A new ice sheet model validated by remote sensing of the Greenland ice sheet

Accurate prediction of future sea level rise requires models that accurately reproduce and explain the recent observed dramatic ice sheet behaviours. This study presents a new multi-phase, multiple-rheology, scalable and extensible geofluid model of the Greenland ice sheet that shows the credential of successfully reproducing the mass loss rate derived from the Gravity Recovery and Climate Experiment (GRACE), and the microwave remote sensed surface melt area over the past decade. Model simulated early 21st century surface ice flow compares satisfactorily with InSAR measurements. Accurate simulation of the three metrics simultaneously cannot be explained by fortunate model tuning and give us confidence in using this modelling system for projection of the future fate of Greenland Ice Sheet (GrIS). Based on this fully adaptable three dimensional, thermo-mechanically coupled prognostic ice model, we examined the flow sensitivity to granular basal sliding, and further identified that this leads to a positive feedback contributing to enhanced mass loss in a future warming climate. The rheological properties of ice depend sensitively on its temperature, thus we further verified modelâ?s temperature solver against in situ observations. Driven by the NCEP/NCAR reanalysis atmospheric parameters, the ice model simulated GrIS mass loss rate compares favourably with that derived from the GRACE measurements, or about ?147 km³/yr over the 2002–2008 period. Increase of the summer maximum melt area extent (SME) is indicative of expansion of the ablation zone. The modeled SME from year 1979 to 2006 compares well with the cross-polarized gradient ratio method (XPGR) observed melt area in terms of annual variabilities. A high correlation of 0.88 is found between the two time series. In the 30-year model simulation series, the surface melt exhibited large inter-annual and decadal variability, years 2002, 2005 and 2007 being three significant recent melt episodes.     

影响副高活动的热力强迫作用——动力学解析模型

采用最优化搜索方法,对影响副高活动的东亚季风区位势场和季风雨带降水场进行了函数拟合,并用拟合出的函数作为基函数和热力强迫因子代入正压涡度方程,对涡度方程解的性质进行了讨论。分析和模拟结果表明:中心位于我国华北一带东亚季风雨带凝结潜热释放易导致副高的西伸和北抬;而中心位于赤道附近的南海季风槽降水热力作用可导致副高出现东退和西伸两种可能。     

Development and carbon sequestration of tropical peat domes in south-east Asia: links to post-glacial sea-level changes and Holocene climate variability

Tropical peatlands of SE-Asia represent a significant terrestrial carbon reservoir of an estimated 65 Gt C. In this paper we present a comprehensive data synthesis of radiocarbon dated peat profiles and 31 basal dates of ombrogenous peat domes from the lowlands of Peninsular Malaysia, Sumatra and Borneo and integrate our peatland data with records of past sea-level and climate change in the region. Based on their developmental features three peat dome regions were distinguished: inland Central Kalimantan (Borneo), Kutai basin (Borneo) and coastal areas across the entire region. With the onset of the Holocene the first peat domes developed in Central Kalimantan as a response to rapid post-glacial sea-level rise over the Sunda Shelf and intensification of the Asian monsoon. Peat accumulation rates in Central Kalimantan strongly declined after 8500 cal BP in close relation to the lowering rate of the sea-level rise and possibly influenced by the regional impact of the 8.2 ka event. Peat growth in Central Kalimantan apparently ceased during the Late Holocene in association with amplified El Niño activity as exemplified by several truncated peat profiles. Peat domes from the Kutai basin are all younger than ～8300 cal BP. Peat formation and rates of peat accumulation were driven by accretion rates of the Mahakam River and seemingly independent of climate. Most coastal peat domes, the largest expanse of SE-Asian peatlands, initiated between 7000 and 4000 cal BP as a consequence of a Holocene maximum in regional rainfall and the stabilisation and subsequent regression of the sea-level. These boundary conditions induced the highest rates of peat accumulation of coastal peat domes. The Late Holocene sea-level regression led to extensive new land availability that allowed for continued coastal peat dome formation until the present. The time weighted mean Holocene peat accumulation rate is 0.54 mm yr^?1 for Central Kalimantan, 1.89 mm yr^?1 for Kutai and 1.77 mm yr^?1 for coastal domes of Sumatra and Borneo. The mean Holocene carbon sequestration rates amount to 31.3 g C m^?2 yr^?1 for Central Kalimantan and 77.0 g C m^?2 yr^?1 for coastal sites, which makes coastal peat domes of south-east Asia the spatially most efficient terrestrial ecosystem in terms of long term carbon sequestration.     

