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1.
Observational data from satellite altimetry were used to quantify the performance of CMIP6 models in simulating the climatological mean and interannual variance of the dynamic sea level (DSL) over 40°S–40°N. In terms of the mean state, the models generally agree well with observations, and high consistency is apparent across different models. The largest bias and model discrepancy is located in the subtropical North Atlantic. As for simulation of the interannual variance, good agreement can be seen across different models, yet the models present a relatively low agreement with observations. The simulations show much weaker variance than observed, and bias is apparent over the subtropics in association with strong western boundary currents. This nearshore bias is reduced considerably in HighResMIP models. The underestimation of DSL interannual variance is at least partially due to the misrepresentation of ocean processes in the CMIP6 historical simulation with its relatively low resolution. The results identify directions for future model development towards a better understanding of the mean and interannual variability of DSL.摘要本研究采用卫星测高数据与第六次国际耦合模式比较计划 (CMIP6) 海平面动力进行对比, 重点针对40°S–40°N地区的动力海平面 (DSL) , 评估了模式对其平均态与年际变率的综合模拟能力. 结果表明, 对于DSL平均态的模拟, 模式与观测结果非常吻合, 模式之间的差异较小. 其中, 副热带北大西洋是模拟偏差和模式间差异较为显著的区域. 对于DSL年际变率的模拟, 模式之间保持较高的一致性, 但是, 模式与观测结果存在明显差异, 模式普遍低估了DSL的年际方差; 其中, 误差大值区域出现在副热带西边界流附近. 模式分辨率会影响CMIP6对中小尺度海洋过程的重现能力, 这可能是导致CMIP6历史模拟出现误差的原因之一.  相似文献   

2.
Coordinated numerical ensemble experiments with six different state-of-the-art atmosphere models were used to evaluate and quantify the impact of global SST (from reanalysis data) on the early winter Arctic warming during 1982–2014. Two sets of experiments were designed: in the first set (EXP1), OISSTv2 daily sea-ice concentration and SST variations were used as the lower boundary forcing, while in the second set (EXP2) the SST data were replaced by the daily SST climatology. In the results, the multi-model ensemble mean of EXP1 showed a near-surface (~850 hPa) warming trend of 0.4 °C/10 yr, which was 80% of the warming trend in the reanalysis. The simulated warming trend was robust across the six models, with a magnitude of 0.36–0.50 °C/10 yr. The global SST could explain most of the simulated warming trend in EXP1 in the mid and low troposphere over the Arctic, and accounted for 58% of the simulated near-surface warming. The results also suggest that the upper-tropospheric warming (~200 hPa) over the Arctic in the reanalysis is likely not a forced signal; rather, it is caused by natural climate variability. The source regions that can potentially impact the early winter Arctic warming are explored and the limitations of the study are discussed.摘要本文使用六个不同的最新大气模式进行了协调数值集合实验, 评估和量化了全球海表面温度 (SST) 对1982–2014年冬季早期北极变暖的影响.本研究设计了两组实验:在第一组 (EXP1) 中, 将OISSTv2逐日变化的海冰密集度和SST数据作为下边界强迫场;在第二组 (EXP2) 中, 将逐日变化的SST数据替换为逐日气候态.结果表明: (1) EXP1的多模式集合总体平均值显示0.4 °C/10年的近地表 (约850 hPa) 升温趋势, 为再分析数据结果中升温趋势的80%. (2) 在这六个模式中, 模拟的变暖趋势均很强, 幅度为0.36–0.50 °C/10年. (3) 全球海表温度可以解释北极对流层中低层EXP1的大部分模拟的变暖趋势, 占再分析数据结果的58%. (4) 再分析数据结果中, 北极上空的对流层上层变暖 (约200 hPa) 不是由强迫信号而可能是由自然气候变率引起的.本文还探索了影响北极初冬变暖的可能源区, 并讨论了该研究的局限性.  相似文献   

