C. R. de Freitas

Assessment of human bioclimate based on thermal response

To assess the thermal component of human climate, the adequacy of two body-environment energy balance models is tested. Requirements are that these models should include the full range of atmospheric variables using a system which embraces both the attributes of those exposed and the functional attributes of the environment. They should also account for thermal stress on the body as well as the feedback thermophysiological responses as a result of that stress, and produce a unitary thermal index. Based on detailed field assessment, the study provides an interpretation of index values in terms of thermal sensation and pleasantness using standardised verbal scales. Detailed statistical analysis shows that the associations between index values and thermal sensation votes are strong giving correlation coefficients in the order of 0.86 which is considerably larger than those from comparable results reported in the literature. Optimal thermal conditions for sedentary activity appear to be located in the zone of vasomotor regulation against heat, subjectly interpreted as slightly warm, rather than precisely at the point of minimum heat stress. Sensitivity of model output and thermal sensation are greater in the zone of heat stress than in the zone of cold stress.

Influence of the Southern Oscillation on tropospheric temperature

Time series for the Southern Oscillation Index (SOI) and global tropospheric temperature anomalies (GTTA) are compared for the 1958−2008 period. GTTA are represented by data from satellite microwave sensing units (MSU) for the period 1980–2008 and from radiosondes (RATPAC) for 1958–2008. After the removal from the data set of short periods of temperature perturbation that relate to near-equator volcanic eruption, we use derivatives to document the presence of a 5- to 7-month delayed close relationship between SOI and GTTA. Change in SOI accounts for 72% of the variance in GTTA for the 29-year-long MSU record and 68% of the variance in GTTA for the longer 50-year RATPAC record. Because El Nino−Southern Oscillation is known to exercise a particularly strong influence in the tropics, we also compared the SOI with tropical temperature anomalies between 20°S and 20°N. The results showed that SOI accounted for 81% of the variance in tropospheric temperature anomalies in the tropics. Overall the results suggest that the Southern Oscillation exercises a consistently dominant influence on mean global temperature, with a maximum effect in the tropics, except for periods when equatorial volcanism causes ad hoc cooling. That mean global tropospheric temperature has for the last 50 years fallen and risen in close accord with the SOI of 5–7 months earlier shows the potential of natural forcing mechanisms to account for most of the temperature variation.

Weather and place-based human behavior: recreational preferences and sensitivity

This study examines the links between biometeorological variables and the behavior of beach recreationists along with their rating of overall weather conditions. To identify and describe significance of on-site atmospheric conditions, two separate forms of response are examined. The first is sensory perception of the immediate atmospheric surround expressed verbally, which was the subject of earlier work. In the research reported here, on-site observations of behavior that reflect the effects of weather and climate are examined. By employing, independently, separate indicators of on-site experience, the reliability of each is examined and interpreted and apparent threshold conditions verified. The study site is King’s Beach located on the coast of Queensland, Australia. On-site observations of atmospheric variables and beach user behavior are made for the daylight hours of 45 days spread over a 12-month period. The results show that behavioral data provide reliable and meaningful indications of the significance of the atmospheric environment for leisure. Atmospheric conditions within the zone of acceptability are those that the beach users can readily cope with or modify by a range of minor behavioral adjustments. Optimal weather conditions appear to be those requiring no specific behavioral adjustment. Attendance levels reflect only the outer limits of acceptability of the meteorological environment, while duration of visit enables calibration of levels of approval in so far as it reflects rating of on-site weather within a broad zone of tolerance. In a broad theoretical sense, the results add to an understanding of the relationship between weather and human behavior. This information is potentially useful in effective tourism management and planning.

