Knowledge Resource Center for Ecological Environment in Arid Area
| 丝绸之路沿线地区土壤温度-大气相互作用研究 | |
| 其他题名 | The soil temperature-atmosphere interaction over the areas along the silk road |
| 杨凯 | |
| 出版年 | 2018 |
| 学位类型 | 博士 |
| 导师 | 张井勇 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 丝绸之路沿线地区是我国“一带一路”重大战略中“丝绸之路经济带”的主要区域，其气候变化对国家战略和经济发展有着非常重要的影响。目前对丝绸之路沿线地区陆气相互作用，尤其是土壤温度–大气相互作用的研究相对缺乏。本文以丝绸之路沿线地区土壤温度–大气相互作用为主线开展了一系列的研究。首先利用中国626个站点的土壤温度观测数据对4套最新的土壤温度再分析资料进行了评估。随后基于再分析资料对丝绸之路沿线地区土壤温度和土壤温度记忆的时空分布特征进行了分析。以敦煌站为代表，利用敦煌站陆气系统野外观测数据研究了典型干旱区陆气相互作用的特征，并用因果关系诊断方法分析了土壤温度与大气变量之间的关系。基于敦煌站陆气相互作用的整体框架，利用再分析资料对丝绸之路沿线地区土壤温度–大气相互作用进行探究和分析，并尝试分析土壤温度影响大气的物理机制。最后讨论了丝绸之路遥相关型与丝绸之路沿线地区土壤温度之间的关系。主要结论如下：（1）土壤温度再分析资料评估ERA-interim/land、MERRA-2、CFSR和GLDAS-2.0 四套再分析资料对中国夏季和冬季土壤温度季节平均、年际变率、线性趋势、记忆长度的空间分布的描述与观测基本一致，但也存在一些差异。再分析资料总体均低估了中国区域的土壤温度。对于全国平均土壤温度的估算，ERA-interim/land数据和GLDAS-2.0数据优于MERRA-2数据和CFSR数据。ERA-interim/land数据和GLDAS-2.0数据中土壤温度季节平均的空间分布与观测最为接近。ERA-interim/land数据和CFSR数据分别对夏季和冬季土壤温度年际变率的空间分布估算得最好。再分析资料基本能够反映出中国土壤温度记忆由西北向东南逐渐减小的趋势。我们发现再分析资料对4月到6月土壤热通量的估计会影响其对夏季土壤温度的估计，对冬季土壤热通量的估计会影响其对冬季土壤温度的估计。再分析资料所估计的土壤温度整体偏低可能原因是模式在地形、雪盖以及土地利用等方面描述能力不足。在夏季，再分析资料表现较差的一个主导原因可能是夏季降水对土壤温度的影响。（2）丝绸之路沿线地区土壤温度和土壤温度记忆时空分布特征在丝绸之路沿线地区，ERA-interim/land、MERRA-2、CFSR和GLDAS-2.0这4套再分析资料对四个季节土壤温度的空间分布估计比较一致，4个季节的土壤温度空间分布之间也比较相似。除青藏高原由于地形原因土壤温度较低外，丝绸之路沿线地区土壤温度随着纬度的增加而逐渐减小。不同土壤层的土壤温度年际变率的空间分布基本一致。土壤温度年际变率较大的区域主要包括里海周边地区、中国西边界区域、巴基斯坦北部以及新疆和蒙古北侧、贝加尔湖东侧等区域。4个季节土壤温度记忆的空间分布略有差异。除冬季高纬度地区浅层土壤温度由于雪盖作用记忆较长以外，夏季丝绸之路沿线地区的土壤温度记忆比其他几个季节长。干旱和半干旱区的土壤温度记忆长于湿润区。夏季中国西边界、蒙古、华北以及里海西南侧地区的土壤温度记忆较长。而冬季记忆较长的区域主要分布在高纬度地区、中国西边界以及里海西侧区域。（3）敦煌站土壤温度–大气相互作用特征及因果分析夏季敦煌站陆气系统各变量除较深层土壤外均存在明显的日循环。大气变量以及地表温度和表层土壤温度的日循环在很大程度上受到太阳辐射日循环的影响。土壤层越深的土壤温度日内变化幅度越小，20cm以下土壤温度没有明显日循环。ERA-interim再分析资料中敦煌站各个变量的日循环与观测基本相同。敦煌站的各个变量存在明显的季节变化。土壤温度的峰值随着土壤深度的增加而滞后。ERA-interim数据中敦煌站各个变量的季节变化曲线与观测非常接近，但对长波辐射存在明显地低估，对净辐射和感热通量的估算存在高估。ERA-interim数据对气温、地表温度和土壤温度整体存在低估。夏季敦煌站陆气系统各变量在日尺度上显著地耦合在一起。土壤温度与地表及边界层各变量之间存在明显的耦合关系。表层土壤温度向上与长波辐射、地表温度、气温以及感热通量等相互作用，向下与深层土壤温度紧密联系在一起。ERA-interim数据明显低估了敦煌站土壤温度与感热通量的耦合强度。敦煌站夏季土壤温度在土壤温度–感热耦合关系中的重要作用在因果关系分析方法中得到了验证。（4）丝绸之路沿线地区土壤温度–大气相互作用及与丝绸之路遥相关型的关系 再分析资料中丝绸之路沿线地区夏季土壤温度和地表温度以及气温存在强耦合。前期土壤温度与夏季大气变量高相关的关键区主要分布在里海西南部、伊朗西北部地区；中国西边界周围，中国与吉尔吉斯斯坦、塔吉克斯坦接壤地区以及新疆西南部地区；蒙古西部和哈萨克斯坦东部以及新疆北部地区。在前期土壤温度与夏季大气变量相关较高的区域，土壤温度的异常信号可持续到夏季并在局地的陆气系统中起到重要作用。通过对局地垂直温度的持续影响，5月份土壤温度正异常对应夏季对流层低层出现低压异常，对流层高层出现高压异常。在非局地作用较小的区域，5月土壤温度可以作为夏季气温和降水，尤其是洪涝、干旱、高温热浪等极端气候的潜在预报因子。丝绸之路遥相关型对部分丝绸之路沿线地区的土壤温度有重要影响。土壤温度对环流场的影响相对独立于丝绸之路遥相关型的共同作用。土壤温度与丝绸之路遥相关型的耦合机制可以加强丝绸之路遥相关型所对应的环流异常。 |
| 英文摘要 | The areas along the silk road are important region of the Silk Road Economic Belt, part of the national strategy of the Belt and Road. The climate change over this region is very important for government policy and economic development. However, the land–atmosphere interaction over the areas along the silk road is poorly investigated, especially for the soil temperature –atmosphere interaction. In this paper, a series of studies have been carried out to investigate the soil temperature–atmosphere interaction over the areas along the silk road. The soil temperature in four reanalysis datasets has been evaluated against the observations. And based on these reanalysis data, we investigate the spatiotemporal characteristics of soil temperature and soil temperature memory over the areas along the silk road. The observations in Dunhuang station have been adopted to investigate the characteristics of land–atmosphere interaction over the arid region. The hot spot of soil temperature–atmosphere interaction over the areas along the silk road is identified using