Subtropical Climate Region Research Articles

Interactions between louvers and ceiling geometry for maximum daylighting performance

The impact of ceiling geometries on the performance of louvers was investigated using physical model experiments and Radiance simulations. Two performance indicators, the illuminance level and its distribution uniformity, were used to assess daylighting performance in a room located in a subtropical climate region. It was found that the performance of the louvers can be improved by changing the ceiling geometry. The illuminance level increased in the rear of the room, and decreased in the front—near the window—compared to rooms having horizontal ceilings. Radiance results were found to be in good agreement with physical model data obtained under a clear sky and high solar radiation. Louvers' daylighting performance was reduced by tilting the louvers downward. The best ceiling shape was found to be one that is chamfered in the front and rear of the room.

Digital Earth in support of global change research

The Digital Earth concept as originally proposed by former US Vice president Al Gore is now well established and widely adopted internationally. Similarly, many researchers world-wide are studying the causes, effects and impacts of Global Change. The authors commence by describing a five-step approach to the development of Digital Earth technologies. This is followed by a detailed account of Digital Earth research and developments in China. The authors then present the research results of Global Change studies carried out in China, based on the Digital Earth approach. These research results are based on a classification of global change regions. This covers the following global change situations: Forest and grassland fires in Northern China, temperate region desertification and dust storms, underground coal fires, deforestation and carbon sequestration, protection and utilisation of wetlands, Avian Influenza and the spread of diseases, Tibet Plateau uplift and sub-tropical monsoon climate region, and sea-level rise. The research results show that the environment does not behave in a way easily understood by the traditional disciplinary approach. Although man is clearly a contributing factor to certain Global Change aspects, such as underground coal fires, desertification, land use changes etc., many of the aspects of Global Change are naturally occurring phenomena which have been changing over centuries, and will continue to do so, no matter what actions we undertake to reverse these processes. Hence, in their conclusions, the authors propose that the communities involved in Digital Earth modelling and in Global Change research co-operate closer to overcome the limitations inherent in the current ‘conventional’ scientific approach, where scientists have very much stayed within their respective scientific boundaries. Such an integrated approach will enable us to build the next level of scientific infrastructure required to understand and predict naturally occurring environmental changes, as well as that of coupled human–environmental systems.

Energy impact of indoor environmental policy for air-conditioned offices of Hong Kong

Air-conditioned office buildings are one of the biggest energy consumers of electricity in developed cities in the subtropical climate regions. A good energy policy for the indoor environment should respond to both the needs of energy conservation and the needs for a desirable indoor healthy environment with a reduction in carbon dioxide (CO 2) generation. This study evaluates energy implications and the corresponding CO 2 generation of some indoor environmental policies for air-conditioned office buildings in the subtropical climate. In particular, the thermal energy consumption in an air-conditioned office building was evaluated by the heat gains through the building fabric, the transport of outdoor fresh air for ventilation, and the heat generated by the occupant and equipment in the space. With the Monte-Carlo sampling technique and the parameters from the existing office building stocks of Hong Kong, the energy consumption profiles of air-conditioned office buildings in Hong Kong were evaluated. Energy consumption profiles were simulated for certain indoor environmental quality (IEQ) policies on indoor air temperature and CO 2 concentration settings in the offices, with other building parameters remaining unchanged. The impact assessment and the regression models described in this study may be useful for evaluation of energy performances of IEQ policies. They will also be useful for the promotion of energy-saving measures in air-conditioned office buildings in Hong Kong. This study presented a useful source of references for policymakers, building professionals and end users to quantify the energy and environmental impacts due to an IEQ policy for air-conditioned office buildings.

Optimizing performance of the lightshelf by modifying ceiling geometry in highly luminous climates

The impact of ceiling geometries on the performance of lightshelves was investigated using physical model experiments and radiance simulations. Illuminance level and distribution uniformity were assessed for a working plane in a large space located in sub-tropical climate regions where innovative systems for daylighting and shading are required. It was found that the performance of the lightshelf can be improved by changing the ceiling geometry; the illuminance level increased in the rear of the room and decreased in the front near the window compared to rooms having conventional horizontal ceilings. Moreover, greater uniformity was achieved throughout the room as a result of reducing the difference in the illuminance level between the front and rear of the room. Radiance simulation results were found to be in good agreement with physical model data obtained under a clear sky and high solar radiation. The best ceiling shape was found to be one that is curved in the front and rear of the room.