Patterns of species composition, recruitment, and growth within canopy gaps in two New Zealand kauri (Agathis australis) forests

Abstract Within-gap patterns of forest species composition, tree growth, and associated micro-climate were investigated in two kauri (Agathis australis) forests in northern New Zealand. Detrended correspondence analysis (DCA) of sites at Trounson Kauri Park revealed a gradient of changing species composition from gap centre to forest understorey. However, while some species were typical either of the understorey (e.g., Dysoxlylum spectabile) or the centre of large gaps (e.g., Knightia excelsa, Leucopogon fasciculata), no species was restricted solely to gap edge sites. Growth of potted tree seedlings over 6 months at different locations in and near a large canopy gap revealed a significant positive relationship between percent canopy openness (%CO) and height increase for each of the five species tested. The early successional tree Kunzea ericoides showed the greatest height increase at gap centre, while the long-lived conifer Dacrydium cupressinum had the greatest height increase in the forest understore...

Microclimatic differences between and within canopy gaps in a temperate rainforest

The microclimate in the understorey and in two canopy gaps of different size (249 m2 and 12.6 m2) within a temperate rainforest in northern New Zealand were characterised using net all-wave radiation (Q*), vapour pressure deficit (VPD), vertical air temperature gradient (VTG), and maximum and minimum air temperatures. Hemispherical fisheye photographs were used to define the exposure to the sky at each microclimate recording site both within and between gaps, and in the understorey. Under condiions of clear skies during the summer, with the sun close to its maximum altitude, the large gap centre had a mean daytime (0700–1700 hours)Q* of 452 W/m2. This value was similar to that estimated for an open field nearby, but three times greater thanQ* at the centre of the small gap, and six times greater than in the understorey. The east and west sides of both gaps had higher values ofQ* than the north and south sides. BothQ* and mean daily maximum temperature were strongly correlated with the amount of sky exposure. VPD and VTG were higher in gaps than in the understorey, with maximum values for both variables occurring at the centre of the large gap.

The Acclimatization Thermal Strain Index (ATSI): a preliminary study of the methodology applied to climatic conditions of the Russian Far East

Travel to distant places where the climate is different to that at home involves a period of short-term acclimatization adjustment following arrival during which the traveler might experience thermally-induced physiological strain. This may be expressed as an “acclimatization thermal loading” (ATL). The first signs of this show up in the respiratory organs. In the current study, the Acclimatization Thermal Strain Index (ATSI) is developed and used for assessment of ATL for recreational travel over a range of climatic conditions. ATSI estimates the impact of short-term acclimatization calculated as the ratio of a difference between respiratory heat losses at the traveler’s home location to respiratory heat losses at the trip destination upon first arriving there. The Russian Far East region is used as a case study. The research focuses on the effects of travel from two locations in the study region. The results show that ATSI values can be significantly different when considering places of trip origin. For example, travel from Anadyr to other locations within the Russian Far East could lead to large ATSI in summer. In contrast, ATSI values are small for travel almost anywhere in the region during winter, but this is against a backdrop of extreme cold for the region as a whole. Here, the diversity of climatic conditions of both heat and cold means short-term adjustment to conditions could be stressful or worse for those who travel to participate in outdoor activities.

Studies of condensation/evaporation processes in the Glowworm Cave, New Zealand

The condensation/evaporation process is important in caves, especially in tourist caves where there is carbon dioxide enriched air caused by visitors. The cycle of condensation and evaporation of condensate is believed to enhance condensation corrosion. The problem is condensation is difficult to measure. This study addresses the problem and reports on a method for measuring and modelling condensation rates in a limestone cave. Electronic sensors for measuring condensation and evaporation of the condensate as part of a single continuous process of water vapour flux are tested and used to collect 12 months of data. The study site is the Glowworm tourist cave in New Zealand. The work describes an explanatory model of processes leading to condensation using data based on measurements of condensation and evaporation as part of a single continuous process of water vapour flux. The results show that the model works well. However, one of the most important messages from the research reported here is the introduction of the condensation sensor. The results show that condensation in caves can actually be measured and monitored, virtually in real time. In conjunction with the recent developments in data logging equipment, this opens exciting perspectives in cave climate studies, and, more generally, in hydrogeological studies in karst terrains.

