scholarly journals Characteristic of the Regional Rainy Season Onset over Vietnam: Tailoring to Agricultural Application

2020 ◽  
Author(s):  
Nachiketa Acharya ◽  
Elva Bennett
Keyword(s):  
Rainy Season ◽  
Southern Oscillation ◽  
Practical Importance ◽  
Onset Date ◽  
Central Coast ◽  
Enso Events ◽  
South Central ◽  
Decadal Scale ◽  
Central Highlands ◽  
Agroclimatic Zones

Owing to its unique position within multiple monsoon regimes, latitudinal extent, and complex topography, Vietnam is divided into seven agroclimatic zones, each with distinct rainy season characteristics. Variation in the dominant rainfall system across zones affects the rainfall climatology, the primary water resource for regional crops. This study explores the creation of an agronomic rainy season onset based on high-resolution rainfall data for each agroclimatic zone for applications in an agricultural context. Onset information has huge practical importance for both agriculture and the economy. The spatiotemporal characteristics of zonal onset date are analyzed using integrated approaches of spatial and interannual variability, temporal changes, and estimation of predictability using teleconnection with Niño 3.4 sea surface temperature anomalies (SSTA) for 1980 to 2010. Results suggest that northern and southern zones experience regional onset dates in May, while the central zones experience rainy season onset in late August. The regional variability of rainy season onset is lower in a single dominant monsoon regime (northern and southern zones) and higher in latitudinally extended zones on the border of monsoon regimes (central zones). The interannual variation in rainy season onset date is found to be approximately 2 weeks across all agroclimatic zones. The significant negative trend in rainy season onset date is found for Central Coast and South Central Coast zones, suggesting that the onset date shifted earlier for the entire period. In the decadal scale, the zonal mean onset date shifted later in the Northwest and earlier in the Central Highlands. Out of the seven climate zones, a significant positive correlation is only noticed in the Central Highlands and South zones between zonal mean onset date and Niño 3.4 SSTA for Dec-Jan-Feb, suggesting the potential of seasonal scale predictability of rainy season onset date with respect to preceding El Niño-Southern Oscillation (ENSO) events.

scholarly journals Characteristic of the Regional Rainy Season Onset over Vietnam: Tailoring to Agricultural Application

Atmosphere ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 198
Author(s):  
Nachiketa Acharya ◽  
Elva Bennett
Keyword(s):  
Rainy Season ◽  
Southern Oscillation ◽  
Practical Importance ◽  
Onset Date ◽  
Central Coast ◽  
Enso Events ◽  
South Central ◽  
Decadal Scale ◽  
Central Highlands ◽  
Agroclimatic Zones

Owing to its unique position within multiple monsoon regimes, latitudinal extent, and complex topography, Vietnam is divided into seven agroclimatic zones, each with distinct rainy season characteristics. Variation in the dominant rainfall system across zones affects the rainfall climatology, the primary water resource for regional crops. This study explores the creation of an agronomic rainy season onset based on high-resolution rainfall data for each agroclimatic zone for applications in an agricultural context. Onset information has huge practical importance for both agriculture and the economy. The spatiotemporal characteristics of zonal onset date are analyzed using integrated approaches of spatial and interannual variability, temporal changes, and estimation of predictability using teleconnection with Niño 3.4 sea surface temperature anomalies (SSTA) for 1980 to 2010. Results suggest that northern and southern zones experience regional onset dates in May, while the central zones experience rainy season onset in late August. The regional variability of rainy season onset is lower in the northern and southern zones and higher in the central zones which are latitudinally extended. The interannual variation in rainy season onset date is found to be approximately two weeks across all agroclimatic zones. The significant negative trend in rainy season onset date is found for Central Coast and South Central Coast zones, suggesting that the onset date shifted earlier for the entire period. In the decadal scale, the zonal mean onset date shifted later in the Northwest zone and earlier in the Central Highlands. Out of the seven climate zones, a significant positive correlation is only noticed in the Central Highlands and South zones between zonal mean onset date and Niño 3.4 SSTA for Dec–Jan–Feb, suggesting the potential of seasonal scale predictability of rainy season onset date with respect to preceding El Niño-Southern Oscillation (ENSO) events.

