Precipitation Temperature Changes Research Articles

Recent precipitation trends, flash floods and landslides in southern Brazil

In order to understand the rising number of flash floods and landslides in the densely populated region of southeastern Brazil, this study analyzes the spatial and temporal changes in precipitation from 1978 to 2014. We focus on the sensitivity of mountainous regions, specifically the Rio de Janeiro (RJMR) and Santa Catarina (SCMR) regions. Daily rainfall observations are aggregated into annual and seasonal indexes, and RClimdex is used to evaluate a suite of precipitation and extreme event indexes. Results show positive annual and seasonal precipitation trends during all seasons except for the winter season in the RJMR. Diverse change points in their time series, spatial differences in the trends at individual stations, and trends associated with elevation suggest that despite the close proximity of these two regions, climate impacts are not uniform across all of southeastern Brazil. The majority of precipitation-related indexes present positive trends, especially in the extreme precipitation indexes (PRCPTOT, RX1day, Rx5day and R30 mm). Statistically significant positive correlations are discovered between landslides/flash floods events and annual maximum 1-day and 5-day consecutive precipitation, and these indexes may be useful indicators of natural hazard events for this region.

Desarrollo del sistema de información de la red de pluviómetros alternativos en medios rurales. Caso estado Anzoátegui, Venezuela

Knowledge of temporal changes in precipitation and its interaction with other components of the agricultural system facilitates agricultural planning, allowing better use of resources. The aim of this work was to develop an information system Network Alternative Pluviometers in rural areas of Anzoategui state. 22 Units of agricultural production plant located in different municipalities in the state were selected. Methodology of participatory action research and social intervention method was applied. Subsequently, network was integrated to the Information System of Agroecological Areas of the National Institute for Agricultural Research (INIA, by its Spanish acronym), providing opportunity to learn local characteristics of rain. The information system network aims to boost domestic development of communities where creation of new alternatives for use and management practices with ecological, economic and alternative approach makes possible, by strengthening capacity to innovate and disseminate technologies like based on planning in agriculture.

Performance evaluation and hydrological trend detection of a reservoir under climate change condition

Water is the key of development and stability of any region. Under climate change condition, water systems are less reliable and more vulnerable. In this study, performance of Saline reservoir in Odisha, India has been evaluated under the climate change condition. The study mainly focused on the trend analysis for identified the temporal changes in precipitation and inflow time series using Mann–Kendall test, quantification of inflows to reservoir using ARNO model and performance evaluation of reservoir using WEAP model under climate change condition. In the results, it has been observed that there is no significant trend for annual, seasonal and for any monthly rainfall. Variation in precipitation shows that rainy days are decreasing whereas number of intense rainy days (>100 mm) are increasing. A significant rising trend with test statistic value of +3.18 is observed for daily inflow series at 95 % confidence level. Evaluation of inflow to reservoir, ARNO model shows that the change in simulated flow is directly proportional to the change in rainfall. In order to 25 % Change, decrease or increase in rainfall amount resulted in equal amount of decrease or increase in the inflow. Performance evaluation of reservoir using WEAP model shows that if inflows reduced by 20 % there would be a decrease in supply reliability and it would not be possible to increase supplies. Reducing live storage by 10 % influence supply delivered in May and June, but again has little impact on the rest of the year.

Multi-millennial streamflow dynamics in two forested watersheds on Vancouver Island, Canada

Holocene streamflow was reconstructed for two rivers on Vancouver Island, British Columbia, Canada in 500-yr intervals. The San Juan River watershed is located on the wetter western side of the island, whereas the Koksilah River watershed is positioned on the drier eastern side. Both watersheds are forested. To reconstruct streamflow, temporal changes in precipitation (estimated using a pollen-based transfer function) and evapotranspiration were established for each watershed and integrated into a water balance model, calibrated using modern data. While seasonal streamflow variability was maintained throughout the Holocene, with greater flow in the winter relative to the summer, the amount of discharge has changed markedly through time. Lowest simulated flow occurred in the earliest Holocene, with low-flow conditions beginning earlier in the year and extending later into the fall. Such conditions may have inhibited salmon from using many of the smaller rivers in the region. Streamflow steadily increased throughout the early Holocene so that by ca. 6500calyr before present near-modern flow regimes were established. As climate changes in the future, the San Juan and Koksilah watersheds are expected to remain as pluvial hydroclimatic regimes, though with an extended season of low flow similar to conditions during the early Holocene.

