华山树木年轮年表的建立

本文以秦岭东部的华山为例，论述了建立常规标准化、差值、自回归标准化这三种树木年轮年表的途径，指出了在半湿润地区利用这种途径建立树木年轮气候学年表的必要性，并进一步分析了三种年表对气候要素的响应及其差异。在取样环境较复杂的地点，建立多种年表有利于深入探讨气候要素与树木生长之间的关系，有推广的价值。     

气候变化对中国木本植物物候的可能影响

本文根据我国的３０年的物候资料和气候资料的统计分析，论证了气温是影响中国木本植物物候的主要因子，在此基础上建立了物候与年平均气温的线性统计模式，又利用此模式分析计算了未来全球年平均气温升高０．５－２．０℃和未来大气中ＣＯ２浓度倍增而增暖情况下，我国主要木本植物物候期的大致变幅。     

Radiometric dating of lake sediments from Signy Island (maritime Antarctic): evidence of recent climatic change

Sediment cores from three lakes (Moss, Sombre and Heywood) in the maritime Antarctic (Signy Island, South Orkney Islands) have been successfully dated radiometrically by²¹⁰Pb and¹³⁷Cs. The core inventories of both fallout radionuclides are an order of magnitude higher than that which can be supported by the direct atmospheric flux at this latitude. The elevated values may be explained by fallout onto the catchment during the winter being delivered directly to the lakes during the annual thaw. Two of the lakes (Sombre and Heywood) show marked increases in sediment accumulation afterc. 1950. This appears to be associated with a documented rise in temperature in the South Orkney Islands, which has caused extensive deglaciation at Signy Island.This is the tenth of a series of papers to be published by this journal following the 20 ^th anniversary of the first application of²¹⁰Pb dating of lake sediments. Dr P.G. Appleby is guest editing this series.     

Rock-magnetic proxies of climate change in the loess-palaeosol sequences of the western Loess Plateau of China

Results of the first detailed study of the climate proxy record in the loess-palaeosol sequence at Xining-one of the few palaeoclimate sites in the currently arid western Loess Plateau of China-illustrate the importance of making many types of rock-magnetic measurements other than susceptibility. A multiparameter approach yielded confirmation that here, as elsewhere in the Loess Plateau, the susceptibility enhancement in palaeosols was caused primarily by ultrafine magnetite and maghaemite. Nevertheless, magnetic enhancement was caused not exclusively by changes in relative grain size, but also by variations in concentration and mineralogy of the magnetic fraction.
The effects of concentration variations were removed through normalization of susceptibility and anhysteretic remanence with saturation magnetization and saturation remanence, respectively. the resulting signal was ascribed more confidently to variation in magnetic grain size, which in turn was interpreted as a better proxy of pedogenesis than simple susceptibility. Variations in magnetic mineralogy were also determined to constrain interpretations further. the data were then used to discuss climate history at Xining. Finally, results from Xining were compared with other western sites and contrasted with eastern sites.
In summary: (1) data is presented from a new Loess Plateau site which also appears to yield a global climate signal; (2) a demonstration is made of a more rock-magnetically robust way to separate concentration, composition and grain-size controls on susceptibility and other magnetic parameters; and (3) models are provided for inter-regional comparisons of palaeoclimate proxy records.     

Issues of Spatial and Temporal Variability in Climate Impact Studies

The accuracy of impact estimates relating climate change to regional-scale agricultural production is constrained by the temporal and spatial resolution of climate change projections. Several techniques have been used to compensate for these limitations in order to provide reasonable estimates of the impact of climate change on crop yield. One approach assumes that variability over time can substitute for spatial variability, thereby reducing the need to estimate the impacts at a spatially dense network of stations—an assumption that has not been generally tested. This study evaluates this assumption using methods similar to those employed in the climate impact literature. The findings suggest that current practices are generally defensible if the goal is to provide a range of possible crop responses to climate change. However, the results also show that the assumption is highly sensitive to specific interactions at the soil-plant-atmosphere interface and, consequently, does not hold under certain circumstances.     

Comparing Human and Neural Network Learning of Climate Categories

This study compares how humans and neural networks classify climate types. Human subjects were asked to classify climates from monthly temperature and precipitation patterns. To model their learning process, the same data were used to produce input vectors that trained a pattern associator neural network. Both human subjects and the neural network classified climates accurately after 10 rounds of supervised learning. The neural network successfully modeled the rate of human learning and the ability to learn specific climate categories. Moreover, the neural network weights used to classify climates correspond to distinct visual characteristics in temperature and precipitation. These results suggest that neural networks can model the formation of visual categories.     

THE NUMERICAL SIMULATION OF THE ICE AGE CLIMATE

Using the lAP two-level general circulation model,the ice age July climate was simulated through the surface conditions of 18 000 years before present assembled by the CLIMAP Project.Comparing with the present July simulation results,the ice age atmosphere is found to have a substantially lower temperature,precipitation,and cloudiness,higher sea-level pressure,especially in the high latitude land region of the Northern Hemisphere and Antarctica.When the CO₂ content is set as the modern value the climatic response is very small,which shows that the problems of CO₂ sensitivity should be studied by means of coupled models.It is also pointed out that there are some common characteristics between CO2-induced climatic changes and the ice age surface condition-induced climatic changes,which may give us some insight into how climate responds to external forcings.     

ADVANCES IN APPLIED RESEARCH OF THE OUTGOING LONGWAVE RADIATION IN CHINA

The outgoing longwave radiation(OLR)observed by NOAA satellite series has widely applied in various researchfields since the 1980s in China.In this paper,advances of the applied research of OLR are described in the following re-spects:(1)Studies of the global ITCZ;(2)Climatology of the subtropical high over northern Pacific;(3)Studies of the tropical cyclone over West Pacific;(4)Characteristics of the intraseasonal variation(ISV)of tropical convective activities;(5)Divergence wind and large scale circulation over the tropics;(6)Studies of the air-sea interaction;(7)Estimation of precipitation over the Tibetan Plateau and the Yangtze River(Changjiang River)basin during therainy season;(8)Analyses of regional climates of China;(9)Studies of prediction of the severe and disastrous weather and climate;(10)Atlas of OLR.The distinctive features of these advances are reviewed and the focal points of the OLR applied research in futureare also suggested.     

中尺度非均—边界层气候的数值研究——(Ⅱ)夏季的数值试验

用修改的 Nickerson 等提出的中尺度模式,对我国北方夏季非均一下垫面上的边界层气候特征进行了研究。结果表明,在晴朗、静风和无扰动系统的条件下,下垫面的非均一性对边界层气候起着决定性的影响。边界层气候特征和低空急流强度与局地环流关系密切。干燥裸地上边界层内出现的逆湿现象,是由下垫面非均一的湿度场和中尺度平流共同引起的。