常常会使风向风速传感器冻结,造成风要素资料失真或监测数据缺测,影响数据可用性,造成气象数据历史延续空白,导致无法弥补的历史数据损失。该文利用三穗县国家基准气候站2008—2020年冬季逐日、逐时、逐分钟风向风速、气温、相对湿度以及降水等地面气象监测资料,详细分析冬季冰冻期间风向风速缺测时段的气温、相对湿度、降水等相关信息,找出风向风速冻结与气温、相对湿度、风速大小的对应关系,从而判定风向、风速易冻结的气象要素阈值,采用USB碳纤维发热片,科学搭建低压加热方式,确保风向、风速传感器设备加热时不被灼伤受损,ZQZ-TF风向、风速监测资料连续可靠。     

安徽省电线积冰标准冰厚的气象估算模型

基于逐步多元线性回归和人工神经网络两种方法,利用安徽省有电线积冰观测的15个气象台站建站至2008年的观测资料,建立了安徽省3个不同区域电线积冰标准冰厚的气象估算模型。结果表明:相比人工神经网络模型,逐步多元线性回归模型预测效果较好;在覆冰机理认识上,印证了影响标准冰厚主要是气温、湿度和风速3个因子的配置,其中气温是影响覆冰的最重要因子;平原和丘陵地区的标准冰厚受当日气象条件影响更多,而高山地区与前几日及当日的气象条件均密切相关,且26个气象因子 (1987—2008年资料) 构建的模型的预测效果好于24个气象因子长序列 (建站—2008年资料) 效果。最后利用最优模型推算各区域非观冰站电线积冰标准冰厚,为冰冻灾害的评估以及风险区划的开展提供了基础。     

Changes in ice-season characteristics of a European Arctic lake from 1964 to 2008

The long-term ice record (from 1964 to 2008) of an Arctic lake in northern Europe (Lake Kilpisj?rvi) reveals the response of lake ice to climate change at local and regional scales. Average freeze-up and ice breakup occurred on 9 November and 19 June, respectively. The freeze-up has been significantly delayed at a rate of 2.3 d per decade from 1964 onward (P?<?0.05). No significant change has taken place in ice breakup. Annual average ice thickness has become smaller since the mid-1980s (P?<?0.05). Air temperature during the early ice season significantly affected the ice thickness. The freeze-up date exhibits the highest correlation with the 2-month average daily minimum air temperature centered at the end of October, while the ice breakup date exhibits the highest correlation with the 2-month average daily maximal air temperature centered in mid May. A 1°C increase in the surface air temperature corresponds to a freeze-up later by 3.4?days and an ice breakup earlier by 3.6?days. Snow cover is a critical factor in lake-ice climatology. For cumulative November to March precipitation of less than 0.13?m, the insulating effect of the snow dominated, while higher rates of precipitation favored thicker ice due to the formation of snow ice. Variations in ice records of Lake Kilpisj?rvi can serve as an indicator of climate variations across the northern Europe. The North Atlantic Oscillation (NAO) does not significantly affect the ice season there, although both the local air temperatures and winter precipitation contain a strong NAO signal.     

Modelling of Water Surface Temperature of Three Lakes on the Tibetan Plateau using a Physically Based Lake Model

ABSTRACT

This study was carried out to quantify the physical processes of lakes in the Tibetan Plateau using the Community Land Model, version 4.5 (CLM4.5), coupled with a physically based, 10-layer lake model developed by the National Center for Atmospheric Research. The CLM was forced with 10?km resolution reanalysis data to attempt to understand detailed lake processes and how these processes affect lake surface temperature. In this study, we simulated seasonal and interannual variations of lake surface temperature for Lake Qinghai, Zhaling Co, and Nam Co in the Tibetan Plateau and compared these simulations with observations. The results showed that the CLM4.5 lake model simulations reproduced the observed lake surface temperatures for Lake Qinghai and Zhaling Co well but reproduced those for Nam Co poorly. Through detailed analysis, we found that the simulated biases for Nam Co result largely from the unrealistic parameterization of eddy diffusivity. By expanding this parameter, the lake surface temperature simulations improved remarkably. In addition, erroneous lake ice cover simulations contributed to the simulated lake surface temperature bias in the cold seasons.     