Magnetic properties and geochemistry of the Xiashu Loess in the present subtropical area of China, and their implications for pedogenic intensity

Variations in the magnetic susceptibility of Chinese loess have been used to indicate pedogenic intensity and therefore past climate across the Chinese Loess Plateau (CLP). However, the relationship between climate and magnetic properties has not been fully resolved, and therefore a study of loess sections distributed over a wider climatic region is timely. In this study, we have investigated a 22.1 m loess section (named the Xiashu Loess) at Dagang, China, by integrating both rock magnetic and geochemical proxies. This loess profile is situated in a modern subtropical climate region with annual mean precipitation and temperature of 1100 mm and 15.4 °C, respectively, and therefore has experienced a stronger weathering intensity due to its lower latitude, higher temperature and rainfall. Geochemical and magnetic evidence indicate the same source area for the Xiashu Loess as for loess in northern China. The magnetic mineral assemblage of the Xiashu Loess is dominated by a higher concentration of superparamagnetic (SP)/single domain (SD) magnetite/maghemite grains in strongly weathered paleosols than in the loess layers, consistent with the production of fine-grained ferrimagnetic minerals during pedogenic processes. Nevertheless, compared to loess in the CLP, the Xiashu Loess shows: 1) reduced contrasts in magnetic susceptibility ( χ), Hard Isothermal Remanent Magnetization (HIRM) and remanence of coercivity ( B cr) between loess and paleosols units, which indicates that the loess units have undergone stronger pedogenic alterations; 2) lower peak values of HIRM and χ in paleosols. In addition, the ratios SIRM/ χ, χ ARM/SIRM (where SIRM and χ ARM are Saturation Isothermal Remanent Magnetization and the susceptibility of Anhysteretic Remanent Magnetization, respectively) and B cr are found to be significantly correlated with the quotient (CaO ⁎ + Na 2O + MgO)/TiO 2, a geochemical indicator of pedogenic intensity. Overall, it seems that pedogenic processes in the Xiashu Loess lead to a relative increase in fine-grained ferrimagnetic SP/SD grains but depletion of anti-ferromagnetic minerals. Magnetic and geochemical proxies indicate strengthened East Asia summer monsoon during Marine Isotope Stages 13, 11 and 5, which is in good agreement with the records from the CLP and the South China Sea.

The fundamental and realized niche of the Monterey Pine aphid, Essigella californica (Essig) (Hemiptera: Aphididae): implications for managing softwood plantations in Australia

ABSTRACT Essigella californica is a pine aphid native to western North America. In Australia, E. californica is considered an invasive pest that has the potential to cause severe economic loss to the Australian forestry industry. Two CLIMEX models were developed to predict the Australian and global distribution of E. californica under current climate conditions based upon the aphid's known North American distribution. The first model (model I) was fitted using the reasonably contiguous set of location records in North America that constituted the known range of E. californica, and excluded consideration of a single (reliable) location record of the aphid in southern Florida. The second model (model II) was fitted using all known records in North America. Model I indicated that the aphid would be climatically restricted to the temperate, Mediterranean and subtropical climatic regions of Australia. In northern Australia it would be limited by hot, wet conditions, while in more central areas of Australia it is limited by hot, dry conditions. Model II is more consistent with the current Australian distribution of E. californica. The contrast in geographical range and climatic conditions encompassed between the two models appears to represent the difference between the realized niche (model I) and fundamental niche (model II) of E. californica. The difference may represent the strength of biotic factors such as host limitation, competition and parasitism in limiting geographical spread in the native range. This paper provides a risk map for E. californica colonization in Australia and globally. E. californica is likely to remain a feature of the Australian pine plantations, and any feasibility studies into establishing coniferous plantations in lower rainfall areas should consider the likely impact of E. californica.

Diseases and Disorders of Ornamental Palms.