3.
Stemming from the multi-scale interactions of various processes, long-term memory (LTM) has become a well-recognized property in the climate system. Whether a dynamic model can reproduce the observed LTM is a widely used criterion for model evaluation, especially regarding its ability in simulating natural variabilities. While many works have shown poor model skill in simulating the LTM of land surface air temperature (LSAT), it is not yet known whether CMIP6 models offer any improvement. In this study, the performances of 60 CMIP6 models in simulating the LTM characteristics in LSAT were evaluated. Results showed that most models reproduced the LTM in the global-mean LSAT, among which AWI-ESM-1-1-LR and E3SM-1-0 performed best. All 60 models reproduced the variation in LTM with latitude. CNRM-CM6-1 and HadGEM3-GC31-LL performed best in simulating the LTM of LSAT at the global scale. The multi-model mean (MMM) performed better than any single model. The biases of the MMM and CRUTEM5, and among the 60 models, were significant in the equatorial and coastal regions, which may be attributable to the simulation differences of the models in terms of their ocean–atmosphere coupling processes.摘要利用去趋势涨落分析 (DFA) 方法计算序列的长程记忆性 (LTM) , 以CRUTEM5数据集的结果作为观测参照, 评估了60个参与第六次国际耦合模式比较计划 (CMIP6) 的气候模式对地表气温LTM的再现能力. 结果表明: 大部分模式可以再现全球平均地表气温序列的LTM特征, 其中AWI-ESM-1-1-LR和E3SM-1-0的模拟效果最好; 60个模式均能模拟LTM随纬度带的变化; 综合来说, 全球水平上CNRM-CM6-1和HadGEM3-GC31-LL对地表气温LTM的模拟性能最好; 多模式平均相比单一模式模拟性能更好; 多模式平均与观测结果的偏差以及模式之间的模拟差异显著体现在赤道和沿海区域, 这种偏差可能源于模式对海气耦合过程的模拟差异.  相似文献   

4.
With its rapid rise in temperatures and accelerated urbanization in recent decades, eastern China may be affected by both global warming and the urban heat island effect. To investigate the influence of anthropogenic forcing and urbanization on extreme temperature, the authors conducted detection and attribution analyses on 16 extreme indices using extended observational data during 1958–2020 and the models that participated in CMIP5 and CMIP6. The extended observational data till 2020 show continued warming in extreme temperatures in recent years. Most of the indices display an increase in warm extremes and decrease in cold extremes. Both CMIP5 and CMIP6 models are able to reflect these warming features, albeit the models can over- or underestimate some extreme indices. The two-signal detection with anthropogenic and urbanization effects jointly considered showed that the anthropogenic and urban signals can be simultaneously detected and separated only in two frequency indices, i.e., the frequency of warm and cold nights. The anthropogenic forcing explains about two-thirds of the warming, while URB contributes about one-third for these two indices. For most of the other indices, only the anthropogenic signal can be detected. This indicates that the urban signal is distinct from the natural variability mainly for the nighttime frequency indices but not for the other extreme temperature indies. Given the important influence of nighttime extremes on human health, this suggests an urgent need for cities to adapt to both global warming and urbanization.摘要作为中国经济最发达的地区, 中国东部受到城市热岛效应和温室气体排放等人类活动的明显影响. 本文利用最新的观测和全球气候模式资料, 对极端温度强度, 频率和持续时间等16个极端温度指数进行了检测归因分析, 研究了人为强迫和城市化效应对中国东部极端温度变化的影响. 结果表明, 近年来极端温度持续增暖, 极端暖事件增加, 极端冷事件减少. 新一代全球气候模式能够合理地反映这些变暖特征, 但是部分模式可能高估或低估了观测到的变化. 基于最优指纹方法的双信号检测表明, 人为信号和城市化效应只能在暖夜和冷夜两个频率指标上同时被检测并分离, 其变化约三分之二可归因于人类活动, 剩余的三分之一可归因于城市化效应. 而在极端温度其他指数的变化中, 只有人类活动的影响能够被检测到.  相似文献   

