scholarly journals Responses of groundwater to precipitation variability and ENSO in the Vietnamese Mekong Delta

2021 ◽  
Author(s):  
Phong V. V. Le ◽  
Hai V. Pham ◽  
Luyen K. Bui ◽  
Anh N. Tran ◽  
Chien V. Pham ◽  
...  
Keyword(s):  
Water Resources ◽  
Climate Variability ◽  
Time Scales ◽  
Groundwater Level ◽  
Southern Oscillation ◽  
Mekong Delta ◽  
Precipitation Variability ◽  
Annual Precipitation ◽  
Aquifer Recharge ◽  
Deep Aquifers

Abstract Groundwater is a critical component of water resources and has become the primary water supply for agricultural and domestic uses in the Vietnamese Mekong Delta (VMD). Widespread groundwater level declines have occurred in the VMD over recent decades, reflecting that extraction rates exceed aquifer recharge in the region. However, the impacts of climate variability on groundwater system dynamics in the VMD remain poorly understood. Here, we explore recent changes in groundwater levels in shallow and deep aquifers from observed wells in the VMD and investigate their relations to the annual precipitation variability and El Niño–Southern Oscillation (ENSO). We show that groundwater level responds to changes in annual precipitation at time scales of approximately 1 year. Moreover, shallow (deep) groundwater in the VMD appears to correlate with the ENSO over intra-annual (inter-annual) time scales. Our findings reveal a critical linkage between groundwater level changes and climate variability, suggesting the need to develop an understanding of the impacts of climate variability across time scales on water resources in the VMD.

scholarly journals Interannual-to-multidecadal Hydroclimate Variability and its Sectoral Impacts in northeastern Argentina

2018 ◽  
Author(s):  
Miguel A. Lovino ◽  
Omar V. Müller ◽  
Gabriela V. Müller ◽  
Leandro C. Sgroi ◽  
Walter E. Baethgen
Keyword(s):  
Water Resources ◽  
Time Scales ◽  
Southern Oscillation ◽  
Singular Spectrum Analysis ◽  
Principal Component ◽  
Economic Sectors ◽  
Discharge Temperature ◽  
Hydroclimate Variability ◽  
Nonlinear Trends ◽  
Northeastern Argentina

Abstract. This study examines the relation between hydroclimate variability (precipitation, river discharge, temperature) and water resources, agriculture and human settlements at different time scales in northeastern Argentina. It also discusses the impacts on these productive and socio-economic sectors. The leading patterns of variability, their nonlinear trends, and cycles are identified by means of a Principal Component Analysis (PCA) complemented with a Singular Spectrum Analysis (SSA). Interannual hydroclimatic variability centres on two broad frequency bands: one of 2.5–6.5 years corresponding to El Niño Southern Oscillation (ENSO) periodicities and the second of about 9 years. Interdecadal variability is characterized by low-frequency trends and multidecadal oscillations that have induced a transition to wetter and warmer climate starting in the mid-twentieth century. The hydroclimate variability at all time scales had significant sectoral impacts. Frequent wet events between 1970 and 2005 favoured floods that affected agricultural and livestock productivity and forced population displacements. On the other hand, agricultural droughts produced soil moisture deficits affecting crops at critical growth periods. Hydrological droughts affected surface water resources causing water and food scarcity and stressed the capacity for hydropower generation. Lastly, increases in minimum temperature reduced wheat and barley yields.

scholarly journals Climate Variability, Fish, and Fisheries

2006 ◽  
Vol 19 (20) ◽  
pp. 5009-5030 ◽  
Author(s):  
P. Lehodey ◽  
J. Alheit ◽  
M. Barange ◽  
T. Baumgartner ◽  
G. Beaugrand ◽  
...  
Keyword(s):  
Climate Variability ◽  
Time Scales ◽  
Large Scale ◽  
Southern Oscillation ◽  
Low Frequency ◽  
Fish Population ◽  
Marine Ecology ◽  
Fish Populations ◽  
Global Ocean ◽  
Close Link

