Home  About us  Contact
 

Dry Months (dry + month)

Distribution by Scientific Domains
Earth and Environmental Science60%

Selected Abstracts

Atmospheric conditions associated with the exceptional fire season of 2003 in Portugal

INTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 13 2006
Ricardo M. Trigo
Abstract The summer of 2003 was characterised by exceptional warm weather in Europe, particularly during the first two weeks of August, when a devastating sequence of large fires was observed, reaching an amount of circa 450 000 ha, the largest figure ever recorded in Portugal in modern times. They were concentrated in two relatively confined regions of Portugal and a considerable proportion of burnt area was due to fires started on the 2nd and 3rd of August. It is shown that the 850 hPa temperature values observed over Portugal for the 1st and 2nd of August 2003 were the highest recorded since 1958. Using data from synoptic stations covering the entire Portuguese territory, the event was characterised in fine detail, including the evolution of both maximum and minimum temperatures, surface relative humidity, and wind anomaly fields. The different spatial extent of maximum and minimum temperatures is analysed leading to the new all-time Portuguese records of 47.3 °C for maximum and 30.6 °C for minimum temperatures that were recorded on the 1st of August near the main area of occurrence of the largest fire. Finally, it is shown that the summer of 2003 was preceded by a wet winter followed by a very dry month of May, a precipitation anomalous regime that contributed to a climatic background that favoured the role played by the early August heatwave and the associated meteorological surface conditions. Copyright Š 2006 Royal Meteorological Society [source]

Effects of the North Atlantic oscillation on the probability for climatic categories of local monthly rainfall in southern Spain

INTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 4 2003
D. Muņoz-Díaz
Abstract In many regions of the world, planning agricultural and water management activities is usually done based on probabilities for seasonal or monthly rainfall, for specified intervals of values. These intervals of rainfall amounts are commonly grouped into three categories: drought, normal rainfall, and abundant rainfall. Changes in the probabilities of occurrence of rainfall amounts within these climatic rainfall categories will influence the decisions that farmers and water managers will take. This research explores the changes produced by the North Atlantic oscillation (NAO) on the probability that local monthly rainfall takes in the southern Iberian Peninsula. The evolution of the NAO was divided into three phases: negative NAO, ,normal' NAO, and positive NAO, and local rainfall series were divided into three groups, corresponding to each NAO phase. The resulting empirical distribution functions were analysed and modelled by Gamma distributions. The results allow one to estimate the change in the probabilities of wet and dry months when a change in NAO phase is produced. The main result of this work is that changes in the probability of occurrence of climate categories of rainfall are more complex than only an increase of rainfall amount during the negative NAO phase and a decrease during the positive NAO phase. In fact, a certain asymmetry is detected in January, with more extremes linked to the negative NAO phase. Copyright Š 2003 Royal Meteorological Society [source]

TEMPORAL RESPONSES OF SURFACE-WATER AND GROUND-WATER TO PRECIPITATION IN ILLINOIS,

JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 3 2001
Wayne M. Wendland
ABSTRACT: Illinois data from 168 months (1986,1999) were investigated to determine the responses of surface-water and ground-water resources to precipitation. Such responses were generally within the month of occurrence or one to two months later, with recovery being reached another one to three months into the future, depending on season of the year. Although the drought of 1988 immediately impacted surface-water and ground-water resources, the time of recovery was substantially longer compared to those of individual dry months, generally continuing for several months. The extremely wet summer of 1993 resulted in elevated responses in water resources almost immediately, but in this instance continued through the following fall and winter, into the spring of 1994. [source]

Rice versus fish revisited: On the integrated management of floodplain resources in Bangladesh

NATURAL RESOURCES FORUM, Issue 2 2004
Bhavani Shankar
Abstract Disproportionately little attention has been paid to the dry season trade-off between rice and (inland capture) fish production on the floodplains of Bangladesh, compared to the same trade-off during the flood season. As the rural economy grows increasingly dominated by dry-season irrigated rice production, and floodplain land and water come under ever-increasing pressure during the dry winter months, there is an urgent need to focus attention on these dry months that are so critical to the survival and propagation of the floodplain resident fish, and to the poor people that depend on these fish for their livelihood. This article examines three important dry-season natural resource constraints to floodplain livelihoods in Bangladesh, and finds a common factor at the heart of all three: rice cultivation on lands at low and very low elevations. The article articulates the system interlinkages that bind these constraints and the long-run trend towards irrigated rice cropping on lower-lying lands, and suggests a management approach based on locally tailored strategies to arrest this trend. Apart from its direct relevance to the floodplains of Bangladesh, which support more than 100 million people, these lessons have relevance for river floodplain systems elsewhere in the developing world, notably the Mekong Delta. [source]

Complementary use of natural and artificial wetlands by waterbirds wintering in Doņana, south-west Spain

AQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 7 2009
Janusz Kloskowski
Abstract 1.The Doņana wetland complex (SW Spain) holds more wintering waterfowl than any other wetland in Europe. 2.This study focused on the use made by 12 common waterbirds (eight ducks and four waders) of the natural seasonal marshes in Doņana National Park (DNP) and the adjacent Veta la Palma (VLP) fish ponds created in the early 1990s. Data used were from aerial and terrestrial surveys collected between October and February during six consecutive winters from 1998/99 to 2003/04. Changes in distribution of each bird taxon were related to changes in the extent of flooded marshes within DNP. Up to 295,000 ducks were counted in VLP during dry periods, and up to 770,000 in DNP when it was flooded. 3.The timing and extent of flooding in DNP was highly variable, but there was a consistent pattern in which ducks concentrated in VLP during dry months and winters but redistributed to DNP as more of it was flooded. This refuge effect was also strong for black-tailed godwits Limosa limosa, but much less so for other waders. Waders feed mainly on invertebrates, and invertebrate biomass in VLP was found to be higher than in DNP. Ducks feed mainly on seeds and plant material, which are more abundant in DNP when flooded. 4.When water levels in DNP were stable over the course of a winter, or controlled for in multivariate models, the numbers of ducks at VLP declined over time, probably due to reduced availability of plant foods. In contrast, numbers of waders at VLP were more stable, and their invertebrate prey became more abundant over time, at least in the winter 2003/4. 5.In this extremely important wetland complex, the value of natural and artificial wetlands for wintering waterbirds are complementary, providing suitable habitat for different species and for different conditions in a highly variable Mediterranean environment. Copyright Š 2009 John Wiley & Sons, Ltd. [source]