scholarly journals Cut-Off Low Patterns and Its Simultaneous Precipitation Over Iran

2021 ◽  
Author(s):  
Ghasem Azizi ◽  
Hossein Rezaei
Keyword(s):  
Heavy Rainfall ◽  
Annual Precipitation ◽  
Positive Trend ◽  
Upper Troposphere ◽  
The Earth ◽  
Northwest Of Iran ◽  
Detection Capabilities ◽  
Systematic Identification ◽  
Low Pressures ◽  
Low Precipitation

Abstract Iran located in arid and semiarid area of the earth with low precipitation. Iran's rainfall is mainly received in the cold period of the year. Although the total annual precipitation is low but sometime, the country receives heavy rainfall. One of the conditions that lead to heavy rainfall is cut-off low patterns. Cut-off low-pressure systems are defined as closed lows in the upper troposphere that have become completely detached from the main westerly current. The characteristics of Cut-off Lows in Iran are studied for the period of 1976–2015. To identify these systems, the Raul Nieto algorithm was used with automatic detection capabilities. The systematic identification of Cut-off Lows is realized by applying an original automated scheme using mean daily geo-potential height, wind and air temperature at 500 hPa NCEP. Cut-off Lows are more frequent during spring in the Iran, with a maximum of frequency in March. Over the period of 1976–2015, the annual Cut-off Lows frequency exhibits a weak positive trend. In this study, the most cut-off lows lasted only 2 days. Simultaneous precipitation with cut-off low pressures was compared with annual precipitation of stations. Northwest of Iran has a larger share of Cut-off low precipitation. Different Cut-off Low patterns were identified under 6 separate patterns. The highest frequency of cut-off lows are the eastern arm of omega pattern.

scholarly journals Sensitivity of Rhizoctonia Isolates to Phenazine-1-Carboxylic Acid and Biological Control by Phenazine-Producing Pseudomonas spp.

2017 ◽  
Vol 107 (6) ◽  
pp. 692-703 ◽  
Author(s):  
Ahmad Kamil Mohd Jaaffar ◽  
James A. Parejko ◽  
Timothy C. Paulitz ◽  
David M. Weller ◽  
Linda S. Thomashow
Keyword(s):  
Carboxylic Acid ◽  
Geographic Distribution ◽  
Root Rot ◽  
Cropping Systems ◽  
Annual Precipitation ◽  
Columbia Plateau ◽  
Pseudomonas Spp ◽  
Rhizoctonia Root Rot ◽  
Precipitation Zone ◽  
Low Precipitation

Rhizoctonia solani anastomosis groups (AG)-8 and AG-2-1 and R. oryzae are ubiquitous in cereal-based cropping systems of the Columbia Plateau of the Inland Pacific Northwest and commonly infect wheat. AG-8 and R. oryzae, causal agents of Rhizoctonia root rot and bare patch, are most commonly found in fields in the low-precipitation zone, whereas R. solani AG-2-1 is much less virulent on wheat and is distributed in fields throughout the low-, intermediate-, and high-precipitation zones. Fluorescent Pseudomonas spp. that produce the antibiotic phenazine-1-carboxylic acid (PCA) also are abundant in the rhizosphere of crops grown in the low-precipitation zone but their broader geographic distribution and effect on populations of Rhizoctonia is unknown. To address these questions, we surveyed the distribution of PCA producers (Phz+) in 59 fields in cereal-based cropping systems throughout the Columbia Plateau. Phz+ Pseudomonas spp. were detected in 37 of 59 samples and comprised from 0 to 12.5% of the total culturable heterotrophic aerobic rhizosphere bacteria. The frequency with which individual plants were colonized by Phz+ pseudomonads ranged from 0 to 100%. High and moderate colonization frequencies of Phz+ pseudomonads were associated with roots from fields located in the driest areas whereas only moderate and low colonization frequencies were associated with crops where higher annual precipitation occurs. Thus, the geographic distribution of Phz+ pseudomonads overlaps closely with the distribution of R. solani AG-8 but not with that of R. oryzae or R. solani AG-2-1. Moreover, linear regression analysis demonstrated a highly significant inverse relationship between annual precipitation and the frequency of rhizospheres colonized by Phz+ pseudomonads. Phz+ pseudomonads representative of the four major indigenous species (P. aridus, P. cerealis, P. orientalis, and P. synxantha) suppressed Rhizoctonia root rot of wheat when applied as seed treatments. In vitro, mean 50% effective dose values for isolates of AG-8 and AG-2-1 from fields with high and low frequencies of phenazine producers did not differ significantly, nor was there a correlation between virulence of an isolate and sensitivity to PCA, resulting in rejection of the hypothesis that tolerance in Rhizoctonia spp. to PCA develops in nature upon exposure to Phz+ pseudomonads.