Introduction Linnaeus named palms “Principes,” the princes of the plant world (15). This noble stature is reflected in the size of some species, with the largest leaves and seeds known in the plant kingdom found in the palm family. The leaves of Raphia regalis can reach 82 feet long (18), and the famous double coconut seed of Lodoicea maldivica can weigh 50 pounds (13). Besides their stature, few plant families provide both food and shelter to people, while at the same time are admired and collected for aesthetic reasons. Palms belong to a natural but distinctly separate family of plants called the Palmae (synonym = Arecaceae) (18). There are approximately 2700 species of palms in 200 genera that are currently placed in six subfamilies. These plants are highly diverse morphologically and ecologically, and are common in tropical, subtropical and Mediterranean climatic regions of the world. Palms are a source of food and oil; fiber for coir, cord, rope, baskets, hats and mats; rattan used in furniture production; tannin; lumber; thatch for roofing material; wine and other beverages; and for providing a narcotic high (8,13). Besides this value to humans, palms are also widely employed in interiorscapes, landscapes, and in many national and international tropical gardens, with impressive palm collections housed in greenhouses in temperate climates (e.g., The Palm House at the Royal Botanical Gardens, Kew Gardens in England). In the U.S., primarily in California, Florida and Hawaii, palms are produced for the ornamental industry as potted, greenhouse-grown specimen plants for interior use, or containerand field-grown plants for landscape use. This is in contrast to the plantation fields of palms grown for food, oil and other commercial uses. Ornamental palms are also grown in other parts of the U.S., southern Europe, Central and South America, Japan and Australia.

Long-term effects of intercropping and bio-litter recycling on soil biological activity and fertility status of sub-tropical soils

On-farm field experiments were carried out at two sites having 38- and 10-year-old orchard cropping systems under sub-tropical climatic regions to evaluate changes in organic carbon accumulation and chemical and microbiological properties of the soils. Under a system of different intercropped fruit trees, the cultivation of coconut ( Cocos nucifera L.) intercropped with guava ( Psidium guajava L.) enhanced the soil microbial activity approximately 2-fold after 38 yrs over 10 yrs of the same intercropped system. Soil organic carbon increased from 3.4 to 7.8 and 2.4 to 6.2 g kg −1 after 38 and 10 yrs, respectively, following the establishment of orchards. The increase was attributed to greater recycling of bio-litters. Levels of dehydrogenase, phosphatase and soil microbial biomass under field conditions generally depended more on the nature of the cropping system than on soil types. Similarly, average carbon inputs of bio-litter to the soil in monocrop (0.98 Mg ha −1 yr −1) was less than intercropped fruit trees (2.07 Mg ha −1 yr −1). The average level of soil microbial biomass carbon was 1158 kg ha −1 (0–0.15 m depth) and the organic carbon turnover rate was 8.5 yr −1 after 38 yrs of intercropped fruit trees, which resulted in a lower ratio (1.81) of carbon inputs to soil microbial biomass carbon.

Fractal analysis of rainfall observed in two different climatic regions

The importance of high-resolution rainfall data to understand the intricacies of the dynamics of hydrological processes and describe them in a sophisticated and accurate way has been increasingly realized. The present study investigates the general suitability of fractal (or scaling) theory for understanding the rainfall behaviour and transforming rainfall data from one time scale to another. The study, employing a multi-fractal approach, follows the research undertaken earlier by the author (Sivakumar, 2000) employing a mono-fractal approach in which some preliminary indication as to the possibility of existence of (multi-) fractals was obtained. Rainfall data of three different resolutions, six-hourly, daily, and weekly, observed over a period of 25 years in two different climatic regions: a subtropical climatic region (Leaf River basin, Mississippi, USA); and an equatorial climatic region (Singapore) are analysed. The existence of multi-fractal behaviour in the rainfall data is investigated using (a) the power spectrum method; (b) the empirical probability distribution function (PDF) method; (c) the statistical moment scaling method; and (d) the probability distribution multiple scaling (PDMS) method. The results achieved from all these methods for the six different rainfall data sets considered indicate the existence of multi-fractal behaviour of rainfall observed in Leaf River basin and Singapore, providing further support to the results obtained using the mono-fractal approach (Sivakumar, 2000). The suitability of a multi-fractal framework to characterize the behaviour of rainfall observed in the above two significantly different climatic regions, subtropical and equatorial, seems to suggest the general suitability of the fractal theory for transforming rainfall from one time scale to another. Investigations with rainfall data from several other climatic regions are underway with a view to strengthening the above conclusions.