Annual and seasonal changes in means and extreme events of precipitation and their connection to elevation over Yunnan Province, China

Based on daily precipitation records at 29 meteorological stations over Yunnan province, the spatial and temporal changes in precipitation index are analyzed during 1960–2013. Eleven indices of precipitation extremes are studied. The results show that regional annual total precipitation shows a significantly decreasing trend and most other precipitation indices are strongly correlated with annual total precipitation. Seasonally, a significant increase in precipitation was discovered for spring, while a decrease in precipitation was found for winter, summer, and autumn. Two significant decreasing trends are found for summer and autumn. Average consecutive dry days, number of heaviest precipitation days, very wet day precipitation, extremely wet day precipitation, maximum 1-day precipitation and simple daily intensity index show increasing trends, but only the last is statistically significant. Decreasing trends are found for consecutive wet days, wet day precipitation, number of heavy precipitation days, number of very heavy precipitation days and maximum 5-day precipitation, but only the first is significant at the 95% level. Spatial changes of precipitation extreme indices show differences, and they are not clustered. For maximum 1-day and 5-day precipitation, the spatial and temporal changes in monthly precipitation are not the same. There are no significant correlations between elevation and trend magnitude of precipitation extremes. An enhanced sensitivity of precipitation extremes at higher elevations is apparent.

Investigation of changes in water resources and grain production in China: changing patterns and uncertainties

Water resources are very important for grain production in China. In this study, we investigate the changes in streamflow and grain production in China from 1956 to 2008. Since the 1980s, the increase of total grain production was mainly contributed by northern China where significantly decreasing precipitation and available water resources were observed. From 1985 to 2008, northern China accounted for 92.9 % of the national total grain production growth. Consequently, the main grain production area has shifted from the south to the north. However, the shift was mismatching the spatial distributions and temporal changes in precipitation and available water resources in China. During 1956 through 2008, precipitation decreased in the main grain production areas of the northern China by 1.23-1.27 mm per year. During the same period, observed streamflows in the five major rivers in northern China decreased by 13.4-92.4 %. Current grain production in northern China is dependent on overexploitation of groundwater. From 1987 to 2000, the average groundwater table declined 10.8 m with a maximum decrease of 34.8 m in North China Plain. Furthermore, the impacts of climate change and projected industrial development exacerbate the uncertainty of grain supply by northern China in the future. This study also indicated the potential of southern China for a more important role in ensuring sustainable food security of China, with increasing precipitation and streamflows observed in the Yangtze River and Pearl River basins.

Precipitation–temperature changes and evolution of a small glacier in the southeastern European Alps during the last 90 years

ABSTRACTVery small glaciers (area <0.1 km2) have received increased scientific attention during recent years, both for their rapid responses to the climate forcing and because they are characterized by microclimatic conditions, often marginal to glacier formation. They are particularly sensitive to climate changes and characterized by a great mass turnover, particularly evident in maritime areas with high precipitation. Here we consider the evolution from 1920 of the ‘Canin Eastern Glacier’ (Italian Southeastern Alps) in order to correlate its evolution to the precipitation–temperature trends. We reconstructed a precipitation–temperature record at the altitude of the glacier, filling a lack of knowledge in this alpine sector. We observed a decrease in the mean annual precipitation of 10% in 90 years and a warming trend of 0.1°C decade−1 since 1851, and of 0.7°C decade−1 in the last 20 years. An inverse correlation between precipitation and mean air temperature during summer and ablation periods was also observed. Glacier dynamics revealed a phase of stability between 1945 and 1985 that seems to be a peculiar characteristic of this area. Moreover, through a general regression model the glacial terminus variations seem to be statistically influenced only by winter precipitation. This fact opens interesting perspectives for the possible future evolution of this small glacier and, more in general, to other small glaciers in maritime areas in regard to climate change scenarios.

