El Nino

Designing a fuel-sampling program that accurately and efficiently assesses fuel load at relevant spatial scales requires knowledge of each sample method’s strengths and weaknesses. We obtained loading values for six fuel components using five fuel load sampling techniques at five locations in western Montana, USA. The techniques included fixed-area plots, planar intersect, photoloads, a photoload macroplot, and a photo series. For each of the six fuels, we compared (1) the relative differences in load values among techniques and (2) the differences in load between each method and a reference sample. Totals from each method were rated for how much they deviated from totals for the reference in each fuel category. The planar-intersect method, which used 2.50 km of transects, was rated best overall for assessing the six fuels. Bootstrapping showed that at least 1.50 km of transect were needed to obtain estimates that approximate the reference sample. A newly developed photoload method,...

Unravelling the epidemiology of cholera has been one of the most elusive problems in tropical medicine. The early contest between 'contagionists' and 'localists' in the last century finds a modern equivalent in the on-going debate on whether the epidemiology of cholera has significant environmental determinants. This study investigates the role of climate and geography on seasonality and interannual variations of cholera, using historical mortality data between 1891 and 1940 from 24 districts of Bengal. The coastal districts exhibit a bi-annual seasonal cycle, as previously described for cholera in this region, but with a dominant peak in the spring. Spring mortality, particularly in the coastal region, shows significant correlations (r = 0.50, p < 0.001) with sea surface temperatures in the Bay of Bengal. During post-Niño years (a total of 13 events) when coastal sea temperatures rise, spring epidemics with excess mortality (over 15 000 deaths on average) occur, resulting in a shift away from the usual seasonal pattern. Significant correlations (r = 0.58, p < 0.001) between sea temperatures in the Pacific (an El Niño index) and cholera's spring deaths, and a peak at a frequency of approximately 1 /4.2 years in the power spectrum, support the influence of this climatic forcing. Cholera's winter peak, dominant further away from the estuary, appears less consistently associated with water temperatures in the Bay of Bengal, and accounts for most of the interannual variation in the geographical spread of cholera in Bengal. The differences in our results for spring and winter suggest the possibility of different aquatic reservoirs for the pathogen. As sea water temperature can only explain part of the historical variability in cholera deaths, and the seasonality of temperature is similar to that of other environmental parameters, further studies to elucidate causal pathways are warranted. Here, we provide geographical and climatological support for the hypothesis that environmental factors are important in the dynamics of endemic cholera.

We tested the hypothesis that the El Niño Southern Oscillation influences forest-wide fruit production, which, in turn, limits frugivorous and granivorous mammals on Barro Colorado Island (BCI), Panama. Observations of BCI mammals have been compiled for 49 years. ...

The parameter terms (second column) for log (Aerial shrub cover + 1) × scale and log (Aerial tree cover + 1) × scale were incorrectly given positive rather than negative values. The correct values are: log (Aerial shrub cover + 1) × scale = −0.005 (0.002) log (Aerial tree cover + 1) × scale = −0.002 (0.001)

Considerable evidence has emerged of a substantial decade-long change in the north Pacific atmosphere and ocean lasting from about 1976 to 1988. Observed significant changes in the atmospheric circulation throughout the troposphere revealed a deeper and eastward shifted Aleutian low pressure system in the winter half year which advected warmer and moister air along the west coast of North America and into Alaska and colder air over the north Pacific. Consequently, there were increases in temperatures and sea surface temperatures (SSTs) along the west coast of North America and Alaska but decreases in SSTs over the central north Pacific, as well as changes in coastal rainfall and streamflow, and decreases in sea ice in the Bering Sea. Associated changes occurred in the surface wind stress, and, by inference, in the Sverdrup transport in the north Pacific Ocean. Changes in the monthly mean flow were accompanied by a southward shift in the storm tracks and associated synoptic eddy activity and in the surface ocean sensible and latent heat fluxes. In addition to the changes in the physical environment, the deeper Aleutian low increased the nutrient supply as seen through increases in total chlorophyll in the water column, phytoplankton and zooplankton. These changes, along with the altered ocean currents and temperatures, changed the migration patterns and increased the stock of many fish species. A north Pacific (NP) index is defined to measure the decadal variations, and the temporal variability of the index is explored on daily, annual, interannual and decadal time scales. The dominant atmosphere-ocean relation in the north Pacific is one where atmospheric changes lead SSTs by one to two months. However, strong ties are revealed with events in the tropical Pacific, with changes in tropical Pacific SSTs leading SSTs in the north Pacific by three months. Changes in the storm tracks in the north Pacific help to reinforce and maintain the anomalous circulation in the upper troposphere. A hypothesis is put forward outlining the tropical and extratropical realtionships which stresses the role of tropical forcing but with important feed-backs in the extratropics that serve to emphasize the decadal relative to interannual time scales. The Pacific decadal timescale variations are linked to recent changes in the frequency and intensity of El Niño versus La Nina events but whether climate change associated with “global warming” is a factor is an open question.

