scholarly journals Characterization of Monsoonal Rainfall in the Sudano-Sahelian Zone of Northwestern Nigeria

2021 ◽  
Vol 1 (2) ◽  
pp. 123-135
Author(s):  
Abdullahi Umar ◽  
Saadu Umar Wali ◽  
Ibrahim Mustapha Dankani

Wavelet transform has been underutilized in characterization of rainfall (Real Onset Dates and Real Cessation Dates) in the study area. This study aims at the characterization of monsoonal rainfall. Daily rainfall data of four stations for the period 1981-2018 were collected from Nigerian Meteorological Agency. The Intra-seasonal Rainfall Monitoring Index (IRMI) was generated and used in determining the RODs and RCDs. The Mann–Kendall test was used to detect trends of the rainfall characteristics. Wavelet transform was used in modelling RODs and RCDs. Findings revealed that RODs vary between stations. There is low (0.3 Spearman’s Rank r) correlation between latitudes and Early Cessations (ECs) of rains. The Morlet wavelet analysis revealed that from 1999 to 2018, there were more of EOs and NOs especially in Kano station. We conclude that from 1981 to 2018 there has been a minimal increase in the retreat dates of rainfall in the study area.

2010 ◽  
Vol 49 (12) ◽  
pp. 2559-2573 ◽  
Author(s):  
Matthew G. Slocum ◽  
William J. Platt ◽  
Brian Beckage ◽  
Steve L. Orzell ◽  
Wayne Taylor

Abstract Wildfires are often governed by rapid changes in seasonal rainfall. Therefore, measuring seasonal rainfall on a temporally finescale should facilitate the prediction of wildfire regimes. To explore this hypothesis, daily rainfall data over a 58-yr period (1950–2007) in south-central Florida were transformed into cumulative rainfall anomalies (CRAs). This transformation allowed precise estimation of onset dates and durations of the dry and wet seasons, as well as a number of other variables characterizing seasonal rainfall. These variables were compared with parameters that describe ENSO and a wildfire regime in the region (at the Avon Park Air Force Range). Onset dates and durations were found to be highly variable among years, with standard deviations ranging from 27 to 41 days. Rainfall during the two seasons was distinctive, with the dry season having half as much as the wet season despite being nearly 2 times as long. The precise quantification of seasonal rainfall led to strong statistical models describing linkages between climate and wildfires: a multiple-regression technique relating the area burned with the seasonal rainfall characteristics had an of 0.61, and a similar analysis examining the number of wildfires had an of 0.56. Moreover, the CRA approach was effective in outlining how seasonal rainfall was associated with ENSO, particularly during the strongest and most unusual events (e.g., El Niño of 1997/98). Overall, the results presented here show that using CRAs helped to define the linkages among seasonality, ENSO, and wildfires in south-central Florida, and they suggest that this approach can be used in other fire-prone ecosystems.


Author(s):  
Gadekar Deepak Janardhan ◽  
Soniya Sonkar

The three major characteristics of rainfall are mainly its amount, frequency and intensity. The value of rainfall varies greatly from day to day, place to place, month and year to year. Generally Akole tehsil receives the highest rainfall and Karjat and Jamkhed tehsils receives the least rainfall. The main reason for the highest rainfall in Akole tehsil is orographic type rainfall. The rainfall characteristics and distribution in drought prone area in study area. The research covers rainfall data from 1981 to 2014 and the rainfall data is taken from the statistical department website of Ahmednagar district.