5.
The authors explore the response of the Northern African (NAF) monsoon to orbital forcing in the Last Interglacial (LIG) compared with its response to greenhouses gas (GHG) forcing under the SSP5-8.5 scenario simulated in CMIP6. When the summer surface air temperature increases by 1 °C over the Northern Hemisphere, the NAF monsoon precipitation and its variability during the LIG increase by approximately 51% and 22%, respectively, which is much greater than under SSP5-8.5 (2.8% and 4.3%, respectively). GHG forcing enhances the NAF monsoon mainly by increasing the atmospheric moisture, while the LIG's orbital forcing intensifies the NAF monsoon by changing the monsoon circulation. During the LIG, models and data reconstructions indicate a salient hemispheric thermal contrast between the North and South Atlantic, strengthening the mean-state NAF monsoon precipitation. The interhemispheric temperature contrast enhances atmosphere–ocean interaction and the covariability of the northward sea surface temperature gradient and Saharan low, strengthening the NAF monsoon variability.摘要与人为强迫引起的全球变暖相比, 末次间冰期是轨道强迫引起的过去80万年来最暖的一个间冰期, 但鲜有人研究末次间冰期中北非季风的响应. 因此, 本文基于CMIP6多模式模拟结果对比研究了末次间冰期和SSP5–8.5情景下北非季风的响应, 发现末次间冰期下北非季风平均降水及其降水变率均远大于SSP5–8.5情景下的结果. 轨道强迫导致的北大西洋暖于南大西洋增加了北非季风环流和平均降水, 同时, 南北大西洋海温梯度变化通过增强热带北大西洋的海气相互作用增大了海温梯度和撒哈拉低压的变率, 从而增强了北非季风降水变率.  相似文献   

6.
SST–precipitation feedback plays an important role in ENSO evolution over the tropical Pacific and thus it is critically important to realistically represent precipitation-induced feedback for accurate simulations and predictions of ENSO. Typically, in hybrid coupled modeling for ENSO predictions, statistical atmospheric models are adopted to determine linear precipitation responses to interannual SST anomalies. However, in current coupled climate models, the observed precipitation–SST relationship is not well represented. In this study, a data-driven deep learning-based U-Net model was used to construct a nonlinear response model of interannual precipitation variability to SST anomalies. It was found that the U-Net model outperformed the traditional EOF-based method in calculating the precipitation variability. Particularly over the western-central tropical Pacific, the mean-square error (MSE) of the precipitation estimates in the U-Net model was smaller than that in the EOF model. The performance of the U-Net model was further improved when additional tendency information on SST and precipitation variability was also introduced as input variables, leading to a pronounced MSE reduction over the ITCZ.摘要SST–降水反馈过程在热带太平洋ENSO演变过程中起着重要作用, 能否真实地在数值模式中表征SST–降水年际异常之间的关系及相关反馈过程, 对于准确模拟和预测ENSO至关重要. 例如, 在一些模拟ENSO的混合型耦合模式中, 通常采用大气统计模型 (如经验正交函数; EOF) 来表征降水 (海气界面淡水通量的一个重要分量) 对SST年际异常的线性响应. 然而在当前的耦合模式中, 真实观测到的降水–SST统计关系还不能被很好地再现出来, 从而引起 ENSO模拟误差和不确定性. 在本研究中, 使用基于深度学习的U-Net模型来构建热带太平洋降水异常场对SST年际异常的非线性响应模型. 研究发现: U-Net模型的性能优于传统的基于EOF方法的模型. 特别是在热带西太平洋海区, U-Net模型估算的降水误差远小于EOF模型的模拟. 此外, 当SST和降水异常的趋势信息作为输入变量也被同时引入以进一步约束模式训练时, U-Net模型的性能可以进一步提高, 如能使热带辐合带区域的误差显著降低.  相似文献   

7.
Topography as well as its attributes are fundamental factors during precipitation generation. Various models with different complexity have been established to interpret the topography–precipitation relationship. In this study, the topography–precipitation relationships simulated by two dynamical downscaling models (DDMs) at the kilometer-scale and traditional quarter-degree resolution in eastern China are evaluated by utilizing multi-scale geographically weighted regression with station precipitation observations as reference. The precipitation simulated by the kilometer-scale DDM had a higher agreement with observations than the quarter-degree simulation. For the effects of topography on precipitation, observations revealed a dominant role played by the topographical relief in the precipitation distribution at most stations in the study region. The kilometer-scale DDM generally reflected this dominant role of topographical relief. However, the quarter-degree DDM showed an excessive dependency of the precipitation distribution on the topographical elevation. This research highlights the key role of underground sub-grid variations on the precipitation in eastern China, which implies a potential way forward for precipitation simulation improvements.摘要与传统的1/4度 (≈25-30 km) 动力降尺度模拟相比, 公里尺度模拟的降水空间分布与观测结果更为接近. 为了研究这一差异原因, 本研究以华东地区为例, 探究了地形因子在观测和模拟的降水中的作用. 为了更好地体现地形因子对降水分布非均匀性的影响, 以及不同地形因子作用的尺度差异, 本研究采用多尺度地理加权回归模型, 对五个主要地形因子与公里尺度和1/4度分辨率模拟的降水的关系进行了评估. 基于观测数据的研究结果显示地形起伏度, 地形高程和离海岸线距离对华东地区降水分布的非均匀性都有重要影响, 其中地形起伏度在研究区大部分站点降水分布中起主导作用; 公里尺度模拟结果基本反映了地形起伏度的主导作用; 而1 / 4度模拟结果表现出降水对地形高程的过度依赖. 本研究揭示了公里尺度地形分布对中国东部降水的非均匀分布的关键作用, 研究结果可以为改进降水模拟提供新的思路.  相似文献   