Abstract Fish population variability and fisheries activities are closely linked to weather and climate dynamics. While weather at sea directly affects fishing, environmental variability determines the distribution, migration, and abundance of fish. Fishery science grew up during the last century by integrating knowledge from oceanography, fish biology, marine ecology, and fish population dynamics, largely focused on the great Northern Hemisphere fisheries. During this period, understanding and explaining interannual fish recruitment variability became a major focus for fisheries oceanographers. Yet, the close link between climate and fisheries is best illustrated by the effect of “unexpected” events—that is, nonseasonal, and sometimes catastrophic—on fish exploitation, such as those associated with the El Niño–Southern Oscillation (ENSO). The observation that fish populations fluctuate at decadal time scales and show patterns of synchrony while being geographically separated drew attention to oceanographic processes driven by low-frequency signals, as reflected by indices tracking large-scale climate patterns such as the Pacific decadal oscillation (PDO) and the North Atlantic Oscillation (NAO). This low-frequency variability was first observed in catch fluctuations of small pelagic fish (anchovies and sardines), but similar effects soon emerged for larger fish such as salmon, various groundfish species, and some tuna species. Today, the availability of long time series of observations combined with major scientific advances in sampling and modeling the oceans’ ecosystems allows fisheries science to investigate processes generating variability in abundance, distribution, and dynamics of fish species at daily, decadal, and even centennial scales. These studies are central to the research program of Global Ocean Ecosystems Dynamics (GLOBEC). This review presents examples of relationships between climate variability and fisheries at these different time scales for species covering various marine ecosystems ranging from equatorial to subarctic regions. Some of the known mechanisms linking climate variability and exploited fish populations are described, as well as some leading hypotheses, and their implications for their management and for the modeling of their dynamics. It is concluded with recommendations for collaborative work between climatologists, oceanographers, and fisheries scientists to resolve some of the outstanding problems in the development of sustainable fisheries.

Atmospheric and Oceanic Origins of Tropical Precipitation Variability

2017 ◽  
Vol 30 (9) ◽  
pp. 3197-3217 ◽  
Author(s):  
Jie He ◽  
Clara Deser ◽  
Brian J. Soden
Keyword(s):  
Time Scales ◽  
Ocean Circulation ◽  
Large Scale ◽  
Southern Oscillation ◽  
Noise Spectrum ◽  
Precipitation Variability ◽  
Ocean Dynamics ◽  
Atmospheric Variability ◽  
Tropical Precipitation ◽  
Summer Hemisphere

The intrinsic atmospheric and ocean-induced tropical precipitation variability is studied using millennial control simulations with various degrees of ocean coupling. A comparison between the coupled simulation and the atmosphere-only simulation with climatological sea surface temperatures (SSTs) shows that a substantial amount of tropical precipitation variability is generated without oceanic influence. This intrinsic atmospheric variability features a red noise spectrum from daily to monthly time scales and a white noise spectrum beyond the monthly time scale. The oceanic impact is inappreciable for submonthly time scales but important at interannual and longer time scales. For time scales longer than a year, it enhances precipitation variability throughout much of the tropical oceans and suppresses it in some subtropical areas, preferentially in the summer hemisphere. The sign of the ocean-induced precipitation variability can be inferred from the local precipitation–SST relationship, which largely reflects the local feedbacks between the two, although nonlocal forcing associated with El Niño–Southern Oscillation also plays a role. The thermodynamic and dynamic nature of the ocean-induced precipitation variability is studied by comparing the fully coupled and slab ocean simulations. For time scales longer than a year, equatorial precipitation variability is almost entirely driven by ocean circulation, except in the Atlantic Ocean. In the rest of the tropics, ocean-induced precipitation variability is dominated by mixed layer thermodynamics. Additional analyses indicate that both dynamic and thermodynamic oceanic processes are important for establishing the leading modes of large-scale tropical precipitation variability. On the other hand, ocean dynamics likely dampens tropical Pacific variability at multidecadal time scales and beyond.

scholarly journals Water resources and flooding risk in Kumamoto based on observed hydrologic data analysis

2020 ◽  
Author(s):  
Makoto Higashino ◽  
Heinz G. Stefan
Keyword(s):  
Water Resources ◽  
Rainy Season ◽  
Daily Precipitation ◽  
Southern Oscillation ◽  
Monsoon Season ◽  
Annual Precipitation ◽  
Daily Maximum ◽  
Annual Maximum ◽  
Hydrologic Data ◽  
Flooding Risk

Abstract Variability and change of precipitation were investigated in Kumamoto on Kyushu Island in southwestern Japan, to assess water resources and flooding risk. Annual precipitation, annual maximum daily precipitation, and annual maximum hourly precipitation have increased over the period from 1891 to 2018 (128 years). Trends are 26.2 mm per decade, 6.07 mm/day per decade, and 2.17 mm/h/decade, respectively. Precipitation in the rainy season (June and July) is on average 37% (ranging from 12 to 59%) of annual precipitation for the 128-year period. Maximum daily precipitation in a year occurred at Kumamoto in the rainy season in 92/128 (72%) of the years of observation from 1891 to 2018, in the typhoon (August to November) season in 23/128 (18%), and in the March to May season in 12/128 (10%). This indicates that the rainy monsoon season poses the largest daily flooding risk. A wavelet analysis revealed that from 1891 to 2018 annual precipitation and daily maximum precipitation fluctuate with 2 and 4 years periods, which may be related to the El Nino-Southern Oscillation (ENSO). It is likely that air temperature rises, ENSO and topographical characteristics contributed to an increase in precipitation in the period. The analysis also showed that typhoons hitting or approaching Kumamoto have significantly affected annual precipitation and annual maximum daily precipitation, while the interval between typhoons affecting Kumamoto has been getting longer since the 1970s.