Recently available hydrological data from Hukou station at the junction of the Poyang Lake with the Yangtze River along with other data from stations in the Poyang Lake basin have allowed further examination and understanding of the basin effect (basin discharge generated by rainfall) and the Yangtze River blocking effect on variations of the Poyang Lake level and floods at annual to decadal scales. Major results show that the basin effect has played a primary role influencing the level of Poyang Lake and development of severe floods, while the Yangtze River played a complementary role of blocking outflows from the lake. In most cases, only when the basin effect weakened did the river effect become large, a relationship indicating that the river's blocking effect diminishes when the lake level is high from receiving large amount of basin discharge, albeit a few exceptions to this relationship occurred when river flow also was elevated from receiving large rainfall discharges in upstream areas. Moreover, the basin effect has become stronger in the period 1960-2003 in accordance with the increase of warm season rainfall in the Poyang Lake basin. In particular, large increases of the basin's rainfall in the 1990s corresponded to the most severe floods (in 1998, 1995, and 1992) of the last 4 decades. The strong increase of warm season rainfall in the Poyang Lake basin in the 1990s is consistent with the recent southward shift of major warm season rain bands in eastern China. Results of this study provide a utility for improving predictions of the Poyang Lake level and floods, which affect a population of about 10 million. ª

Pup mortality and the timing of birth of South American sea lions Otaria flavescens were investigated to determine the possible relationship between fluctuations in prey availability in the Peruvian upwelling ecosystem and current and future reproductive success of sea lions during six consecutive breeding seasons. Our study from 1997 to 2002 encompassed the strongest El Niño on record and one La Niña event. Pup mortality ranged from 13% before El Niño to 100% during El Niño, and was negatively correlated with prey availability. Abortions were also more frequent when prey availability was low. However, pup mortality remained high following El Niño due to the punctuated short-term effects it had on population dynamics and subsequent maternal behaviour. Births occurred later in the season after years of low food availability and earlier following years of high food availability. The peak of pupping occurred around the peak of mortality in all years, and may have been the product of intensive competition between bulls at the peak of the breeding season. The stronger and more frequent El Niños that appear to be occurring along the Peruvian coast may produce significant stochastic changes in future births and pup mortality, which may place the vulnerable South American sea lion population in Peru at greater risk.

The main purpose of this work is to provide a broad assessment of the influence of the El Niño–southern oscillation (ENSO) on the frequency of extreme temperature events throughout the year in Argentina. The cold and warm events, defined by the persistence of significant anomalies arising from the maximum and minimum temperatures, are more intense in the subtropical latitudes, north of Argentina (northeast for cold events and northwest for warm events), during the coldest months, and in the south (higher latitudes) in the warmest months. The persistence of the air masses is always greater in the north. The warm (cold) events have a preferential region of dissipation in the northwest (northeast) of Argentina, close to the Andes. The effect of the ENSO phases on the probability of occurrences of these events has a large inter-monthly variability. The different La Niña episodes are more homogeneous in relation to their effects and feasibility for the prediction of extreme temperatures within the region, especially for cold events. During La Niña episodes, all 2 month periods (except August–September) present a higher occurrence probability of very persistent and intense cold events, compared with Neutral months in different regions of the country. Conversely, the different El Niño episodes are more heterogeneous and, therefore, their effects on temperature are more varied and so less predictable. However, El Niño episodes exhibit a stronger signal, which is associated with the tropical air incursions that generate extreme warm events, particularly in winter. These events have a higher occurrence probability in the north and a lower one in the south during the months of June to November. Cold events have a lower occurrence probability in different regions, during the El Niño phase, in the period April to September. In some cases, the ENSO signal is stronger in daily temperature values than in monthly ones over Argentina. Copyright © 2002 Royal Meteorological Society

