基于CCSM3气候模式的同化模拟试验

基于美国NCAR及其他科学家合作发展的共同气候系统模式CCSM3,利用nudging方法开展了把15 m到465 m的次表层海温同化到该模式的研究。1980—2000年的同化试验结果表明,经过同化得到的模拟结果与实际较为一致,较好的再现了中低纬太平洋海洋和大气的平均特征和随时间演变的规律,但仍存在如海表温度偏高、降水偏强等问题。尤其是在大洋的东边界,陆地地形比较陡峭的地区,通常出现较大的偏差。

不同分辨率CCSM4对东亚和中国气候模拟能力分析

本文利用通用气候系统模式CCSM4在三种水平分辨率下的工业化革命前期气候模拟试验,结合观测和再分析资料,比较了各分辨率下模式对中国温度和降水、东亚海平面气压和850hPa风场的模拟能力,综合评价了模式分辨率对东亚和中国气候模拟的影响。结果表明,三种分辨率对中国温度均具有很好的模拟能力,除春季外,低分辨率(T31,约3.75°×3.75°)对全年温度的模拟能力均要稍好于中(f19,约1.9°×2.5°)、高(f09,约0.9°×1.25°)分辨率;各分辨率对中国降水的模拟能力远不如温度,除冬季外全年都出现的中部地区虚假降水并未因为模式分辨率提高而得到本质改善;对于东亚海平面气压场,低分辨率在冬季模拟能力相对最好,中等分辨率在夏季相对较好,而高分辨率的模拟能力均表现最差;低分辨率对850hPa东亚冬季风和夏季风的模拟能力均要好于中、高分辨率,而两种较高分辨率的模拟能力则比较接近。总的来说,低分辨率CCSM4在东亚和中国气候模拟中表现出了较大优势,加之其计算代价小,适合进行需要较长时间积分的气候模拟研究。

CCSM4模式对东北气温和降水的模拟及预估

利用东北地区162个气象观测站逐月气温和降水资料对CCSM4模式的模拟性能进行了评价,并预估了2021—2050年东北地区的气候变化情景。结果表明:CCSM4模式长期历史气候模拟实验模拟的1961—2005年月平均气温、降水量值能较好地再现东北区域年平均气温、降水量的空间分布形态,但气温模拟值比观测偏低,91. 4%站点误差在1. 5℃以内;降水中心比观测略偏北,全区平均偏多35. 18 mm。2021—2050年东北区域年平均气温呈增温趋势,高纬度地区的增温幅度明显大于低纬度地区,与基准年相比,RCP2. 6、RCP4. 5和RCP8. 5情景下全区分别偏高6. 00℃、5. 86℃和6. 42℃。年降水量分布呈东南向西北递减的形态,降水大值中心出现在东南部吉林与辽宁交界处,RCP2. 6、RCP4. 5和RCP8. 5情景下全区分别偏多15. 2%、3. 1%和2. 0%。

CCSM3对太平洋年代际振荡的敏感性试验

利用NCAR的CCSM3模式进行控制试验和1870—1999年的130 a模拟试验(敏感性试验),与相应的再分析资料进行对比,分析了太平洋海区的海温变化趋势和北太平洋年代际变率的时空结构,并且讨论了CO2对于北太平洋年代际变率的影响。结果表明:CCSM3模式能够模拟出北太平洋年代际变率的主要特征,其空间分布类似于典型的PDO海温异常分布型。特别是考虑了CO2增长变化以后,模式的结果更加接近再分析资料,其时间变化反映了20世纪北太平洋海温异常所经历的3次位相的转变。CO2增长变化,可以使这种太平洋年代际变化的周期增长,并且太平洋这种年代际位相转变也与CO2的变化增长有关。模式在考虑了CO2增长变化以后,双核的位置会偏东偏深,东西方向的温差将减少,也就是说CO2的增长变化,对PDO的位置和强度都有影响。

