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1

The analysis of the El Niño phenomenon in the East Nusa Tenggara Province, Indonesia

Karuniasa Mahawan, Pambudi Priyaji Agung

Journal of Water and Land Development

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2022

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no. 52

180--185

EN

Climate change causes various events, such as El Niño , and we experience their larger frequency. This study based on a quantitative approach uses observation data from the Umbu Mehang Kunda Meteorological Station and the Ocean Niño Index (ONI). As a result, East Sumba, which has an arid climate, has more challenges in dealing with drought and water deficits during El Niño. This study identifies rainfall when the El Niño phenomenon takes place in East Sumba through data contributing to the ONI value and dry day series from 1982 to 2019. The analysis was carried out by reviewing these data descriptively and supported by previous literature studies. The research found that there was a decrease in the accumulative total rainfall in El Niño years. The annual rainfall in the last six El Niño events is lower than the annual rainfall in the first six El Niño events. The dry day series is dominated by an extreme drought (>60 days) which generally occurs from July to October. This drought clearly has a major impact on livelihoods and causes difficulties in agriculture as well as access to freshwater. This results in crop failure, food shortages, and decreased income. The phenomenon triggers price inflation in the market and potential increase in poverty, hunger, and pushes the country further away from the first and second Sustainable Development Goals. This phenomenon and problems related to it need to be dealt with by multistakeholders.

2

Comparison of Amplitude Variations of Seasonal and Sub-Seasonal Oscillations in Length of Day and Total Solar Irradiance

Kosek Wiesław, Gabryszuk Justyna

Journal of Ecological Engineering

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2020

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Vol. 21, nr 7

52--57

EN

The aim of the study was to identify and compute oscillations in two different time series with similar amplitude variations using length of day data with tide model removed (LODR) and total solar irradiance (TSI) data. The combination of the Fourier transform band pass filter and Hilbert transform allows detecting amplitude variations as a function of the oscillation period. The amplitude variations in two different time series enable computation of frequency dependent or time-frequency correlation coefficients between them. It allows also identifying such oscillations in two time series which have similar amplitude variations. The method applied to LODR and TSI data, enable to detect a possible relationship between them. This comparison method can be applied to any time series which consist of oscillations with non-constant amplitudes.

3

Non-linear sea level variations in the eastern tropical Pacific

Niedzielski T.

Artificial Satellites : Journal of Planetary Geodesy

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2010

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Vol. 45, No. 1

1--10

EN

The objective of this paper is to provide an insightful interpretation for the non-linearity of the inter-annual signal in sea level change in the eastern tropical Pacific. Such a non-linearity has been already discussed elsewhere for global ocean. Herein, the residual sea level anomaly time series from TOPEX/Poseidon and Jason-1 altimetry is obtained by removing the significant deterministic signals from the original sea level anomaly data. Since the eastern tropical Pacific is a profound region where many processes responsible for driving the El Niño/Southern Oscillation (ENSO) act, it is possible to link a few of them with the non-linearity of sea level change. In particular, not only local, usually weak, oceanatmosphere interactions exist in the eastern equatorial Pacific but this region is also remotely impacted by climatic processes acting in the western equatorial Pacific where the oceanatmosphere coupling is the strongest. The detected non-linearity of sea level change is due to the asymmetry between warm and cold ENSO episodes. Such an asymmetry can be driven by the non-linear dynamical heating associated with strong ENSO events.

4

Empirical hydrologic predictions for southwestern Poland and their relation to ENSO teleconnections

Niedzielski T.

Artificial Satellites : Journal of Planetary Geodesy

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2010

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Vol. 45, No. 1

11--26

EN

Recent investigations confirm meaningful but weak teleconnections between the El Niño/Southern Oscillation (ENSO) and hydrology in some European regions. In particular, this finding holds for Polish riverflows in winter and early spring as inferred from integrating numerous geodetic, geophysical and hydrologic time series. The purpose of this study is to examine whether such remote teleconnections may have an influence on hydrologic forecasting. The daily discharge time series from southwestern (SW) Poland spanning the time interval from 1971 to 2006 are examined. A few winter and spring peak flows are considered and the issue of their predictability using empirical forecasting is addressed. Following satisfactory prediction performance reported elsewhere, the multivariate autoregressive method is used and its modification based on the finite impulse response filtering is proposed. The initial phases of peak flows are rather acceptably forecasted but the accuracy of predictions in the vicinity of local maxima of the hydrographs is poorer. It has been hypothesized that ENSO signal slightly influences the predictability of winter and early spring floods in SW Poland. The predictions of flood wave maxima are the most accurate for floods preceded by normal states, less accurate for peak flows after La Niña episodes and highly inaccurate for peak flows preceded by El Niño events. Such a finding can be interpreted in terms of intermittency. Before peak flows preceded by El Niño there are temporarily persistent low flows followed by a consecutive melting leading to a considerable intermittency and hence to difficulties in forecasting. Before peak flows preceded by La Niña episodes there exist ENSO-related positive temperature and precipitation anomalies in SW Poland causing lower, but still considerable, intermittency and thus better, but not entirely correct, predictability of hydrologic time series.