Chl-Zr 26 and Chl-ZML relationships. This important role of ocean physics indicates that the observed Chl changes primarily reflect biomass changes due to dampened or increased nutrient fluxes to the upper lit layers. Changes in the photoacclimation state of phytoplankton probably also intervene, without obscuring the global picture, however. Quantifying the respective role of both phenomena would require the parallel examination of Chl and other quantities more directly tied to biomass.

Wildland fuelbeds are exceptionally complex, consisting of diverse particles of many sizes, types and shapes with abundances and properties that are highly variable in time and space. This complexity makes it difficult to accurately describe, classify, sample and map fuels for wildland fire research and management. As a result, many fire behaviour and effects software prediction systems use a generalised description of fuels to simplify data collection and entry into various computer programs. There are several major fuel description systems currently used in the United States, Canada and Australia, and this is a source of confusion for many in fire management. This paper (1) summarises the challenges of describing fuels, (2) contrasts approaches (association, classification and abstraction) for developing fuel description systems and (3) discusses possible future directions in wildland fuel description and science to transition to a universal fuel description system. Most discussio...

Paleoenvironmental reconstruction combining data from diatom, pollen, macrophytic, and archaeological analyses had not been attempted previously for coastal Peru. We analyzed two radiocarbondated sediment cores extracted from the "sacred" Urpi Kocha Lagoon at the pre-Hispanic religious center of Pachacamac (ca. AD 350e1533), near Lima, to characterize the paleoenvironment of the site. The data reveal an environmental history characterized by alternating periods of severe drought and catastrophic flood. Recurrent pulses with distinctive sediment, diatom, pollen, and macrophytic characteristics reflecting variations in water depth, substrate, turbidity and salinity, usually contain a thick basal sandy storm deposit overlain by thin organic accumulations of peat, gyttja, and snails. The most intense of these disturbance pulses, when correlated with pollen, plant macrofossils, radiocarbon dates, and regional proxy data, provide local evidence of four major floods associated with sustained, catastrophic El Niño events, tsunamis and/or severe storms in the Andean highlands over the last 2000 years.

Regional and interannual variations of the rainy season over Indonesia are investigated using daily rainfall data during 1961-90. Pentad-mean rainfall data, with a relatively better continuity have been obtained for 46 stations, and the annual and semi-annual cycles of rainfall at these stations have been objectively analyzed by harmonic analysis. The onset of southern-hemispheric spring/summer (SON/ DJF) rainy season starts from the Indian Ocean side of Jawa in the middle September, and propagates northward (in Jawa) and eastward (to Nusa Tenggara in middle December). Another route of rainy sea-

Tornadoes are a significant hazard in some parts of Canada, particularly in the southern Prairie provinces and southwestern Ontario, though they are not as common as in some parts of the US. Since the early 1980s, the regional weather offices in Canada have been recording tornado event information on a routine basis, and thus data exists that can be used to update older analyses of tornado frequencies. On average, about 60 tornadoes are reported each year, though many doubtless occur that are not observed or recorded in the Environment Canada records. An analysis of tornado frequencies with El Niñ o-Southern Oscillation (ENSO) events suggest that the cooler La Niñ a events tend to suppress tornadic activity, while El Niñ o events tend to enhance it (though there are exceptions to this trend).