8.
The evaluation of East Asian summer monsoon (EASM) simulations could improve our understanding of Asian monsoon dynamics and climate simulations. In this study, by using Phase 6 of the Coupled Model Intercomparison Project (CMIP6) experiments of the Atmospheric Model Intercomparison Project (AMIP) and historical runs of the Chinese Academy of Sciences (CAS) Flexible Global Ocean–Atmosphere–Land System (FGOALS-f3-L) model, the model simulation skill for the interannual variability in the EASM was determined. According to multivariate empirical orthogonal function (MV-EOF) analysis, the major mode of the EASM mainly emerged as a Pacific-Japan pattern in the western Pacific accompanied by a local anticyclonic anomaly with a total variance of 24.6%. The historical experiment could suitably reproduce this spatial pattern and attained a closer total variance than that attained by the AMIP experiment. The historical experiment could also better simulate the time frequency of the EASM variability than the AMIP experiment. However, the phase of principal component 1 (PC1) was not suitably reproduced in the historical experiment since no initialization procedure was applied at the beginning of the integration in the historical simulation process, whereas the sea surface temperature (SST) was preset in the AMIP experiment. Further analysis revealed that air–sea interactions in the Indian Ocean and tropical western Pacific were important for the model to provide satisfactory EASM simulations, while El Niño–Southern Oscillation (ENSO) simulation was possibly related to the climate variability in the EASM simulations, which should be further analyzed.摘要对东亚夏季季风(EASM)模拟的评估可以提高我们对亚洲季风动力和气候模拟的理解. 在这项研究中, 通过使用中国科学院(CAS)全球海洋-大气-陆地系统(FGOALS-f3-L)模式参加的第六次耦合模式相互比较计划(CMIP6)中的大气模式相互比较计划(AMIP)和历史(historical)试验, 明确了EASM的年际变率的模拟能力. 通过多变量经验正交函数(MV-EOF)分析发现, 观测的EASM的主导模态为西太平洋上的太平洋-日本模态, 并伴有局部反气旋异常. 主导模态的方差贡献率为24.6%. 历史(historical)试验可以基本再现这种空间模态, 其方差贡献率较AMIP试验更接近于观测. 与AMIP试验相比, 历史(historical)试验还能更好地模拟EASM变率的时间频率. 然而, 由于历史(historical)模拟没有在积分开始时应用初始化过程, 而AMIP试验受到海表面温度(SST)的约束, 因此主成分(PC1)的位相在历史(historical)试验中没有得到较好地再现. 进一步分析发现, 印度洋和西太平洋热带地区的海气相互作用对EASM的模拟非常重要, 而EASM气候变率的模拟可能与厄尔尼诺-南方涛动(ENSO)的模拟能力有关, 这值得进一步分析.  相似文献   

