新疆河流年径流量对夏季0C层高度变化的响应

According to climate features and river runoff conditions, Xinjiang could be divided into three research areas: The Altay-Tacheng region, the Tianshan Mountain region and the northern slope of the Kunlun Mountains. Utilizing daily observations from 12 sounding stations and the annual runoff dataset from 34 hydrographical stations in Xinjiang for the period 1960-2002, the variance of the summertime 0℃ level height and the changing trends of river runoff are analyzed both qualitatively and quantitatively, through trend contrast of curves processed by a 5-point smoothing procedure and linear correlation. The variance of the summertime 0℃ level height in Xinjiang correlates well with that of the annual river runoff,especially since the early 1990s, but it differs from region to region, with both the average height of the 0℃ level and runoff quantity significantly increasing over time in the Altay-Tacheng and Tianshan Mountain regions but decreasing on the northern slope of the Kunlun Mountains. The correlation holds for the whole of Xinjiang as well as the three individual regions, with a 0.01 significance level. This indicates that in recent years, climate change in Xinjiang has affected not only the surface layer but also the upper levels of the atmosphere, and this raising and lowering of the summertime 0℃ level has a direct impact on the warming and wetting process in Xinjiang and the amount of river runoff. Warming due to climate change increases the height of the 0℃ level, but also speeds up, ice-snow melting in mountain regions, which in turn increases river runoff, leading to a season of plentiful water instead of the more normal low flow period.     

Future Changes in the Relationship Between the South and East Asian Summer Monsoons in CMIP6 Models

The future changes in the relationship between the South Asian summer monsoon (SASM) and the East Asian summer monsoon (EASM) are investigated by using the high-emissions Shared Socioeconomic Pathway 5-8.5 (SSP5- 8.5) experiments from 26 coupled models that participated in the phase 6 of the Coupled Model Intercomparison Project (CMIP6). Six models, selected based on their best performance in simulating the upper- and lower-level pathways related to the SASM-EASM teleconnection in the historical run, can capture the positive relationship between the SASM and the rainfall over northern China. In the future scenario, the upper-level teleconnection wave pattern connecting the SASM and the EASM exhibits a significant weakening trend, due to the rainfall anomalies decrease over the northern Indian Peninsula in the future. At the lower level, the western North Pacific anticyclone is projected to strengthen in the warming climate. The positive (negative) rainfall anomalies associated with positive (negative) SASM rainfall anomalies are anticipated to extend southward from northern China to the Yangtze-Huai River valley, the Korea Peninsula, and southern Japan. The connection in the lower-level pathway may be strengthened in the future.     

An Exploration of the Interplay between the Measurement Uncertainty and the Number of Samples in Contaminated Land Investigations

In the assessment of potentially contaminated land, the number of samples and the uncertainty of the measurements (including that from sampling) are both important factors in the planning and implementation of an investigation. Both parameters also effect the interpretation of the measurements produced, and the process of making decisions based upon those measurements. However, despite their importance, previously there has been no method for assessing if an investigation is fit‐for‐purpose with respect to both of these parameters. The Whole Site Optimised Contaminated Land Investigation (WSOCLI) method has been developed to address this issue, and to allow the optimisation of an investigation with respect to both the number of samples and the measurement uncertainty, using an economic loss function. This function was developed to calculate an ‘expectation of (financial) loss’, incorporating costs of the investigation itself, subsequent land remediation, and potential consequential costs. To allow the evaluation of the WSOCLI method a computer program ‘OCLISIM’ has been developed to produce sample data from simulated contaminated land investigations. One advantage of such an approach is that as the ‘true’ contaminant concentrations are created by the program, these values are known, which is not the case in a real contaminated land investigation. This enables direct comparisons between functions of the ‘true’ concentrations and functions of the simulated measurements. A second advantage of simulation for this purpose is that the WSOCLI method can be tested on many different patterns and intensities of contamination. The WSOCLI method performed particularly well at high sampling densities producing expectations of financial loss that approximated to the true costs, which were also calculated by the program. WSOCLI was shown to produce notable trends in the relationship between the overall cost (i.e., expectation of loss) and both the number of samples and the measurement uncertainty, which are: (a) low measurement uncertainty was optimal when the decision threshold was between the mean background and the mean hot spot concentrations. (b) When the hot spot mean concentration is equal to or near the decision threshold, then mid‐range measurement uncertainties were optimal. (c) When the decision threshold exceeds the mean of the hot spot, mid‐range measurement uncertainties were optimal. The trends indicate that the uncertainty may continue to rise if the difference between hot spot mean and the decision threshold increases further. (d) In any of the above scenarios, the optimal measurement uncertainty was lower if there is a large geochemical variance (i.e., heterogeneity) within the hot spot. (e) The optimal number of samples for each scenario was indicated by the WSOCLI method, and was between 50 and 100 for the scenarios considered generally; although there was significant noise in the predictions, which needs to be addressed in future work to allow such conclusions to be clearer.     

