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.     

Emission of methane and nitrous oxides from agricultural soils and related global warming potentials of Murshidabad District,West Bengal

Agricultural activities emit substantial amounts of methane (CH4) and nitrous oxides (N2O), the two important greenhouse gases (GHG) with high global warming potentials (GWP). So far, many studies have already been carried out at national and state level, but lack micro‐level (district or block‐level) inventory in India. The present study sheds light on the flux of CH4 and N2O (from all possible sources) from agricultural soil of various blocks in the Murshidabad district, based on the inventory prepared, using the IPCC methodology, with adjusted emission factors and coefficients appropriate for the local level. The economy of the Murshidabad district almost completely rests on agriculture as more than 80 per cent of the population is directly or indirectly dependent on it for their livelihood. Paddy is the dominating crop, cultivated on more than 60 per cent of the gross cropped area. The present work is based on the review of various literature and reports collected from respective state government offices and websites. Results show that CH4 and N2O emission from the agricultural fields are 126.405 Gg and 0.652 Gg respectively for the year 2011?12 with a large scale spatial variation (block‐level) within the district.     

IPCC第六次评估报告中的《图集》

决策者和公众正在越来越多地关注气候变化带来的影响,而这需要更加丰富的、区域尺度上的当前和未来气候状况的精细信息.《图集》与IPCC第六次评估报告(AR6)第一工作组(WGI)报告中其他章节相协调,评估区域气候变化的观测、归因、预估的基本信息,并建立了在线交互图集系统.《图集》包含图集章节和交互图集两部分:图集章节基于新...     

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。     

Simulation of Precipitation in Monsoon Regions of China by CMIP3 Models

The output of 25 models used in the Coupled Model Intercomparison Project phase 3 （CMIP3） were evaluated, with a focus on summer precipitation in eastern China for the last 40 years of the 20th century. Most models failed to reproduce rainfall associated with the East Asian summer monsoon （EASM）, and hence the seasonal cycle in eastern China, but provided reasonable results in Southwest （SW） and Northeast China （NE）. The simulations produced reasonable results for the Yangtze-Huai （YH） Basin area, although the Meiyu phenomenon was underestimated in general. One typical regional phenomenon, a seasonal northward shift in the rain belt from early to late summer, was completely missed by most models. The long-term climate trends in rainfall over eastern China were largely underestimated, and the observed geographical pattern of rainfall changes was not reproduced by most models. Precipitation extremes were evaluated via parameters of fitted GEV （Generalized Ex- treme Values） distributions. The annual extremes were grossly underestimated in the monsoon-dominated YH and SW regions, but reasonable values were calculated for the North China （NC） and NE regions. These results suggest a general failure to capture the dynamics of the EASM in current coupled climate models. Nonetheless, models with higher resolution tend to reproduce larger decadal trends and annual extremes of precipitation in the regions studied.     

基于IPCC AR4部分耦合模式结果的21世纪长江中下游强降水预估

利用IPCC AR4气候模式诊断和相互比较项目(PCMDI)20世纪模拟试验资料, 通过模式气候态与观测(再分析)气候态的对比, 从存有完整逐日降水资料的14个模式中挑选出7个对东亚模拟较好的模式(即gfdl cm2.0、 gfdl cm2.1、 cgcm、miroc(m)、 cnrm、 echam、 cgcmt47)。然后, 利用这7个模式在A1B、 A2、 B1三种不同温室气体排放情景下21世纪预估试验结果, 分析长江中下游强降水的未来演变。结果表明: 不同模式模拟结果有较好的一致性。相对20世纪后20年(1980—1999年)的平均而言, 21世纪不仅年平均强降水日数、 单次强降水强度呈现上升趋势, 且其年际变率也增强; 就不同排放情景比较而言, A1B、 A2情景下强降水频次与强度的增强趋势均比B1情景下要大; 就多模式平均来看, 在A1B、 A2、 B1排放情景下, 强降水频次分别增加约30%、 20%、 l5％, 强降水强度分别增加约20%、20%、 10%, 强降水频次的年际标准差在三种情景下均增加约20%, 强降水强度年际标准差分别增加约20%、20%、 10%。这些结果意味着, 未来不仅强降水增加, 且极端暴雨、 大暴雨易于出现, 旱涝也将更为频繁。     

Analysis of the Decadal and Interdecadal Variations of the East Asian Winter Monsoon as Simulated by 20 Coupled Models in IPCC AR4