9.
Southeast China has comparable stratus cloud to that over the oceans, especially in the cold seasons (winter and spring), and this cloud has a substantial impact on energy and hydrological cycles. However, uncertainties remain across datasets and simulation results about the long-term trend in low-cloud cover in Southeast China, making it difficult to understand climate change and related physical processes. In this study, multiple datasets and numerical simulations were applied to show that low-cloud cover in Southeast China has gone through two stages since 1980—specifically, a decline and then a rise, with the turning point around 2008. The regional moisture transport plays a crucial role in low-cloud cover changes in the cold seasons and is mainly affected by the Hadley Cell in winter and the Walker Circulation in spring, respectively. The moisture transport was not well simulated in CMIP6 climate models, leading to poor simulation of the low-cloud cover trend in these models. This study provides insights into further understanding the regional climate changes in Southeast China.摘要中国东南地区在冬春冷季节盛行低云, 对局地能量平衡和水文循环有重要的作用. 本研究使用多套数据和数值模拟结果, 分析这一地区冷季节内低云云量在1980年至2017年的长期变化. 结果表明, 低云云量经历了先下降后上升的趋势变化, 转折点出现在2008年左右. 局地水汽通量输送在影响低云云量的变化中起着至关重要的作用, 其在冬季和春季分别受到哈德莱环流和沃克环流的影响. CMIP6中的气候模式对水汽通量输送的模拟能力欠佳, 影响了对低云云量的模拟结果.  相似文献   

10.
This paper assesses the interannual variabilities of simulated sea surface salinity (SSS) and freshwater flux (FWF) in the tropical Pacific from phases 5 and 6 of the Coupled Model Intercomparison Project (CMIP5 and CMIP6). The authors focus on comparing the simulated SSS and FWF responses to El Niño–Southern Oscillation (ENSO) from two generations of models developed by the same group. The results show that CMIP5 and CMIP6 models can perform well in simulating the spatial distributions of the SSS and FWF responses associated with ENSO, as well as their relationship. It is found that most CMIP6 models have improved in simulating the geographical distribution of the SSS and FWF interannual variability in the tropical Pacific compared to CMIP5 models. In particular, CMIP6 models have corrected the underestimation of the spatial relationship of the FWF and SSS variability with ENSO in the central-western Pacific. In addition, CMIP6 models outperform CMIP5 models in simulating the FWF interannual variability (spatial distribution and intensity) in the tropical Pacific. However, as a whole, CMIP6 models do not show improved skill scores for SSS interannual variability, which is due to their overestimation of the intensity in some models. Large uncertainties exist in simulating the interannual variability of SSS among CMIP5 and CMIP6 models and some improvements with respect to physical processes are needed.摘要通过比较CMIP5和CMIP6来自同一个单位两代模式模拟, 表明CMIP5和CMIP6均能较好地模拟出热带太平洋的海表盐度 (SSS) 和淡水通量 (FWF) 对ENSO响应的分布及其响应间的关系. 与CMIP5模式相比, 大部份CMIP6模式模拟的SSS和FWF年际变化分布均呈现改进, 特别是纠正了较低的中西太平洋SSS和FWF变化的空间关系. 但是, 整体上, CMIP6模式模拟的SSS年际变化技巧没有提高, 与SSS年际变率的强度被高估有关. CMIP5和CMIP6模式模拟SSS的年际变化还存在较大的不确定性, 在物理方面需要改进.  相似文献   

11.
Sugarcane provides around 80% of the world's sugar production and is also one of the most efficient bioenergy crops. China is the third largest sugarcane-producing country in the world, and skillful simulation of the sugarcane yield in China is thus vital for global production and the trade of sugar and ethanol. Global Gridded Crop Models (GGCMs) are commonly used to predict global and regional crop yield as well as to assess the impacts of climate, environment, and agronomic management changes and feedbacks of crop growth. So far, two GGCMs (CLM5-crop and LPJmL) have been able to model sugarcane, but their performance in China remains unknown. In this study, the authors comprehensively evaluated the sugarcane yield simulations of these two models for the period 1980–2009 using the crop yield statistics collected from the National Bureau of Statistics of China. Results showed that these two models substantially underestimate the multi-year average sugarcane yield, with simulated yields less than one quarter of observations. In addition, CLM5-crop successfully simulates the spatial pattern, while LPJmL does not. In terms of temporal variability, the two models can reproduce the significant upward trend for the national average and in most provinces, but underestimate the magnitude. They also fail to simulate the pattern of interannual variability. The two models underestimate the sugarcane yield partly because they incorrectly set the sugarcane yield coming from the grain as other grain crops, which is inconsistent with the fact that the stem is harvested.摘要中国是全球第三大甘蔗生产国, 中国甘蔗产量模拟可服务于全球食糖和乙醇的生产和贸易. 全球格点作物模式CLM5-crop和LPJmL已实现对甘蔗的模拟, 但它们在中国的模拟能力未知. 本文评估结果表明: 两个模式均严重低估了甘蔗产量, 模拟均不足观测的1/4. CLM5-crop能有技巧地模拟产量的空间分布特征, 而LPJmL不能. 两个模式均不能合理模拟产量的年际变化, 且低估了产量的上升趋势. 模式低估甘蔗产量的部分原因是模式假设收割的是甘蔗的穗而非茎.  相似文献   