A Discussion on volcanism and the structure of the Earth - Proposals concerning the variation of volcanic products and processes within the oceanic environment

1972 ◽  
Vol 271 (1213) ◽  
pp. 131-140 ◽  
Keyword(s):  
Structural Model ◽  
Early Stage ◽  
Volcanic Rocks ◽  
Fracture Zones ◽  
Sea Floor ◽  
Stage Of Development ◽  
Incompatible Elements ◽  
The Earth ◽  
Sea Floor Spreading ◽  
Low Pressures

An attempt is made to fit available petrochemical data on oceanic volcanic rocks into the structural model for the ocean basins presented by the plate tectonic theory. It is suggested that there are three major volcanic regimes: (i) the low-potassic olivine tholeiite association of the axial zones of the oceanic ridges where magmatic liquids are generated at low pressures high in the mantle, (ii) the alkalic (Na > K) associations along linear fractures where liquids generated at greater depth gain easy egress to the surface, (iii) those alkalic associations, rich in incompatible elements, of island groups, remote from fracture zones, where magmas created at depth proceed slowly to the surface and in consequence suffer intense fractionation. There are certain discrepancies in this pattern, notably that there is no apparent relation between rate of sea-floor spreading and degree of over-saturation of the axial zone basalts and that certain areas, such as Iceland, are characterized by excess volcanism. Explanation of these anomalies is sought by examining an oceanic area in an early stage of development—the Red Sea. It is tentatively suggested that the initial split of a contiguous continent might be brought about by the linking of profound fractures, caused by domal uplift related to rising isolated lithothermal systems, and that the present anomalies in oceanic volcanism may reflect the variation in rate of thermal convection within the original isolated lithothermal plumes.

scholarly journals Precipitation Trends over Time Using Mann-Kendall and Spearman’s rho Tests in Swat River Basin, Pakistan

2015 ◽  
Vol 2015 ◽  
pp. 1-15 ◽  
Author(s):  
Ijaz Ahmad ◽  
Deshan Tang ◽  
TianFang Wang ◽  
Mei Wang ◽  
Bakhtawar Wagan
Keyword(s):  
River Basin ◽  
Statistical Tests ◽  
Annual Precipitation ◽  
Positive Trend ◽  
Monthly Precipitation ◽  
Significance Level ◽  
Spearman's Rho ◽  
Spearman’S Rho ◽  
Swat River ◽  
Precipitation Trends

Accurately predicting precipitation trends is vital in the economic development of a country. This research investigated precipitation variability across 15 stations in the Swat River basin, Pakistan, over a 51-year study period (1961–2011). Nonparametric Mann-Kendall (MK) and Spearman’s rho (SR) statistical tests were used to detect trends in monthly, seasonal, and annual precipitation, and the trend-free prewhitening approach was applied to eliminate serial correlation in the precipitation time series. The results highlighted a mix of positive (increasing) and negative (decreasing) trends in monthly, seasonal, and annual precipitation. One station in particular, the Saidu Sharif station, showed the maximum number of significant monthly precipitation events, followed by Abazai, Khairabad, and Malakand. On the seasonal time scale, precipitation trends changed from the summer to the autumn season. The Saidu Sharif station revealed the highest positive trend (7.48 mm/year) in annual precipitation. In the entire Swat River basin, statistically insignificant trends were found in the subbasins for the annual precipitation series; however, the Lower Swat subbasin showed the maximum quantitative increase in the precipitation at a rate of 2.18 mm/year. The performance of the MK and SR tests was consistent at the verified significance level.

