Analysis Of Rainfall Variability Research Articles

Rainfall variability analysis and trend assessment in Theni District of Tamil Nadu, India: An implication for crop planning

Rainfall variability analysis and trend assessment in Theni District of Tamil Nadu, India: An implication for crop planning

Analysis of rainfall variability and probability in Theni District, India

Crop planning based probability analysis aids in increasing production. A crop planning research was conducted in the Theni district by examining probability analysis over a 40-year period (1982-2021) using weekly and monthly rainfall data. The mean annual rainfall in the Theni district was 1100.2 mm spread over 90 rainy days. The probability study revealed that obtaining 20mm rainfall per week received for 8 weeks (38 to 45th week), which is beneficial for sowing and planting. On the other side, October had the greatest mean monthly rainfall (191.8 mm), followed by November (147.9 mm). The main crops farmed in this area are rice, sugarcane, and bananas, but they should be replaced with maize, pulses, cowpea, sorghum, ragi, and minor millets since they can grow in a shorter time period and yield higher. Key words: Rainfall, Markov chain analysis, initial and conditional probability and crop planning

Estimation of Fluctuations and Global Tele-connections in the Monsoonal Rainfall and Associated Floods for Barmer District

Abstract: This paper is about the fluctuations and global teleconnections in the monsoonal rainfall and associated floods of Barmer district, Rajasthan, India. For investigation of precipitation and related floods, the precipitation information for period of 1901-2002 is collected from India Meteorological Department (IMD) for Barmer district. Inter-monsoon rainfall variability analysis, percent departure from mean, Normalized Accumulated Departure from Mean (NADM) and conditional probability technique for El Nino and Southern Oscillation (ENSO) have been used for the analyses of monsoonal rainfall data and its effect on floods. The outcomes demonstrate year to year varieties in the precipitation with huge takeoff from mean precipitation. It is seen that greater part of the floods are related with positive takeoff from mean precipitation. The NADM shows epochal conduct of high and low monsoon precipitation of the basin. For analysis of ENSO Sea Surface Temperature (SST) data is obtained from National Oceanic and Atmospheric Administration (NOAA) for years 1950-2019. It is observed that, during La Nina years the rainfall is higher than average annual rainfall. The analysis of ENSO reveals that the probability of the occurrence of the floods is high during cold (La Nina) events and it is very low during warm (El Nino) events. Keywords: Monsoon rainfall, Global Tele-connection, SST, ENSO effect, floods

Analysis of Rainfall Variability in the Province of Quirino

The temporal variability of rainfall in Quirino Province was analyzed through the use of rainfall data of seven (7) rain gauges within the neighboring provinces like Nueva Vizcaya and Aurora. The length of record analyzed from 1997 to 2016. In this study, rainfall frequency analysis and consistency of rainfall data from the different stations through the use of double mass curve analysis was performed and analyzed. The annual series was used to screen each station’s annual rainfall data while the province’s average Thiessen rainfall was screened using maximum period series process. It was found out that all the data of the seven (7) rainfall stations were consistent. To attain allowable error in estimation of 10%, 5% and 1% for the mean annual rainfall the number of rain gauge station needed in the province should be 18, 72 and 1799, respectively.

Analysis of Rainfall Variability in the Province of Quirino

Analysis of Rainfall Variability in the Province of Quirino

BLOCK WISE RAINFALL VARIABILITY ANALYSIS OF DISTRICT SAWAI MADHOPUR, RAJASTHAN, INDIA

An attempt has been made to study the block wise rainfall variability analysis of districts Sawai Madhopur of Rajasthan. Study was performed on data sets of annual rainfall for the period of 1990-2020 (31 years) for district Sawai madhopur of Rajasthan. The coefficient of variation and standard deviation for weekly, monthly and annual rainfall were also computed for district Sawai Madhopur. The normal onset of monsoon in district Sawai Madhopur is between June to September. It was found that the annual rainfall is higher at Sawai madhopur block followed by Gangapur and Khandar block during last second and third decade. The mean annual rainfall is lowest in Bonli block. When the CV for the annual rainfall was examined, it was found be the least in Gangapur block followed by Sawai madhopur, bonli, bamanwas and khandar block, it was the highest.