A preliminary investigation on the scaling behaviour of rainfall observed in two different climates

The problem of transformation of rainfall data from one scale to another has been gaining considerable importance in recent years. Though the application of the concept of fractal theory, in the studies conducted thus far, nearly unanimously points at the possibility of such a transformation, the suitability of the theory to the highly variable rainfall in time and space has very often been questioned. A preliminary attempt is made herein to address this issue by investigating the existence of temporal scaling behaviour in rainfall data observed in two different climatic regions: (a) a subtropical climatic region (Leaf River basin, Mississippi, USA) and (b) an equatorial climatic region (Singapore). Rainfall data of three different resolutions, six-hourly, daily, and weekly, observed over a period of 25 years, are investigated. A mono- or simple-scaling method (box dimension method) is employed. The results achieved for the different data sets clearly indicate the existence of temporal scaling in rainfall observed in the two regions, an encouraging news on the suitability of fractal theory in understanding and modelling the rainfall process. However, the insufficiency of a single dimension to characterize the rainfall behaviour is realized, as the dimension depends on the rainfall intensity level, which, in turn, may be related to the rainfall generating mechanisms. A comparison of the box-dimension results obtained for data of different resolutions, from each of the regions, seems to indicate a possible connection between them, a prospect of tremendous practical importance. Another interesting observation is the similarity between the box dimension results obtained for rainfall data from Leaf River basin and Singapore, but this is also clearly related to the intensity level. The dependence of the dimension on the intensity threshold suggests the use of a multi-dimensional fractal approach, where the process is characterized by more than one dimension (or a dimension function) instead of one single dimension. On the basis of the present results, some potential areas for further study are identified.

Molecular characterization of the toxic cyanobacterium Cylindrospermopsis raciborskii and design of a species-specific PCR.

Cylindrospermopsis raciborskii is a toxic-bloom-forming cyanobacterium that is commonly found in tropical to subtropical climatic regions worldwide, but it is also recognized as a common component of cyanobacterial communities in temperate climates. Genetic profiles of C. raciborskii were examined in 19 cultured isolates originating from geographically diverse regions of Australia and represented by two distinct morphotypes. A 609-bp region of rpoC1, a DNA-dependent RNA polymerase gene, was amplified by PCR from these isolates with cyanobacterium-specific primers. Sequence analysis revealed that all isolates belonged to the same species, including morphotypes with straight or coiled trichomes. Additional rpoC1 gene sequences obtained for a range of cyanobacteria highlighted clustering of C. raciborskii with other heterocyst-producing cyanobacteria (orders Nostocales and Stigonematales). In contrast, randomly amplified polymorphic DNA and short tandemly repeated repetitive sequence profiles revealed a greater level of genetic heterogeneity among C. raciborskii isolates than did rpoC1 gene analysis, and unique band profiles were also found among each of the cyanobacterial genera examined. A PCR test targeting a region of the rpoC1 gene unique to C. raciborskii was developed for the specific identification of C. raciborskii from both purified genomic DNA and environmental samples. The PCR was evaluated with a number of cyanobacterial isolates, but a PCR-positive result was only achieved with C. raciborskii. This method provides an accurate alternative to traditional morphological identification of C. raciborskii.

Clear Sky Luminance Patterns: Analysis, Comparison and Modelling

In tropical, subtropical and temperate maritime climate regions the clear and quasi-clear skies are often the most frequent and relevant sources of daylight, therefore the measurement, analysis, and comparison of their luminance patterns as well as additional simultaneous daylight conditions is of considerable interest. From three sets of regular scanning measurements in Berkeley, Tokyo, and Sydney homogeneous clear sky distributions were selected to analyse their scattering indicatrices and gradations with the aim of comparing these to CIE standards as well as to check the influences of turbidity and sun position. The paper demonstrates the reliability of the CIE standard sky models and other relatively simple but practical design skies.

