Solar resonant diffusion waves as a driver of terrestrial climate change

A theory is described based on resonant thermal diffusion waves in the sun that explains many details of the paleotemperature record for the last 5.3 million years. These include the observed periodicities, the relative strengths of each observed cycle, and the sudden emergence in time for the 100 thousand year cycle. Other prior work suggesting a link between terrestrial paleoclimate and solar luminosity variations has not provided any specific mechanism. The particular mechanism described here has been demonstrated empirically, although not previously invoked in the solar context. The theory, while not without its own unresolved issues, also lacks most of the problems associated with Milankovitch cycle theory.     

Solar terminator-related ionosphere derived from GPS TEC measurements: A case study

We present a case study of ionospheric wave activity during solar terminator crossing using GPS TEC measurements. As a basic tool, the spatial gradient of total electron content (TEC) has been used. We tested with positive result the hypothesis on anisotropic response to assumed one-dimensional solar terminator forcing. The approximate drift velocity of irregularities has been computed. The wavelet analysis gave an interesting insight into variable frequency content of TEC gradient time series. We also proposed a filtering with respect to spatial scale allowing for resolving the spatio-temporal ambiguity.     

The impacts of climate extremes on the terrestrial carbon cycle:A review

The increased frequency of climate extremes in recent years has profoundly affected terrestrial ecosystem functions and the welfare of human society. The carbon cycle is a key process of terrestrial ecosystem changes. Therefore, a better understanding and assessment of the impacts of climate extremes on the terrestrial carbon cycle could provide an important scientific basis to facilitate the mitigation and adaption of our society to climate change. In this paper, we systematically review the impacts of climate extremes(e.g. drought, extreme precipitation, extreme hot and extreme cold) on terrestrial ecosystems and their mechanisms. Existing studies have suggested that drought is one of the most important stressors on the terrestrial carbon sink, and that it can inhibit both ecosystem productivity and respiration. Because ecosystem productivity is usually more sensitive to drought than respiration, drought can significantly reduce the strength of terrestrial ecosystem carbon sinks and even turn them into carbon sources. Large inter-model variations have been found in the simulations of drought-induced changes in the carbon cycle, suggesting the existence of a large gap in current understanding of the mechanisms behind the responses of ecosystem carbon balance to drought, especially for tropical vegetation. The effects of extreme precipitation on the carbon cycle vary across different regions. In general, extreme precipitation enhances carbon accumulation in arid ecosystems, but restrains carbon sequestration in moist ecosystems. However, current knowledge on the indirect effects of extreme precipitation on the carbon cycle through regulating processes such as soil carbon lateral transportation and nutrient loss is still limited. This knowledge gap has caused large uncertainties in assessing the total carbon cycle impact of extreme precipitation. Extreme hot and extreme cold can affect the terrestrial carbon cycle through various ecosystem processes. Note that the severity of such climate extremes depends greatly on their timing, which needs to be investigated thoroughly in future studies. In light of current knowledge and gaps in the understanding of how extreme climates affect the terrestrial carbon cycle, we strongly recommend that future studies should place more attention on the long-term impacts and on the driving mechanisms at different time scales.Studies based on multi-source data, methods and across multiple spatial-temporal scales, are also necessary to better characterize the response of terrestrial ecosystems to climate extremes.     

Solar forcing of the Northern hemisphere land air temperature: New data

It has previously been demonstrated that the mean land air temperature of the Northern hemisphere could adequately be associated with a long-term variation of solar activity as given by the length of the approximately 11-year solar cycle. Adding new temperature data for the 1990s and expected values for the next sunspot extrema we test whether the solar cycle length model is still adequate. We find that the residuals are now inconsistent with the pure solar model. We conclude that since around 1990 the type of Solar forcing that is described by the solar cycle length model no longer dominates the long-term variation of the Northern hemisphere land air temperature.     

