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The Effect of ENSO on the Upwelling Intensity in the Seas along the Northern Coast of Papua: A Case Study of the 2015–2016 El Niño and the 2010–2011 La Niña Events

Lesmana Petrik Siano Okta Prima, Wirasatriya Anindya, Setiyono Heryoso, Suryoputro Agus Anugroho Dwi, Wijaya Yusuf Jati, Ismunarti Dwi Haryo, Haryanti Dwi, Abdillah Muhammad Rais

Ecological Engineering & Environmental Technology

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2024

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Vol. 25, iss. 2

243--253

EN

The seas along the Northern Coast of Papua constitute a region with complex oceanographic conditions as they are situated within the Indo-Pacific warm pool (IPWP). The geographical location in the southern hemisphere induces upwelling during the west monsoon season (December-January-February). Additionally, interannual phenomena such as the El Niño Southern Oscillation (ENSO) can impact the intensity of upwelling in these waters. This study aimed to compare the upwelling intensity in the seas along the Northern Coast of Papua during neutral phases and ENSO phases. The main indicators of upwelling are sea surface temperature (SST) and Ekman mass transport (EMT). The data utilized in this study include SST from GHRSST and surface wind from ASCAT. The data processing employed the monthly composite method with spatiotemporal analysis based on anomaly results derived from monthly climatology. The analysis results reveal that El Niño 2015–2016 led to an increase in upwelling intensity ranging from 1.82 to 4.00 m/s2, while La Niña 2010–2011 resulted in a weakening of upwelling intensity ranging from 4.95 to 6.56 m/s2 in the seas along the Northern Coast of Papua. On the basis of correlation and regression analysis, it can be concluded that offshore EMT significantly influences upwelling anomalies in the southeastern waters, whereas the northwestern waters are more influenced by the shifting IPWP during ENSO.

2

Rainfall and rainy days trend and ENSO phenomena in Himalayan Kingdom of Bhutan

Sharma Vasker, Adhikari Kirtan

Acta Geophysica

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2022

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Vol. 70, no 4

1855--1869

EN

The study explores the seasonal rainfall and rainy days trend in the Himalayan Kingdom of Bhutan. Mann-Kendall and Sen’s slope test was applied to detect the trend and magnitude of the trend for both the rainfall and rainy days. The trends are also analyzed with respect to the elevation of the climatic stations. Further, an attempt has been made to recognize the El-Ni ño-Southern Oscillation (ENSO)-rainfall interaction using station-based rainfall with the ENSO cycle considering the period of 33 years. Cross-correlation of ENSO and rainfall with respect to elevation has also been presented. The trend analysis showed that in the localized regions, both the rainfall and rainy days trend was significantly declining, however, the trend in most of the stations is hardly conspicuous which may be attributed to the influence of the orographic phenomena. From the ENSO-rainfall assessment, it was observed that rainfall in the southern foothills correlates negatively with the ENSO phenomena indicating intense rainfall after 1–2 months of the cooling phase of the Pacifc Ocean. However, such an ENSO effect is not observed in the majority of the meteorological stations which may be attributed to the location of the station in the mountainous region where the topography affects the rainfall variation.

3

A short note on the natural and anthropogenic variations in the water storage changes at Visakhapatnam, Andhra Pradesh, India

Mathews Gathala Vinod, Rajesh Rekapalli, Begum Shaik Kareemunnisa

Acta Geophysica

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2022

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Vol. 70, no 4

1847--1854

EN

We analyze the periodic and stochastic/random dynamics in the water storage changes at Visakhapatnam, Andhra Pradesh, India. We used time-variable gravity data in terms of Equivalent Water Thickness (EWT) measured from Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow-On satellite missions for the period 2002 to 2021 along with average rainfall data to assess the natural and anthropogenic impacts on water storage changes. We employ Wavelet Spectrum and Singular Spectrum Analysis (SSA) methods to analyze the non-stationary variation of spectral power and principal components. The water storage in the study area shows a significant positive trend with a peak correlation of 0.52 with the rainfall data at a lag of 3 months. The first, second, third, fourth, and fifth principal components depicting the monotonic trend and oscillations together contribute 69.48% to the total water storage changes. The wavelet spectrum of the SSA reconstructed signal from the first four principal components revealed non-stationary annual and 1.3 to 8 years periodicities associated with natural solar and El-Nino Southern Oscillations (ENSO) respectively. The phase plot of the residual signal of ~ 30% variance suggests the random dynamics. Thus the study suggests: (i) an increasing groundwater trend in the study area, (ii) nearly 70% of the water storage changes are linked with natural solar and ENSO variations, and (iii) 30% of water storage changes are with random dynamics possibly linked with anthropogenic activities and catastrophic climatic episodes of shorter duration at Visakhapatnam, Andhra Pradesh, India.

4

Understanding the hydrometeorological characteristics and relationships in the semiarid region of Maharashtra (western India): implications for water management

Todmal Rahul S.