Reproductive Behavior of Artemisia annua in Subtropical North India

ABSTRACT Artemisia annua is a xeromorphic temperate plant that contains promising antimalarial drugs, the sesquiterpene lactone artemisinin and derivatives of this compound. An examination of the growth and flowering behavior of Artemisia annua in the subtropical climate region of India demonstrated the plant grew normally and flowered profusely in the winter cropping season, late October to late April, at Lucknow, India. Considerable inter-plant variation was observed, however, in growth habit and flowering time. Plants could be grouped into four classes: early maturing dwarf, early maturing tall, late maturing dwarf, and late maturing tall. Early maturing plants which flowered in February and March, produced fertile achenes, completing the life cycle in 7 to 8 months. Late flowering plants that flowered in May and June, when the maximum day temperature was over 40°C, produced florets without seeds. The high temperature conditions to which the late flowering plants were exposed, appeared to prematurely dry the stigma. Late flowering plants sprouted branches from the vegetative and flowering parts of the plant during the rainy season.

DIFFERENCES BETWEEN MODELED SURPLUS AND USGS‐MEASURED DISCHARGE IN LAKE PONTCHARTRAIN BASIN, LOUISIANA1

ABSTRACT: A one‐layer decreasing‐availability monthly water balance model is used to estimate monthly surplus that flows into the Lake Pontchartrain Basin from the Amite, Tickfaw, Natalbany, Tangipahoa, and Tchefuncte Rivers for water years 1949 through 1990. The modeled annual surplus for each drainage basin is compared to gauged annual discharge obtained from the United States Geological Survey. This provides an estimate of the differential success of the model over watersheds of various sizes, and also suggests appropriate adjustment factors to be used in future water balance analyses of similar basins in humid subtropical climate regions. Results show that annual surplus values agree well with the USGS values, after an annual adjustment of about 140 mm (11 to 28 percent of the basin surplus) is subtracted from the annual modeled totals to compensate for overestimation by the model. However, inter‐annual variability is high in the annual cycles. Winter and spring discharges can also be modeled successfully.

Ant recolonisation of rehabilitated bauxite mines of Poços de Caldas, Brazil

ABSTRACTThe ant species were sampled in one campo (grassy shrubland), one mata (semideciduous rain forest) and 11 rehabilitated bauxite mine plots at Poços de Caldas, in the humid sub-tropical climatic region of Brazil. Rehabilitation was either by planting AustralianEucalyptusspp, the BrazilianMimosa scabrellatree, or by planting mixed mata trees. Sixty-eight ant species were recorded, of which 26 were exclusively found in the native vegetation and 16 were confined to the rehabilitated plots. Ant species richness built up most rapidly in areas rehabilitated with mixed mata species and least rapidly in areas withEucalyptus. Younger rehabilitated plots appeared to be developing a campo-type ant community, although evidence indicates that more mata ant species will colonise once tree canopy closure takes place. Rate of ant return in Australia is positively correlated with the quantity and distribution of rainfall – the rates in the current study concur with those from humid sub-tropical climatic zones within Australia, suggesting that similar constraints to the succession may be operating. If found to be the case, this would have practical implications for planning and evaluating the success of rehabilitation.

Distribution and genesis of red and yellow soils in the central subtropics of southeast China

In the subtropical climatic region of southeast China, which is influenced by the monsoon climate, red soils are widespread. According to the Chinese soil classification system the main soil groups are subdivided on the base of the degree of allitic weathering. This is mainly characterized by the SiO 2:Al 2O 3 molar ratio of the clay fraction (according to the Chinese classification the fraction <1μm). The weathering stage and soil properties are determined by the horizontal and vertical climatic zonation. In basin regions and lower altitudes of the mountains up to about 600 m above sea level Red Earths (central subtropics) and Lateritic Red Earths (south subtropics) are developed on silicate rocks. In higher altitudes these soils change to Yellow Earths with goethitic B-horizons. In order to obtain information of the main soil forming processes of typical and widely distributed soils in the central subtropical region, a Red Earth from Middle Pleistocene red sediments of a basin region (Quaternary Red Clay) and two profiles of a Red Earth - Yellow Earth toposequence from granite of the neighbouring mountainous region were investigated by morphological, mineralogical and pedochemical methods. During the youngest phase of morphodynamic stability the recent soils developed on pre-weathered parent materials (basin sediments and saprolite) containing kaolinite and gibbsite formed in ancient weathering periods. In the course of soil formation weathering proceeded with the transformation of halloysite to kaolinite and mica minrals through the stages illite and vermiculite to Al-chlorite. Pedochemical characteristics are dominated by an almost complete leaching of bases and a high Al-saturation of the sorption complex. The type and intensity of soil characteristics show a marked relation to the altitude of the sites, depending on differences in humidity and intensity of leaching processes. With increasing altitude the accumulation of organic substances and the neoformation of goethite and Al-chlorite increase, while with decreasing altitude the neoformation of hematite and intensity of lessivation increases. Bt horizons, which occur only in the Red Earths show that lessivation was an important process during soil genesis, although these soils developed from pre-weathered, acid parent materials. In Yellow Earths from different parent materials no indications to clay migration were found. According to the FAO legend the Red Earths in the area investigated belong to the soil unit of Ferric Acrisols and the Yellow Earths to the soil unit of Dystric Cambisols. It appears that the soil colour and the SiO 2:Al 2O 3 molar ratio of the clay fraction used as criteria for soil systematics cannot sufficiently indicate the degree of weathering, soil genesis and site properties.