A theoretical study on terrestrial gravimetric data refinement by Earth gravity models

The idea of this paper is to present estimators for combining terrestrial gravity data with Earth gravity models and produce a high‐quality source of the Earth's gravity field data through all wavelengths. To do so, integral and point‐wise estimators are mathematically developed, based on the spectral combination theory, in such a way that they combine terrestrial data with one and/or two Earth gravity models. The integral estimators are developed so that they become biased or unbiased to a priori information. For testing the quality of the estimators, their global mean square errors are generated using an Earth gravity model08 model and one of the recent products of the gravity field and steady‐state ocean circulation explorer mission. Numerical results show that the integral estimators have smaller global root mean square errors than the point‐wise ones but they are not efficient practically. The integral estimator of the biased type is the most suited due to its smallest global root mean square error comparing to the rest of the estimators. Due largely to the omission errors of Earth gravity models the point‐wise estimators are not sensitive to the Earth gravity model commission error; therefore, the use of high‐degree Earth gravity models is very influential for reduction of their root mean square errors. Also it is shown that the use of the ocean circulation explorer Earth gravity model does not significantly reduce the root mean square errors of the presented estimators in the presence of Earth gravity model08. All estimators are applied in the region of Fennoscandia and a cap size of 2° for numerical integration and a maximum degree of 2500 for generation of band‐limited kernels are found suitable for the integral estimators.     

GPS大气掩星技术在全球气候变化研究中的应用

人类活动引起全球变暖,衡量全球气候变化的指标有陆地、大气和海洋温度,水汽含量等等.研究对流层底层大气温度和水汽含量变化的传统方法是用数值天气预报模型和微波声纳,尚未实现用全球均匀覆盖的数据来做精确的定量研究.和GNSS系列卫星计划比较,最近发射的COSMIC卫星气象探测数据的空间、时间以及垂直分辨率都大大提高.采用COSMIC数据可以改进和量化南极洲的大气压力模型,并综合GNSS系列卫星测量的水汽和温度剖面研究全球气候变化.用一维协方差算法估计南极洲及附近海洋的大气压、温度和湿度剖面.把COSMIC卫星密集测量期间演算得到的大气折射率和GNSS系列卫星的结果进行比较.再和独立测量数据进行比较,包括南极洲自动气象观测站资料,数值天气预报模型资料,多种测高卫星水汽资料和海洋表面温度资料以及区域GPS水汽图.上述工作将改进发展中的气象遥感技术并应用于天气预报和空间天气预报及全球气候变化研究.     

Solar cosmic rays: 70 years of ground-based observations

The main data have been summarized, and the results, achieved using data from the worldwide network during the entire period of ground-based observations of solar cosmic rays (SCRs) from February 28, 1942, when they were discovered, have been generalized. The methods and equipment for registering SCRs have been described. The physical, methodical, and applied aspects, related to the SCR generation, as well as the SCR interaction with the solar atmosphere, transport in the IMF, motion in the Earth’s magnetosphere, and the affect on the Earth’s atmosphere, have been discussed. It has been indicated that the fundamental results were achieved in this field of space physics during 70 years of studies. Special attention has been paid to up-to-date models and concepts of ground-level enhancement (GLE). The most promising tendencies in the development and application of this effective method of solar-terrestrial physics have been outlined.     

与日夜交替线移动相关的中尺度电离层扰动GPS网观测

本文选取由国际GPS服务中心(IGS)提供的北美中纬度地区GPS网TEC观测数据,通过多通道最大熵频谱分析方法研究了2005年（太阳活动低年）地磁活动平静期间日出和日落时由于日夜交替线的移动而激发的中尺度电离层扰动(MSTID),并统计分析其季节变化特性.结果表明：(1) 日出或日落期间,在中纬度地区经常观测到由日夜交替线移动激发的中尺度电离层扰动.扰动主要沿日夜交替线运动方向传播,平均持续时间约2～3 h;振幅在0.2～0.8 TECU之间,水平波长,水平相速度和周期分别为300±150 km,150±80 m/s和25±15 min;(2) 由日夜交替线移动激发的中尺度电离层扰动在春秋分出现率较少;在夏季,扰动在黄昏时出现率达最大值,在日出后少量出现;而冬季则日出后的扰动效应更为明显.分析表明,在中纬地区,这种扰动出现率随季节的变化与不同季节的日出日落时刻太阳EUV辐射通量变化过程的快慢,以及电离层中离子损失过程快慢有关.     