物理过程参数化方案对中国夏季降水日变化模拟的影响

国际耦合模式比较计划第六阶段(CMIP6)新增的高分辨率模式比较计划(HighResMIP)首次提供全球高分辨率(25—50 km)多模式集合的气候模拟试验结果。利用8个CMIP6 HighResMIP模式评估了高分辨率全球气候模式对青藏高原夏季小时降水与极端降水的模拟能力,结果表明：CMIP6高分辨率模式高(低)估了青藏高原地区的降水量和频率(强度),过多的降水量主要来自模式对降水频率的高估,尤其是弱降水(< 2 mm·h^-1)的发生频率。模拟偏差与地形海拔密切相关,偏差大值区主要位于高原南坡和东坡陡峭地形区。模式不能准确再现降水量与海拔之间的关系,高(低)估了高(低)海拔地区的降水量。模式低估了降水强度随海拔升高而降低的变化速率。在日变化方面,模式能够模拟出青藏高原降水傍晚至午夜的峰值特征,但明显低估了降水的日变化振幅。在小时极端降水方面,模式低估了高原区域平均极端降水第95百分位数阈值,仅为观测值的57%。

     

Interpretation of IPCC AR6 on buildings北大核心CSCD

IPCC于2022年4月正式发布了第六次评估报告(AR6)第三工作组(WGⅢ)报告《气候变化2022:减缓气候变化》,该报告以已发布的第一和第二工作组报告作为基础,评估了各领域减缓气候变化的进展。报告的第九章建筑章节系统全面地评估了全球建筑领域的温室气体排放现状、趋势和驱动因素,综述并评估了建筑减缓气候变化的措施、潜力、成本和政策。报告主要结论认为,全球建筑领域有可能在2050年实现温室气体净零排放,但如果政策措施执行不力,将有可能在建筑领域形成长达几十年的高碳锁定效应。报告的主要结论将成为全球建筑领域应对气候变化行动的重要参考,对于我国建筑领域实现碳达峰、碳中和目标也有非常重要的借鉴意义。     

CAS FGOALS-g3 Model Datasets for the CMIP6 Scenario Model Intercomparison Project(ScenarioMIP)

This paper describes the datasets from the Scenario Model Intercomparison Project(ScenarioMIP) simulation experiments run with the Chinese Academy of Sciences Flexible Global Ocean–Atmosphere–Land System Model,GridPoint version 3(CAS FGOALS-g3). FGOALS-g3 is driven by eight shared socioeconomic pathways(SSPs) with different sets of future emission, concentration, and land-use scenarios. All Tier 1 and 2 experiments were carried out and were initialized using historical runs. A branch run method ...     

滇西变泥质岩的白云母b_0值及其构造－地层意义

据３３３个白云母ｂ０值，结合区域地层和构造的研究成果，提出：（１）原称昌宁－孟连变质带解体为西盟－勐统变质带（加里东期中压变质带）和澜沧双变质带的高压亚带，两期高压变质作用分别与海西－印支期的洋壳消减和陆－陆碰撞有关；（２）石鼓变质带是三个逆冲岩片的叠置，各岩片内岩石的变质作用各具特色；（３）金沙江洋盆为地块间小洋盆，其消减及嗣后的弧－弧碰撞可能不产生高压变质作用。在此基础上探讨了白云母ｂ０值在造山带研究中的意义。     

Surface air temperature changes over the Tibetan Plateau: Historical evaluation and future projection based on CMIP6 models