Frequency of Moisture Deficits and Surpluses in the Humid Subtropical Climatic Region of the United States

Frequency of Moisture Deficits and Surpluses in the Humid Subtropical Climatic Region of the United States

Present status and future of the solar stills : Nebbia, Giorgio United Nations Conference on New Sources of Energy, Rome, 1961, 12. p., Illus.

In the present work, availability of solar radiation for south-facing flat surfaces in Humid Subtropical Climatic Region of India has been estimated. Measurements of global and diffuse solar radiation for Aligarh (27.89°N, 78.08°E) which lies in the Humid Subtropical Climatic Region were performed for over a period of three years. Monthly, seasonal and annual optimum tilt angles were estimated. Comparison of total incident solar radiation was performed between Aligarh and New Delhi (Capital of India, 28.61°N, 77.20°E). Annual optimum tilt angle for Aligarh and New Delhi was found as 27.62° and 27.95° respectively (close to the latitude of the respective location). Estimated gains in annual average solar radiation (based on monthly, seasonal and annual optimum tilt angles) in comparison to a horizontal surface were 12.92%, 11.61% and 6.51% (for Aligarh) and 13.13%, 11.80% and 7.58% (for New Delhi) respectively. A loss of 1.16% and 5.68% energy (for Aligarh) and 1.18% and 4.91% (for New Delhi) were estimated with surface at seasonal and annual optimum tilt angles respectively compared to a surface at monthly optimum tilt angle. Based on the study, it was recommended that the inclined surface must be tilted on monthly or seasonal optimum tilt angle for better utilization of solar energy.

Der Jahresgang des mittleren geographischen Höhengradienten der Lufttemperatur in den verschiedenen Klimagebieten der Erde

The average vertical gradient of air temperature, like all other climatic elements, shows a variation throughout the year, its course running differendly in the different climatic regions of the world. An investigation of this feature was suggested by H. Lautensach and carried out by R. Bögel, who made use of the data of 297 pairs of terrestrial weather Stations on mountains throughout the world. Because of the all too great distance between two stations of a pair, auxiliary stations had frequently to be used. Wherever possible observation data of the free atmosphere were used for comparison. Nine types of annual variation of the vertical temperature gradient were found. Middle Europe is governed by the "normal" type where the maximum occurs in summer and the minimum during the winter. In the regions of subtropical climate with dry summers (Köppen's Cs climate) the Cs-Type, showing a summer minimum and a winter maximum, prevails. The type of the poles of coldness is characterised by negative values of the vertical temperature gradient, i. e. an increase of the monthly mean temperature with altitude. The origin and distribution of these types is explained by reference to the respective different properties of the "base layer" of the troposphere as they have become known from the investigations of Schneider-Carius in 1953. Since the average vertical gradient, regionally as well as seasonally, is subject to pronounced variations which, according to the data used, lie between + 1.16° C and - 1.84° C per 100 m., it will no longer be permissible to reduce mean temperatures to sea level everywhere and for every month simply by means of the usual amount of 0.5° C per 100 m. Rather is it necessary to differentiate the reduction factor regionally as well as seasonally, and the reduction of the annual variations of the monthly temperature to sea level must also be clone accordingly.