Mean length in the catch of Peruvian hake (Merluccius gayi peruanus) declined drastically by 8 cm in a few months in 1992. The 1991-93 El Niño event marked the beginning of changes in bottom environmental conditions, that along with other changes in the ecosystem, were the cause of the disappearance of large sized old hake from the traditional fishing grounds and the invasion of these areas by high concentrations of small sized young hake, traditionally distributed in the southern areas. A misinterpretation of this change gave an optimistic perception of the state of the stock, leading to a large increase of the fishing fleet and therefore to an increase of the fishing pressure on this resource. Catch increased quickly to very high levels in 1996, the fishery indicators of relative abundance remained stable, while global abundance of hake was diminishing. The resource responded to these natural variations of environment and to the intense fishing pressure with changes in some aspects of its biology and ecology. The most remarkable was the decrease of the length and age at first maturity that led to spawning by 1 year old (19 cm) individuals in a species whose observed longevity was 14 years.

Wildfires that spread into wildland-urban interface (WUI) communities present significant challenges on several fronts. In the United States, the WUI accounts for a significant portion of wildland fire suppression and wildland fuel treatment costs. Methods to reduce structure losses are focussed on fuel treatments in either wildland fuels or residential fuels. There is a need for a well-characterised, systematic testing of these approaches across a range of community and structure types and fire conditions. Laboratory experiments, field measurements and fire behaviour models can be used to better determine the exposure conditions faced by communities and structures. The outcome of such an effort would be proven fuel treatment techniques for wildland and residential fuels, risk assessment strategies, economic cost analysis models, and test methods with representative exposure conditions for fire-resistant building designs and materials.

Among the large rivers rising on the Tibetan Plateau and adjacent high mountains, the discharge and suspended sediment load of the Ayeyarwady (Irrawaddy) River are the least well known. Data collected between 1969 and 1996 at Pyay (Prome) are analysed to provide the best available modern estimate of discharge (379 š 47 ð 10 9 m 3 /year) and suspended sediment load (325 š 57 ð 10 6 t/year) for the river upstream of the delta head. A statistical comparison with data collected in the nineteenth century (1871 to 1879) shows discharge has significantly decreased in the last ¾100 years. Regression and correlation analyses between discharge in the modern period and indices of El Niño-Southern Oscillation (ENSO) show a relationship.

Extensive regions around the world are influenced by the El Niño Southern Oscillation (ENSO). El Niño events occur irregularly but typically once every three to six years 1 . Although the effects of global warming on ENSO oscillations are difficult to predict, recent high resolution climatic models suggest that the frequency of El Niño-like conditions are expected to increase over the coming decades 2 . During an El Niño episode, rainfall dramatically increases in certain areas of the world, whereas severe droughts occur in other regions . The rainfall during El Niño years can be four to ten times higher than average, and the phenomenon lasts approximately one year. The next phase, known as La Niña, produces roughly the opposite climate patterns to those found during an El Niño episode.

Legal liability is an issue that concerns volunteer firefighters and may affect the ability of fire managers to perform their tasks. There are calls to guarantee firefighters will not be personally liable for actions undertaken in good faith. This paper reviews post-wildfire litigation in Australia and claims for compensation made against the New South Wales Rural Fire Service. Although the data are incomplete and likely to underestimate the actual claims history, analysis of the available data does show that the number of claims for compensation is small given the very large number of fires and hazard reduction burns across Australia. There is no evidence of extensive post-fire litigation or of fire agencies or firefighters being held liable for actions taken in the course of firefighting The evidence does not support assertions that there is an ‘increasing flood’ of legal claims arising from firefighting. Post-fire litigation is compared with other proceeding such as Royal Commiss...