CCSM4/WRF-CMAQ动力降尺度预估RCP8.5情景下京津冀地区空气质量的潜在变化

目前,针对气候变化对区域空气质量影响的研究相对较少,并且多采用统计降尺度方法对全球气候模式结果进行处理.采用WRF中尺度气象模式对CCSM4气候模式的CMIP5 RCP8.5情景预估结果进行动力降尺度处理,并为CMAQ空气质量模式提供气象场;在2012年清华大学MEIC大气污染物排放清单的基础上,选取2005年作为气候现状代表年、2049—2051年作为未来气候代表年,对京津冀地区典型月份(1月、4月、7月、10月)的气象及空气质量数值模拟结果进行对比,以此预估气候变化背景下京津冀地区空气质量潜在变化.结果表明,在排放情况不变及RCP8.5情景下,未来代表年与现状代表年相比,京津冀地区以典型月份为代表的年均气象因素整体呈现温度升高,风速、相对湿度及大气边界层高度均降低的趋势;年均大气污染物浓度整体呈现升高的趋势,其中,温度升高约0.8℃,风速降低约0.11 m/s,相对湿度降低约2%,大气边界层高度降低约8 m,ρ(PM2.5)升高约2.4μg/m3,ρ(SO_2)升高约1.8μg/m3,ρ(NOx)升高约1.0μg/m3;此外,主要的气象条件(温度、风速、相对湿度、大气边界层高度)中,风速及大气边界层高度的降低可能是造成这些大气污染物浓度变化的主要气象因素,并且风速及大气边界层高度的降低与ρ(PM2.5)降低的相关系数分别约为-0.44和-0.26.研究显示,气候变化会对京津冀地区造成污染物浓度升高的潜在风险,同时由于现阶段缺乏可用于空气质量模式的未来排放情景数据、在线耦合模式日臻完善,在我国气候-空气质量的研究领域亟待进行更深层次的研究.

基于CCSM4.0长期积分试验评估不同辐射强迫对中国干旱半干旱区降水的影响

本文基于气候系统模式CESM4.0长期积分试验,分析评估了工业革命前(1850年)及当前(2000年)两种辐射强迫作用(分别为太阳活动和温室气体)对中国北方干旱半干旱区降水的影响。结果表明,模拟结果与观测之间尽管存在一定的偏差,但仍能再现降水气候态的空间分布以及季节变化特征;两种辐射强迫下的降水长期变化均无明显趋势,但二者的差异却呈现出70~100年的准周期振荡;由人类活动引起的当前辐射强迫作用对降水的多年际变率幅度有一定影响,造成极端强降水事件出现的概率增多,而由太阳活动引起的辐射强迫作用主要对降水多年代际周期具有一定的调制作用。进一步分析表明,两种辐射强迫下中国北方干旱半干旱区降水年多年代际变率的主要模态基本一致,但人类活动引起的辐射强迫作用会影响降水多年代际变率与热带海温异常的相互作用的强度,从而改变降水多年代际变率的幅度。

基于CCSM4气候模式的未来气候变化对黑河绿洲玉米产量影响预测

【目的】探明未来气候变化对黑河绿洲玉米产量的影响。【方法】以研究区广泛种植的玉米为研究对象,基于第5次国际耦合比较计划(Coupled Model Intercomparison Project Phase 5,CMIP5)公布的CCSM4气候预估资料,结合DSSAT-Maize模型模拟RCP4.5和RCP8.5情景下21世纪早期、中期、末期玉米产量,分析了气候变化对玉米产量的影响,并提出了适应性措施。【结果】(1)气温是玉米生育期内未来气象因子动态变化幅度最大的,预估到21世纪末,RCP4.5情景下平均增温2.5℃左右,RCP8.5情景下增温更加明显,平均增温7.3℃左右;(2)在无任何适应性措施下,2种情景下玉米潜在产量及生育期长度均呈下降趋势,预估到21世纪末期,在RCP4.5和RCP8.5情景下分别减产15%左右和29%左右;(3)模拟验证得知,气温是影响玉米产量变化的主要因素,并进一步得出该区域玉米最佳年均气温为7℃,对应的生育期平均温度为10.5℃,当超过此温度时,玉米产量与温度呈显著负相关关系;(4)面对气候变化对玉米产量的影响,通过调整玉米种植日期,可降低气候变化对作物产量带来的负效应,模拟得到年均温度从7~12℃每增加1℃对应调整后的最佳播种日期分别为每年的4月10日、4月8日、4月3日、3月30日、3月24日及3月17日左右。【结论】未来气候变化将导致该区域玉米减产,针对未来不同升温程度通过调整播种日期可以在一定程度上降低减产量。

Dynamic Downscaling of Summer Precipitation Prediction over China in 1998 Using WRF and CCSM4

To study the prediction of the anomalous precipitation and general circulation for the summer（June–July–August） of1998, the Community Climate System Model Version 4.0（CCSM4.0） integrations were used to drive version 3.2 of the Weather Research and Forecasting（WRF3.2） regional climate model to produce hindcasts at 60 km resolution. The results showed that the WRF model produced improved summer precipitation simulations. The systematic errors in the east of the Tibetan Plateau were removed, while in North China and Northeast China the systematic errors still existed. The improvements in summer precipitation interannual increment prediction also had regional characteristics. There was a marked improvement over the south of the Yangtze River basin and South China, but no obvious improvement over North China and Northeast China. Further analysis showed that the improvement was present not only for the seasonal mean precipitation, but also on a sub-seasonal timescale. The two occurrences of the Mei-yu rainfall agreed better with the observations in the WRF model,but were not resolved in CCSM. These improvements resulted from both the higher resolution and better topography of the WRF model.

