scholarly journals Explaining and forecasting interannual variability in the flow of the Nile River

2014 ◽  
Vol 11 (5) ◽  
pp. 4851-4878
Author(s):  
M. S. Siam ◽  
E. A. B. Eltahir
Keyword(s):  
Interannual Variability ◽  
Southern Oscillation ◽  
Eastern Pacific ◽  
Nile River ◽  
Data Sets ◽  
Bayesian Theorem ◽  
The Bible ◽  
The Pacific ◽  
Hybrid Forecasting ◽  
First Time

Abstract. The natural interannual variability in the flow of Nile River had a significant impact on the ancient civilizations and cultures that flourished on the banks of the river. This is evident from stories in the Bible and Koran, and from the numerous Nilometers discovered near ancient temples. Here, we analyze extensive data sets collected during the 20th century and define four modes of natural variability in the flow of Nile River, identifying a new significant potential for improving predictability of floods and droughts. Previous studies have identified a significant teleconnection between the Nile flow and the Eastern Pacific Ocean. El Niño–Southern Oscillation (ENSO) explains about 25% of the interannual variability in the Nile flow. Here, we identify, for the first time, a region in the southern Indian Ocean with similarly strong teleconnection to the Nile flow. Sea Surface Temperature (SST) in the region (50–80° E and 25–35° S) explains 28% of the interannual variability in the Nile flow. During those years with anomalous SST conditions in both Oceans, we estimate that indices of the SSTs in the Pacific and Indian Oceans can collectively explain up to 84% of the interannual variability in the flow of Nile. Building on these findings, we use classical Bayesian theorem to develop a new hybrid forecasting algorithm that predicts the Nile flow based on global models predictions of indices of the SST in the Eastern Pacific and Southern Indian Oceans.

scholarly journals Explaining and forecasting interannual variability in the flow of the Nile River

2015 ◽  
Vol 19 (3) ◽  
pp. 1181-1192 ◽  
Author(s):  
M. S. Siam ◽  
E. A. B. Eltahir
Keyword(s):  
Interannual Variability ◽  
Southern Oscillation ◽  
Eastern Pacific ◽  
Nile River ◽  
Data Sets ◽  
Bayesian Theorem ◽  
The Pacific ◽  
Model Predictions ◽  
Hybrid Forecasting ◽  
Floods And Droughts

Abstract. This study analyzes extensive data sets collected during the twentieth century and defines four modes of natural variability in the flow of the Nile River, identifying a new significant potential for improving predictability of floods and droughts. Previous studies have identified a significant teleconnection between the Nile flow and the eastern Pacific Ocean. El Niño–Southern Oscillation (ENSO) explains about 25% of the interannual variability in the Nile flow. Here, this study identifies a region in the southern Indian Ocean, with a similarly strong teleconnection to the Nile flow. Sea surface temperature (SST) in the region (50–80° E and 25–35° S) explains 28% of the interannual variability in the flow of the Nile River and, when combined with the ENSO index, the explained variability of the flow of the Nile River increases to 44%. In addition, during those years with anomalous SST conditions in both oceans, this study estimates that indices of the SSTs in the Pacific and Indian oceans can collectively explain up to 84% of the interannual variability in the flow of the Nile. Building on these findings, this study uses the classical Bayesian theorem to develop a new hybrid forecasting algorithm that predicts the Nile flow based on global model predictions of indices of the SST in the eastern Pacific and southern Indian oceans.

Interannual Modality of Upper-Ocean Temperature: 4D Structure Revealed by Argo Data

2015 ◽  
Vol 28 (9) ◽  
pp. 3441-3452 ◽  
Author(s):  
Ge Chen ◽  
Hanou Chen
Keyword(s):  
Interannual Variability ◽  
Southern Oscillation ◽  
Hadley Circulation ◽  
Walker Circulation ◽  
Upper Ocean ◽  
Kelvin Wave ◽  
Argo Data ◽  
Sea Temperature ◽  
Equatorial Undercurrent ◽  
The Pacific

Abstract Using the newly available decade-long Argo data for the period 2004–13, a detailed study is carried out on deriving four-dimensional (4D) modality of sea temperature in the upper ocean with emphasis on its interannual variability in terms of amplitude, phase, and periodicity. Three principal modes with central periodicities at 19.2, 33.8, and 50.3 months have been identified, and their relationship with El Niño–Southern Oscillation (ENSO) is investigated, yielding a number of useful results and conclusions: 1) A striking tick-shaped pipe-like feature of interannual variability maxima, which is named the “Niño pipe” in this paper, has been revealed within the 10°S–10°N upper Pacific Ocean. 2) The pipe core extends downward from ~50 m at 130°E to ~250 m near the date line before tilting upward to the sea surface at about 275°E, coinciding nicely with the pathway of the Pacific equatorial undercurrent (EUC). 3) The double-peak zonal modality pattern of the Niño pipe in the upper Pacific is echoed in the subsurface Atlantic and Indian Oceans through Walker circulation, while its single-peak meridional modality pattern is mirrored in the subsurface North and South Pacific through Hadley circulation. 4) A coherent three-peak modal structure implies a strong coupling between sea level variability at the surface and sea temperature variability around the thermocline. Accumulating evidence suggests that Rossby/Kelvin wave dynamics in tandem with EUC-based thermocline dynamics are the main mechanisms of the three-mode Niño pipe in ENSO cycles.