scholarly journals The Forcing of Monthly Precipitation Variability over Southwest Asia during the Boreal Cold Season

2015 ◽  
Vol 28 (18) ◽  
pp. 7038-7056 ◽  
Author(s):  
Andrew Hoell ◽  
Shraddhanand Shukla ◽  
Mathew Barlow ◽  
Forest Cannon ◽  
Colin Kelley ◽  
...  
Keyword(s):  
Climate Variability ◽  
Rossby Wave ◽  
Rossby Waves ◽  
Decadal Variability ◽  
Southern Oscillation ◽  
Cold Season ◽  
Precipitation Variability ◽  
Annual Rainfall ◽  
Monthly Precipitation ◽  
Southwest Asia

Abstract Southwest Asia, defined as the region containing the countries of Afghanistan, Iran, Iraq, and Pakistan, is water scarce and receives nearly 75% of its annual rainfall during the boreal cold season of November–April. The forcing of southwest Asia precipitation has been previously examined for the entire boreal cold season from the perspective of climate variability originating over the Atlantic and tropical Indo-Pacific Oceans. This study examines the intermonthly differences in precipitation variability over southwest Asia and the atmospheric conditions directly responsible in forcing monthly November–April precipitation. Seasonally averaged November–April precipitation over southwest Asia is significantly correlated with sea surface temperature (SST) patterns consistent with Pacific decadal variability (PDV), El Niño–Southern Oscillation (ENSO), and the long-term change of global SST (LT). In contrast, the precipitation variability during the individual months of November–April is unrelated and is correlated with SST signatures that include PDV, ENSO, and LT in different combinations. Despite strong intermonthly differences in precipitation variability during November–April over southwest Asia, similar atmospheric circulations, highlighted by a stationary equivalent barotropic Rossby wave centered over Iraq, force the monthly spatial distributions of precipitation. Tropospheric flow on the eastern side of the equivalent barotropic Rossby wave modifies the flux of moisture and advects the mean meridional temperature gradient, resulting in temperature advection that is balanced by vertical motions over southwest Asia. The forcing of monthly southwest Asia precipitation by equivalent barotropic Rossby waves is different from the forcing by baroclinic Rossby waves associated with tropically forced–only modes of climate variability.

Assessing Water Availability for Development in Africa using GRACE Satellites

2021 ◽  
Author(s):  
Bridget R Scanlon ◽  
Ashraf Rateb ◽  
Hua Xie
Keyword(s):  
Water Resources ◽  
Southern Oscillation ◽  
Water Storage ◽  
Critical Issue ◽  
Sub Saharan Africa ◽  
Spatiotemporal Variability ◽  
Aquifer Recharge ◽  
Climate Cycles ◽  
Aquifer Systems ◽  
Grace Satellites

<p>Access to water is a critical issue in Sub-Saharan Africa. The objective of our work was to assess spatiotemporal variability in water storage using GRACE satellites in the major aquifers and potential for development. Results show that Total Water Storage (TWS) variability tracked by GRACE satellites is dominated by interannual variability in most aquifer systems driven by dry and wet climate cycles, such as El Nino Southern Oscillation, Indian Ocean Dipole, Pacific Decadal Oscillation and others. Climate cycles result in systems being subjected to droughts or floods, which is challenging for water resources management. Linear trends in TWS were limited to west Africa attributed to land use change and north Africa linked to water use. Variability in storage of some reservoirs and groundwater hydrographs is similar to storage variability from GRACE satellites. Examples of approaches toward sustainable management of water resources include storage of excess flood water for use during droughts in surface reservoirs, conjunctive use of surface water and groundwater, and managed aquifer recharge. Understanding the linkages between climate cycles and water storage should help optimize water management within this framework.</p>

scholarly journals Orbital Insolation Variations, Intrinsic Climate Variability, and Quaternary Glaciations

2021 ◽  
Author(s):  
Keno Riechers ◽  
Takahito Mitsui ◽  
Niklas Boers ◽  
Michael Ghil
Keyword(s):  
Climate Variability ◽  
Time Scales ◽  
Southern Oscillation ◽  
Recent Theory ◽  
Relative Role ◽  
Orbital Forcing ◽  
Intrinsic Variability ◽  
Unified Framework ◽  
Quaternary Glaciation