Influence of Internal Decadal Variability on the Summer Rainfall in Eastern China as Simulated by CCSM4

The combined impact of the Pacific Decadal Oscillation （PDO） and Atlantic Multidecadal Oscillation （AMO） on the summer rainfall in eastern China was investigated using CCSM4. The strongest signals occur with the combination of a positive PDO and a negative AMO （＋PDO- AMO）, as well as a negative PDO and a positive AMO （-PDO ＋ AMO）. For the ＋PDO- AMO set, significant positive rainfall anomalies occur over the lower reaches of the Yangtze River valley （YR）, when the East Asian summer monsoon becomes weaker, while the East Asian westerly jet stream becomes stronger, and ascending motion over the YR becomes enhanced due to the jet-related secondary circulation. Contrary anomalies occur over East Asia for the -PDO ＋ AMO set. The influence of these two combinations of PDO and AMO on the summer rainfall in eastern China can also be observed in the two interdecadal rainfall changes in eastern China in the late 1970s and late 1990s.

Future projection of East China Sea temperature by dynamic downscaling of the IPCC_AR4 CCSM3 model result

Future temperature distributions of the marginal Chinese seas are studied by dynamic downscaling of global CCSM3 IPCC_AR4 scenario runs. Different forcing fields from 2080-2099 Special Report on Emissions Scenarios （SRES） B1, A1, and A2 to 1980-1999 20C3M are averaged and superimposed on CORE2 and SODA2.2.4 data to force high-resolution regional future simulations using the Regional Ocean Modeling System （ROMS）. Volume transport increments in downscaling simulation support the CCSM3 result that with a weakening subtropical gyre circulation, the Kuroshio Current in the East China Sea （ECS） is possibly strengthened under the global wanning scheme. This mostly relates to local wind change, whereby the summer monsoon is strengthened and winter monsoon weakened. Future temperature fluxes and their seasonal variations are larger than in the CCSM3 result. Downscaling 100 years＇ temperature increments are comparable to the CCSM3, with a minimum in B1 scenario of 1.2-2.0~C and a maximum in A2 scenario of 2.5-4.5~C. More detailed temperature distributions are shown in the downscaling simulation. Larger increments are in the Bohai Sea and middle Yellow Sea, and smaller increments near the southeast coast of China, west coast of Korea, and southern ECS. There is a reduction of advective heat north of Taiwan Island and west of Tsushima in summer, and along the southern part of the Yellow Sea warm current in winter. There is enhancement of advective heat in the northern Yellow Sea in winter, related to the delicate temperature increment distribution. At 50 meter depth, the Yellow Sea cold water mass is destroyed. Our simulations suggest that in the formation season of the cold water mass, regional temperature is higher in the future and the water remains at the bottom until next summer. In summer, the mixed layer is deeper, making it much easier for the strengthened surface heat flux to penetrate to the bottom of this water.

藏药察次塞曼(Ccsm)对高血脂小鼠降血脂作用的实验研究

目的:探讨C csm对高血脂小鼠血脂的影响。方法:按照文献方法制造高血脂小鼠模型,并检测小鼠血清总胆固醇(TC G)、甘油三酯(TG)、低密度脂蛋白(LD L-C)的水平。结果:高、中剂量组对甘油三酯(TG)有降低效果,*p<0.5;高、中剂量组对低密度脂蛋白(LD L-C)降低的很明显(**p<0.01)。对降低总胆固醇(TC G)没有明显作用。结论:C csm对高血脂小鼠有一定的降低血脂作用,对甘油三酯和低密度蛋白有较好的降低作用。

Indian Ocean Dipole Response to Global Warming: A Multi-Member Study with CCSM4

Based on a coupled ocean-atmosphere model, the response of the Indian Ocean Dipole (IOD) mode to global warming is investigated with a six member ensemble of simulations for the period 1850-2100. The model can simulate the IOD features rea-listically, including the east-west dipole pattern and the phase locking in boreal autumn. The ensemble analysis suppresses internal variability and isolates the radiative forced response. In response to increasing greenhouse gases, a weakening of the Walker circula-tion leads to the easterly wind anomalies in the equatorial Indian Ocean and the shoaling thermocline in the eastern equatorial Indian Ocean (EEIO), and sea surface temperature and precipitation changes show an IOD-like pattern in the equatorial Indian Ocean. Al-though the thermocline feedback intensifies with shoaling, the interannual variability of the IOD mode surprisingly weakens under global warming. The zonal wind feedback of IOD is found to weaken as well, due to decreased precipitation in the EEIO. Therefore, the atmospheric feedback decreases much more than the oceanic feedback increases, causing the decreased IOD variance in this model.

