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Droughts and floods are two longstanding and devastating climatic threats to mankind. They are challenging to predict mainly due to the significant spatial and temporal variations of precipitation. Using historical archives back from 1646 CE, here we present a high-resolution catchment level dataset of droughts and floods in the southern Chinese Loess Plateau (hereafter, CLP) within the middle reaches of River Jing. We have analysed the occurrences of floods and droughts based a specially-developed statistics from historical archives, as well as the daily rainfall from present-day observations within the catchment. Overall, our results show that the frequency of droughts and floods in the region is synchronous on decadal timescales with solar activities and the Pacific Decadal Oscillation (hereafter, PDO) index, and they are also broadly in phase with changes in both global and regional reconstructed temperatures. At decadal to interannual timescales, PDO and El Nino and Southern Oscillation (hereafter, ENSO) drive an uneven distribution of precipitation in different seasons in the southern CLP, which could be one of the reasons for the strong association of floods and droughts with the PDO and ENSO signals in our catchment. If the global temperature continues to rise in the future, we expect that the risk of both droughts and floods in the study region will also increase.

There has been a sustained need to quantify past climate changes from proxy records to better understand the driving mechanisms and thus to improve the prediction of the future. Transfer function is an intuitive and frequently used method in this regard. However, this method is unable to provide interpretive and predictive results from proxy records, because physical processes are not included. The inverse proxy modelling method opened up a new avenue for quantitative palaeoclimate reconstructions through the integration of proxy records with deterministic models. It is fundamentally different from the statistical approach, representing a conceptual advance in quantitative palaeoclimatology. Here we demonstrate the potential of this method by placing a mechanistic model and a 6000 year long peat cellulose δ18O record obtained from the high-cold and monsoonal eastern Tibetan Plateau ( c. 3500 m a.s.l.) in a Bayesian paradigm. In this worked example, the marginal posterior probability distributions of palaeoclimate variables such as the δ18O of soil water, temperature, and relative humidity were inferred jointly through the solution to an ill-posed inverse problem using the Markov chain-Monte Carlo method. Our results indicate that the observed variation of the peat cellulose δ18O record in this monsoonal area essentially reflects the changes in the oxygen isotopic composition of soil water, which is closely linked to that of rainfall. Compared with hydrology, temperature and humidity have little influence on the oxygen isotope fractionation of leaf water.

Previous sedimentological studies on peat sequences from the eastern Tibetan Plateau showed that there have been eolian dust inputs to the wetlands on the eastern Tibetan Plateau, thereby providing an opportunity to reconstruct the history of the Asian winter monsoon at a higher temporal resolution. Here the dust flux and the content of trace metallic elements (Ti, Ni, and V) in a peat sequence from the Hongyuan Swamp (32°46.7′N, 102°31.0′E) are used to reconstruct variations in the intensity of the Asian winter monsoon during the Holocene. This record, when compared with the summer monsoon proxy, can help elucidate the phase relationship between these two systems. Our proxy-based reconstructions show different patterns of changes in the Asian winter and summer monsoons before and after 5.5 cal. ka BP. Generally, the two monsoons varied reciprocally before 5.5 cal. ka BP; however, after 5.5 cal. ka BP, these two systems exhibit synchronous changes. Moreover, both the frequency and amplitude of the variations in these two monsoons are different before and after 5.5 cal. ka BP. The rate of changes in the solar insolation during the Holocene matches well with these monsoon records, implying that the mid-Holocene climate transition may have resulted from orbital forcing.

Technological and theoretical advancements in modern radiocarbon chronology make the precise dating of archaeological and geological events possible. Here, we show examples of how these state-of-the-art methods can be used to establish and refine the archaeological cultural chronology for the Shangluo area in the Qinling Mountains of central China. In this study, the Donglongshan and Zijing sites were dated using the high-precision accelerator mass spectrometry (AMS) 14C method. Also, detailed magnetic-susceptibility measurements were conducted at both sites to gain preliminary information about past climate changes. The 14C dates, after being treated with Bayesian statistics, provide a firm constraint on the archaeological chronological framework for this area. Within this framework, the Malan loess-Holocene soil transition can be placed at 10,400–10,090 BC, while the duration of the Yangshao and Longshan cultures was dated to ∼4200–2900 and ∼2900–2100 BC, respectively, revealing an undisrupted history of human occupation in this area until the early dynastic period. Magnetic susceptibility values began to increase in the early Holocene, indicating a progressive amelioration of regional climate. The widespread development of paleosol during the middle Holocene indicates that warm and wet climate conditions prevailed, providing a favorable environmental context within which the Yangshao culture thrived. Magnetic susceptibility values then decreased from ∼2100 BC when the Xia Dynasty started, and loess accumulated again, pointing to cooling and drying climate conditions that may have led to a cultural transition from the Neolithic to the dynastic civilization.

A simple model for reconstructing the paleomagnetic field intensity with 10Be production rate was used for the first time in Loess 10Be studies of Luochuan profile. Using the LGM (Last Glacial Maxmium) method, the climatic effects and geomagnetic modulation effects on loess 10Be was separated and in turn the 80 ka geomagnetic excursion sequence reconstructed, of which the globally remarkable geomagnetic excursion events such as the Laschamp (42 ka), Mono Lake (32 ka) during the Last Glacial period were revealed and the paleo-geomagnetic intensity curve from Loess 10Be over the past 80 ka was quantitatively reconstructed. The reconstructed paleo-intensity fits well with the paleo-intensity curves (SINT200 and NAPIS75), which indicates the significance of global criterion of the 10Be paleo-intensity curve and the future direction of loess 10Be tracing studies. Results show the irregular variability of the East Asian monsoon precipitation in Loess Plateau is the main cause that has resulted in the ambiguity of the geomagnetic modulation of the 10Be record in the loess, and the intrinsic source component of the loess 10Be and inherited fraction of magnetic susceptibility (SUS) are characterized by the “quasi-homogeneous distribution” manner.

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Objective: to investigate the effect of therapy to local infection using He-Ne laser. Method: we adopt He-Ne laser made in Harbin Laser Institution to irradiate directly infected gluteal surface areas. Result: all cases were cured. Conclusion: He-Ne laser is benefit for infected gluteal muscles.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.