12.
高质量和高分辨率的降水产品在天气预报,数值模式模拟和气象防灾减灾方面起着重要的作用.本文利用四川地区高密度的地面降水传感器观测数据,比较CMPAS四种不同时空尺度的降水实况分析产品,评估CMPAS的融合准确性与在四川地区的适用性.研究表明:四种CMPAS降水产品都在四川盆地内精度较高,攀西地区和川西高原次之.随着降水量...  相似文献   

13.
A novel multivariable prediction system based on a deep learning (DL) algorithm, i.e., the residual neural network and pure observations, was developed to improve the prediction of the El Niño–Southern Oscillation (ENSO). Optimal predictors are automatically determined using the maximal information for spatial filtering and the Taylor diagram criteria, enabling the best prediction skills at lead times of eight months compared with most operational prediction models. The hindcast skill for the most challenging decade (2011–18) outperforms the multi-model ensemble operational forecasts. At the six-month lead, the correlation (COEF) skill of the DL model reaches 0.82 with a normalized root-mean-square error (RMSE) of 0.58 °C, which is significantly better than the average multi-model performance (COEF = 0.70 and RMSE = 0.73°C). DL prediction can effectively alleviate the long-standing spring predictability barrier problem. The automatically selected optimal precursors can explain well the typical ENSO evolution driven by both tropical dynamics and extratropical impacts.摘要本文基于残差神经网络和观测数据构建了一套深度学习多因子预报测模型, 以改进厄尔尼诺-南方涛动(ENSO)的预报. 该模型基于最大信息系数进行因子时空特征提取, 并根据泰勒图的评估标准可自动确定关键预报因子进行预报. 该模型在超前8个月以内的预报性能要优于当前传统的业务预报模式. 2011–2018年间, 该模型的预报性能优于多模式集成预报的结果. 在超前6个月预报时效上, 模型预报相关性可达0.82, 标准化后的均方根误差仅为0.58°C, 多模式集成预报的相关性和标准化后的均方根误差分别为0.70和0.73°C. 该模型春季预报障碍问题有所缓解, 并且自动选取的关键预报因子可用于解释热带和副热带热动力过程对于ENSO变化的影响.  相似文献   

14.
降水日变化受大气热力,动力过程以及复杂地形影响,演变特征复杂且区域差异显著.本文采用中国气象局发布的中国地面与CMORPH融合逐小时降水产品(2008-2019年),分析了新疆省暖季降水日变化特征.研究结果表明:(1)新疆大部分地区降水主峰值发生在清晨;(2)持续时间超过三小时的降水事件是新疆地区主要降水事件,贡献了南...  相似文献   

15.
利用中科院大气所开发并发展的三维对流云模式对十一届全运会开幕式当天影响山东的对流过程进行了数值模拟和过量催化试验。结果表明模拟自然云与观测事实吻合较好;设计96组催化方案对该个例进行消(减)雨模拟试验、催化试验表明,在模拟云3.5km高度的最大过冷水含量中心引入3600.0g碘化银催化剂,连续催化消(减)雨效果较好(地面降水总量减少97.5%),此次模拟对比分析了模拟自然云与催化云,从微观上探讨了消(减)雨的基本原理,模拟所用催化剂量、催化部位与当天山东人影办的作业实际基本一致,对指导实际作业有一定的参考价值。  相似文献   