scholarly journals Massive strandings of pleustonic Portuguese Man-of-War (Physalia physalis) related to ENSO events along the southeastern Pacific Ocean

2020 ◽  
Vol 48 (5) ◽  
pp. 806-817
Author(s):  
Antonio Canepa ◽  
Jennifer E. Purcell ◽  
Pablo Córdova ◽  
Miguel Fernández ◽  
Sergio Palma
Keyword(s):  
Pacific Ocean ◽  
Large Scale ◽  
Mixed Model ◽  
Southern Oscillation ◽  
Enso Events ◽  
The North ◽  
Southeastern Pacific ◽  
South Central ◽  
Cross Correlation Analysis ◽  
Physalia Physalis

Blooms of stinging pelagic cnidarians have been causing increasing health problems for humans worldwide. Physalia physalis is among the worst stinging species in the Atlantic and Pacific oceans along the North and South American coasts. This siphonophore species has a large gas float and lives at the ocean surface, where its distribution is affected mainly by winds. P. physalis's strandings were observed in the southeastern Pacific Ocean for three consecutive years (2014 to 2016). Data of stranded P. physalis were gathered daily through a collaborative effort between the Chilean Navy and the Chilean Ministry of Health. The association between oceanographic variables and the stranded P. physalis was assessed using a generalized additive mixed model (GAMM) and cross-correlation analysis. The largest stranding occurred along more than 2600 km of coastline and totaled 44,683 colonies. Most of the strandings were along the central and south-central coast of Chile, where almost 200 people were stung, and more than 120 beaches were closed in summer 2016. The GAMM model showed that the oceanographic conditions of warmer temperatures during the winter periods and the weakening of the westerly winds associated with the Niño Southern Oscillation (ENSO) were the most likely causes for the arrival of transport from the colonies to the coast. Also, our analysis illustrates the utility of collaborations among scientists and public organizations to promote large-scale and long-term understanding and provide a model for predicting this dangerous species' arrival and warning for beaches and swimmers, which is of global importance for human health.

scholarly journals Warming Patterns Affect El Niño Diversity in CMIP5 and CMIP6 Models

2020 ◽  
Vol 33 (19) ◽  
pp. 8237-8260 ◽  
Author(s):  
Mandy B. Freund ◽  
Josephine R. Brown ◽  
Benjamin J. Henley ◽  
David J. Karoly ◽  
Jaclyn N. Brown
Keyword(s):  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Central Pacific ◽  
Enso Events ◽  
Warming Pattern ◽  
Decadal Scale ◽  
El Niño Events ◽  
Mean State ◽  
El Nino Events

AbstractGiven the consequences and global significance of El Niño–Southern Oscillation (ENSO) events it is essential to understand the representation of El Niño diversity in climate models for the present day and the future. In recent decades, El Niño events have occurred more frequently in the central Pacific (CP). Eastern Pacific (EP) El Niño events have increased in intensity. However, the processes and future implications of these observed changes in El Niño are not well understood. Here, the frequency and intensity of El Niño events are assessed in models from phases 5 and 6 of the Coupled Model Intercomparison Project (CMIP5 and CMIP6), and results are compared to extended instrumental and multicentury paleoclimate records. Future changes of El Niño are stronger for CP events than for EP events and differ between models. Models with a projected La Niña–like mean-state warming pattern show a tendency toward more EP but fewer CP events compared to models with an El Niño–like warming pattern. Among the models with more El Niño–like warming, differences in future El Niño can be partially explained by Pacific decadal variability (PDV). During positive PDV phases, more El Niño events occur, so future frequency changes are mainly determined by projected changes during positive PDV phases. Similarly, the intensity of El Niño is strongest during positive PDV phases. Future changes to El Niño may thus depend on both mean-state warming and decadal-scale natural variability.