Modeling of climate tendencies in Arctic seas based on atmospheric forcing EOF decomposition

Ocean Dynamics - The article analyzes the results of the EOF decomposition of climatic data and assesses the role of its components in the formation of climatic ice tendencies of recent decades....     

古今气候略论

自2009年入冬以来北半球经受了创记录的严寒侵袭,联合国IPCC报告的权威性受到质疑。地球气候变化趋向陷入纷争的境地。从地质学和考古学的视角,以更长的时间周期去认识和了解气候变化规律和成因机制,或许对将来气候的长期预报有所启示。地球在漫长的演化史中经历了以千万年计的＂地质气候旋回＂、千百年计的＂史前气候周期＂及近现代以百年计的＂世纪气候波动＂。不同级次的周期均为内在自然因素所制约,CO2含量在地球演化史中趋于波动下降过程,当代的CO2浓度和气温均处于地质史的低点。人类活动可能在百年尺度内存在对气候和生态环境的影响。自20世纪初开始至今近百年升温趋向中,令人关注的是在中国曾有1941年、1969年、2009~2010年之交极度低温的出现,＂低温节点＂时距约为30~40年,似与海洋存在数十年为变化周期之说相近。由此引发对人为因素导致持续增温的质疑。2009年入冬以来的严寒是否为近百年升温波动周期的终结抑或只是次级的突变因素所致,尚有待观察。但自然因素主导的周期波动规律不可逆转,不能被未经实证而被夸大了的＂人为因素＂所左右。     

Recent advances on surface ground deformation measurement by means of repeated space-borne SAR observations

Space-borne Synthetic Aperture Radar interferometry (INSAR) is a well known widely used remote sensing technique to get precise (sub-centimetric) surface deformation measurements on large areas (thousands of km²) and high spatial density of measurement points (hundreds per km²). In this work the recent technological advances of this technique are presented. First, a short review of the INSAR basics is dedicated to readers who are not INSAR specialists. Then, an analysis of the improvement of ground motion measurement offered by multiple repeated space-borne SAR observations gathered by the new generation of high resolution SAR systems is given. An example obtained with the recent German TERRASAR-X system is shown and compared with the measurements obtained with the elder C-band RADARSAT-1 system. Finally, a possible processing of multi-temporal analysis of SAR images that allow extracting ground motion information also from partially coherent targets is given. In this case the core idea is to relax the restrictive conditions imposed by the Permanent Scatterers technique. The results obtained in different test-sites show an increased spatial density of areal deformation trend measurements, especially in extra-urban areas at the cost of missing motions with strong velocity variation.     

Epicenter and magnitude of large earthquake determined from high-rate GPS observations: A case study of the 2008 M8.0 Wenchuan earthquake

For earthquake and tsunami early warning and emergency response,the earthquake epicenter and magnitude should be determined rapidly and correctly.Using high-rate GPS observations,we can readily obtain precise and high resolution displacement time series and the seismic waveforms during the earthquake.In this paper,a new algorithm is proposed for estimating the earthquake epicenter and magnitude with the seismic waveforms derived from high-rate GPS data during the earthquake.A case study of the 2008 Wenchuan earthquake is conducted from 1 Hz GPS data and the epicenter and magnitude are determined.Compared with the results issued by the China Seismological Bureau,the estimation error of the epicenter and the magnitude is about 12 km and 0.1 magnitude unit,respectively.It has shown that high-rate GPS could be a new tool feasible for estimating the earthquake epicenter and magnitude,independent of or combined with seismometers.     

