Sensitivity of boreal forests to possible climatic warming

General circulation models indicate substantial CO₂ warming in high latitudes. In these regions, which include the boreal coniferous forests, the activity of ecosystems is largely controlled by temperature. The effective temperature sum (degree-days) is used in this study for describing the regional variability in the productivity of boreal ecosystems. Although the concept is simple, it takes into account two basic factors: the length of the growing season and the day-to-day level of activity of the ecosystem. This study examines which areas in the boreal coniferous forests would be most sensitive to a possible climatic warming. The data used in the study are for Finland.A regression is estimated between regional forest growth rate and effective temperature sum. A climatic warming is assumed and the corresponding growth response is calculated, using the regression, for northern and southern areas, and for maritime and continental areas. The response is expressed in terms of (i) absolute increase in growth (grams per m² per year) and (ii) relative increase in growth. The results indicate that a given climatic warming would yield the greatest absolute increase in growth in warm (i.e. southern) and maritime parts of the biome. In terms of the relative growth response the sensitivity would increase northward and toward maritime areas.     

Acoustic echo-sounding techniques and their application to gravity-wave,turbulence, and stability studies

This paper is a brief summary of recent experimental studies conducted by the WPL staff in order to: (a) compare acoustic echo strengths with those predicted from measured turbulence intensities and scatter theory; (b) develop optimum experimental geometries for Doppler work, and (c) use the acoustic echo-sounder as a quantitative tool in studies of gravity wave dynamics in, and immediately above, the stable planetary boundary layer. We find that the observed acoustic echo strengths are roughly an order of magnitude greater than those predicted theoretically. This discrepancy might be in part due to partial reflection although the comparison is somewhat clouded by uncertainties in our knowledge of the equipment characteristics, propagation losses, etc. Comparisons between Doppler and in situ wind measurements give confidence in the Doppler results, but further experimentation and comparisons are needed. Preliminary use of acoustic Doppler data in a case study of gravity-wave dynamics in the planetary boundary layer has yielded boundary-layer wind speed and direction profiles which give insight into the mechanisms responsible for the wave generation. The Doppler data yield estimates of the wave associated momentum fluxes (a few dyn cm^–2) as well. The results derived from the acoustic techniques are quite encouraging, but thus far remain unsubstantiated by independent wind and flux measurements.     

The decline of Late Bronze Age civilization as a possible response to climatic change

The disintegration of Eastern Mediterranean civilization at the end of the late Bronze Age (late thirteenth and twelfth centuries B.C.) has traditionally been attributed to the irruption of new peoples into this area. However, the nearly contemporaneous decline of highly organized and powerful states in Greece, Anatolia, Egypt, and Mesopotamia warrants consideration of possible environmental causes likely to operate over sizable areas, especially since archaeological research has not succeeded in establishing the presence of newcomers at the onset of the Bronze Age disturbances.Climatic change is a particularly attractive candidate since temperature and precipitation variations persisting over relatively short times can adversely affect agricultural output. Carpenter (1966) argued that the Mycenaean decline and migrations in and from Greece in the late thirteenth century were caused by prolonged drought and not the incursion of less civilized Dorian tribes. Donley (1971) and Bryson et al. (1974) have presented evidence of a spatial drought pattern which occurred in January 1955 that might be invoked to support this thesis. Population movements in Anatolia at the same time, though not as well established, can be delimited to some degree by the distribution of Hitto-Luwian peoples in the late ninth century B.C. It is hypothesized here that a drought induced migration of Luwian peoples from Western Antolia occurred early in the twelfth century B.C., that it was associated in some fashion with the invasion of Egypt by the Sea Peoples in the reign of Ramesses III, and that the defeated remnants of these peoples settled along the Levantine coast and filtered into North Syria and the upper Euphrates valley.It has been suggested that past climatic patterns recur in the present epoch but with a possibly different frequency. To establish that a spatial drought analogue to the above hypothesized migration can occur, temperature and precipitation records from 35 Greek, Turkish, Cypriot, and Syrian weather stations for the period 1951–1976 were examined. The Palmer drought index, an empirical method of measuring drought severity, was computed for each of these stations for the period of record. Since wheat yields tend to be highly correlated with winter precipitation for the area in question, the drought indices for the winter months were subjected to an empirical eigenvector analysis. An eigenvector (drought pattern) consistent with the postulated population movements in Anatolia occurred within the modern climatological record and was found to have been the dominant pattern in January 1972. The potential problems of eigenvector analysis in investigating problems of this type are discussed.     