Spatio‐temporal rainfall variability and trend analysis in the Tekeze‐Atbara river basin, northwestern Ethiopia

AbstractSpatial and temporal rainfall variability analysis at a basin scale is essential to understand water availability for sustainable water resource management. This study investigated the spatial distribution and temporal rainfall trend in the Tekeze river basin using daily rainfall data collected from 43 meteorological stations with records from 1960 to 2019. Coefficient of variation, seasonality index (SI) and trend index were used to evaluate monthly, seasonal and annual rainfall variability in the basin. The non‐parametric Mann‐Kendall's test was used to understand any rainfall trends. Results showed that there is moderate annual rainfall variability in the basin. Rainfall variability is higher in the Tsedey, Bega and Belg than kiremt season. SI results showed that majority of the Tekeze river basin is categorized as seasonal, most of the rain occurring in less than 3 months. Overall, Mann‐Kendall's test result revealed that there is no significant annual rainfall trend in the basin except for four stations. The seasonal rainfall characteristics and short duration of rain in the basin indicate that there is a need to implement water harvesting measures during the wet season for use in the dry periods.

Rainfall Trend and Variability Analysis in Borana Pastoral Lowland Areas: The Case of Yabello and Eel-wayye Station, Southern Ethiopia

Dry lands are traditionally used and managed by a pastoralist, characterized by variable precipitation, climate variability and water scarcity. Change in rainfall trend and variability’s lead to severe production deficit and decline the balance between pasture and livestock on which pastoral livelihood depends on. The study was undertaken to assess the variability and trends of rainfall in Borana pastoral area using monthly rainfall record for the period 1987-2016 of Yabello and Eel-wayye station. Rainfall variability analysis has been done using variability indices like, coefficient of variation, precipitation concentration index and Standard anomaly index. Trend analysis was carried out using Man-Kendall trend test 5% significance level. The coefficient variation of the study area for Yabello was 21.2%, while for Eel-wayye it was 53% which showed high inter-annual variability. The negative anomalies at Yabello station was 53.3% While in Eel-wayye station, revealed 56%. The analysis result indicted that the rainfall concentration index value ranged from 13.2 to 30.23 for the stations which shows moderate to strong irregularly rainfall distribution. The year 2006 was the most drastic and distinct-wide extreme drought episode in both stations, Except short rainy season at Eel-wayye station, the Mann–Kendal test shows not statistically significant (P<0.05). Increasing tendencies of drought during main rainy season and decreasing tendencies of drought during short rainy season and annually were observed in the study area. This threats the livestock production systems, which is the backbone of the pastorals livelihood. The study, suggests policy makers to develop other sustainable water sources for lowlands pastorals.

Rainfall variability analysis using standardized precipitation index in arid climate of Andhra Pradesh in sub-tropical India

Rainfall variability analysis using standardized precipitation index in arid climate of Andhra Pradesh in sub-tropical India

Seasonal Rainfall Trend and Annual Rainfall Variability Analysis for Selected Meteorological Stations in Bhutan

Seasonal Rainfall Trend and Annual Rainfall Variability Analysis for Selected Meteorological Stations in Bhutan

Rainfall variability analysis using Precipitation Concentration Index: a case study of the western agro-climatic zone of Punjab, India

Due to climate change, the rainfall pattern has changed, which ultimately either cause flood or drought in any region of the world. Hence, a rainfall variability analysis helps to manage the water resources better. Rainfall variability analysis of a long term at particular area reveals vital information about past and future climate. The study's objective was to analyse the rainfall variability and intensity of long term monthly rainfall data (1982–2018) using the Precipitation Concentration Index (PCI). Data was collected from Punjab Agricultural University, Regional Research Station, located at Bathinda, India. The PCI was calculated for the annual, winter, pre-monsoon, monsoon, post-monsoon season, and decadal scale. Results have outlined that PCIAnnual ranges from the lowest of 14.96 in 2006 to the highest of 43.82 in 2000, and the average of 37 years is 23.22. About ≈59.5% of the year PCIAnnual was characterised by Strong Irregularity of Precipitation Distribution (SIPD, PCIAnnual&gt; 20), an indication of SIPD within the 37 years. While ≈2.7% of the year recorded annual value within the moderate irregular range (10&lt;PCIAnuual&lt;15), which indicates an irregular rainfall distribution (MIPD) and concentration across the months. Similarly, the precipitation concentration in China was also found strongly irregular in the western and northern parts of the northwest and the northern region of the Tibetan Plateau. The study recommends that the Bathinda Development Authority (BDA) may use and adopt these results and redevelop the existing groundwater recharge structures (pond) and artificial recharge structures.