ON CHANGES OF CHINA'S MAXIMUM AND MINIMUM TEMPERATURES IN 1951——1990

Based on China's observational data in 1951-1990,after minimizing the possible biasescaused by station relocation and urban heat island,the spatial and temporal distributions of trendsfor maximum and minimum temperatures are studied.The results show that increasing trends ofmaximum temperatures are in the areas west to 95°E,and north to the Huanghe(Yellow)River,while decreasing trends exist in eastern China south to the Yellow River.Minimum temperaturesare generally increasing throughout China,with dominant warming trends at the higher latitudes.This resulted in very obvious decreasing trends in diurnal temperature ranges.The periodic cycles are consistent between the maximum and minimum temperatures,butasymmetric trends are very obvious.The significant increase of minimum(nighttime)temperaturesreflects the evidence of enhancement of greenhouse effect.Further analysis shows that the changesof maximum and minimum temperatures are mainly related to sunshine duration and atmosphericwater vapor content.     

湖北省郧县恐龙化石分布地区古地磁学初步研究

湖北郧县梅铺－带晚白垩世地层以盛产恐龙化石闻名于国内外，在大量地质工作研究的基础上进行了古地磁学研究，给出了该区的古应力方向，为该区建立国家地质公园和地质科学考察研究中心、地学科普教育基地提供了基础参考数据。     

应用探地雷达技术检测隧道衬砌质量

介绍了应用探地雷达检测隧道衬砌质量的原理及技术,阐述了该技术的基本方法及其数据图像处理过程。老木峪隧道衬砌质量检测结果表明,应用探地雷达技术检测隧道衬砌效果良好,其衬砌厚度检测误差在 5 %之内,并能准确检测出衬砌内布筋数量,对回填层密实程度也可作出粗略估计。     

河西内陆河地表水与地下水转化及水资源利用率研究

河西内陆河水资源产生于祁连山区 ,河流出山以后依次穿越山前洪积扇、走廊南部盆地、北部盆地 ,最后进入尾闾湖 .由于山前洪积扇、南北盆地及河床具有良好的通透性和巨大的蓄水能力使地表水易于转化为地下水 ,出山水量的很大一部分渗入地下避免无效蒸散损耗 ;同时由于特殊的串珠状水文地质盆地构造 ,水资源具有同源性和多次转化特点 ,使水资源的利用率大大提高 .研究表明 ,1999年河西水资源总量为 6 3 79× 10 8m3 ,其中 ,地表水资源量为 5 8 36× 10 8m3 ,地下水资源量为 5 6 39× 10 5m3 ,地表水与地下水重复计算量高达 5 0 96× 10 5m3 .三个流域水资源利用率达到 6 1 4%～ 2 11%     

STUDY ON DYNAMICS OF TROPICAL CISK-ROSSBY WAVES AND MECHANISM OF 30-50 DAY OSCILLATIONS

To add to the growing mature research on the tropical 30-50 day oscillations from a new prospective, the current work bases on dynamic analysis of baroclinic quasi-geostrophic models to discuss dynamic mechanisms for the generation and propagation of CISK-Rossby waves, and to understand restraints and effects of different wave structures and thermodynamic forcing on the 30-50 day oscillations in the tropical atmosphere. Some important properties of the oscillation propagation have been explained and, in detail, with respect to its meridional propagation and vertical “baroclinic” structure. The work has come up with some new opinions and viewpoints. New opinions about the propagation and energy dispersion are to be proved by more observations and study.