Millennial reconstruction of the global terrestrial climate: New approaches to the available data

The main aim of the work was to reliably reconstruct the change in global temperature for the last 1000 years using new methods. We have considered two approaches to obtaining composite series based on symbolic analysis and on the so-called ??principle of witnesses,?? respectively. Based on the first approach, it has been indicated that the known reconstruction proposed by Moberg et al. is preferable in the scope of the accepted symbolic analysis variant among the available reconstructions. An approach based on the eyewitness principle made it possible to reveal the years when five different reconstructions give coordinated data on a 1000-year scale. The obtained new reconstructions are in good agreement with instrumental series data on the consistent time interval of their existence.     

全新世初期气候的数值模拟研究

本文尝试用一个完全耦合的大气-海洋-植被模式(Atmosphere-Ocean-Vegetation General Circulation Model, AOVGCM)模拟全新世初期的地球气候.模拟结果表明,耦合模式成功地再现了全新世初期复杂气候条件下的基本特征,为研究这一时期的气候状况提供了重要的模型支持.就全球平均而言,11ka BP冬季地表气温比现代约低1.6 K,夏季比现代低约0.3 K;大气温度从低层到高层有不同的表现,高层反映了太阳辐射的重要作用,而低层气候对下垫面（如冰川、植被和海洋等）的影响比较敏感.从区域分布来看,11 ka BP冬季大部地区比现在偏干,但热带太平洋和南半球少部地区降水偏多;夏季大部地区比现在偏湿,亚洲和非洲季风偏强,主要的季风区降水偏多.     

Solar flare model: Comparison of the results of numerical simulations and observations

The electrodynamic flare model is based on numerical 3D simulations with the real magnetic field of an active region. An energy of ∼10³² erg necessary for a solar flare is shown to accumulate in the magnetic field of a coronal current sheet. The thermal X-ray source in the corona results from plasma heating in the current sheet upon reconnection. The hard X-ray sources are located on the solar surface at the loop foot-points. They are produced by the precipitation of electron beams accelerated in field-aligned currents. Solar cosmic rays appear upon acceleration in the electric field along a singular magnetic X-type line. The generation mechanism of the delayed cosmic-ray component is also discussed.     

Fluctuations of the GPS signals on the tangential paths in the lower terrestrial atmosphere: Influence of the small-scale structure

The small-scale structure of the refractivity distribution due to water vapor density fluctuations in the terrestrial troposphere and lower stratosphere is modeled. Propagation of the signals in the troposphere and lower stratosphere are numerically simulated on the basis of the parabolic equation of diffraction and for occultation geometry. Fluctuations of the signal amplitude on the tangential paths due to small-scale inhomogeneities of the atmospheric refractivity are estimated.     