Variability of Northeast China river break-up date

This paper investigates the variability of the break-up dates of the rivers in Northeast China from their icebound states for the period of 1957–2005 and explores some potential explanatory mechanisms. Results show that the break-up of the two major rivers(the Heilongjiang River and Songhuajiang River) was about four days earlier,and their freeze-up was about 4–7 days delayed,during 1989–2005 as compared to 1971–1987.This interdecadal variation is evidently associated with the warming trend over the past 50...     

Local climatic drivers of changes in phenology at a boreal-temperate ecotone in eastern North America

Ecosystems in biogeographical transition zones, or ecotones, tend to be highly sensitive to climate and can provide early indications of future change. To evaluate recent climatic changes and their impacts in a boreal-temperate ecotone in eastern North America, we analyzed ice phenology records (1975?C2007) for five lakes in the Adirondack Mountains of northern New York State. We observed rapidly decreasing trends of up to 21?days less ice cover, mostly due to later freeze-up and partially due to earlier break-up. To evaluate the local drivers of these lake ice changes, we modeled ice phenology based on local climate data, derived climatic predictors from the models, and evaluated trends in those predictors to determine which were responsible for observed changes in lake ice. November and December temperature and snow depth consistently predicted ice-in, and recent trends of warming and decreasing snow during these months were consistent with later ice formation. March and April temperature and snow depth consistently predicted ice-out, but the absence of trends in snow depth during these months, despite concurrent warming, resulted in much weaker trends for ice-out. Recent rates of warming in the Adirondacks are among the highest regionally, although with a different seasonality of changes (early winter > late winter) that is consistent with other lake ice records in the surrounding area. Projected future declines in snow cover could create positive feedbacks and accelerate current rates of ice loss due to warming. Climate sensitivity was greatest for the larger lakes in our study, including Wolf Lake, considered one of the most ecologically intact ??wilderness lakes?? in eastern North America. Our study provides further evidence of climate sensitivity of the boreal-temperate ecotone of eastern North America and points to emergent conservation challenges posed by climate change in legally protected yet vulnerable landscapes like the Adirondack Park.     

Application of the Canadian regional climate model to the Laurentian great lakes region: Implementation of a lake model

Abstract

This study reports on the implementation of an interactive mixed‐layer/thermodynamic‐ice lake model coupled with the Canadian Regional Climate Model (CRCM). For this application the CRCM, which uses a grid mesh of 45 km on a polar stereographic projection, 10 vertical levels, and a timestep of 15 min, is nested with the second generation Canadian General Circulation Model (GCM) simulated output. A numerical simulation of the climate of eastern North America, including the Laurentian Great Lakes, is then performed in order to evaluate the coupled model. The lakes are represented by a “mixed layer” model to simulate the evolution of the surface water temperature, and a thermodynamic ice model to simulate evolution of the ice cover. The mixed‐layer depth is allowed to vary spatially. Lake‐ice leads are parametrized as a function of ice thickness based on observations. Results from a 5‐year integration show that the coupled CRCM/lake model is capable of simulating the seasonal evolution of surface temperature and ice cover in the Great Lakes. When compared with lake climatology, the simulated mean surface water temperature agrees within 0.12°C on average. The seasonal evolution of the lake‐ice cover is realistic but the model tends to underestimate the monthly mean ice concentration on average. The simulated winter lake‐induced precipitation is also shown, and snow accumulation patterns on downwind shores of the lakes are found to be realistic when compared with observations.     

Temporal evolution of Hudson Bay Sea Ice (1971–2011)

Previous work has found Hudson Bay seasonal sea ice particularly sensitive to climate change with a strong signal of earlier breakup dates. This work extends the previous analysis by including eight additional years of recent sea ice data. The expanded sea ice record, 1971 to 2011, revealed stronger and more statistically significant trends than the earlier work, most strikingly for the later freeze up. The average magnitude of the temporal trend for all 36 locations studied is 0.50 days/year for earlier breakup, 0.46 days/year for the later freeze-up, and 0.91 days/year for longer ice-free period. Of the 36 points, 12 points for the breakup period, 30 points for the freeze-up period, and 22 points for the ice-free season have accelerating temporal trends during the past decade.     