Acta Geophysica

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2020

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Vol. 68, no. 1

189--206

EN

In spite of enormous investment for water harvesting in Maharashtra, the issue of water defciency persist. Therefore, with the proper understanding of recent (1975–2014) hydrometeorological characteristics in the semiarid region of Maharashtra, the study endeavored to suggest management strategies to optimize the water resources. To understand the inherent characteristics of rainfall, runof, dam storages and groundwater, statistical techniques including descriptive statistics, correlation, regression and Student’s t test were applied. The monsoon rainfall has notable control over the water resources. As the study region characterized by signifcantly low water availability with high variability which is accountable for higher frequency and intensity of drought, it should be prioritized while formulating a judicial plan for water management. The major rivers of Maharashtra follow the unimodal pattern of rainfall. Whereas the study area displays a peculiar character of the bimodal and unimodal regimes of rainfall and runof, respectively, this highlights the role of hydrological losses. However, it also indicates that there is a wide scope to harvest surface water, particularly during the months of September and October. Interestingly, the inter-annual variability in the extreme rainfall and runof events over the study basins is observed to be higher in India. Most of the water (>50%) received during fashy rainfall events drains out through fashy discharges. The impoundment of this water and modifed irrigation schedule by considering the recent hydrological characteristics may diminish the variability and defciency of surface and subsurface water. Furthermore, for the precise forecast of water availability in the study area, ENSO condition needs to incorporate, as it has a signifcant connection with rainfall and runof.

5

The impact of climatic patterns on runoff and irrigation water allocation in an arid watershed of northern Mexico

Cohen I. S., Ibarra M. A. I., Arriaga G. E., Paredes J. C., Valle M. A. V., Bustamante W. O.

Meteorology Hydrology and Water Management. Research and Operational Applications

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2018

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Vol. 6, Iss. 2

59--66

EN

The uncertainty of water availability is the main problem in planning for water resources in watersheds of agricultural drylands. Water availability for different uses depends on the runoff that is generated in the upper portion of the watersheds, where there are higher elevations and lower temperatures. Proximity to the ocean is a main factor that defines rainfall amounts. In this research we linked the effects of El Niño to a regional Standardized Precipitation Index (SPI) and the subsequent impact on runoff production and irrigation water allocation. Findings indicate the cascading impacts of the El Niño on the SPI, the SPI on the runoff discharge to the irrigation reservoir, and the final impact on the planted area within the irrigation district. An optimization procedure was applied to maximizing net income in agriculture under different water availability scenarios. The restrictions to the optimization model were: total available water, crop water demand, and available land. Local criteria for defining the maximum allowable planted area by crop also were taken into account. The analysis with various water availability scenarios demonstrated that with limited amounts of water for irrigation, forage area would be limited, thereby increasing the area of crops with lower water demands. In both scenarios the area of forage maize was reduced from 11300 to 1764 ha. Increasing irrigation water use efficiency may save water for expanding the irrigated area, or for other uses.

6

Barycenter reflected equatorial Pacific sea level structure evolution and its indication of ENSO events

Luo W., Yi L., Yu Z., Sun H., Yuan L.

Oceanologia

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2015

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No. 57 (2)

107--115

EN

Focused on the zonal and meridional response of sea level change to El Niño-Southern Oscillation (ENSO) events, this paper retrieves the overall average, positive anomaly and negative anomaly sea surface height (SSH) series of equatorial Pacific area (EPA) from satellite altimetry data from 1993 to 2013. The barycenter method is then applied to each of the three series to get the zonal and meridional barycenter coordinates. The barycenter coordinates are then compared with the Multivariate ENSO index (MEI) to reveal the zonal and meridional response of sea level change to ENSO. The meridional and zonal spatio-temporal evolutionary processes of sea level change in EPA during different ENSO events are reconstructed by the Principle Tensor Analysis of Rank 3 Method (PTA3). Comparative analysis shows that the meridional change of positive anomalies barycenter, rather than the mean series of sea level height anomaly in EPA, can well characterize the intensity and evolutionary process of ENSO events. Meanwhile, the zonal migration of barycenter may reflect the lag adjustment of the sea level to the ENSO signal. The analysis on the meridional and zonal evolution of the sea level change in different ENSO periods shows that the response of sea level change to the ENSO events can be mainly characterized by the position differences between positive and negative sea level anomaly barycenter, SSH gradient in the meridional direction and the inconsistency in the overall spatial structure and temporal evolution characteristics in the zonal direction.

7

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.

8

Lack of synchrony between breeding in two neighbouring starling (Sturnus vulgaris L.) populations in New Zealand : evidence of no regional effect of the ENSO?

Flux J., Bull P., Zduniak P., Tryjanowski P.

Polish Journal of Ecology

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2009

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Vol. 57, nr 2

363-369

EN

Weather and climatic conditions may impact on many aspects of bird populations, including population size, the timing of breeding and synchrony between these variables in local populations. We examined synchrony in population size and the laying date of two starling Sturnus vulgaris populations 25 km apart, at Ohau and Belmont, in New Zealand. Data were collected in nest-boxes in both study plots from 1970 to 2003. Additionally we investigated possible relationships with a large geographical climate index, the El Nino Southern Oscillation (ENSO). Starlings at Ohau bred significantly earlier than at Belmont. The difference in the median of year median date of laying the first egg was 3 days. Simultaneously, the percent of nest boxes used by birds was much higher in Ohau (86%, SE = 4.1) than in Belmont (52%, SE = 2.9). However, we did not find a significant relationship between median dates of laying and the percent of nest boxes used by birds in each breeding season in the two populations. Furthermore, we found no influence of ENSO on (potential) synchrony in starlings. breeding parameters. We suggest that lack of synchrony between two close local populations, both in percentage of occupied nest boxes and time of laying, is due to starlings responding to very local conditions, like food availability. We urge future studies to take advantage of spatially close populations.