Tropical mesoscale rainfall patterns: the opening of the monsoon in the Townsville area,December 1988

Rainfall during six days of monsoonal activity in the 1988/89 wet season is examined in terms of the influence of synoptic scale winds on mesoscale rainfall activity over the Townsville coastal plain (3450 km²). The resulting rainfall patterns. which were based on observations from a dense mesoscale network of 133 gauge points. are presented as isohyetal maps of twenty-four hour totals for each day in the study period. The study has shown that the distribution of rainfall is related to the influence of synoptic scale wind vectors, which provide upper level steering of convective activity. In addition. the interaction between local winds and synoptic circulation is deemed important for inducing convergence and precipitation. Rainfall generated is then directed by the prevailing upper synoptic flow. Orographic effects also appear to be significant, in that rainfall distribution tends to favour slopes on the windward side of the synoptic scale winds. The rainfall patterns described are probably typical of many of those that occurred throughout the 1988/89 wet season, due to the likely persistence of these mesoscale precipitation mechanisms. Similar mechanisms are also likely to occur over the study area in other wet seasons and elsewhere in the seasonally wet and dry tropics.     

Population,Households and Fisheries in the Parish of Hvalsnes,Southwestern Iceland, 1750–1850

Abstract

This is an in-depth study of the parish of Hvalsnes, a small fishing community situated on the Reykjanes peninsula in southwestern Iceland, during the period 1750–1850. The study is inspired by the nordic Coastal Region Project carried out in the 1990s, focussing on the relationship between economic factors and household size and structure. With reference to the concept of ecotype, Hvalsnes is compared to a few farming communities in southern and western Iceland as regards a number of economic and demographic factors. Among the features characterizing the Hvalsnes community was the large proportion of crofter and cottar households in relation to those of independent farmer-fishermen; the former constituted a valuable workforce for the commercial cod fisheries on the abundant Reykjanes banks. At the same time, the study reveals that during the winter season the operation of the fishing fleet was highly dependent on seasonal migration from farming areas. In this perspective Hvalsnes appears to be an Icelandic parallel to Lofoten in Norway. A closer view of the techniques and social organization of fishing in the parish discloses significant differences between its three individual sections. It is argued that these differences help to explain why some sections suffered more, in economic and demographic terms, than others from the natural catastrophes and political changes which took place towards the end of the eighteenth century. However, these changes did not alter the general condition of the landless population: cottars by the seaside and living-in servants in the countryside. Among these groups many individuals continued now as before their seasonal migration between the two ecotypes. Tentatively, it is argued that the seasonal exchange of workforce between fishing and farming communities contributed to an efficient use of the labour capacity of their members.     

历史文化村镇旅游流季节性特征比较研究——以西递、周庄为例

本文以西递和周庄为例,对历史文化村镇旅游流季节性特征进行比较。研究表明,两地在旅游流季节分布不均匀性、季节分布模式和季节划分方面均存在一定差异。对基尼系数和季节性强度指数的分析表明,两者在描述旅游流的季节性变动特征方面具有可替代性,且前者在一定程度上优于后者。另外,旅游地发展阶段也会对旅游流季节性特征有一定影响。论文建议旅游流季节性特征可作为旅游地发展阶段的一项评估指标。     

Changing Fire Management in the Pastoral Lands of Cape York Peninsula of northeast Australia, 1623 to 1996

Accounts of European explorers between 1623 and 1880 indicate that fires were lit by Aboriginal people on Cape York Peninsula in northeast Australia throughout the dry season (May–October). Diaries kept by three generations of pastoralists in the Musgrave area (1913–1952, 1953–1974 and 1976–1992) show that burning activities were largely confined to a two to six week period between May and early August. The timing of burning depended on the amount and date of cessation of wet season rainfall. More rarely, ‘storm‐burning’, burning under hot conditions within a few days of the first heavy rains of the wet season, was undertaken. Long‐term pastoralists felt a responsibility to use fire wisely and had a detailed knowledge of the role of fire in land management. Their decisions to burn were based on the extent of grass curing, and soil and weather conditions, all of which affected the extent of each burn. They used early dry season fires mainly to maintain forage and control cattle movements. Storm‐burns were reputed to control woody weeds, but were used infrequently because of difficulty in controlling their spread and uncertainty as to when the next rains would stimulate new grass growth.     