藏药察次塞曼(Ccsm)对高血脂大鼠血脂影响的实验研究

目的:探讨Ccsm对高血脂大鼠血脂的影响。方法:按照文献方法制造高血脂大鼠模型。检测大鼠血清总胆固醇(CHOL)、甘油三酯(TRIG)、高密度脂蛋白(HDL)、低密度脂蛋白(LDL)的水平。结果:高剂量组对总胆固醇有降低效果,*p<0.5;高、中剂量组对低密度脂蛋白降低的很明显(**p<0.01)。结论:Ccsm对高血脂大鼠有一定的降低血脂作用,对总胆固醇和低密度蛋白有较好的降低作用。

Climate variability and predictability associated with the Indo-Pacific Oceanic Channel Dynamics in the CCSM4 Coupled System Model

An experiment using the Community Climate System Model(CCSM4), a participant of the Coupled Model Intercomparison Project phase-5(CMIP5), is analyzed to assess the skills of this model in simulating and predicting the climate variabilities associated with the oceanic channel dynamics across the Indo-Pacific Oceans. The results of these analyses suggest that the model is able to reproduce the observed lag correlation between the oceanic anomalies in the southeastern tropical Indian Ocean and those in the cold tongue in the eastern equatorial Pacific Ocean at a time lag of 1 year. This success may be largely attributed to the successful simulation of the interannual variations of the Indonesian Throughflow, which carries the anomalies of the Indian Ocean Dipole(IOD) into the western equatorial Pacific Ocean to produce subsurface temperature anomalies, which in turn propagate to the eastern equatorial Pacific to generate ENSO. This connection is termed the "oceanic channel dynamics" and is shown to be consistent with the observational analyses. However, the model simulates a weaker connection between the IOD and the interannual variability of the Indonesian Throughflow transport than found in the observations. In addition, the model overestimates the westerly wind anomalies in the western-central equatorial Pacific in the year following the IOD, which forces unrealistic upwelling Rossby waves in the western equatorial Pacific and downwelling Kelvin waves in the east. This assessment suggests that the CCSM4 coupled climate system has underestimated the oceanic channel dynamics and overestimated the atmospheric bridge processes.

The relationship between the Arctic Oscillation and ENSO as simulated by CCSM4

The correlation between the Arctic Oscillation （AO） and ENSO reflects the strength of the interaction between climate systems in the low and high latitudes. Based on the long-term （501 years） control simulation of CCSM4, the authors investigated the linkage between the AO and ENSO in boreal winter. Based on the correlation coefficients between them, the authors divided the entire period into two groups： one that included the years with statistically significant correlations （G1）, and the other the years with insignificant correlations （G2）. in G1, the AO-related atmospheric circulation pattern resembles the ENSO-related one. The Aleutian Low （AL） acts as a bridge linking these two modes, in G2, however, the AO and ENSO signals are confined to the mid-high and mid-low latitudes, respectively. There is no significant linkage between the AO and ENSO in boreal winter, showing a low correlation coefficient. Further analysis suggests that changes in the climatological features, including the strengthened AO, the negative Pacific Decadal Oscillation phase, and the weakened AL, may be responsible for the enhanced relationships.

CCSM3模式下汉江流域设计暴雨计算

分析气候变化对降雨频率的影响,有助于水利工程的设计和规划。根据大气环流模式CCSM3的结果,结合IPCC第四次评估报告中给出的SRA1B、SRA2和SRB1三种排放情景,利用随机天气发生器LARS-WG生成汉江流域20个站点2020s时期逐日降雨资料,通过线性矩方法计算各个站点的百年一遇设计暴雨值,并通过克里金方法插值至整个汉江流域。结果表明,百年一遇设计暴雨值在汉江流域呈现由下游向上游逐渐递减的特征没有明显改变,SRA1B和SRA2情景下,最大设计暴雨值出现在流域出口处的武汉站;三种排放情景下,百年一遇最大设计暴雨值都有所增加,SRA1B情景和SRA2情景下都有40mm左右的增幅;SRA2和SRB1情景下,上游地区的设计暴雨值则有减小的趋势。