2020 ◽  
Vol 13 (4) ◽  
pp. 1425
Author(s):  
Layara Campelo Dos Reis ◽  
Cláudio Moisés Santos e Silva ◽  
Bergson Guedes Bezerra ◽  
Maria Helena Constantino Spyrides

A análise sobre a variabilidade dos padrões climatológicos espaciais e temporais das chuvas fornecem informações valiosas para a condução de cultivos agrícolas, principalmente em condições de sequeiro. Assim, o presente estudo objetivou caracterizar a variabilidade da precipitação no MATOPIBA, região produtora de soja, sob influência das fases do ENSO e do gradiente térmico do Atlântico Tropical. Foram utilizados dados diários de precipitação do período de 1980-2013 dispostos em uma grade de espaçamento de 0,25º x 0,25°, abrangendo 963 pontos sobre a região. O acumulado mensal da precipitação foi especializado por meio de sistemas geográficos de informação e da geoestatística. A variabilidade da precipitação foi analisada por meio da aplicação do teste de Mann-Kendall, considerando três cenários de condições meteorológicas (climatologia, favorável-wet e desfavorável-dry) à ocorrência da precipitação. Os volumes de chuvas foram relativamente maiores no cenário da fase fria do ENSO combinado com o gradiente inter-hemisférico apontando para o Sul (favorável-wet), em contrapartida, verificou-se um aumento de condições de risco hídrico nos anos com ocorrência da fase quente do ENSO e o gradiente apontando para o Norte (desfavorável-dry), embora com exceções registradas em algumas áreas no mês de Janeiro e Fevereiro. Tendências positivas e negativas foram identificadas, constatando indícios de alterações nos padrões da variável, previamente para os cenários da climatologia e desfavorável (dry). Os resultados poderão contribuir para o desenvolvimento de soluções e direcionamento na tomada de decisões pelos agentes da cadeia produtiva que visem a mitigação de impactos em decorrência da variabilidade da precipitação na região estudada.  Characterization of rainfall variability in the MATOPIBA, soybean producing region AbstractThe analysis of spatial and temporal rainfall patterns variability provides invaluable information for the development of dryland agriculture systems. Therefore, the aim of the present study was to characterize the variability of rainfall in the MATOPIBA, an important soybean producing region, under the influence of ENSO phases and the tropical Atlantic thermal gradient. We used daily rainfall data for the period from 1980-2013 arranged in a 0.25º x 0.25º spacing grid, comprising 963 points over the study region. Monthly accumulated rainfall has been specialized through geographic information systems and geostatistics. Variability rainfall was analyzed by applying the Mann-Kendall test, considering three scenarios of meteorological conditions (climatology, favorable-wet and unfavorable-dry) to the occurrence of precipitation. Rainfall volumes were relatively higher in the ENSO cold phase scenario combined with the southward-favorable interhemispheric gradient. ENSO and the gradient pointing north (unfavorable-dry), although with exceptions recorded in some areas in January and February. Positive and negative trends were identified, showing evidence of changes in the variable's patterns, previously for the climatology and unfavorable (dry) scenarios. The results may contribute to the development of solutions and decision making direction by the agents of the productive chain aiming at mitigating impacts due to the variability of precipitation in the studied region.Keywords: Climate variability; ENSO; Agrometeorology  


Author(s):  
Dr. Sumit M. Dhak

Abstract: A detailed trend analysis of monthly 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. In this study, to analyse the trend, the non-parametric test (Mann-Kendall test) and Sen’s slope estimator were used. For developing a functional relationship between variables, a linear trend of rainfall data for the studied area evaluated using the linear regression. The results showed that the trend analysis of monthly rainfall has a varied trend of rainfall in the rainy months in tehsil of Palghar District. The month of July significant increasing trend was observed at Jawhar (42.91 mm/year), Vikramgad (29.90 mm/year), Wada (24.06 mm/year), Talasari (31.36 mm/year), Palghar (25.299 mm/year), Mokhada (29.96 mm/year) and Dahanu (38.14 mm/year), whereas non-significant increasing trend 2.76 mm/year was observed at Vasai tehsil of Palghar District during 1998-2019. The month of June, August, September and October rainfall did not show any significant trend in tehsil of Palghar District and non significant decreasing as well as non significant increasing trend was observed in tehsil of Palghar District during 1998 – 2019. The result concluded that annual rainfall trend was increased in Jawhar, Vikramgad, Wada, Talasari, Palghar, Mokhada and Dahanu; whereas Vasai tehsil rainfall trend was decreased in tehsil of Palghar District during 1998 -2019. Keywords: Rainfall, Trend Analysis, Mann Kendall’s Test, Sen Slopes, Regression