海南入境旅游季节性特征与调控措施

本文利用2006-2010年海南入境旅游资料,采用旅游月日指数、季节性集中指数,研究海南入境旅游季节性特征,得出以下结论:(1)海南入境旅游旺季为11月到次年4月,淡季为6、9月,国外游客市场、香港、澳门和台湾市场旅游淡旺季不同步;(2)近年海南入境客流季节性强度呈逐年减弱趋势;(3)不同入境旅游市场中,澳门市场旅游季节性强度最强,国外市场、香港、台湾市场依次减弱;国外市场中主要客源国的旅游季节性特征不同;(4)自然因素是海南入境旅游季节性形成的主要影响因素,制度因素在自然因素基础上产生叠加作用;(5)可通过制定季节性价格、完善旅游设施、丰富旅游产品、加强营销手段等策略调控季节性变化,拓展海南省入境旅游,缩小旅游淡旺季差距。     

Nari (calcrete) outcrop contribution to ancient agricultural terraces in the Southern Shephelah,Israel: insights from digital terrain analysis and a geoarchaeological field survey

A field survey revealed that Byzantine and Early Arab (ca. 5th to 8th century C.E.) agricultural systems in the semi-arid region of the Shephelah (central Israel) were similar to runoff agricultural systems in the arid region of the Negev (southern Israel). This similarity led to the hypothesis that systems in the Shephelah also function as runoff farms. This hypothesis is not trivial since runoff values in semi-arid regions are generally low due to intensive but short rainfall events, and due to the presence of sink patches that absorb runoff on slope surface. The aim of the current research is to examine whether runoff potential in a representative agricultural system in the Shephelah is sufficient for sustaining runoff farming. A geoarchaeological field survey and digital terrain analysis show that large Nari (calcrete) outcrops on the footslopes generate high runoff values that improve water potential. Hydrological simulations and calculations show that 230 mm of direct rainfall generates a water potential equivalent to 300 mm of direct rainfall. In view of these results, it is reasonable to conclude that the presence of Nari enabled runoff agricultural farming in the Shephelah region, even in drought years.     

Farm size and work ethic: measuring the success of immigrant farmers on the American grasslands, 1875–1925

With the general increase in the scale of American farming over the last 100 years, farm size has sometimes been used as a measure of financial success. This measure requires considerable modification, particularly when the intensity of farming is introduced. The average size of farms also varied according to government land granting policy, stage of settlement, accessibility to markets, fluctuations in market prices for farm produce and variations in climate which affected harvest yields. In this essay the validity of farm size as a measure of success is considered and then applied to three immigrant groups in central Kansas to determine the importance of the work ethic in their value systems. The Mennonites, not unexpectedly, appear to have been the most successful farmers, but the French-Canadians, contrary to general wisdom, achieved a higher level of success than Swedish immigrant farmers.     

A tidal wind model for 85–120 km based on CIRA-86: a feasibility study

This paper examines the feasibility of deriving a climatology of the diurnal variations of the wind in the 85–120 km region from the tidal components of temperature, density, and composition contained in the new COSPAR International Reference Atmosphere, CIRA-1986, Part I: Thermosphere Models [(1988), Adv. Space Res.8, 9]. To derive the wind field, we used the zonal and meridional momentum equations which have been modified from the characteristic scales of the tidal components observed in the 85–120 km region. The CIRA temperature and density model was used to derive the eastward (westerly) and northward (southerly) pressure gradient forces which serve as the forcing functions in the coupled momentum equations. Ground-based wind data from the Mesosphere-Lower Thermosphere (MLT) radar network is used as an independent data set to check the accuracy of the derived tidal wind model. At midlatitudes, the model reproduces some of the general features observed in the radar tidal data, such as the dominant semidiurnal tide with increasing amplitude with height and clockwise (counterclockwise) rotation of the velocity vector observed in the northern (southern) hemisphere. The model overestimates the semidiurnal amplitudes observed by radar by 50–75% during most seasons with the best agreement found during the equinoctial months. The model exhibits little phase variation with height or season, whereas the radar data exhibit a downward phase progression during most seasons (other than summer) characteristic of upward propagating tidal waves, and large seasonal phase variations associated with seasonal changes in vertical wavelengths. The diurnal tidal amplitudes, which are generally 5–20 m s⁻¹ at mid-latitude radar stations and are dominant over the semidiurnal amplitudes at lower latitudes, are less than 5 m s⁻¹ at all latitudes in the model.     