东亚夏季大气环流模拟的对比分析:CCSM3和CCSM4

利用ERA40再分析资料,评估了参与国际耦合模式比较计划第五阶段的CCSM4模式对东亚夏季不同要素场的气候态和年际变化的模拟能力,并与第三阶段的CCSM3模式进行了对比。结果表明:1CCSM3和CCSM4均能较好地模拟出东亚夏季海平面气压、850hPa风场、500hPa高度场气候态的空间分布特征,总体来说,CCSM4对各要素的模拟效果更好;2虽然模式对东亚地区不同要素年际变率的模拟能力整体偏弱,但相对来说,CCSM4的模拟能力有不同程度的提高;3模式对副高、印度热低压的变化趋势有一定的模拟能力,但CCSM3对副高面积指数,印度热低压及印度热低压槽指数的模拟效果反而表现的更好。对于三种典型的东亚夏季风指数,虽然CCSM4的模拟能力较CCSM3有一定的提高,但也均不能模拟出东亚夏季风的变化特征。

Modeling Study of Foehn Wind Events in Antarctic Peninsula with WRF Forced by CCSM

Significant changes have occurred in the Antarctic Peninsula(AP) including warmer temperatures, accelerated melting of glaciers, and breakup of ice shelves. This study uses the Weather Research and Forecasting model(WRF)forced by the Community Climate System Model 4(CCSM) simulations to study foehn wind warming in AP. Weather systems responsible for generating the foehn events are two cyclonic systems that move toward and/or cross over AP. WRF simulates the movement of cyclonic systems and the resulting foehn wind warming that is absent in CCSM. It is found that the warming extent along a transect across the central AP toward Larsen C Ice Shelf(LCIS) varies during the simulation period and the maximum warming moves from near the base of leeward slopes to over 40 km away extending toward the attached LCIS. Our analysis suggests that the foehn wind warming is negatively correlated with the incoming air temperature and the mountain top temperature during periods without significant precipitation, in which isentropic drawdown is the dominant heating mechanism. On the other hand, when significant precipitation occurs along the windward side of AP, latent heating is the major heating mechanism evidenced by positive relations between the foehn wind warming and 1) incoming air temperature, 2) windward precipitation, and 3)latent heating. Foehn wind warming caused by isentropic drawdown also tends to be stronger than that caused by latent heating. Comparison of WRF simulations forced by original and corrected CCSM data indicates that foehn wind warming is stronger in the original CCSM forced simulation when no significant windward precipitation is present.The foehn wind warming becomes weaker in both simulations when there is significant windward precipitation. This suggests that model’s ability to resolve the foehn warming varies with the forcing data, but the precipitation impact on the leeward warming is consistent.

IPCC气候情景下全球海平面长期趋势变化

利用CCSM3(Community Climate System Model version 3)气候系统模式模拟20世纪海平面变化,在IPCC SRES A2(IPCC,2001)情景假设下预测21世纪全球海平面长期趋势变化。模拟显示20世纪海平面上升约4.0cm,且存在0.004 8mm/a2的加速度,这个结果仅为热盐比容的贡献。在A2情景假设下,21世纪海平面上升存在很大的区域特征,呈纬向带状分布;总体上北冰洋上升大,南大洋高纬度海区上升小,大西洋上升值比太平洋的大;整个21世纪全球平均比容海平面上升了约30cm,且呈加速上升的趋势。同时发现,中深层水温度和盐度变化对区域比容海平面变化具有重要贡献。北太平洋增暖主要集中在上层700m以内,而北大西洋的增暖可达2 500m的深度,南大洋南极绕极流海区热盐变化则是发生在整个深度。

基于TM图像的农业区域植被覆盖变化检测

以交叉相关光谱匹配(cross correlogram spectral matching,CCSM)为基础构建土地覆盖变化强度指标,利用华北农业植被覆盖区2期不同时相的TM图像计算该地区土地覆盖变化强度图像。认为变化强度图像任意二阶邻域中像素的变化强度服从隐马尔可夫模型,用马尔可夫随机场-最大后验估计(maxium a posteriori estimation of markovrandom field,MRF-MAP)的方法从变化强度图像中提取植被变化区域。实验证明:该方法能够有效识别各种外源噪声造成的农业植被覆盖区域同物异谱的现象,可准确提取植被变化区域;但对于水体区域存在误判现象。