Analysis of Rainfall Variability and Trends Over Nzoia River Basin, Kenya

Nzoia river is mainly rain fed and the basin is one of the regions that is highly vulnerable to climate change in Kenya. Understanding rainfall variability and trends is important for better water resources management and economic development in the basin. The aim of this study is to assess variability and trends in rainfall at 13 sites within Nzoia River Basin over the period, 1970 to 2001, using the parametric test of Linear regression analysis and the non-parametric Mann–Kendall statistical test. Data for this study was obtained from the Kenya Meteorological Department (KMD). The basin experiences four rainfall seasons in a year as a result of the Inter-Tropical Convergence Zone (ITCZ). There are two rainy seasons and two dry seasons. Annual rainfall through Linear regression analysis shows 6 stations, Kaimosi Tea Estate Ltd, Kakamega Meteorological Station, Bungoma Water Supply, Nzoia Forest Station, Malava Forest Station and Webuye Agricultural Office with declining rainfalls. The remaining 7 stations, Leissa Farm Kitale, Turbo Forest Nursery, Chorlim ADC Farm, Kaptagat Forest Station, Kimilili Agricultural Department, Bunyala Irrigation Scheme and Kadenge Yala Swamp showed increasing rainfalls. The majority of stations with increasing annual rainfall are in the upper catchment whereas those with decreasing rainfall are in the middle and lower catchment. Only 3 out of the 13 stations showed statistically significant trends in rainfall with two in the upper catchment and one in the middle; the remaining 10 stations had statistically insignificant trends. These observed changes in rainfall, although most time series are not convincing as they show predominantly no significance, along with the reported climatic warming in most parts of the basin may have future implications on human health, water resources management, various plant and animal species bio-diversity and the overall economic development of the basin.

Parametric Analysis of Rainfall Variability Over Some Selected Locations in Nigeria

Rainfall is one meteorological parameter that affects virtually all human activities. For instance, the amount of rainfall received in an area is an important determining factor in estimating or quantifying the amount of water available to meet various demands, such as agricultural, industrial, domestic water supply, and power generation. Climate change has generally been accepted to be a result of the emission of excess greenhouse gases. It has caused an increase in flooding, severe and more frequent droughts, increase in wildfires, and heatwaves in various parts of the globe. Climate change is said to have a considerable impact on the variability in hydro-meteorological variables such as rainfall, temperature, and evaporation. In this study, we carry out a parametric analysis of rainfall variability over some selected locations in Nigeria and determine the trend using surface observation data from seven weather stations. The datasets of rainfall used in this study were acquired; from the Nigerian Meteorological Agency (NIMET) for a period of 30 years (1980 to 2010) from seven locations; which are Abuja, Enugu, Ikeja, Ilorin, Maiduguri, Port Harcourt, and Sokoto, representing the six geographical zones of Nigeria. The results gotten showed an upward movement in the trend line which indicated an increase in the amount of rainfall received by the study areas. While some Cities (Maiduguri, Sokoto) received a large increase in the amount of rainfall received yearly, others received a slight increase such as Lagos, Port Harcourt, Ilorin, Abuja and Enugu.

Statistical Analysis of Rainfall Variability for Tehsils of Palghar District, Maharashtra State, India

A detailed statistical analysis of monthly, seasonal and annual rainfall for Tehsils of Palghar district were carried out using 22 years (1998-2019) daily rainfall data taken from Department of Agriculture, Maharashtra State. The mean, standard deviation and coefficient of variation for monthly, seasonal and annual rainfall were computed for tehsils of Palghar districts. The month of July received maximum monthly mean rainfall for all years (1998 to 2019) in tehsils of Palghar district. The result showed that monthly mean rainfall in month of July was maximum at Jawhar (1147.1 mm) followed by Vikramgad (1071.9 mm), Talasari (1014.3 mm), Vasai (1009.9 mm), Wada (998.5 mm), Mokhada (949.6 mm), Palghar (948.7 mm) and Dahanu (841.6) with contributes 40.4 %, 39.1 %, 38.5 %, 35.4 %, 37.3 %, 37.3 %, 36.9 % and 36.3 % of the annual mean rainfall (1998 to 2019) respectively. The result showed that contribution of rainfall during Monsoon season ranges from 95.5 % to 97.0 % of the annual total rainfall for tehsils of Palghar District. The result showed that average annual rainfall (1998 to 2019) of Vasai, Jawhar, Vikramgad, Wada, Talasari, Palghar, Mokhada and Dahanu were 2855.9 mm, 2839.1 mm, 2738.9 mm, 2674.0 mm, 2633.3 mm, 2570.8 mm, 2543.6 mm and 2318.5 mm respectively.