Assessment of the RegCM4 over East Asia and future precipitation change adapted to the RCP scenarios

In this study, we investigated spatial and temporal changes in precipitation over the Coordinated Regional Climate Downscaling Experiment (CORDEX) East Asia domain, for present (1986–2005) and future (2031–2050) periods using the Regional Climate Model version 4 (RegCM4). Future meteorology produced by the Hadley Center Global Environmental Model version 2 coupled with the Atmosphere–Ocean (HadGEM2-AO) following global climate change scenarios (Representative Concentration Pathways (RCP) 4.5 and 8.5) was used as meteorological boundary conditions for the RegCM4. Six subregions (South Korea, North China, South China, Japan, Mongolia, and India) in the CORDEX East Asia domain were considered for analysis. The RegCM4 simulated spatial distributions of precipitation over East Asia with a correlation coefficient of 0.7 against Climate Research Unit data. The simulation skills of its temporal variability varied based on geographical regions and seasons, showing relatively poorer performance (underestimation in rainfall amount) in summer than in winter, in general. The future climate simulations by the RegCM4 presented that the East Asian continental regions will be warmer and more humid, leading to increased precipitation amounts, especially in the summer. The summer precipitation amount was projected to increase by about 5%, on average, over the East Asian domain, 5−15% in most subregions, and even higher (44% and 24%) in the South Korean region for the RCP 4.5 and 8.5 scenarios, respectively. It was also expected that heavy rainfall (> 50 mm/d) events may occur more frequently in the future possibly owing to meteorological changes that are favorable to convective heavy precipitation.

Chemical Composition and Isotopic Characteristics of the Carbonate Cements in Sandstone Reservoir Layer of Dongying Sinking

The chemical composition of the carbonate cements in reservoir sandstones was determined by the EPMA. The generation sequence is: calcite, dolomite, ferrous calcite, ankerite, and the latest are coarse-grained and fine-grained calcites which are veined. In the MnO-FeO-MgO triangular diagram, the samples fall clearly on the four areas. The carbon and oxygen isotope data on the carbonate cements show that δ13C are from −6.44 to +4.79, δ18O are from −4.25 to −15.21, focused on three areas in the map. The paleosalinity Z from 107 to 133 calculated by the carbon and oxygen isotope value reflects the characteristics that salinity changes are caused by fresh water filling lake water. The average temperature of calcite precipitation calculated by the oxygen isotope value is 650°C, while dolomite precipitation is 70.6°C. The precipitation temperature changes greatly and shows negative correlation with temperature and salinity, which reflects the characteristics of lake sediments.

Expanded response-surfaces: a new method to reconstruct paleoclimates from fossil pollen assemblages that lack modern analogues