攀枝花市旅游气候资源分析及开发建议

利用攀枝花市长年代、高质量的气象观测资料，分析了攀枝花的气候特点，把分析结果与一些著名旅游城市比较，发现攀枝花市“冬暖”得天独厚，它是本地区旅游业开发的主要自然资源之一。然后，为了使旅游业成为近期本市经济的一个快速增长点，必须大力发展特色旅游。从长远的观点看，为了使全市旅游业可持续发展，在发展生态观光旅游的时候，我们必须加强生态环境保护和建设，那么未来攀枝花市的社会经济发展与自然资源环境将进入良性循环，从而找到具有攀枝花市特点和旅游发展模式。     

攀枝花市旅游气候资源分析及开发建议

利用攀枝花市长年代、高质量的气象观测资料,分析了攀枝花的气候特点,把分析结果与一些著名旅游城市比较,发现攀枝花市"冬暖"得天独厚,它是本地区旅游业开发的主要自然资源之一.然而,为了使旅游业成为近期本市经济的一个快速增长点,必须大力发展特色旅游.从长远的观点看,为了使全市旅游业可持续发展,在发展生态观光旅游的时候,我们必须加强生态环境保护和建设,那么未来攀枝花市的社会经济发展与自然资源环境将进入良性循环,从而找到具有攀枝花市特点的旅游发展模式.     

西伯利亚风暴轴的气候特征及其可能维持机制

基于1959—2014年NCEP/NCAR的逐日再分析资料,首先研究了西伯利亚风暴轴各季节的气候平均特征,然后以冬季为例,利用能量诊断方程,从能量学的角度对其的可能维持机制进行了探讨,并在上述分析过程中与北半球两大洋风暴轴的特征进行了对比。结果表明:(1)西伯利亚风暴轴一年四季都独立存在,虽强度要比两大洋风暴轴的强度弱很多且位置偏北,但可以定义为一个弱风暴轴。(2)比较来看,西伯利亚风暴轴强度的季节变化与北太平洋风暴轴的季节变化类似。与两大洋风暴轴位于急流东北侧不同,冬季西伯利亚风暴轴位于东亚温带急流的西侧。(3)进一步的能量分析结果表明,与两大洋风暴轴一样,斜压不稳定的能量转换(Ke4)也是西伯利亚风暴轴区域天气尺度扰动动能的主要来源;而扰动非地转位势通量散度项(Ke3)和时间平均气流对扰动动能的平流输送项(Ke1)也是风暴轴下游发展所需的扰动动能来源之一。     

丹寨气候资源分析及应用

利用丹寨县气象观测站1961～2000年的气象资料，对光、温、水及风能资源进行分析，重点分析热量资源和水资源。总的来看，丹寨气候资源比较丰富，其主要特征表现为：空中云水资源丰富，降水主要集中在4～8月上半月，雨量比较稳定，与作物需水高峰期相一致；夏季气候凉爽，日最高气温一般在32℃左右，非常适宜避暑；热量资源较丰富，作物生育期积温保证率高；日照与全国相比，虽处于低值区，但基本能保证作物进行光合作用。     

1985-2005年锦州地区大豆物候期变化及气候响应

利用1985—2005年锦州大豆物候期及同期气象资料,应用数理统计方法,分析大豆物候期的气候响应。结果表明:大豆生长期的长短主要受积温和降水的影响,出苗期主要受积温和日照的影响。积温、降水和日照在大豆不同物候期内的作用不同,三叶期和成熟期是积温、日照和降水共同作用的结果,分枝期主要是受积温和日照的影响,开花和结荚期主要是受累计积温的影响。     