The statistics of extremes have played an important role in engineering practice for water resources design and management. How recent developments in the statistical theory of extreme values can be applied to improve the rigor of hydrologic applications and to make such analyses more physically meaningful is the central theme of this paper. Such methodological developments primarily relate to maximum likelihood estimation in the presence of covariates, in combination with either the block maxima or peaks over threshold approaches. Topics that are treated include trends in hydrologic extremes, with the anticipated intensification of the hydrologic cycle as part of global climate change. In an attempt to link downscaling (i.e., relating large-scale atmosphereocean circulation to smaller-scale hydrologic variables) with the statistics of extremes, statistical downscaling of hydrologic extremes is considered. Future challenges are reviewed, such as the development of more rigorous statistical methodology for regional analysis of extremes, as well as the extension of Bayesian methods to more fully quantify uncertainty in extremal estimation. Examples include precipitation and streamflow extremes, as well as economic damage associated with such extreme events, with consideration of trends and dependence on patterns in atmosphere-ocean circulation (e.g., El Niñ no phenomenon).

Global synthesis of the findings from ¾140 recharge study areas in semiarid and arid regions provides important information on recharge rates, controls, and processes, which are critical for sustainable water development. Water resource evaluation, dryland salinity assessment (Australia), and radioactive waste disposal (US) are among the primary goals of many of these recharge studies. The chloride mass balance (CMB) technique is widely used to estimate recharge. Average recharge rates estimated over large areas (40-374 000 km 2 ) range from 0Ð2 to 35 mm year 1 , representing 0Ð1-5% of long-term average annual precipitation. Extreme local variability in recharge, with rates up to ¾720 m year 1 , results from focussed recharge beneath ephemeral streams and lakes and preferential flow mostly in fractured systems. System response to climate variability and land use/land cover (LU/LC) changes is archived in unsaturated zone tracer profiles and in groundwater level fluctuations. Inter-annual climate variability related to El Niño Southern Oscillation (ENSO) results in up to three times higher recharge in regions within the SW US during periods of frequent El Niños relative to periods dominated by La Niñas (1941)(1942)(1943)(1944)(1945)(1946)(1947)(1948)(1949)(1950)(1951)(1952)(1953)(1954)(1955)(1956)(1957). Enhanced recharge related to ENSO is also documented in Argentina. Climate variability at decadal to century scales recorded in chloride profiles in Africa results in recharge rates of 30 mm year 1 during the Sahel drought (1970)(1971)(1972)(1973)(1974)(1975)(1976)(1977)(1978)(1979)(1980)(1981)(1982)(1983)(1984)(1985)(1986) to 150 mm year 1 during non-drought periods. Variations in climate at millennial scales in the SW US changed systems from recharge during the Pleistocene glacial period (½10 000 years ago) to discharge during the Holocene semiarid period. LU/LC changes such as deforestation in Australia increased recharge up to about 2 orders of magnitude. Changes from natural grassland and shrublands to dryland (rain-fed) agriculture altered systems from discharge (evapotranspiration, ET) to recharge in the SW US. The impact of LU change was much greater than climate variability in Niger (Africa), where replacement of savanna by crops increased recharge by about an order of magnitude even during severe droughts. Sensitivity of recharge to LU/LC changes suggests that recharge may be controlled through management of LU. In irrigated areas, recharge varies from 10 to 485 mm year 1 , representing 1-25% of irrigation plus precipitation. However, irrigation pumpage in groundwater-fed irrigated areas greatly exceeds recharge rates, resulting in groundwater mining. Increased recharge related to cultivation has mobilized salts that accumulated in the unsaturated zone over millennia, resulting in widespread groundwater and surface water contamination, particularly in Australia. The synthesis of recharge rates provided in this study contains valuable information for developing sustainable groundwater resource programmes within the context of climate variability and LU/LC change.

Recent decades have seen a resurgence of interest in human ecodynamics—the relationship among climate, environment, and culture. Most published research concentrates on the potential causal role of climate and environment in culture change. We approach the issue from the other side: The archaeological record often incorporates important, sometimes unique, proxy records of climate, of environment, and of change in both. We detail four case studies, from South America, Southwest Asia, North America, and the Shetland Islands. In each case, the paleoclimatic and/or paleoenvironmental data resulted from multidisciplinary archaeological projects whose major objective was to understand past human behavior. Nevertheless, in each case, the projects generated important information about the natural world in the past. Often, these data play a role in modeling future climatic and environmental change of potential significance to humans. We note a growing use of archaeological proxy data by clim...