利用GPS垂直位移反演区域陆地水储量变化的TSVD-Tikhonov正则化方法

利用GPS垂直位移反演区域陆地水储量变化（TWSC）属于典型的病态问题,其关键是如何进行稳定求解并提高反演结果的精度和可靠性.本文引入TSVD-Tikhonov组合正则化方法对利用GPS垂直位移反演区域TWSC的病态问题进行求解,并以四川省TWSC反演为例进行分析与验证.首先,通过数值模拟对TSVD、Tikhonov和TSVD-Tikhonov正则化方法采用不同正则化参数选取策略（RMSE最小准则、GCV法和L-curve法）进行反演,结果显示基于TSVD-Tikhonov正则化反演的TWSC比单独使用TSVD或Tikhonov正则化反演结果的精度和可靠性更高,这三种正则化方法反演2005年1月至12月的TWSC差值的平均STD分别为14.97 mm、7.03 mm和5.04 mm.其次,利用中国地壳运动观测网络（CMONOC）的72个GPS测站的垂直位移数据,基于TSVD-Tikhonov正则化反演了四川省2010年12月至2021年2月的TWSC时间序列,结果表明GPS反演的TWSC与GRACE/GFO Mascon模型（JPL、CSR和GSFC）的空间分布特征及季节性变化符合较好,但其TWSC信号的振幅比GRACE/GFO Mascon模型更强.最后,采用广义三角帽方法（GTCH）融合不同类型的降水、蒸散发和径流数据,并根据水量平衡方程计算的dTWSC/dt序列（PER-dS/dt）对GPS反演的dTWSC/dt序列（GPS-dS/dt）和GRACE/GFO Mascon模型融合的dTWSC/dt序列（GRACE/GFO-dS/dt）进行验证,结果表明这三类dTWSC/dt序列的季节性变化符合较好,平滑后GPS-dS/dt和GRACE/GFO-dS/dt序列与PER-dS/dt序列的相关系数分别为0.78和0.87,但GPS相比GRACE/GFO对降水变化的响应更为敏感.本文研究证明了TSVD-Tikhonov组合正则化方法能够提高GPS垂直位移反演区域TWSC的精度和可靠性,同时也表明GPS观测数据对局部水质量负荷变化更为敏感,可作为GRACE/GFO反演区域TWSC的有益补充.

     

A precise velocity field of tectonic deformation in China as inferred from intensive GPS observations

##正##Active tectonics, e.g., faulting, folding, and rifting are clearly manifested over the vast territory of China. The in-tensive crustal deformation with long-lived structures has given rise to numerous highly-elevated mountains in the western China with the Yangtze and Yellow rivers downstreaming to the east,     

Projected 21st century climate change on snow conditions over Shasta Dam watershed by means of dynamical downscaling

Snow is an important component of the Earth's climate system and is particularly vulnerable to global warming. It has been suggested that warmer temperatures may cause significant declines in snow water content and snow cover duration. In this study, snowfall and snowmelt were projected by means of a regional climate model that was coupled to a physically based snow model over Shasta Dam watershed to assess changes in snow water content and snow cover duration during the 21st century. This physically based snow model requires both physical data and future climate projections. These physical data include topography, soils, vegetation, and land use/land cover, which were collected from associated organizations. The future climate projections were dynamically downscaled by means of the regional climate model under 4 emission scenarios simulated by 2 general circulation models (fifth‐generation of the ECHAM general circulation model and the third‐generation atmospheric general circulation model). The downscaled future projections were bias corrected before projecting snowfall and snowmelt processes over Shasta Dam watershed during 2010–2099. This study's results agree with those of previous studies that projected snow water equivalent is decreasing by 50–80% whereas the fraction of precipitation falling as snowfall is decreasing by 15% to 20%. The obtained projection results show that future snow water content will change in both time and space. Furthermore, the results confirm that physical data such as topography, land cover, and atmospheric–hydrologic data are instrumental in the studies on the impact of climate change on the water resources of a region.     

A study of GPS ionospheric scintillations observed at Guilin

The occurrence of strong ionospheric scintillations with S4≥0.2 was studied using global positioning system (GPS) measurements at Guilin (25.29°N, 110.33°E; geomagnetic: 15.04°N, 181.98°E), a station located near the northern crest of equatorial anomaly in China. The results are presented for data collected from January 2007 to December 2008. The results show that amplitude scintillations occurred only during the first five months of the considered years. Nighttime amplitude scintillations, observed mainly in the south of Guilin, always occurred with phase scintillations, total electron content (TEC) depletions, and Rate Of change of TEC (ROT) fluctuations. However, TEC depletions and ROT fluctuations were weak during daytime amplitude scintillations, and daytime amplitude scintillations usually occurred in most of the azimuth directions. GPS scintillation/TEC observations recorded at Guilin and signal-to-noise-ratio measurements obtained from GPS-COSMIC radio occultation indicate that nighttime and daytime scintillations are very likely caused by ionospheric F region irregularities and sporadic E, respectively.