Major quasi-periodic fluctuations in the drought indices

Bhalme, H. N.; Jadhav, S. K.

doi:10.1007/bf02273982

Cited by 4 publications

(5 citation statements)

References 10 publications

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“…A quasi-triennial oscillation has been found in this study to be common to all regional series, except for the dates of onset of rainfall in the Midland Zone (Table 11). Oscillations of a similar order have been found in the drought series of the interior plains of North America (Oladipo, 1987), Indian drought indices (Bhalme and Mooley, 1983), East African annual rainfall series (Rodhe and Virji, 1976) and in West African rainfall series (Ayoade, 1973;Klaus, 1978). This oscillation is close to that of the Southern Oscillation (SO), which possesses a modal peak in the 3-5-year range (see Rodhe and Virji (1976)).…”

Section: Periodicities In the Onset Retreat And Duration Of The Raisupporting

confidence: 59%

A study of climatic variability in Nigeria based on the onset, retreat, and length of the rainy season

Olaniran

Sumner

1989

Intl Journal of Climatology

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The long-term variability of rainfall conditions in Nigeria in terms of the onset, retreat, and length of the rainy season has been analysed, using pentad data for the period 1919-1985. Data were grouped into four areas, arranged in a south-north transect; the Coastal, Guinea-Savanna, Midland and Sahelian Zones. The series for retreat of rainfall showed evidence for quasi-triennial and quasi-6-year oscillations, while that for rainy season length displayed quasi-biennial and quasi-triennial oscillations. No consistent spectral peaks emerged for changes in the date of onset of the rainy season. There is spatial coherence in variation in the date of the retreat of rainfall over the whole country, whilst for the date of onset of the season spatial coherence is limited to southern Nigeria (Coastal and Guinea-Savanna Zones). Northern Nigeria (Midland and Sahelian Zones) and southern Nigeria (Coastal and Guinea-Savanna) emerge as distinct areas in terms of spatial coherence in the variation of the length of the rainy season. There is also evidence for a secular change in the date of the retreat of rainfall for the whole country during the period 1939-1985, and in the date of onset of rainfall for southern Nigeria for 1968-1985.

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Section: Periodicities In the Onset Retreat And Duration Of The Raisupporting

confidence: 59%

A study of climatic variability in Nigeria based on the onset, retreat, and length of the rainy season

Olaniran

Sumner

1989

Intl Journal of Climatology

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“…Illinois, Iowa and Missouri). The quasi-triennial periodicity has also been verified for the Indian drought indices (Bhalme and Mooley, 1983) and is suggested to be close to the first modal peak of the Southern Oscillation (SO). This would suggest persistence of large-scale atmospheric pressure patterns during dry/wet conditions.…”

Section: Results (A) Power Spectramentioning

confidence: 85%

“…A thorough treatment of the subject is given in Jenkins and Watts (1968) and its recent applications to meteorological time series are available in Jones and Kearns (1976) and Madden (1977). It can be shown (Box and Jenkins, 1976) that the power spectrum P m for white noise has a constant value 20:(03 is the variance for the estimated error in the series) over the frequency (f) interval (0.0,0.5). Thus integrated spectrum for white noise is…”

Section: (E) Statistical Significance Of Periodicitiesmentioning

confidence: 99%

“…where q = ( N -2)/2 when N is even and q = ( N -1)/2 when N is odd, N is the total number of data points, a is the stated probability, and k, are given in Box and Jenkins (1976). Then the standard chi-square (x2)/degrees of freedom confidence limits are used to judge whether or not a single spectral estimate differs significantly from some null hypothesis.…”

Section: (E) Statistical Significance Of Periodicitiesmentioning

confidence: 99%

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Power spectra and coherence of drought in the interior plains

Oladipo

1987

J. Climatol.

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Mean growing season (April-September) precipitation series at 407 stations in the Interior Plains of North America, dating back to 1985 in some stations, are used to derive a Bhalme and Mooley-type drought index for the region. Linear trend, representing first order non-stationarity, is first removed from the drought series. Then the periodogram via the Fast Fourier Transform (FFT), Maximum Entropy (ME) and Non-Integer (NI) spectral techniques are applied to search for significant periodicities in the temporal characteristics of the drought series. Cross-spectral technique is also used to characterize the extent of spectral coherence in the drought series.It is found that no significant power in drought is present at periods greater than about 6 years. Spectra of drought in the Interior Plains are dominated by three peaks in the quasi-biennial, quasi-triennial and quasi-5-year oscillations. The periodic 18.6-year lunar nodal cycle obtained by others for the Drought Area Index (DAI) for the region is completely absent in the spectra of the analysed drought index series. Also the well-known 11-year sunspot cycle is only evident in the drought index series for a few of the stations. In general there is an ill-defined drought recurrence interval.Moreover the areal extent of peaks contained within these oscillations do not indicate any significant spatial coherence. These periodicities can be evident at one station while being absent at another a few hundred kilometres away. On the basis of the spectral results, it is concluded that obtained significant periodicities are only short-lived time variabilities in drought as recorded by individual stations and do not represent any persistent drought characteristics over a broad geographical region. A cross-spectral analysis of the drought series with sunspot numbers shows no evidence to indicate a significant relation between drought and the single sunspot cycle. In general, the growing season drought series in the Interior Plains displays only what appears to be a random variation, with the possible superimposition of the quasi-biennial oscillation.KEY WORDS Drought Periodogram maximum entropy and non-integer spectral techniques Drought spectral coherence Cycles

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“…Besides, some drought hazard models are used to assess the drought in different places of the world. Scholars have studied many aspects of drought used above methods, such as duration 12,13 , mechanism 14 , classification 15,16 , severity 13,17,18 , spatial extent 19,20 , the overall change trend and periodic oscillation of the drought 21 .Undeniable, those studies made process in drought studies. Because the drought has the relationship with precipitation, climate, and other factors, as one of the natural phenomena, drought has spatial and temporal dimensions.…”

Section: Introductionmentioning

confidence: 99%

Assessment of Spatial Agglomeration of Agricultural Drought Disaster in China from 1978 to 2016

Wang

Liu

Zhang

et al. 2019

Sci Rep

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Drought disaster space agglomeration assessment is one of the important components of meteorological disaster prevention and mitigation. Agriculture affected by drought disaster is not only a serious threat to world food security, but also an obstacle to sustainable development. Additionally, China is an important agricultural import and export country in the world. Therefore, we used the global Moran’s I and the local indicators of spatial autocorrelation (LISA) to reveal the spatial agglomeration of agricultural drought disaster in China from1978 to 2016, respectively. The results showed that China’s agricultural drought disaster presents local spatial autocorrelation of geographical agglomeration at national level during the study period. The spatial agglomeration regions of China’s agricultural drought disaster were in Inner Mongolia, Jilin province, Heilongjiang province, Liaoning province, Shanxi province, Hebei province, Shandong province, Shaanxi province and Henan province, indicating that agricultural drought disaster mainly distributed in North and Northwest China, especially occurred in the Yellow River Basin and its north areas. We also found that the overall movement direction of agricultural drought disaster agglomeration regions was northwest, and the maximum moving distance was 722.16 km. Our results might provide insight in early warning and prevention for drought disaster.

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Major quasi-periodic fluctuations in the drought indices

Cited by 4 publications

References 10 publications

A study of climatic variability in Nigeria based on the onset, retreat, and length of the rainy season

A study of climatic variability in Nigeria based on the onset, retreat, and length of the rainy season

Power spectra and coherence of drought in the interior plains

Assessment of Spatial Agglomeration of Agricultural Drought Disaster in China from 1978 to 2016

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