The increasing extent of wildfires has prompted investigation into alternative fire management approaches to complement the traditional strategies of fire suppression and fuels manipulation. Wildfire prevention through ignition reduction is an approach with potential for success, but ignitions result from a variety of causes. If some ignition sources result in higher levels of area burned, then ignition prevention programmes could be optimised to target these distributions in space and time. We investigated the most common ignition causes in two southern California sub-regions, where humans are responsible for more than 95% of all fires, and asked whether these causes exhibited distinct spatial or intra-annual temporal patterns, or resulted in different extents of fire in 10–29-year periods, depending on sub-region. Different ignition causes had distinct spatial patterns and those that burned the most area tended to occur in autumn months. Both the number of fires and area burned va...

This paper reports results from a study of the flame characteristics of 22 wind-aided pine litter fires in a laboratory wind tunnel and 32 field fires in southern rough and litter-grass fuels. Flame characteristic and fire behaviour data from these fires, simple theoretical flame models and regression techniques are used to determine whether the data support the derived models. When the data do not support the models, alternative models are developed. The experimental fires are used to evaluate entrainment constants and air/fuel mass ratios in the model equations. Both the models and the experimental data are consistent with recently reported computational fluid dynamics simulations that suggest the existence of buoyancy-and convection-controlled regimes of fire behaviour. The results also suggest these regimes are delimited by a critical value of Byram's convection number. Flame heights and air/fuel ratios behave similarly in the laboratory and field, but flame tilt angle relationships differ.

Climate change and global warming have severe consequences for the survival of scleractinian (reefbuilding) corals and their associated ecosystems. This review summarizes recent literature on the influence of temperature on coral growth, coral bleaching, and modelling the effects of high temperature on corals. Satellite-based sea surface temperature (SST) and coral bleaching information available on the internet is an important tool in monitoring and modelling coral responses to temperature. Within the narrow temperature range for coral growth, corals can respond to rate of temperature change as well as to temperature per se. We need to continue to develop models of how non-steady-state processes such as global warming and climate change will affect coral reefs.

This paper was presented at the conference ‘Integrating spatial technologies and ecological principles for a new age in fire management’, Boise, Idaho, USA, June 1999 Fuel maps are essential for computing spatial fire hazard and risk and simulating fire growth and intensity across a landscape. However, fuel mapping is an extremely difficult and complex process requiring expertise in remotely sensed image classification, fire behavior, fuels modeling, ecology, and geographical information systems (GIS). This paper first presents the challenges of mapping fuels: canopy concealment, fuelbed complexity, fuel type diversity, fuel variability, and fuel model generalization. Then, four approaches to mapping fuels are discussed with examples provided from the literature: (1) field reconnaissance; (2) direct mapping methods; (3) indirect mapping methods; and (4) gradient modeling. A fuel mapping method is proposed that uses current remote sensing and image processing technology. Future fuel ...

The Colorado River system exhibits the characteristics of a heavily over-allocated or 'closing water system'. In such systems, development of mechanisms to allow resource users to acknowledge interdependence and to engage in negotiations and agreements becomes necessary. Recently, after a decade of deliberations and environmental assessments, the Glen Canyon Dam Adaptive Management Program (GCDAMP) was established to monitor and analyze the effects of dam operations on the Grand Canyon ecosystem and recommend adjustments intended to preserve and enhance downstream physical, cultural and environmental values. The Glen Canyon Dam effectively separates the Colorado into its lower and upper basins. Dam operations and adaptive management decisions are strongly influenced by variations in regional climate. This paper focuses on the management of extreme climatic events within the Glen and Grand Canyon Region of the Colorado River. It illustrates how past events (both societal and physical) condition management flexibility and receptivity to new information. The types of climatic information and their appropriate entry points in the annual cycle of information gathering and decision-making (the 'hydro-climatic decision calendar') for dam operations and the adaptive management program are identified. The study then describes how the recently implemented program, lessons from past events, and new climate information on the Colorado River Basin, facilitated responses during the major El Niño-Southern Oscillation (ENSO) event of 1997-1998. Recommendations are made for engaging researchers and practitioners in the effective use of climatic information in similar settings where the decision stakes are complex and the system uncertainty is large.