辽宁省植被覆盖度时空演变及其对气候因子的响应

基于MODIS-NDVI数据及像元二分模型,对辽宁省植被覆盖度进行估算,并在此基础上探讨了辽宁植被覆盖度时空演变特征及其对气候因子的响应,结果表明：2000-2018年辽宁省植被覆盖度整体呈波动增加趋势,年平均增长速率为0.38%,呈增加趋势的面积占总面积的92.3%;2000年以来,裸地及低覆盖区域占比逐年减小,中低覆盖、中覆盖及高覆盖区域占比分别增加11.35%、11.00%和9.22%;辽宁省植被覆盖度与气候因子的关系表现出明显的空间差异性,其中,西部易旱地区覆盖度与气温呈显著负相关,与降水呈正相关,东部地区覆盖度与气温呈正相关,与降水呈负相关;辽宁植被覆盖度对降水的响应存在一个月的滞后期,对气温的响应无滞后效应。     

Harvest dates in ancient mesopotamia as possible indicators of climatic variations

Butzer (1958; also, Lamb, 1968) puts forward observations to the effect that about 2500 B.C. a period of increased aridity set in in the general area of the Near East, including Mesopotamia, and that rainier conditions returned after about 850 B.C. Because in the Mediterranean type of climate (winter rains) of the Near East winter temperatures and seasonal rainfall are highly correlated in a negative sense, we expect that the above mentioned period of aridity was also a period of relative warmth, whereas the period after 850 B.C. up to Roman times, was a period of cool winters. This negative correlation is thought to be due to the fact that in the Near East rainfall is usually produced in the migratory cyclones, especially close and behind the associated cold fronts which bring in cold air as well. A failure of these cyclones to reach the region in numbers, manifests itself both in reduced rainfall and comparatively high winter temperatures. In order to check on these ideas on temperature conditions, a search was undertaken of references to barley harvest dates in the literature (clay tablets) of ancient Babylonia comprising two periods: 1800-1650 B.C. (Late Old Babylonian Period = L.O.B.P.) and 600-400 B.C. (Neo-Babylonian Period = N.B.P.). It turns out that in the former, the harvest began late in March or early in April, while in the latter, it began late in April or in May, amounting to a difference of about a month or slightly more. In our own era, in what was once central and northern Babylonia, harvest begins in the second half of April or so. Thus in the L.O.B.P., harvest opened 10–20 days earlier and in the N.B.P. 10–20 days later than at present. The differences between the harvest dates of the two periods seem to be too large to be explained by changes in the barley varieties cultivated. On the other hand, the above mentioned inverse relationship between rainfall and winter temperatures supports the interpretation that the L.O.B.P. was warmer, and the N.B.P. cooler than the present era, and goes some way toward explaining the inferred differences in harvest dates.     

桂南农业气候资源及其开发利用

分析了桂南地区光、温及雨水3大气候资源，主要作物气候生产潜力，指出了影响作物气候生产潜力的主要气候因素，并提出了开发对策。     

贵州畜牧气候资源开发及利用研究

从气候条件对牲畜机体产生的影响和牲率机体对环境条件变化具有各种调节的能力入手，分析了温，光，水，湿等气象条件与之生长发育的关系以及贵州发展畜牧业的气候资源优势，并根据贵州畜牧气候资源的特点和优势，从6个方面提出开发利用策略，措施和建议。     

Variability of rainfall and effective onset and length of the monsoon season over a sub-humid climatic environment

The study has analyzed the variability and trends in monthly, seasonal and annual rainfall and rainy days of four locations over different agro-ecological zones of Bihar, namely Samastipur (zone-I), Madhepura (zone-II), Sabour (zone-IIIA) and Patna (zone-IIIB). The Mann–Kendall nonparametric test was employed for detection of statistical significance and slopes of the trend lines were determined using the method of least square linear fitting. The variability and trends of onset of effective monsoon and length of monsoon period were also analyzed using the same method. The mean annual rainfall varies from 1137 mm at Patna to 1219 mm at Sabour. July is the rainiest month in all the zones followed by August. Maximum increase in annual rainfall was found at Sabour (40.1% of mean/30 years at 95% confidence level) and minimum for Patna (10.1% of mean/30 years). Significant increasing trend of rainfall during July, August and September at rates of 41.9, 83.2, and 112.7% of the mean/30 years, respectively has been noticed at Madhepura. Analysis of rainy days indicates that rainy days increased during winter and annually for all the sites. The mean effective onset of monsoon varies from 18th June at Sabour to 28th June at Patna. The trends in the date of effective onset of monsoon indicate that the date tends to be early in all the sites except Madhepura. But a significant delayed trend in the onset at a rate of 2.8% of the mean/30 years has been observed for Madhepura. The early trend of the effective onset of monsoon and increasing trends of length of monsoon season have been observed for Samastipur, Sabour and Patna.     