Modeling and forecasting of rainfall reoccurrence changes using Markov Switching in Iran

This paper represents the recurrence (reoccurrence) changes in the rainfall series using Markov Switching models (MSM). The switching employs a dynamic pattern that allows a linear model to be combined with nonlinearity models a discrete structure. The result is the Markov Switching models (MSM) reoccurrence predicting technique. Markov Switching models (MSM) were employed to analyze rainfall reoccurrence with spatiotemporal regime probabilities. In this study, Markov Switching models (MSM) were used based on the simple exogenous probability frame by identifying a first-order Markov process for the regime probabilities. The Markov transition matrix and regime probabilities were used to analyze the rainfall reoccurrence in 167 synoptic and climatology stations. The analysis results show a low distribution from 0.0 to 0.2 (0–20%) per day spatially from selecting stations, probability mean of daily rainfall recurrence is 0.84, and a different distribution based on the second regime was found to be more remarkable to the rainfall variability. The rainfall reoccurrence in daily rainfall was estimated with relatively low variability and strong reoccurrence daily with ranged from 0.851 to 0.995 (85.1–99.5%) per day based on the spatial distribution. The variability analysis of rainfall in the intermediate and long variability and irregular variability patterns would be helpful for the rainfall variability for environmental planning.

Trend and Variability Analysis of Rainfall and Temperature Trends in Ilorin Metropolis, Kwara State, Nigeria

ABSTRACT Rainfall and temperature are the most important physical parameters that influence climate. This paper examines the trend and variability of rainfall and temperature of Ilorin township in Nigeria between2010- 2018, using standard statistical descriptors. Rainfall had an increasing trend (positive slope value of 5.30), moderate precipitation concentration index of 12.15 percent and extremely high degree of variability with a coefficient of variation ranging between 33.54 percent and 155.73 percent. Temperature also had a slight warming or increasing trend (positive slope value of 0.012) with minimal degree of variability of coefficient of variation between 5.49 percent and 7.31 percent. The oscillating structure of both rainfall and temperature anomalies further confirm yearly fluctuations as well as change in the distribution and characteristics. It is recommended that government and non-government agencies should formulate plans and policies that will accommodate changes in rainfall and temperature patterns to successfully manage the environment.

Identification of a Representative Stationary Period for Rainfall Variability Description in the Sudano-Sahelian Zone of West Africa during the 1901–2018 Period

Many studies have been undertaken on climate variability in West Africa since the drastic drought of 1970s. These studies rely in many cases on different baseline periods chosen with regard to the reference periods defined by the World Meteorological Organization. A method is developed in this study to determine a stationary baseline period for rainfall variability analysis. The method is based on an application of three statistic tests (on deviation and trend) and a test of shifts detection in rainfall time series. The application of this method on six different gridded rainfall data and observations from 1901 to 2018 shows that the 1917–1946 period is the longest stationary period. An assessment of the significance of the difference between the mean annual rainfall amount during this baseline period and the annual rainfall amount during the other years shows that the “Normal” annual rainfall amount is defined by an interval delineated by ±the standard deviation (STD). With regard to this interval, a very wet/dry year is defined with a surplus/gap over/below the STD. Overall the 1901–2018 period, the 1950–1970 period presents the most important number of significant wet years and the 1971–1990 period presents the most important number of significant dry years.

Time Series Analysis of Rainfall Variability at North Jordan: A Case Study at Yarmouk River Basin

Water represents a key challenge to sustain the progress of Jordan. Providing healthy drinking water, along with current scarcity is one of the most major constraints in the water sector. This paper pursues to investigate the Spatio-temporal distribution of rainfall variability for time slice 1985-2014 over the Yarmouk River Basin (YRB) – Jordan side. Ten rainfall gauges were selected within the basin over the observation period. Applying two nonparametric statistical tests; Mann-Kendall to detect the rainfall trend in YRB, and Kolmogorov–Smirnov to detect the variations of rainfall distribution. Besides, the GIS spatial analyst tool was utilised to create interpolated rainfall map using the Thiessen polygons method. The results indicated that YRB will witness a potential decline in annual rainfall in most stations. Further, a shift in rainy season timing 2 and 58 days was observed at late in the start of the season (SoS) and 2 to 48 days for an early end of the season (EoS) on a decade’s basis accompanied by the significant uptrend in the long-term.