Using the output data of 20 coupled climate models used in IPCC AR4 and observational data from NCEP, the capability of the models to simulate the boreal winter climatology of the East Asian sea level pressure, 850-hPa wind, and surface air temperature; the decadal variations of the East Asian winter mon- soon (EAWM) intensity and EAWM-related circulation, and the interdecadal variations of EAWM-related circulation are systematically evaluated. The results indicate that 16 models can weakly simulate the declin- ing trend of the EAWM in the 1980s. More than half of the models produce relatively reasonable decadal variations of the EAWM-related circulation and the interdecadal di?erences of EAWM-related circulation between the boreal winters of 1960-1985 and 1986-1998, including the weakened Siberian high, Aleutian low, and East Asian trough, the enhanced Arctic oscillation and North Pacific oscillation, and a deepened polar vortex. It is found that the performance of the multi-selected-model ensemble in reproducing the spatial dis- tribution of the variations is encouraging, although the variational amplitudes are generally smaller than the observations. In addition, it is found that BCCR_BCM2.0, CGCM3.1_T63, CNRM_CM3, CSIRO_MK3.0, GISS-ER, INM_CM3.0, and MRI_CGCM2.3.2 perform well in every aspect     

PRINCIPES FONDAMENTAUX DE LA THEORIE DU MOUVEMENT DES EAUX SOUTERRAINES

ABSTRACT

In southeastern Arizona, almost all summer rainfall results from widely-scattered high-intensity afternoon or evening thunderstorms of limited areal extent. For eleven years of record on the Walnut Gulch Experimental Watershed, Tombstone, Arizona, about 70 percent of the annual rainfall of 11 1/2 inches and over 95 percent of the annual runoff occurred in July, August, and early September. In contrast, about 5 percent of the rainfall occurred in the previous 3 months, and about 25 percent in the remaining 6 1/2 months.

Therefore, summer rainfall, although highly variable, represented the most dependable source of water to the Walnut Gulch watershed. On the average, significant rainfall was recorded on some part of the watershed on 40 percent of the days in the critical July-August period. The maximum frequency was 3 out of every 4 days in 1955, and the minimum 3 out of every 10 days in 1960.

The wettest year was 1955, with a continuous rainy period of 47 days; whereas, the driest was 1960, with the longest rainy period lasting only 5 days. The longest summer drought during the period of record occurred in 1962, when no rain fell for 17 days in August, following a 14-day rainy period in late July.

As yet, there are not enough data to determine reliable expectancies for summer rainy or drought periods.     

Climatic control on river discharge simulations,Zackenberg River drainage basin,northeast Greenland

A spatially distributed, physically based, hydrologic modeling system (MIKE SHE) was applied to quantify intra‐ and inter‐annual discharge from the snow and glacierized Zackenberg River drainage basin (512 km²; 20% glacier cover) in northeast Greenland. Evolution of snow accumulation, distribution by wind‐blown snow, blowing‐snow sublimation, and snow and ice surface melt were simulated by a spatially distributed, physically based, snow‐evolution modelling system (SnowModel) and used as input to MIKE SHE. Discharge simulations were performed for three periods 1997–2001 (calibration period), 2001–2005 (validation period), and 2071–2100 (scenario period). The combination of SnowModel and MIKE SHE shows promising results; the timing and magnitude of simulated discharge were generally in accordance with observations (R² = 0·58); however, discrepancies between simulated and observed discharge hydrographs do occur (maximum daily difference up to 44·6 m³ s^?1 and up to 9% difference between observed and simulated cumulative discharge). The model does not perform well when a sudden outburst of glacial dammed water occurs, like the 2005 extreme flood event. The modelling study showed that soil processes related to yearly change in active layer depth and glacial processes (such as changes in yearly glacier area, seasonal changes in the internal glacier drainage system, and the sudden release of glacial bulk water storage) need to be determined, for example, from field studies and incorporated in the models before basin runoff can be quantified more precisely. The SnowModel and MIKE SHE model only include first‐order effects of climate change. For the period 2071–2100, future IPCC A2 and B2 climate scenarios based on the HIRHAM regional climate model and HadCM3 atmosphere–ocean general circulation model simulations indicated a mean annual Zackenberg runoff about 1·5 orders of magnitude greater (around 650 mmWE year^?1) than from today 1997–2005 (around 430 mmWE year^?1), mainly based on changes in negative glacier net mass balance. Copyright © 2007 John Wiley & Sons, Ltd.