Bison breeding characteristics and interpretation of archaeological seasonality revisited

Bison breeding behaviour has been used for the last three decades as the basis for developing methods for assigning season‐of‐occupation estimates to archaeological sites on the North American Plains. These methods are based upon the supposition that the North American bison breeding season is extremely short and that genetically controlled ontological characteristics such as foetal growth and tooth eruption sequences can therefore be used to infer site seasonality in a reasonably straightforward and precise manner. This paper reviews bison population studies conducted during the past 30 years to reassess present understandings of the length of North American bison breeding seasons. It is concluded that the bison breeding season regularly extends over a period of three to four months, and that initiation of ontological development will therefore also vary over the same period of time. Bison development characteristics cannot provide a reliable or precise means of assigning seasonality to archaeological sites on the North American Plains. It is suggested that methods using physical characteristics such as dental cementum incrementation which are directly affected by seasonal changes could be more productive. Copyright © 2006 John Wiley & Sons, Ltd.     

Meteorological Sub‐divisional Scale Rainfall Monitoring Using Kalpana‐1 VHRR Measurements

Geostationary satellites provide measurements over a wider geographical area with high temporal sampling, while microwave measurements are more accurate but sparse. For continuous monitoring of the Indian monsoon, geostationary platform would be ideal. In this study, INSAT (Indian National Satellite) Multi‐spectral Rainfall Algorithm (IMSRA) has been used for the estimation of rainfall from Kalpana‐1 very high resolution radiometer (VHRR) measurements. IMSRA benefits from the relative advantages of infrared and microwave sensors and is operational at the India Meteorological Department (IMD). In this paper, rainfall is estimated over India at meteorological sub‐divisional scale during the south‐west monsoon season of 2009 using Kalpana‐1 satellite measurements. This is the first experimental attempt to generate meteorological sub‐divisional scale rainfall maps using Kalpana‐1 satellite measurements. The rainfall maps for the south‐west monsoon season over the Indian land region are successfully utilised as a space input for the drought monitoring of the year 2009. The results have been compared with the IMD gauge‐based accumulated rainfall maps at monthly and seasonal time scales. The qualitative comparison suggests that rainfall maps generated using the present methodology is in good agreement with the IMD rainfall maps. The quantitative comparison of the sub‐divisional monthly accumulated rainfall shows a correlation of 0.77 and standard error of 71 mm over the non‐orographic regions, whereas a correlation of 0.60 and standard error of 117 mm is observed over the orographic regions. The present study shows that Kalpana‐1 satellite‐based rainfall estimates (IMSRA technique) can act as a complementary tool for the monsoon monitoring over the Indian meteorological sub‐divisions and can be used for various meteorological and hydrological applications.     

Results inferred from electron density measurements at Saskatoon,Canada (L = 4.4) by a partial reflection technique—I. Variations of nitric oxide in the D-region during quiet periods

Measurements of electron densities at Saskatoon (52°N, 106° W, L = 4.4) from 1976 to 1979 reveal seasonal variations which cannot be explained solely by solar zenith angle variations. These profiles have been used to infer the variations of nitric oxide density with season and solar activity for quiet-time conditions. It is found that while nitric oxide varies with season, it remains unchanged with the change in solar activity. The summer and spring profiles are much lower than the measured values of Baker et al. (1977) for heights below 85 km, while the winter estimated values show differences from the measured values in the height range 77.5–85 km. Above 85 km the values for all the seasons are close to the measured values. A dip in the nitric oxide distribution is obtained in all the cases around 80–82 km and the values of nitric oxide at the minimum are less than those measured by Baker et al. (1977) or Meira (1971).     