reanalysis data and the influence of soil temperature in troposphere is investigated. The main conclusions are as follows:1. Evaluation of reanalysis datasets against observational soil temperature dataWe evaluated soil temperature from four reanalysis datasets, namely ERA-interim/land, MERRA-2, CFSR, and GLDAS-2.0, in terms of climatological mean, interannual variability, linear trend and memory lengths by comparison with observational data over China for 1981 to 2005. The magnitude of soil temperature averaged over the study period is generally underestimated by all four reanalysis datasets, which can be due to the limitations of models at reproducing the topographic characteristics, snow cover and land use changes. The ERA-interim/land and GLDAS-2.0 datasets have a relatively closer national mean to the observations than the MERRA-2 and CFSR datasets. For soil temperature at 40 cm, the four datasets all rebuild similar spatial distributions to the observations, and the GLDAS-2.0 dataset stands out as having a smaller bias in both summer and winter. The ERA-interim/land dataset shows a similar spatial distribution to the GLDAS-2.0 dataset for soil temperature in summer. The spatial distribution for the interannual variability of soil temperature, as characterized by standard deviation, is well reproduced by the ERA-interim/land dataset in summer and by the CFSR dataset in winter. The reanalysis products generally perform better in the east of China than in the west of China, which could be due to the fact that the orography over the west of China is much more difficult to describe than over the east of China. Furthermore, the reanalysis products perform better in winter than in summer. The estimation of summer precipitation can have an important influence on the estimation of summer soil temperature. We have demonstrated that summer soil temperature is highly correlated with the soil heat flux during April to June, and winter soil temperature is related to the soil heat flux in winter, which highlights the importance of the estimation of land surface energy balance components on the estimation of soil temperature.2. Spatiotemporal characteristics of soil temperature and soil temperature memory over the areas along the silk roadOver the areas along the silk road, the soil temperature of four reanalysis data show similar spatial patterns. And the soil temperature in four seasons also has the similar spatial distributions. Generally, the soil temperature in the areas along the silk road is decreasing as a function of latitude, except for the soil temperature over Tibet Plateau, which is relatively low because of the high altitude. The interannual variability of soil temperature at different soil depths has similar spatial pattern. The relatively large interannual variability of soil temperature is found over the surrounding area of Caspian Sea, the west border of China, the north of Pakistan, the north of Xinjiang and Mongolia, and the east area of Lake Baikal. The soil temperature memory in summer over the areas along silk road is longer than in other seasons. The soil temperature over arid–semiarid region has relatively longer memories than other regions. The spatial distributions of soil temperature memory in four seasons have some differences. In summer, the soil temperature over the west border of China, Mongolia, north China and southwest of the Caspian Sea has longer memories than in other regions, while the winter soil memory is longer over the high latitude areas, the west border of China and the west