NCEP/NCAR再分析资料在纳木错流域湖泊/冰川区适用性分析

利用中国科学院青藏高原研究所纳木错多圈层综合观测研究站在念青唐古拉峰扎当冰川垭口(30.47°N、90.65°E,5800m)和纳木错站(30.77°N、90.99°E,4730m)的逐日平均气温、相对湿度、气压等资料,与同期NCEP/NCAR再分析资料进行了对比分析,讨论了再分析资料在纳木错流域湖泊/冰川区气候变化研究中的适用性.结果表明:扎当冰川垭口和纳木错站气压再分析资料的可信度好于气温,相对湿度稍差:扎当冰川垭口气压和相对湿度再分析值与实测值的差值在冬季偏大,夏季偏小,气温则相反.在研究期间,总体上再分析资料在冰川区的可信度好于湖泊区,再分析资料能很好地反映该地区地面气压、气温和相对湿度的日变化特征,在应用到该地区气候变化的研究时应考虑地形的影响.     

Ice phenomena terms on the water bodies of Northwestern Russia

The dependence of ice phenomena (the dates of ice freeze-up and break-up) on the air temperature and geographic factors (geographic latitude, height above sea level, and average depth and area of lakes) is investigated on the basis of the data of long-term observations on the water bodies of Northwestern Russia. The regression models with rather high accuracy level are proposed not requiring a large number of input parameters unlike the deterministic models.     

Historical Trend in River Ice Thickness and Coherence in Hydroclimatological Trends in Maine

We analyzed long-term records of ice thickness on the Piscataquis River in central Maine and air temperature in Maine to determine whether there were temporal trends that were associated with climate warming. The trend in ice thickness was compared and correlated with regional time series of winter air temperature, heating degree days (HDD), date of river ice-out, seasonal center-of-volume date (SCVD) (date on which half of the stream runoff volume during the period 1 Jan. to 31 May has occurred), water temperature, and lake ice-out date. All of these variables except lake ice-out date showed significant temporal trends during the 20th century. Average ice thickness around 28 February decreased by about 23 cm from 1912 to 2001. Over the period 1900 to 1999, winter air temperature increased by 1.7 °C and HDD decreased by about 7.5%.Final ice-out date on the Piscataquis River occurred earlier (advanced), by 0.21 days yr^–1 over the period 1931 to 2002, and the SCVD advancedby 0.11 days yr^–1 over the period 1903 to 2001. Ice thickness was significantly correlated (P-value <0.01) with winter air temperature, HDD, river ice-out, and SCVD. These systematic temporal trends in multiple hydrologic indicator variables indicate a coherent response to climate forcing.     

近40年西藏色林错流域湖泊面积变化及影响因素分析

本文根据1975年地形图、1976～2016年Landsat (MSS\TM\ETM\OLI-TIRS)卫星遥感数据以及流域周围的气象资料分析湖面面积和流域周围冰川变化,并探讨了湖泊面积变化的可能影响气象原因。结果表明:1975～2016年间色林错、错鄂和班戈错湖面面积变化趋势有所不同。这一段时间内色林错湖面面积一直处于增长态势,面积增长为757.35km2,增长幅度为46.7%,增长速率为475.2km2/10a;而错鄂湖面面积在这一段时间内有增有减,但面积增量较小,总体保持稳定,面积增长为3.07km2,增长幅度为1.17%;班戈错湖面在这一段时间内面积略有波动,呈增长趋势,增长为49.75km2,增长速率为19.71km2/10a。从空间动态分布来看,色林错扩大较明显的区域为该湖的北部,班戈错扩大明显区域在东北部。色林错流域,近50a降水量年际变化波动较大,总体上呈增加趋势,平均每10a增加13.72mm。地表年平均气温呈显著上升趋势,平均每10年升高0.37℃。20世纪70年代至90年代以气温偏低为主,进入21世纪后,气温快速升温。1986～2016年间色林错流域冰川面积呈现出退缩、减少状态,总共减少了50.16km2,冰川面积变化率为7.57%。综合分析表明,色林错流域湖泊面积变化与气温和降水都有关,同时反映出该区域气温升高使得冰川融水量增加对湖泊补给有一定的作用。