MAUSAM ◽  
2021 ◽  
Vol 61 (4) ◽  
pp. 487-498
Author(s):  
AVIK GHOSH DASTIDAR ◽  
SARBARI GHOSH ◽  
U. K. DE ◽  
S. K. GHOSH

Seasonal, monthly and daily rainfall characteristics of meteorological sub-divisions of Sub Himalayan West Bengal (SHWB) and Gangetic West Bengal (GWB) have been studied using rainfall data of 23 stations of India Meteorological Department (IMD) over the state of West Bengal. The two subdivisions have distinctive characteristics, though two stations lying in the plain region of SHWB have behaviour more alike the stations of GWB.  Krishnagar is a station with least seasonal rainfall in the entire state. Kurtosis and Skewness of the seasonal rainfall distribution have been studied and found that, for most of the stations they lie within reasonable limits. From the time series analysis, it is found that the seasonal rainfall has no trend.     


2017 ◽  
Vol 7 (4) ◽  
pp. 30 ◽  
Author(s):  
Jurgen D. Garbrecht ◽  
Rabi Gyawali ◽  
Robert W. Malone ◽  
John C. Zhang

Long-term observations of daily rainfall are common and routinely available for a variety of hydrologic applications. In contrast, observations of 10 or more years of continuous hourly rainfall are rare. Yet, sub-daily rainfall data are required in rainfall-runoff models. Rainfall disaggregation can generate sub-daily time-series from available long term daily observations. Herein, the performance of Multiplicative Random Cascade (MRC) model at disaggregating daily-to-hourly rainfall was investigated. The MRC model was parameterized and validated with 15 years of continuous observed daily and hourly rainfall data at three weather stations in Oklahoma. Model performance, or degree to which the disaggregated rainfall time series replicated observations, was assessed using 46 variables of hourly rainfall characteristics, such as longest wet spell duration, average number of rainfall hours per year, and largest hourly rainfall. Findings include: a) average-type hourly rainfall characteristics were better replicated than single value characteristics such as longest, maximum, or peak hourly rainfall; b) the large number of sub-trace hourly rainfall values (<0.254 mm h-1) generated by the MRC model were not supported by observations; c) the random component of the MRC model led to a variation under 15% of the average value for most rainfall characteristics with the exceptions of the “longest wet spell duration” and “maximum hourly rainfall”; and d) the MRC model produced fewer persistent rainfall events compared to those in the observed rainfall record. The large number of generated trace rainfall values and difficulties to replicate reliably extreme rainfall characteristics, reduces the number of potential hydrologic applications that could take advantage of the MRC disaggregated hourly rainfall. Nevertheless, in most cases, the disaggregated rainfall generated by the MRC model replicated observed average-type rainfall characteristics well.


2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
S. Nandargi ◽  
S. S. Mulye

There are limitations in using monthly rainfall totals in studies of rainfall climatology as well as in hydrological and agricultural investigations. Variations in rainfall may be considered to result from frequency changes in the daily rainfall of the respective regime. In the present study, daily rainfall data of the stations inside the Koyna catchment has been analysed for the period of 1961–2005 to understand the relationship between the rain and rainy days, mean daily intensity (MDI) and seasonal rainfall over the catchment on monthly as well as seasonal scale. Considering the topographical location of the catchment, analysis of seasonal rainfall data of 8 stations suggests that a linear relationship fits better than the logarithmic relationship in the case of seasonal rainfall versus mean daily intensity. So far as seasonal rainfall versus number of rainy days is considered, the logarithmic relationship is found to be better.