scholarly journals ­Trends and Zonal Variability of Extreme Rainfall Events Over East Africa During 1960-2017

2021 ◽  
Author(s):  
Moses.A Ojara ◽  
Yunsheng Lou ◽  
Hasssen Babaousmail ◽  
Peter Wasswa
Keyword(s):  
Extreme Events ◽  
Heavy Rainfall ◽  
Rainwater Harvesting ◽  
Southern Oscillation ◽  
Extreme Rainfall ◽  
Mitigation Measures ◽  
Fluctuation Analysis ◽  
Positive Trend ◽  
Extreme Rainfall Events ◽  
Rainfall Events

Abstract East African countries (Uganda, Kenya, Tanzania, Rwanda, and Burundi) are prone to weather extreme events. In this regard; the past occurrence of extreme rainfall events is analyzed for 25 stations following the Expert Team on Climate Change Detection and Indices (ETCCDI) regression method. Detrended Fluctuation Analysis (DFA) is used to show the future development of extreme events. Pearson’s correlation analysis is performed to show the relationship of extreme events between different rainfall zones and their association with El Niño -Southern Oscillation (ENSO and Indian Ocean dipole (IOD) IOD-DMI indices. Results revealed that the consecutive wet day's index (CWD) was decreasing trend in 72% of the stations analyzed, moreover consecutive dry days (CDD) index also indicated a positive trend in 44% of the stations analyzed. Heavy rainfall days index (R10mm) showed a positive trend at 52% of the stations and was statistically significant at a few stations. In light of the extremely heavy rainfall days (R25mm) index, 56% of the stations revealed a decreasing trend for the index and statistically significant trend at some stations. Further, a low correlation coefficient of extreme rainfall events in the regions; and between rainfall extreme indices with the atmospheric teleconnection indices (Dipole Mode Index-DMI and Nino 3.4) (r = -0.1 to r = 0.35). Most rainfall zones showed a positive correlation between the R95p index and DMI, while 5/8 of the rainfall zones experienced a negative correlation between Nino 3.4 index and the R95p. In light of the highly variable trends of extremes events, we recommend planning adaptation and mitigation measures that consider the occurrence of such high variability. Measures such as rainwater harvesting, stored and used during needs, planned settlement, and improved drainage systems management supported by accurate climate and weather forecasts is highly advised.

scholarly journals Identificação de Tendência da Precipitação na Microrregião do Cariri Paraibano (Identification of Precipitation Trend in the Microregion of Cariri Paraibano)

2013 ◽  
Vol 6 (5) ◽  
pp. 1400 ◽  
Author(s):  
Jaricélia Patrícia de Oliveira Sena ◽  
Daisy Beserra Lucena
Keyword(s):  
Regression Analysis ◽  
Rainy Season ◽  
Sudden Change ◽  
Climate Prediction ◽  
Annual Precipitation ◽  
Positive Trend ◽  
Precipitation Trend ◽  
Executive Agency ◽  
Year 2000 ◽  
Climate Prediction Center