16.
The Chinese Academy of Sciences Flexible Global Ocean–Atmosphere–Land System atmospheric component model (FGOALS-f3-L) participated in Phase 6 of the Coupled Model Intercomparison Project, but its reproducibility of surface temperature (Ts) over the Tibetan Plateau (TP) as a key climatically sensitive region remains unclear. This study evaluates the capability of FGOALS-f3-L in reproducing the climatological Ts over the TP relative to the Climate Forecast System Reanalysis. The results show that FGOALS-f3-L can reasonably capture the spatial pattern of Ts but underestimates the annual mean Ts for the whole TP. The simulated Ts for the whole TP shows a cold bias in winter and spring and a warm bias in summer and autumn. Further quantitative analysis based on the surface energy budget equation shows that the surface albedo feedback (SAF) term strongly contributes to the annual, winter, and spring mean cold bias in the western TP and to the warm bias in the eastern TP. Compared with the SAF term, the surface sensible and latent heat flux terms make nearly opposite contributions to the Ts bias and considerably offset the bias due to the SAF term. The cloud radiative forcing term strongly contributes to the annual and seasonal mean weak cold bias in the eastern TP. The longwave radiation term associated with the overestimated water vapor content accounts for a large portion of the warm bias over the whole TP in summer and autumn. Improving land surface and cloud processes in FGOALS-f3-L is critical to reduce the Ts bias over the TP.摘要中国科学院全球海洋–大气–陆地耦合模式 (FGOALS-f3-L) 参加了耦合模式比较计划的第六阶段 (CMIP6) 试验,但是其对关键气候敏感地区青藏高原的地表温度的再现能力还不清楚.这项研究用再分析资料CFSR评估了FGOALS-f3-L模式对青藏高原地表温度的再现能力.结果表明, FGOALS-f3-L可以合理模拟整个高原上年平均地表温度的空间分布, 但低估了整个高原上年平均地表温度.模拟的地表温度在整个高原上冬春季表现为冷偏差, 夏秋季表现为暖偏差.基于地表能量平衡方程的进一步定量分析表明, 地表反照率反馈 (SAF) 项极大地贡献了高原西部年平均, 冬春季平均地表温度的冷偏差, 而对高原东部是暖偏差贡献.与SAF项相比, 地表感热项对地表温度偏差的贡献几乎相反, 这大大抵消了SAF项引起的偏差.云辐射强迫项对高原东部的年平均和季节平均弱冷偏差有很大贡献.与高估的水蒸气含量有关的长波辐射项造成了夏秋季整个高原上大部分的暖偏差.该研究表明, 提高FGOALS-f3-L中的陆面和云过程对降低高原上地表温度偏差至关重要.  相似文献   

17.
The global high-resolution marine reanalysis products that were independently developed by the National Marine Environmental Forecasting Center based on the Chinese Global Oceanography Forecasting System (CGOFS), are evaluated by comparing their climatologies with internationally recognized data from WOA (Word Ocean Atlas), SODA (Simple Ocean Data Assimilation), AVISO (Archiving, Validation, and Interpretation of Satellite Oceanographic Data), and C-GLORS (Global Ocean Reanalysis System). The results show that the SST RMSEs of CGOFS and SODA against WOA are 0.51 °C and 0.43 °C respectively; and in the North Pacific, the SST of CGOGS is closer to that of WOA than SODA. The SSS RMSEs of CGOFS and SODA compared with WOA are 0.48 PSU and 0.40 PSU, respectively. CGOFS can reproduce the main large-scale ocean circulation globally, and obtain a similar vertical structure of the Equatorial Undercurrent as SODA. The RMSE of the CGOFS global sea-level anomaly against AVISO is 0.018 m. The monthly averaged sea-ice extents are between those of SODA and C-GLORS in each month; the growth and ablation characteristics of the ice volume are consistent with SODA and C-GLORS; but the ice volume of CGOFS is greater than that of SODA and C-GLORS. In general, the climatology of the CGOFS global high-resolution reanalysis products are basically consistent with similar international products, and can thus provide reliable data for the improvement of marine science and technology in China.摘要通过同化系统将观测资料与海洋数值模式融合得到的海洋再分析产品为海洋科学研究提供了重要的资料基础.本文采用WOA,SODA,AVISO和GLORS四种数据资料与我国自主研发的中国全球海洋预报系统(CGOFS)的气候态结果进行了对比, 结果表明:CGOFS和SODA的全球海表面温度与WOA的均方根误差分别为0.51 和 0.43°C.CGOFS和SODA的海表面盐度与WOA的均方根误差分别为0.48和0.40 PSU;海流方面, CGOFS能较好的刻画主要大洋环流分布及赤道潜流的垂向结构;CGOFS的全球海表面高度异常与AVISO的均方根误差为0.018m;多年月平均海冰外缘线覆盖面积介于SODA 和 GLORS之间, 海冰体积的生消规律与SODA 和 GLORS一致.总体来看, CGOFS全球高分辨率海洋再分析产品的气候态结果与国际同类产品基本一致, 可为提升我国海洋综合科技实力提供可靠的资料保障.  相似文献   