2000 ◽  
Vol 18 (3) ◽  
pp. 316-331 ◽  
Author(s):  
D. Pancheva ◽  
P. Mukhtarov

Abstract. On the basis of bispectral analysis applied to the hourly data set of neutral wind measured by meteor radar in the MLT region above Bulgaria it was demonstrated that nonlinear processes are frequently and regularly acting in the mesopause region. They contribute significantly to the short-term tidal variability and are apparently responsible for the observed complicated behavior of the tidal characteristics. A Morlet wavelet transform is proposed as a technique for studying nonstationary signals. By simulated data it was revealed that the Morlet wavelet transform is especially convenient for analyzing signals with: (1) a wide range of dominant frequencies which are localized in different time intervals; (2) amplitude and frequency modulated spectral components, and (3) singular, wave-like events, observed in the neutral wind of the MLT region and connected mainly with large-scale disturbances propagated from below. By applying a Morlet wavelet transform to the hourly values of the amplitudes of diurnal and semidiurnal tides the basic oscillations with periods of planetary waves (1.5-20 days), as well as their development in time, are obtained. A cross-wavelet analysis is used to clarify the relation between the tidal and mean neutral wind variability. The results of bispectral analysis indicate which planetary waves participated in the nonlinear coupling with the atmospheric tides, while the results of cross-wavelet analysis outline their time intervals if these interactions are local.Key words: Meteorology and atmospheric dynamics (middle atmosphere dynamics; waves and tides) - Radio science (nonlinear phenomena)


2021 ◽  
Author(s):  
Abdullahi Umar ◽  
Ibrahim Mustapha Dankani ◽  
Ibrahim Ishiaku ◽  
Ismail Usman Kaoje ◽  
Saadu Umar Wali

Abstract This study was aimed at assessing monsoonal rainfall real onset dates (RODs), real cessation dates (RCDs) and extent of association between cumulative rainfall (CR) and length of growing season (LGS) in the context of climate adaptation planning for sustainable rain-fed agriculture in the Sudano-Sahelian area of Northwestern Nigeria. Daily rainfall data of four stations purposively selected namely: Gusau, Kano, Katsina and Sokoto for the period 1981–2018 were collected from Nigerian Meteorological Agency. The data were analyzed and the Intra-seasonal Rainfall Monitoring Index (IRMI) was generated. IRMI was used in determining the RODs and RCDs of rainfall and LGS and CR. The Mann–Kendall test was used to detect trends in rainfall characteristics. Findings revealed that RODs, unlike RCDs of rainfall in the study area, show extensive variations from one station to another. There is a very low correlation (0.07 coefficient) between latitudes and early onsets (EOs). There is however a strong positive correlation (0.8 coefficient) between meridians and EOs of rains. Late onsets (LOs) recognize latitudinal differences to the extent that there is strong positive correlation (0.7 coefficient) between lines of parallels and LOs of rains. The three types of onsets interchanged with one another annually without a clear trend in the RODs and RCDs phases. We conclude that non-definite trends in RODs and RCDs pose a strong challenge to long term adaptation planning. The recommendations of the study are geared towards enhancing climate change adaptation in the context of complicated rainfall characteristics of the study area.


2019 ◽  
Vol 5 (1) ◽  
Author(s):  
Nur Afifah Sari ◽  
Etih Hartati ◽  
M. Candra Nugraha

<p class="IJOPCMKeywards">Based on the hydrological cycle, one of the main water sources is rainwater. weather or climate conditions that occur will greatly affect the nature and condition of a rain or rainy season. On a global scale, the existence of water naturally is constant, only occurs in variations both in time and space on a regional scale. Analysis of the rainfall characteristics of Pantai Indah Kapuk (PIK) residential and commercial areas 2  Cluster "C" in Tangerang Regency, Banten Province, is for to find out the intensity of rainfall used for drainage planning. The daily rainfall data used includes 5 rain catching stations with a duration of 25 years (1994 - 2018). The Van Breen method is used to process rainfall data within a certain period into rainfall intensity with various times for drainage planning used. In the planning of drainage channels the rainfall return period used is PUH 2 for tertiary lines with selected rainfall data of 192 mm / day and PUH 5 for secondary lines with selected rainfall data of 219 mm / day. The IDF curve shows that rainfall intensity is affected by the time and return period of rainfall, where the shorter the rainfall time and the greater the return period of rainfall, the higher the intensity of rainfall produced.</p>


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