O teste paramétrico de análise de regressão e o teste não-paramétrico de Mann Kendall foram utilizados com o intuito de identificar a existência de tendência na série de precipitação anual e para o período chuvoso na microrregião do Cariri Paraibano. Os dados de precipitação utilizados foram provenientes do Climate Prediction Center (CPC) e da Agência Executiva de Gestão das Águas do Estado da Paraíba (AESA), durante os anos de 1979 a 2010 e 1995 a 2010, respectivamente. Com base nos resultados encontrados, foi verificada a existência de uma tendência positiva da precipitação anual. Observa-se uma mudança brusca em torno do ano de 2000, onde antes deste ano tem-se redução de 13% e após um aumento de 24,5% na precipitação anual. Não foi verificada nenhuma tendência para o período chuvoso concluindo que outros meses é que contribuem para o aumento da precipitação anual encontrada.   ABSTRACT   The parametric test of regression analysis and the nonparametric Mann Kendall’s test were used to identify the existence of the trend in annual precipitation series and for the rainy season in the microregion of Cariri Paraibano. The precipitation data used were from the Climate Prediction Center (CPC) and the Executive Agency for Water Management in the State of Paraíba (AESA) during the years 1979-2010 and 1995-2010, respectively. Based on these results, it was verified the existence of a positive trend of annual precipitation. There is a sudden change around the year 2000, where before this year has been reduced 13% and after an increase of 24,5% in annual precipitation. Was not checked any significant tendency for the rainy season concluding that other months is contributing to the increase in annual precipitation found.   KEYWORDS: Regression Analysis, Mann Kendall’s test, Pettitt’s test, precipitation trend.  

Amphibian functional diversity is related to high annual precipitation and low precipitation seasonality in the New World

2019 ◽  
Vol 28 (9) ◽  
pp. 1219-1229 ◽  
Author(s):  
Leticia Margarita Ochoa‐Ochoa ◽  
Nancy R. Mejía‐Domínguez ◽  
Julian A. Velasco ◽  
Katharine Ann Marske ◽  
Carsten Rahbek
Keyword(s):  
Functional Diversity ◽  
New World ◽  
Annual Precipitation ◽  
Precipitation Seasonality ◽  
Low Precipitation

scholarly journals Changes of Annual Precipitation and Probability Distributions for Different Climate Types of the World

Water ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 2092 ◽  
Author(s):  
Sharma ◽  
Ojha
Keyword(s):  
Northern Hemisphere ◽  
Land Surface ◽  
Inverse Relationship ◽  
Probability Distributions ◽  
Annual Precipitation ◽  
Precipitation Pattern ◽  
The Earth ◽  
The World ◽  
Increasing Trend ◽  
Spatio Temporal

Analysis of Spatio-temporal changes in precipitation (Pre) on the land surface of the earth was the focus of this study. Thiel-Sen median slopes and Modified Mann-Kendall (MMK) test were utilized to draw inferences. Majority of the regions were identified to show an increasing trend of annual precipitation except some of the low to mid-latitude regions in Northern hemisphere. The trends of wet-day frequency (Wet) were found in agreement with precipitation for most of the regions, but the inverse relationship was found for the subtropical regions of Northern hemisphere. These changes were examined for the world climate types based on Koppen-Gieger climate classes. Also, it was tried to find the probability distribution, which best describes the annual precipitation pattern in different climate types of the world among 21 commonly assumed probability distributions.

scholarly journals Planetary Sciences, Geodynamics, Impacts, Mass Extinctions, and Evolution: Developments and Interconnections

2016 ◽  
Vol 2016 ◽  
pp. 1-13 ◽  
Author(s):  
Jaime Urrutia-Fucugauchi ◽  
Ligia Pérez-Cruz
Keyword(s):  
High Pressure ◽  
Mass Extinctions ◽  
Multiple Systems ◽  
Meteorite Impacts ◽  
The Earth ◽  
Technological Advances ◽  
Wide Range ◽  
Detection Capabilities ◽  
Spatio Temporal ◽  
Research Frontiers

Research frontiers in geophysics are being expanded, with development of new fields resulting from technological advances such as the Earth observation satellite network, global positioning system, high pressure-temperature physics, tomographic methods, and big data computing. Planetary missions and enhanced exoplanets detection capabilities, with discovery of a wide range of exoplanets and multiple systems, have renewed attention to models of planetary system formation and planet’s characteristics, Earth’s interior, and geodynamics, highlighting the need to better understand the Earth system, processes, and spatio-temporal scales. Here we review the emerging interconnections resulting from advances in planetary sciences, geodynamics, high pressure-temperature physics, meteorite impacts, and mass extinctions.

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