18.
西伯利亚地区异常的升温可能会给生态系统带来灾难性的影响.本文从气候角度分析西伯利亚地区初夏升温的特征以及北极海冰减小的可能贡献.观测和再分析资料表明,1979-2020年间西伯利亚地区6月地表气温有很强的升温趋势(0.9℃/10年),明显高于同纬度地区平均的升温趋势(0.46℃/10年).升温从地表延伸至300hPa左...  相似文献   

19.
This study presents the simulated aerosol spatiotemporal characteristics over the Tibetan Plateau (TP) with a newly developed coupled aerosol–climate model (FGOALS-f3-L). The aerosol properties are simulated over the TP for the period 2002–11. The results indicate that soil dust, sulfate, and carbonaceous aerosols (black carbon (BC), organic carbon (OC) and BC/OC) account for 53.6%, 32.2%, and 14.2% of the total aerosol mass over the TP, respectively. The simulated aerosol surface mass concentrations and aerosol optical depths (AODs) are evaluated with ground-based and satellite observations, respectively. Underestimations of the aerosol surface mass concentration are found at the Lhasa site, especially for BC and OC. The spatial distribution and interannual variation of AOD are consistent with MODIS observations, with the RMSE of 0.081 and bias of 0.036. Due to the uncertainty of the parameterization of dust emissions, the model's performance in summer and autumn is much better than that in spring.摘要基于新耦合气溶胶气候模式FGOALS-f3-L模拟分析了2002–2011年青藏高原地区气溶胶时空分布特征.结果表明:青藏高原地区, 沙尘,硫酸盐,碳质气溶胶 (包括黑碳,有机碳和混合碳) 地表质量浓度分别占比为53.6%, 32.2%, 14.2%;在拉萨站点, 模拟的气溶胶地表质量浓度被低估, 尤其是黑碳和有机碳气溶胶;模拟的气溶胶光学厚度 (AOD) 时空分布与卫星观测结果较为一致, 均方根误差和偏差分别为0.081和0.036;由于模式中沙尘排放参数化的不确定性, 模式对AOD的模拟效果在夏季和秋季优于春季  相似文献   

20.
This study aims to quantify the response of a westerly-trough rainfall episode that occurred in summer 2020 to multi-scale topographic control in southwestern China, based on observations and numerical simulations. The multi-scale topography is composed of the Tibetan Plateau, Hengduan Cordillera (HC), and Sichuan Basin (SB). The westerly trough was characterized by southeastward deepening together with an in-phase propagating rainfall episode. By utilizing the results of numerical experiments, how the multi-scale topography impacted this westerly trough rainfall episode is explored. It is found that HC was the pivotal topographic factor affecting the southeastward extension of the trough and related rainfall, while SB accerelated the eastward movement of the westerly trough and changed the tilting direction of the trough line, thus further changing the location and orientation of precipitation. For extreme rainfall with intensity exceeding 10 mm h?1, a roughly threefold rise in the cover ratio (from 1.8% to 7.2%) and fourfold increase in the areal rainfall amount per hour occurred by removing the HC barrier, due to the strongest vorticity and long-distance transport capacity to potential vorticy mass accompanying the southeast-stretching trough. Our results quantitatively reveal a strong response of westerly trough rainfall to multi-scale topographic control in southwestern China, therefore serving as an important reference for future decision making and effective model improvement.摘要中国西南部地形复杂, 降水频发, 地形对降水的影响至关重要. 本文基于观测和数值模拟, 定量揭示了青藏高原, 横断山脉和四川盆地多尺度地形对该地区西风槽降水的影响. 发现横断山脉是影响槽东南伸展, 降水传播的关键地形要素, 而四川盆地可加速西风槽东移, 改变槽线倾斜方向, 进而改变降水的位置和方向. 对于极端降水事件, 移除横断山脉屏障后, 降水覆盖率约增加3倍 (从1.8%增至7.2%), 小时面雨量增强4倍. 这些研究, 可为地形复杂地区降水的未来预报决策和有效模式改进提供参考.  相似文献   

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