Climate and physiological heat strain during exercise

A body-atmosphere energy exchange model (BIODEX) using heat transfer theory and empirical relationships is described which predicts the change in body core temperature during exercise as an index of thermal strain. Index values may be interpreted as the length of the period of activity before the heat load on the body causes internal body temperature to rise to critical levels. The performance of the model tested under controlled laboratory conditions using human subjects was found to be reliable. BIODEX is used to show the thermal significance of midsummer climatic conditions in New Zealand for those jogging out-doors.

A comparison and appraisal of a comprehensive range of human thermal climate indices

Numerous human thermal climate indices have been proposed. It is a manifestation of the perceived importance of the thermal environment within the scientific community and a desire to quantify it. Schemes used differ in approach according to the number of variables taken into account, the rationale employed, and the particular design for application. They also vary considerably in type and quality, method used to express output, as well as in several other aspects. In light of this, a three-stage project was undertaken to deliver a comprehensive documentation, classification, and overall evaluation of the full range of existing human thermal climate indices. The first stage of the project produced a comprehensive register of as many thermal indices as could be found, 165 in all. The second stage devised a sorting scheme of these human thermal climate indices that grouped them according to eight primary classification categories. This, the third stage of the project, evaluates the indices. Six evaluation criteria, namely validity, usability, transparency, sophistication, completeness, and scope, are used collectively as evaluation criteria to rate each index scheme. The evaluation criteria are used to assign a score that varies between 1 and 5, 5 being the highest. The indices with the highest in each of the eight primary classification categories are discussed. The work is the final stage of a study of the all human thermal climatic indices that could be found in literature. Others have considered the topic, but this study is the first detailed, genuinely comprehensive, and systematic comparison. The results make it simpler to locate and compare indices. It is now easier for users to reflect on the merits of all available thermal indices and decide which is most suitable for a particular application or investigation.

Are Observed Changes in the Concentration of Carbon Dioxide in the Atmosphere Really Dangerous

ABSTRACT Statements made by the United Nations Intergovernmental Panel on Climate Change (IPCC) have been used to put pressure on governments to formulate policies in response to the perceived threat of the climate change resulting from a build up of greenhouse gases in the atmosphere. The Kyoto Protocol proposed by the United Nations calls for industrialized countries to cut greenhouse gas emissions by five percent from 1990 levels by the year 2012. The enormity of the perceived economic consequences of this has led to intense arguments between governments over the appropriateness of reduction targets. But the real reason behind the failure to agree on a global climate treaty is disagreement on tradeoffs between the economic and environmental risks involved. Contrary to the IPCC predictions, global temperature has not risen appreciably in the last 20 years. Most surface temperature data free from the influence of surrounding buildings and roads show no warming. Data from satellites support this. Sea level has been rising since the end of the last ice age, long before industrialization, but historical records show no acceleration in sea level rise in the twentieth century. Increases in carbon dioxide appear to pose no immediate danger to the planet. The gas is not a pollutant. An understanding of global warming hinges on the answers to certain key questions. Is global climate warming? If so, what part of that warming is due to human activities? How good is the evidence? What are the risks? The task of answering these questions is hindered by widespread confusion regarding key facets of global warming science. The confusion has given rise to several fallacies or misconceptions. These myths and misconceptions, and how they relate to the above questions, are explained. Although the future state of global climate is uncertain, there is no reason to believe that catastrophic change is underway. The atmosphere may warm due to human activity, but if it does, the expected change is unlikely to be much more than 1 degree Celsius in the next 100 years. Even the climate models promoted by the IPCC do not suggest that catastrophic change is occurring. They suggest that increases in greenhouse gases are likely to give rise to a warmer and wetter climate in most places; in particular, warmer nights and warmer winters. Generally, higher latitudes would warm more than lower latitudes. This means milder winters and, coupled with increased atmospheric carbon dioxide, it means a more robust biosphere with greater availability of forest, crops and vegetative ground cover. This is hardly a major threat. A more likely threat is policies that endanger economic progress. The negative effect of such policies would be far greater than any change caused by global warming. Rather than try to reduce innocuous carbon dioxide emissions, we would do better to focus on air pollution, especially those aspects that are known to damage human health. End_Page 297------------------------