With its amplification simultaneously emerging in cryospheric regions, especially in the Tibetan Plateau, global warming is undoubtedly occurring. In this study, we utilized 28 global climate models to assess model performance regarding surface air temperature over the Tibetan Plateau from 1961 to 2014, reported spatiotemporal variability in surface air temperature in the future under four scenarios (SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5), and further quantified the timing of warming levels (1.5, 2, and 3 °C) in the region. The results show that the multimodel ensemble means depicted the spatiotemporal patterns of surface air temperature for the past decades well, although with differences across individual models. The projected surface air temperature, by 2099, would warm by 1.9, 3.2, 5.2, and 6.3 °C relative to the reference period (1981–2010), with increasing rates of 0.11, 0.31, 0.53, and 0.70 °C/decade under the SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5 scenarios for the period 2015–2099, respectively. Compared with the preindustrial periods (1850–1900), the mean annual surface air temperature over the Tibetan Plateau has hit the 1.5 °C threshold and will break 2 °C in the next decade, but there is still a chance to limit the temperature below 3 °C in this century. Our study provides a new understanding of climate warming in high mountain areas and implies the urgent need to achieve carbon neutrality.     

The rapidly shrinking cryopshere in the past decade：an interpretation of cryospheric changes from IPCC WGI Sixth Assessment Report北大核心CSCD

The Working Group I report of the Sixth Assessment Report（AR6）of the Intergovernmental Panel on Climate Change（IPCC）was released in August 2021. Base on updated and expanding data, AR6 presented the improved assessment of past changes and processes of cryosphere. AR6 also predicted the future changes us⁃ ing the models in CMIP6. The components of cryosphere were rapid shrinking under climate warming in the last decade. There were decreasing trends in Arctic sea-ice area and thickness. Sea-ice loss was significant. The Greenland Ice Sheet, the Antarctic Ice Sheet and all glaciers lost more mass than in any other decade. Global warming over the last decades had led to widespread permafrost warming, active layer thickness increasing and subsea permafrost extent reducing. Snow cover extent in the Northern Hemisphere also decreased significantly. However, the variations of snow depth and snow water equivalent showed great spatial heterogeneity. The rapid shrinking of the cryosphere accelerated the global mean sea level rise. The impact of human activities on cryo⁃ sphere will become more significant in the future. The Arctic sea-ice area will decrease, and the Arctic Ocean will likely become practically sea ice-free. The Greenland Ice Sheet, the Antarctic Ice Sheet and glaciers will continue to lose mass throughout this century. Permafrost and Northern Hemisphere snow cover extent will con⁃ tinue to decrease as global climate continues to warm. In addition, there are still uncertainties in the prediction of cryosphere due to the absence of observations, the poor sensitivity of models to the components and processes of cryosphere, and the inexplicit represent of the mechanism of light-absorbing impurities. More attentions should be paid on these issues in the future. © 2022 Science Press (China). All rights reserved.     

温度、浓度对流体中氟钛络合物水解的影响:对深部地质过程中钛元素活动的制约

Ti是自然界中丰度最高的高场强元素(HFSE),其主要赋存矿物——金红石的溶解度决定了俯冲带HFSE的活动与循环。而富氟流体被认为是影响Ti等HFSE能否活化、迁移的重要因素。本文对不同浓度的氟钛络合物(K2Ti F6)在100MPa压力和200~500℃温度下的稳定性进行了研究,结果显示其在热液条件下发生显著水解,水解程度与温度和初始浓度密切相关,即温度越高、初始浓度越低,则水解程度越剧烈。对实验数据进行拟合,首次获得了K2Ti F6的表观水解常数与温度的关系式:-ln K=(8972±788)/T-(4.16428±1.40362),其中获得的热力学参数为:ΔrHΘ=74.59±6.55k J/mol,ΔrSΘ=34.62±11.67J/(mol·K)。同时,运用上述获得的关系式将温度推广到俯冲带条件,计算了金红石溶解度和流体中Ti的最大迁移量之间的关系。结果显示,当金红石的溶解度大于1000μg/m L时,富F流体能有效迁移的Ti大于1μg/m L;随着金红石溶解度的增加,Ti的有效迁移百分比也逐渐增大,但俯冲流体中Ti的最大迁移量可能不超过6700μg/m L,比之前的预计要低得多。本文的研究证实了富F流体能最大程度活化并迁移Ti等HFSE。其中,对于岩浆-热液体系而言,F主要通过在岩浆中预富集,然后再大量分配进入晚期流体中而形成富F流体;对于俯冲带而言,多硅白云母的脱水或热解是形成富F流体/超临界流体的有效途径。