Response of flower and boll development to climatic factors in Egyptian cotton (Gossypium barbadense)

Fruiting of cotton plant is determined and influenced by cultivars, climatic conditions, management practices and pests. An understanding of the flowering and boll retention patterns of cotton cultivars can contribute to more efficient and economical crop management. The objective of this investigation was to study the effect of various climatic factors on flower and boll production, and also, the nature of its effects prevailing prior and subsequent to either flowering or boll setting on flower and boll production and retention in Egyptian cotton. This could be used in formulating advanced prediction of the effect of certain climatic conditions on the production of Egyptian cotton. Also, the study focused on four equal periods during the development of flower and bolls stage to study the response of these characters to climatic factors during these periods and to determine the most representative period corresponding to the overall crop pattern. Further, the study predicting effects of climatic factors during convenient intervals (in days) on cotton flower and boll production compared with daily observations to find the optimum interval. Evaporation, sunshine duration, humidity, surface soil temperature at 1800 h, and maximum air temperature, are the important climatic factors that significantly affects flower and boll production. Evaporation; minimum humidity and sunshine duration were the most effective climatic factors during preceding and succeeding periods on boll production and retention. There was a negative correlation between flower and boll production and either evaporation or sunshine duration, while that correlation with minimum humidity was positive. The fourth quarter period of the production stage was the most appropriate and usable time to collect data for determining efficient prediction equations for cotton production. Evaporation, humidity and temperature were the principal climatic factors that governed cotton flower and boll production during the fourth quarter. The five day interval was found to be adequately and sensibly related to yield parameters than other intervals and was closest to the daily observations. Evaporation was found to be the most important climatic variable affecting flower and boll production, followed by humidity. An accurate weather forecast 5–7 days in advance would provide an opportunity to avoid adverse effects of climatic factors on cotton production through utilizing proper cultural practices which would limit and control their negative effects.     

黎平县农业气候资源优势及其开发利用

通过对黎平历年气象资料的计算，分析，得出黎平县气候资源的优势，指出影响农作物产量的主要气候因素，并提出如何合理开发利用农业气候资源来促进农业的发展。     

The application of a present-day climatic model to the late quaternary in southern Africa

A present-day climatic model is presented in which extended wet spells of near-decadal duration and dry spells of similar length are explained on the basis of surface and upper tropospheric circulation variations. Wet spells are shown to be the result of increased tropical atmospheric disturbances and tropical-temperate interaction, and to be linked to variations in the Walker Circulation. Conversely, dry spells are shown to result from diminished tropical activity over southern Africa, equatorward movement of westerly storm tracks and temperate perturbations in the westerlies.The present-day analogue is compared to preliminary spatial reconstructions of the climate of southern Africa over the last twenty-five millennia and is shown to have wide applicability in the explanation of the late-Quaternary palaeoclimates of the subcontinent. In particular, it is argued that the Last Glacial Maximum was associated with northward-displaced circulation conditions similar to those of present-day dry spells over the summer rainfall region, whereas the extensive moist conditions that prevailed for several thousand years after 9000 BP were analogous to present-day wet spell conditions with little apparent displacement of major circulation features.     

灰色系统理论在气候预测中的应用

介绍了灰色系统理论的基本概念,分析了与气候预测相关的灾变与异常值预测、拓扑预测的原理与方法,认为气候系统是较典型的灰色系统,适于应用灰色系统理论预测模型进行预测。