of Caspian Sea.3. The soil temperature–atmosphere interaction over Dunhuang and the causal analysis The variables of the Dunhuang station have obvious diurnal variations, except for the soil temperature at deep layer. The diurnal variation of atmospheric and surface variables is mainly influenced by the diurnal variation of solar radiation. The diurnal variation of soil tempretaue is smaller as the soil is deeper, the soil temperature of the soil deeper than 20 cm doesn’t show diurnal variation. ERA-interim data well rebuild the diurnal variation of each variable in the Dunhuang station. The variables of the Dunhuang station also show obvious annual variations. The annual variation of soil temperature is lag as the soil gets deeper. The ERA-interim data show similar annual variation of variables with observations over the Dunhuang station, while they generally underestimate the longwave radiation and overestimate the surface net radiation and sensible heat fluxes. The ERA-interim data also underestimate the soil temperature, air temperature, and skin temperature of the Dunhuang station. The variables of the Dunhuang station are coupling with each other in summer. The subsurface soil temperature is upward coupling with the variables in land surface and boundary layer, and is downward coupling with the deep soil temperature. The ERA-interim data have underestimated the coupling of soil temperature and sensible heat flux in the Dunhuang station. The soil temperature–sensible heat interaction over the Dunhuang in summer has been comfirmed by CCM.4. The characteristics of soil temperature–atmosphere interaction over the areas along the silk road and its relationship with the Silk Road Pattern The soil temperature over the areas along silk road is significant correlated with skin temperature and air temperature in summer. There are three hot spots of the correlation of preceding soil temperature and summer atmospheric variables over the areas along the silk road. The first is the southwest of the Caspian Sea, northwest of Iran. The second is the southwest of Xinjiang, west border of China, the border area of China and Kyrghyzstan, and the border area of China and Tajikistan. The third is the west of Mongolia, the east of Kazakhstan and the north of Xinjiang. Over the region with high correlation coefficients of May soil temperature and summer atmospheric variables, soil temperature plays an important role in the land surface system. Over the hot spots of soil temperature –atmosphere interaction, positive soil temperature anomalies in May can persisit into summer and induce negitave geopotential height anomalies in lower troposphere and positive geopotential height anomalies in middle troposphere. Soil temperature can influence the precipation in summer over the region where the unlocal effect is limited. The Silk Road pattern (SRP) can influence the summer soil temperature in some regions along the silk road by forcing the circulation. The effect of soil temperature on circulation is relatively independent of the impact of the SRP. The soil temperature –SRP interaction can intensify the circulation anomalies induced by the SRP. |
| 中文关键词 | 土壤温度 ; 丝绸之路沿线地区 ; 陆气相互作用 ; 多时间尺度 |
| 英文关键词 | Soil temperature the silk road land-atmosphere interaction multi-time scale |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 气象学 |
| 来源机构 | 中国科学院大气物理研究所 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/288068 |
| 推荐引用方式 GB/T 7714 | 杨凯. 丝绸之路沿线地区土壤温度-大气相互作用研究[D]. 中国科学院大学,2018. |
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