We investigate the viability of using El Niño-Southern Oscillation (ENSO) and sea surface temperature (SST) data to predict seasonal streamflow for one of the major rivers in Sri Lanka, the Kelani, using correlation analysis, contingency tables, and principal component analysis. The agricultural seasons in Sri Lanka are Yala (April-September) and Maha (October-March). The correlation between the Kelani River streamflow during Yala and ENSO indices (r = À0.41) is significant at 99% level. In addition, the Kelani streamflow during Yala has a correlation with the Central Indian Ocean SST (r = À0.40) that is also significant at the 99% level. The first principal component of the Indo-Pacific Ocean SST is reminiscent of the SST associated with the ENSO mode. A prediction scheme based on this mode for the streamflow during Yala has a skill characterized by a correlation of 0.5 in a cross-validated mode.

Wildfire ignition requires a combination of an open spark, and suitable weather and fuel conditions. Models of fire occurrence and burned area provide a good understanding of the physical and climatic factors that constrain and promote fire spread and recurrence, but information on how humans influence ignition patterns is still lacking at a scale compatible with integrated fire management. We investigated the relative importance of the physical, climatic and human factors regulating ignition probability across Southern California's National Forests. A 30-year exploratory analysis of one-way relationships indicated that distance to a road, distance to housing and topographic slope were the major determinants of ignition frequency. We used logistic and Poisson regression analyses to model ignition occurrence and frequency as a function of the dominant covariates. The resulting models explained ,70% of the spatial variability in ignition likelihood and 45% of the variability in ignition frequency. In turn, predicted ignition probability contributed to some of the spatial variability in burned area, particularly for summer fires. These models may enable estimates of fire ignition risk for the broader domain of Southern California and how this risk may change with future population and housing development. Our spatially explicit predictions may also be useful for strategic fire management in the region.

Semakin banyak fenomena alam yang menyebabkan perubahan musim, salah satunya yang terjadi belakangan ini di perairan Samudera Pasifik, seperti perubahan temperatur dan kenaikan muka air laut yang belum dapat dimengerti sepenuhnya. Perubahan temperatur biasanya dinamakan El Nino dan La Nina yang merupakan suatu penyimpangan iklim di Samudera Pasifik. Dengan adanya fenomena-fenomena alam yang terjadi di perairan Samudera Pasifik, maka dilakukan penelitian di sekitar Samudera Pasifik dengan menggunakan pelampung Triangle Trans-Ocean Bouy Network (TRITON). Salah satu pelampung TRITON berada pada posisi 0°N 138°E sebelah barat daya samudra pasifik. Data-data yang berasal dari pelampung tersebut berupa data temperatur dan salinitas dari tahun 2005 hingga 2011. Dari hasil analisa menunjukkan bahwa daerah di sekitar Indonesia memiliki lapisan thermocline dan halocline pada kedalaman 250 meter. Hubungan temperatur dan salinitas tidak berbanding lurus dan nilainya berubah dengan bertambahnya kedalaman. Tahun 2007 kejadian La Nina mengakibatkan banjir bandang di Timor Leste. Secara global kejadian El Nino dan La Nina menyebabkan turunnya tinggi permukaan air di lautan dan menambah volume air tanah yang menyebabkan banjir di Indonesia dan Australia, misalnya.