A Covering Tour Model for Planning Mobile Health Care Facilities in SuhumDistrict, Ghama

The provision of adequate primary health care in developing countries is often troublesome. The problem is to provide a sufficient number of facilities to be geographically accessible, yet few enough to be properly stocked and staffed. In many less developed countries accessibility problems are exacerbated by extensive rainy seasons in which travel is only possible on paved roads. Using the covering tour model we investigate the use of mobile facilities to resolve this dilemma in Suhum District, Ghana. The model minimizes a mobile facility's travel while serving all population centers within range of a feasible stop. Computational results show that in the rainy season the model cannot provide full coverage; over six percent of the population is beyond a covering distance of eight kilometers. In the dry season, 99 percent of the population can be served by a tour at a covering distance of seven kilometers.Beyond a distance of four kilometers, the dry season problem becomes a trade-off between the distance traveled by healthcare patrons and mobile facilities. These results illustrate the importance of flexibility of mobile systems: if accessibility cannot be provided in all seasons it may still be provided at favorable times of the year.     

MIDDLE HOLOCENE PERIODICITIES IN RAINFALL INFERRED FROM OXYGEN AND CARBON ISOTOPIC FLUCTUATIONS IN PREHISTORIC TROPICAL ESTUARINE MOLLUSC SHELLS

Stable oxygen and carbon isotopic ratios in modern and archaeological estuarine mollusc shells, Polymesoda radiata, change in accordance with seasonal salinity fluctuations in the Acapetahua estuary located on the Pacific coast of southern Mexico. This region receives ?3000 mm of precipitation annually, most during a wet season between April and October. The changing flux of fresh water and organic detritus into the estuary causes large changes in the oxygen and carbon isotopic composition of the estuarine waters and in the carbonate precipitated by P. radiata. Oxygen isotopic ratios in the shells of molluscs collected by late Archaic period populations (5000–4000 BP) in this region indicate that patterns of rainfall were similar to today. Modern shells, however, exhibit much more negative carbon isotopic values than observed in prehistoric shells. This change may be associated with the input of modern fertilizers into the estuary.     

Climate shocks and conflict: Evidence from colonial Nigeria

This paper offers a historical micro-level analysis of the impact of climate shocks on the incidence of civil conflict in colonial Nigeria (1912–1945). Primary historical sources on court cases, prisoners and homicides are used to capture conflict. To measure climate shocks we use the deviation from long-term rainfall patterns, capturing both drought and excessive rainfall. We find a robust and significant curvilinear (U-shaped) relationship between rainfall deviations and conflict intensity, which tends to be stronger in agro-ecological zones that are least resilient to climatic variability (such as Guinean Savannah) and where (pre-) colonial political structures were less centralized. We find evidence that the relationship is weaker in areas that specialize in the production of export crops (such as cocoa and palm oil) compared to subsistence farming areas, suggesting that agricultural diversification acts as an insurance mechanism against the whims of nature. Additional historical information on food shortages, crop-price spikes and outbreaks of violence is used to explore the climate–conflict connection in greater detail.     

Variability in cementum deposition in springbok from the South African Cape

Over the past two decades, cementum increment analysis has played an important role in determining the season of death of ungulates at archaeological sites in many parts of the world, but its potential to address questions of seasonality in South African prehistory has remained largely unexplored. The ability to determine the seasonality of hunting practices would prove an important asset to understanding the foraging strategies and mobility patterns of Middle and Later Stone Age people in this region. A sample of springbok (Antidorcas marsupialis) of known date-of-death was collected from the South African Cape, a region across which three different rainfall regimes are represented. This study documents a very general correspondence between rainfall patterns and cementum development in springbok but also a level of variability that exceeds that observed by studies in other regions. In two sub-samples in which the sex of all individuals is known, cementum deposition among females is more strongly correlated with season of death than it is among males. This difference may reflect the social organization of springbok. The findings for springbok highlight the complexity of applying cementum increment analysis to archaeological studies not only on the Cape but also in regions of similar climatic variability.     