Abstract. The relative role of external forcing and of intrinsic variability is a key question of climate variability in general and of our planet’s paleoclimatic past in particular. Over the last 100 years since Milankovitch’s contributions, the role of orbital forcing has been well established for the last 2.6 Myr and their Quaternary glaciation cycles. A convincing case has also been made for the role of several internal mechanisms that are active on time scales both shorter and longer than the orbital ones. Such mechanisms clearly have a causal role in Dansgaard-Oeschger and Heinrich events, as well as in the mid-Pleistocene transition. We introduce herein a unified framework for the understanding of the interplay between internal mechanisms and orbital forcing on time scales from thousands to millions of years. This framework relies on the fairly recent theory of nonautonomous and random dynamical systems and it has been successfully applied so far in the climate sciences for problems like the El Niño-Southern Oscillation, the oceans’ wind-driven circulation, and other problems on interannual to interdecadal time scales. Finally, we provide further examples of climate applications and present preliminary results of interest for the Quaternary glaciation cycles in general and the mid-Pleistocene transition in particular.

Fluctuations of Annual Precipitation and Water Resources Quality in Ukraine

2016 ◽  
Vol 10 (4s) ◽  
pp. 621-629
Author(s):  
Valentina Pidlisnyuk ◽  
◽  
John Harrington JR ◽  
Yulia Melnyk ◽  
Yuliya Vystavna ◽  
...  
Keyword(s):  
Water Resources ◽  
Surface Waters ◽  
Precipitation Amount ◽  
Ion Concentration ◽  
Annual Precipitation ◽  
Resource Quality ◽  
Phosphate Ion ◽  
Regional Trends

The article focuses on examining the influence of fluctuations in annual precipitation amount on the quality of surface waters. Water quality was estimated with data on BOD, COD and phosphate–ion concentration within five selected regions of Ukraine. Analysis of the precipitation data (1991 – 2010) showed different regional trends. Using the statistics, determination of the interconnection between precipitation amount and water resources quality were done. The obtained regularities and associated uncertainties can be used for prediction of changes in water resource quality and as a guide for future adaptation to possible climate change.

VARIABILIDAD CLIMÁTICA, CAMBIO CLIMÁTICO Y PESQUERÍAS EN EL ECUADOR.

2012 ◽  
Vol 1 (1) ◽  
Author(s):  
Johnny Chavarría Viteri ◽  
Dennis Tomalá Solano
Keyword(s):  
Climate Change ◽  
Climate Variability ◽  
Pacific Decadal Oscillation ◽  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
El Niño Southern Oscillation ◽  
El Nino Southern Oscillation ◽  
Current Action ◽  
Palabras Clave

La variabilidad climática es la norma que ha modulado la vida en el planeta. Este trabajo demuestra que las pesquerías y acuicultura costera ecuatorianas no son la excepción, puesto que tales actividades están fuertemente influenciadas por la variabilidad ENSO (El Niño-Oscilación del Sur) y PDO (Oscilación Decadal del Pacífico), planteándose que la señal del cambio climático debe contribuir a esta influencia. Se destaca también que, en el análisis de los efectos de la variabilidad climática sobre los recursos pesqueros, el esfuerzo extractivo también debe ser considerado. Por su parte, la acción actual de la PDO está afectando la señal del cambio climático, encontrándose actualmente en fases opuestas. Se espera que estas señales entren en fase a finales de esta década, y principalmente durante la década de los 20 y consecuentemente se evidencien con mayor fuerza los efectos del Cambio Climático. Palabras Clave: Variabilidad Climática, Cambio Climático, ENSO, PDO, Pesquerías, Ecuador. ABSTRACT Climate variability is the standard that has modulated life in the planet. This work shows that the Ecuadorian  fisheries and aquaculture are not the exception, since such activities are strongly influenced by ENSO variability (El Niño - Southern Oscillation) and PDO (Pacific Decadal Oscillation), considering that the signal of climate change should contribute to this influence. It also emphasizes that in the analysis of the effects of climate variability on the fishing resources, the extractive effort must also be considered. For its part, the current action of the PDO is affecting the signal of climate change, now found on opposite phases. It is hoped that these signals come into phase at the end of this decade, and especially during the decade of the 20’s and more strongly evidencing the effects of climate change. Keywords: Climate variability, climate change, ENSO (El Niño - Southern Oscillation) and PDO  (Pacific Decadal Oscillation); fisheries, Ecuador. Recibido: mayo, 2012Aprobado: agosto, 2012

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