scholarly journals Characteristics of the Northern Australian Rainy Season

2008 ◽  
Vol 21 (17) ◽  
pp. 4298-4311 ◽  
Author(s):  
I. N. Smith ◽  
L. Wilson ◽  
R. Suppiah
Keyword(s):  
Rainy Season ◽  
Climate Model ◽  
Southern Oscillation ◽  
Monsoon Season ◽  
Daily Rainfall ◽  
Summer Rainfall ◽  
Average Intensity ◽  
Australian Monsoon ◽  
Enso Events ◽  
Independent Features

Abstract A trend of increasing rainfall over much of north and northwest Australia over recent decades has contrasted with decreases over much of the rest of the continent. The increases have occurred during the summer months when the rainy season is dominated by the Australian monsoon but is also affected by other events such as tropical cyclones, Madden–Julian oscillations, and sporadic thunderstorms. The problem of diagnosing these trends is considered in terms of changes in the timing of the rainy season. While numerous definitions for rainy/monsoon season onset exist, most are designed to be useful in a predictive sense and can be limited in their application to diagnostic studies, particularly when they involve predetermined threshold amounts. Here the authors define indices, based on daily rainfall observations, that provide relatively simple, robust descriptions of each rainy season at any location. These are calculated using gridded daily rainfall data throughout the northern Australian tropics and also for selected stations. The results indicate that the trends in summer rainfall totals over the period from 1950 to 2005 appear to be mainly the result of similar trends in average intensity. Furthermore, the links between the September–October average Southern Oscillation index indicate that ENSO events affect season duration rather than average intensity. Because duration and average intensity are derived as independent features of each season, it is argued that the trends in rainfall totals are largely unrelated to trends in ENSO and most likely reflect the influence of other factors. Finally, diagnosing these features of the rainy season provides a basis for assessing the confidence one can attach to different climate model projections of changes to rainfall.

Predictability of the rainy season onset date in Central Highlands of Vietnam

2019 ◽  
Vol 40 (6) ◽  
pp. 3072-3086 ◽  
Author(s):  
Ha Pham‐Thanh ◽  
Roderick Linden ◽  
Thanh Ngo‐Duc ◽  
Quang Nguyen‐Dang ◽  
Andreas H. Fink ◽  
...  
Keyword(s):  
Rainy Season ◽  
Onset Date ◽  
Central Highlands

scholarly journals The Response of Tropical Atmospheric Energy Budgets to ENSO*

2013 ◽  
Vol 26 (13) ◽  
pp. 4710-4724 ◽  
Author(s):  
Michael Mayer ◽  
Kevin E. Trenberth ◽  
Leopold Haimberger ◽  
John T. Fasullo
Keyword(s):  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Warm Pool ◽  
Smooth Transition ◽  
Energy Budgets ◽  
Enso Events ◽  
El Niño Modoki ◽  
Static Energy ◽  
The Tropics

Abstract The variability of zonally resolved tropical energy budgets in association with El Niño–Southern Oscillation (ENSO) is investigated. The most recent global atmospheric reanalyses from 1979 to 2011 are employed with removal of apparent discontinuities to obtain best possible temporal homogeneity. The growing length of record allows a more robust analysis of characteristic patterns of variability with cross-correlation, composite, and EOF methods. A quadrupole anomaly pattern is found in the vertically integrated energy divergence associated with ENSO, with centers over the Indian Ocean, the Indo-Pacific warm pool, the eastern equatorial Pacific, and the Atlantic. The smooth transition, particularly of the main maxima of latent and dry static energy divergence, from the western to the eastern Pacific is found to require at least two EOFs to be adequately described. The canonical El Niño pattern (EOF-1) and a transition pattern (EOF-2; referred to as El Niño Modoki by some authors) form remarkably coherent ENSO-related anomaly structures of the tropical energy budget not only over the Pacific but throughout the tropics. As latent and dry static energy divergences show strong mutual cancellation, variability of total energy divergence is smaller and more tightly coupled to local sea surface temperature (SST) anomalies and is mainly related to the ocean heat discharge and recharge during ENSO peak phases. The complexity of the structures throughout the tropics and their evolution during ENSO events along with their interactions with the annual cycle have often not been adequately accounted for; in particular, the El Niño Modoki mode is but part of the overall evolutionary patterns.