Early prehistoric sedentism and seasonal animal exploitation in the Caribbean lowlands of Colombia

San Jacinto 1 represents a special-purpose settlement that was used by late Archaic foraging groups who logistically moved from base camps to special-purpose camps in order to collect and process subsistence resources at the onset of the dry season in the Caribbean savannas of northern Colombia. Situated in an optimal location for permanent water and seasonal concentrations of dry season subsistence items, the site’s location was part of a logistic strategy in which specific task groups were moved to resources during a short season of availability. Preserved vertebrate and invertebrate faunas at San Jacinto conform to expectations about assemblage ubiquity, richness, and evenness or equitability within the early occupational strata at the site. Specific animals including turtles and fish were pursued, and may have been processed with C3 plants and grasses in ubiquitous earth ovens. Certain local aquatic invertebrates were also procured along with the collection of specific extra-local gastropods.     

Assessment of the Season of Death of Ancient Human from Cementum Annual Layers

Ground sections of the teeth of five humans from the burial grounds of Bronze Age Kalmykia (Russia) were studied. In the teeth of an old man and a child we found no cementum layers. In three other individuals (15–30 years old), analysis of the cementum layers allowed us to estimate age-at-death and season of death. The estimated seasons of death coincided with the seasons of the burials assessed using other methods. This investigation revealed the possibility of assessing the season of death of ancient humans less than 30 years old with permanent dentition, when several teeth in alveoli from the same specimen are available.     

The Forthcoming Congress of the Geographical Society of the USSR and its Program

A factual account of the economy of the Virgin Lands Kray, one of the Soviet Union's most Important wheat-growing areas, established in December 1960 as a distinct administrative entity within the Kazakh SSR. In addition to wheat farming, which suffers from unreliable rainfall, the kray plays an important role as a supplier of iron ore to the Urals and as a prospective producer of aluminum.     

Raised bed agriculture in northwest Europe triggered by climatic change around 850 BC: a hypothesis

A sudden decline of solar activity around 850 calendar years BC caused a shift to a cool and wet climate in northwest Europe. Food production suddenly became problematic because of shorter, wetter growing seasons and increased night frost. This climate change triggered innovation and the development of a new agricultural system in continental northwestern Europe: arable farming on raised beds (Celtic field banks) laid out in a more or less checked pattern. This kind of agriculture mitigated the effects of the climate shift by providing better drainage and lessening damage by night frost and thus lengthening the growing season. Once the advantages of this kind of cultivation, soil enrichment and optimum root growth besides the hydrological effects, became obvious it will have been practised on a large scale and introduced when people thought it useful, independent of the local hydrological situation.     

The trouble with thermospheric vertical winds: geomagnetic,seasonal and solar cycle dependence at high latitudes

The vertical wind component is frequently used to determine the zero-velocity baseline for measurements of thermospheric winds by Fabry-Perot and other interferometers. For many of the upper atmospheric emission lines from which Doppler shifts are determined, for example for the OI 630 nm emission, available laboratory sources are not convenient for long-term use at remote automatic observatories. Therefore, the assumption that the long-term average vertical wind is zero is frequently used to create a baseline from which the Doppler shifts corresponding with the line-of-sight wind from other observing directions can then be calculated. A data base consisting of 1242 nights of thermospheric wind measurements from Kiruna (68°N, 20°E), a high-latitude site, has been analysed. There are many interesting short-term fluctuations of the vertical wind which will be discussed in future papers. However, the mean vertical wind at Kiruna also has a systematic variation dependent on geomagnetic activity, season and solar cycle. This means that the assumption that the average value of the vertical wind is zero over the observing period cannot be used in isolation to determine the instrument reference or baseline. Despite this note of caution, even within the auroral oval, the assumption of a zero mean vertical wind can be used to derive a baseline which is probably valid within 5 ms⁻¹ during periods of quiet geomagnetic activity (K_p < 2), near winter solstice. During other seasons, and during periods of elevated geomagnetic activity, a systematic error in excess of 10 ms⁻¹ may occur.