Analysis of rainfall variability for the October to December over Tanzania on different timescales during 1951–2015

AbstractThis study has utilized spectral analysis to ascertain the nature of decadal rainfall variability, while correlation, singular value decomposition (SVD), and composite analyses were employed to explore and understand the possible associated mechanisms. Inferences were drawn to the interannual timescales. The spectrum analysis of October to December (OND) rainfall revealed dominant signals at 2.4, 2.9, and 5.0, and a band near 16–25 years. These cyclicities suggest that dominant drivers of Tanzania rainfall anomalies evolve on interannual and decadal timescales. Interannual variations in Tanzania rainfall are mostly linked to the Indian and Pacific oceans. Significant sea surface temperature (SST) anomalies in the Indian and Pacific oceans included those associated with Indian Ocean Dipole (IOD) and El Niño‐Southern Oscillations (ENSO), respectively and are linked to changes in the atmospheric circulation anomalies over the western Indian Ocean. The observed circulation variations are most likely to influence Tanzania rainfall. In contrast, wet and dry decades are mostly linked to the Indian and Atlantic oceans. The Indian ocean provides stronger teleconnections with Tanzania rainfall at decadal timescales, consistent with interannual timescales teleconnections. Notably, the ‘dipole’ like forcing observed at interannual timescales is less coherent at decadal timescales over the Indian Ocean. As such, the Indian Ocean displayed a coherent monopole pattern in decadal SST. As a result of these differences, the location of the western Indian ocean centre of convection activities observed at interannual timescales has shifted to around the central Indian Ocean at decadal timescales. Wet decades in Tanzania rainfall are associated with the condition of enhanced convection and increase moisture content centred over the central Indian Ocean. This convective condition was observed to spread to a large area of the Indian Ocean and the African continent, including the study area.

Analysis of rainfall variability over Tanzania in late austral summer

Based on site-observation data, NCEP–NCAR reanalysis data, and Climatic Research Unit gridded data, the rainfall variability over Tanzania during late austral summer (January–March, JFM) was analyzed for the period 1961–2011. Further, the associated atmospheric circulation and SST anomalies (SSTAs) were explored to understand the mechanisms of dry- and wet-year cases based on an interannual time scale. The correlation, Morlet wavelet power spectrum, and composite analysis methods were employed. The results showed that the JFM standardized rainfall anomaly time series exhibited significant time scales of variability at interannual (2–8 years) and quasi-decadal (8–12 years). During dry years, anomalous anticyclonic northeasterly flow originating from western tropical Indian and southeast trades from the Indian Ocean to the southeast were associated with subsiding dry air, which resulted in suppression of rainfall as observed. In the typical wet-year cases, meanwhile, anomalous westerlies from the tropical and southeast Atlantic were strengthened over the Congo basin, delivering more precipitation to the region. Significant correlation was exhibited over the western tropical and southeast Indian Ocean, as well as the southeast and tropical Atlantic Ocean. These SSTA patterns favored atmospheric general circulation anomalies that were closely related to JFM rainfall over Tanzania.摘要利用站点观测资料和再分析资料, 采用相关分析, Morlet小波功率谱分析和复合分析等方法, 研究了1961–2011年南半球夏季后期 (1–3月) 坦桑尼亚降水的年际变化特征, 并探讨了相关的大气环流和海温异常情况, 以及坦桑尼亚干,湿年发生的机制. 研究结果表明: 坦桑尼亚1–3月降水变化存在显著的2–8年的年际变化周期和8–12年准年代变化周期. 在坦桑尼亚1–3月降水异常偏少的典型干旱年, 来自热带西印度的异常反气旋的东北气流和北印度洋东南气流造成干燥空气下沉, 从而抑制坦桑尼亚地区降水; 而在典型多雨年, 来自非洲大陆热带和东南大西洋的异常西风气流在刚果盆地上空显著偏强, 从而带来更多降水. 热带印度洋和印度洋东南部, 大西洋东南部和热带大西洋均表现出显著的相关性. 此外, 热带中太平洋和南太平洋中部也存在显著的相关. 这些海温异常型与坦桑尼亚1–3月的降水及相关大气环流异常有密切的关联.