Pollen-based paleoclimatic interpretations of late-glacial to early Holocene climates (17–9 ka) in Midwestern North America are hampered by samples that lack modern analogues. Unresolved questions include the magnitude and direction of temperature seasonality (i.e. were these climates more or less seasonal than present) and the temporal changes in precipitation. Central to the no-analogue problem is the truncation of modern pollen-climate relationships for abundant late-glacial taxa such as Fraxinus. Here we present a new method called the expanded response-surface (ERS) method, developed to reconstruct climates from no-analogue pollen assemblages and applied to a high-resolution late-glacial pollen record from Crystal Lake, Illinois to test hypotheses about late-glacial climates. The key assumptions central to the ERS method are: (1) plant species and pollen abundances follow symmetrical unimodal distributions along climatic gradients, (2) taxa with truncated distributions in modern climate space occupy a subset of their fundamental niche, and (3) expansion of truncated distributions by mirroring around the distributional mode recovers the portion of the fundamental niche not realized in the modern climate space. With the ERS method, we expanded modern pollen-climate relationships by mirroring pollen abundances for each taxon around a mode defined with respect to four climate axes (mean winter temperature, mean summer temperature, mean winter precipitation, and mean summer precipitation). The ERS method reconstructed past temperatures and precipitation during the height of no-analogue conditions (14 160–12 370 cal yr BP) for 37% of the Crystal Lake samples where techniques that employed only modern observational data found matches for only 13% of the fossil samples. The total climate space of the expanded taxa set allowed analogue matches under more seasonal-than-present climates with higher-than-present precipitation. The ERS climate reconstructions for the height of no-analogue conditions indicated cooler-than-present summer and winter temperatures, similar-to-present seasonal range in temperatures, higher-than-present winter precipitation, and similar-to-present summer precipitation. These results thus suggest that high moisture availability helped drive the formation of the Midwestern no-analogue communities with high Fraxinus nigra abundances, but do not show higher-than-present temperature seasonality notwithstanding the higher-than-present insolation seasonality at this time. During the no-analogue late-glacial interval, Picea mariana, F. nigra, and Larix stands probably grew on low-lying, poorly drained soils in the Crystal Lake region; whereas Abies, Picea glauca, Quercus, and Ostrya/ Carpinus grew on upland positions with better soil drainage.

Temporal variability of selected dissolved elements in the lower Orinoco River, Venezuela

AbstractMonthly analyses of pH, conductance, alkalinity, total suspended solids, dissolved major cations (Na, K, Ca and Mg), and selected dissolved trace elements (Fe, Al, Mn, Cu, Zn and Cr) were conducted on waters of the lower Orinoco River from February 2004 to May 2006. The data show strong seasonal variability. Major cations had maximum concentrations at low water, and were correlated with pH, conductance and alkalinity because of the tributaries coming from the Andean zones, where the weathering of evaporites and carbonate shales controls water chemistry. K concentrations did not show any relation with evaporite weathering, probably because large amounts of K come from the Guayana Shield rivers as a consequence of feldspar weathering. The concentrations of dissolved Fe, Mn and Cu were highest during the high water stage. Concentrations of the elements K, Cr, Zn and Cu are correlated with each other but not with dissolved Fe and Al, which probably are complexed with humic and fulvic substances. Mn concentrations did not show relationships with other variables. Inter‐annual variability of dissolved elements is explained by temporal changes in precipitation. Copyright © 2008 John Wiley & Sons, Ltd.

The Environmental Influence on Tropical Cyclone Precipitation

The intensity, spatial, and temporal changes in precipitation were examined in three North Atlantic hurricanes during 1989 (Dean, Gabrielle, and Hugo) using precipitation estimates made from Special Sensor Microwave/Imager (SSM/I) measurements. In addition, analyses from a barotropic hurricane forecast model and the European Centre for Medium-Range Weather Forecast model were used to examine the relationship between the evolution of the precipitation in these tropical cyclones and external forcing. The external forcing parameters examined were 1) mean climatological sea surface temperatures, 2) vertical wind shear, 3) environmental tropospheric water vapor flux, and 4) upper-tropospheric eddy relative angular momentum flux convergence. The analyses revealed that 1) the SSM/I precipitation estimates were able to delineate and monitor convective ring cycles similar to those observed with land-based and aircraft radar and in situ measurements; 2) tropical cyclone intensification was observed to occur when these convective rings propagated into the inner core of these systems (within 111 km of the center) and when the precipitation rates increased; 3) tropical cyclone weakening was observed to occur when these inner-core convective rings dissipated; 4) the inward propagation of the outer convective rings coincided with the dissipation of the inner convective rings when they came within 55 km of each other; 5) in regions with the combined warm sea surface temperatures (above 26°C) and low vertical wind shear (less than 5 m s−1), convective rings outside the region of strong lower-tropospheric inertial stability could be initiated by strong surges of tropospheric moisture, while convective rings inside the region of strong lower-tropospheric inertial stability could be enhanced by upper-tropospheric eddy relative angular momentum flux convergence.