Rapid detection of changes in the riverbanks of Laigiang river of the South Central Coast Vietnam: A methodology based on Digital Shoreline Analysis System and Sentinel-2

2021 ◽  
Vol 14 (11) ◽  
pp. 13-24
Author(s):  
Anh Tu Ngo ◽  
Stéphane Grivel ◽  
Thai Le Phan ◽  
Huu Xuan Nguyen ◽  
Trong Doi Nguyen
Keyword(s):  
Linear Regression ◽  
Shoreline Change ◽  
The South ◽  
Central Coast ◽  
Shoreline Changes ◽  
South Central ◽  
Digital Shoreline Analysis System ◽  
Analysis System ◽  
End Point Rate ◽  
Sentinel 2

The research focuses on using Sentinel-2 that can be integrated with the Digital Shoreline Analysis System (DSAS) as an effective tool for the determination of changes in the riverbanks and using linear regression to predict shoreline changes. The research applied the assessment of shoreline changes in the period of 2015- 2020 and forecast to 2025 in Laigiang river of the South Central Coast region of Vietnam. Based on the DSAS tool, parameters such as Shoreline Change Envelope (SCE), Net Shoreline Movement (NSM), End Point Rate (EPR) and Linear Regression Rate (LRR) were determined. The analysis results show that the accretion process in the Laigiang river in the period of 2015-2020 with the accretion area ranges from 81.47 ha. Meanwhile, the area of shoreline erosion only fluctuates around 54.42 ha. The rhythm of evolution is a determinant element for this transitional system.

The relationship between the El Niño Southern Oscillation and Australian monsoon rainfall on decadal time-scales

2021 ◽  
Author(s):  
Hanna Heidemann ◽  
Joachim Ribbe ◽  
Benjamin J. Henley ◽  
Tim Cowan ◽  
Christa Pudmenzky ◽  
...  
Keyword(s):  
Monsoon Rainfall ◽  
Decadal Variability ◽  
Southern Oscillation ◽  
Eastern Pacific ◽  
Central Pacific ◽  
Australian Monsoon ◽  
Enso Events ◽  
Pacific Decadal Variability ◽  
Prediction Systems ◽  
Different Response

<p>This research analyses the observed relationship between eastern and central Pacific El Niño Southern Oscillation (ENSO) events and Australian monsoon rainfall (AUMR) on a decadal timescale during the December to March monsoon months. To assess the decadal influence of the different flavours of ENSO on the AUMR, we focus on the phases of the Interdecadal Pacific Oscillation (IPO) over the period 1920 to 2020.  The AUMR is characterized by substantial decadal variability, which appears to be linked to the positive and negative phases of the IPO. During the past two historical negative IPO phases, significant correlations have been observed between central Pacific sea surface temperature (SST) anomalies and AUMR over both the northeast and northwest of Australia. This central Pacific SST-AUMR relationship has strengthened from the first negative IPO phase (mid-1940s to the mid-1970s) to the second (late 1990s to mid-2010s), while the eastern Pacific SST-AUMR influence has weakened. Composite rainfall anomalies over Australia reveal a different response of AUMR to central Pacific El Niño/La Niña and eastern Pacific La Niña events during positive IPO and negative IPO phases. This research clearly shows that ENSO's influence on AUMR is modulated by Pacific decadal variability, however this teleconnection, in itself, can change between similar decadal Pacific states.  Going forward, as decadal prediction systems improve and become more mainstream, the IPO phase could be used as a potential source for decadal predictability of the tendency of AUMR.  </p>

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