We present here the first statistically calibrated and verified tree-ring reconstruction of climate from continental Southeast Asia. The reconstructed variable is March-May (MAM) Palmer Drought Severity Index (PDSI) based on ring widths from 22 trees (42 radial cores) of rare and long-lived conifer, Fokienia hodginsii (Po Mu as locally called) from northern Vietnam. This is the first published tree ring chronology from Vietnam as well as the first for this species. Spanning 535 years, this is the longest cross-dated tree-ring series yet produced from continental Southeast Asia. Response analysis revealed that the annual growth of Fokienia at this site was mostly governed by soil moisture in the pre-monsoon season. The reconstruction passed the calibration-verification tests commonly used in dendroclimatology, and revealed two prominent periods of drought in the mid-eighteenth and late-nineteenth centuries. The former lasted nearly 30 years and was concurrent with a similar drought over northwestern Thailand inferred from teak rings, suggesting a ''mega-drought'' extending across Indochina in the eighteenth century. Both of our reconstructed droughts are consistent with the periods of warm sea surface temperature (SST) anomalies in the tropical Pacific. Spatial correlation analyses with global SST indicated that ENSO-like anomalies might play a role in modulating droughts over the region, with El Niño (warm) phases resulting in reduced rainfall. However, significant correlation was also seen with SST over the Indian Ocean and the north Pacific, suggesting that ENSO is not the only factor affecting the climate of the area. Spectral analyses revealed significant peaks in the range of 53.9-78.8 years as well as in the ENSO-variability range of 2.0 to 3.2 years.

Physics-based coupled fire-atmosphere models are based on approximations to the governing equations of fluid dynamics, combustion, and the thermal degradation of solid fuel. They require significantly more computational resources than the most commonly used fire spread models, which are semi-empirical or empirical. However, there are a number of fire behaviour problems, of increasing relevance, that are outside the scope of empirical and semi-empirical models. Examples are wildland-urban interface fires, assessing how well fuel treatments work to reduce the intensity of wildland fires, and investigating the mechanisms and conditions underlying blow-up fires and fire spread through heterogeneous fuels. These problems are not amenable to repeatable full-scale field studies. Suitably validated coupled atmosphere-fire models are one way to address these problems. This paper describes the development of a three-dimensional, fully transient, physics-based computer simulation approach for modelling fire spread through surface fuels. Grassland fires were simulated and compared to findings from Australian experiments. Predictions of the head fire spread rate for a range of ambient wind speeds and ignition line-fire lengths compared favourably to experiments. In addition, two specific experimental cases were simulated in order to evaluate how well the model predicts the development of the entire fire perimeter.

Daily flow records, rainfall data and tropical cyclone maps during 1970-1998 are used to document the impact of tropical cyclones (TCs) on floods in the Rewa River system, Viti Levu, Fiji. Floods are large, brief, isolated events caused by TCs and non-TC tropical rainstorms. More floods are caused by tropical rainstorms than by TCs, but TC floods are larger. The log Pearson Type III distribution consistently provided the best fit to partial duration flood series and the widelyrecommended generalized Pareto distribution performed very poorly, underscoring the need to test a variety of distributions for a particular geographic location. Tropical cyclones occur more often in Fiji during negative values of the Southern Oscillation Index (SOP) and all TCs that occurred during El Nino conditions caused floods. Peak flood discharges caused by TCs are inversely correlated with the SOI, reflecting possible links with tropical cyclone frequency and precipitation intensity.

Biomass burning by wildland fires has significant ecological, social and economic impacts. Satellite remote sensing provides direct measurements of radiative energy released by the fire (i.e. fire intensity) and surrogate measures of ecological change due to the fire (i.e. fire or burn severity). Despite anecdotal observations causally linking fire intensity with severity, the nature of any relationship has not been examined over extended spatial scales. We compare fire intensities defined by Moderate Resolution Imaging Spectroradiometer Fire Radiative Power (MODIS FRP) products with Landsat-derived spectral burn severity indices for 16 fires across a vegetation structure continuum in the western United States. Per-pixel comparison of MODIS FRP data within individual fires with burn severity indices is not reliable because of known satellite temporal and spatial FRP undersampling. Across the fires, 69% of the variation in relative differenced normalized burn ratio was explained by the 90th percentile of MODIS FRP. Therefore, distributional MODIS FRP measures (median and 90th-percentile FRP) derived from multiple MODIS overpasses of the actively burning fire event may be used to predict potential long-term negative ecological effects for individual fires.