scholarly journals Intraseasonal and Interannual Variability in North American Storm Tracks and Its Relationship to Equatorial Pacific Variability

2013 ◽  
Vol 141 (10) ◽  
pp. 3610-3625 ◽  
Author(s):  
Kevin M. Grise ◽  
Seok-Woo Son ◽  
John R. Gyakum
Keyword(s):  
North America ◽  
Interannual Variability ◽  
North American ◽  
Southern Oscillation ◽  
Extratropical Cyclones ◽  
The North ◽  
The Pacific ◽  
Cyclone Tracks ◽  
Lagrangian Tracking ◽  
The North Atlantic Oscillation

Abstract Extratropical cyclones play a principal role in wintertime precipitation and severe weather over North America. On average, the greatest number of cyclones track 1) from the lee of the Rocky Mountains eastward across the Great Lakes and 2) over the Gulf Stream along the eastern coastline of North America. However, the cyclone tracks are highly variable within individual winters and between winter seasons. In this study, the authors apply a Lagrangian tracking algorithm to examine variability in extratropical cyclone tracks over North America during winter. A series of methodological criteria is used to isolate cyclone development and decay regions and to account for the elevated topography over western North America. The results confirm the signatures of four climate phenomena in the intraseasonal and interannual variability in North American cyclone tracks: the North Atlantic Oscillation (NAO), the El Niño–Southern Oscillation (ENSO), the Pacific–North American pattern (PNA), and the Madden–Julian oscillation (MJO). Similar signatures are found using Eulerian bandpass-filtered eddy variances. Variability in the number of extratropical cyclones at most locations in North America is linked to fluctuations in Rossby wave trains extending from the central tropical Pacific Ocean. Only over the far northeastern United States and northeastern Canada is cyclone variability strongly linked to the NAO. The results suggest that Pacific sector variability (ENSO, PNA, and MJO) is a key contributor to intraseasonal and interannual variability in the frequency of extratropical cyclones at most locations across North America.

Taxonomic remarks on the alpheid shrimp genus Triacanthoneus Anker, 2010, with description of a second eastern Pacific species (Malacostraca: Decapoda)

Zootaxa ◽  
2020 ◽  
Vol 4772 (3) ◽  
pp. 450-468 ◽  
Author(s):  
ARTHUR ANKER
Keyword(s):  
Pacific Coast ◽  
Eastern Pacific ◽  
Single Specimen ◽  
Bocas Del Toro ◽  
The Pacific ◽  
Southern Gulf Of Mexico ◽  
New Material ◽  
First Time ◽  
Pacific Species ◽  
Alpheid Shrimp

The recently described alpheid genus Triacanthoneus Anker, 2010 is reassessed based on new material from the Pacific and Caribbean coasts of Panama, and the southern Gulf of Mexico. Salmoneus armatus Anker, 2010 is tentatively transferred to Triacanthoneus and the latter genus is redefined. A new eastern Pacific species of Triacanthoneus is described based on a single specimen collected by scuba diving off Coiba Island on the Pacific coast of Panama. Triacanthoneus blanca sp. nov. is closely related to its only eastern Pacific congener, T. pacificus Anker, 2010, which is reported for the first time from the Las Perlas Islands in the Gulf of Panama. Morphological variation in T. toro Anker, 2010 is discussed on the basis of new topotypical material from Bocas del Toro, Panama, and a single specimen tentatively reported as T. cf. toro from Sisal, Mexico. An identification key to the seven currently known species of Triacanthoneus, with updated distributional and ecological information, as well as high-resolution colour photographs of four species are also provided. 

Records of mud shrimps (Crustacea: Decapoda: Axiidea and Gebiidae) from Pacific Mexico

2013 ◽  
Vol 94 (2) ◽  
pp. 369-388 ◽  
Author(s):  
Manuel Ayón-Parente ◽  
Michel E. Hendrickx ◽  
Eduardo Ríos-Jara ◽  
José Salgado-Barragán
Keyword(s):  
Pacific Coast ◽  
Eastern Pacific ◽  
Western Atlantic ◽  
Mexican Pacific ◽  
The Pacific ◽  
First Time

A total of 75 specimens belonging to four species of thalassinoids were collected in the intertidal and estuarine zones of two localities along the Pacific coast of Mexico.Callianassa tabogensisis recorded for the first time in Mexico, and is transferred to the genusNeotrypaea. Material ofCallichirusis assigned toCallichirus seilacheriwith some doubts due to taxonomic problems related to this genus in the eastern Pacific.Neocallichiruscf.grandimana, an amphi-American species described for the western Atlantic and previously reported in Ecuador and along the Pacific coast of Panama and Colombia, is reported for the first time in Mexico.Upogebia dawsoniis recorded for the second time from the coast of Jalisco. An updated list of Axiidea and Gebiidea known from the Mexican Pacific is provided, including 35 species.

scholarly journals Decadal sea-level variability in the Australasian Mediterranean Sea

Ocean Science ◽  
2021 ◽  
Vol 17 (5) ◽  
pp. 1473-1487
Author(s):  
Patrick Wagner ◽  
Claus W. Böning
Keyword(s):  
Mediterranean Sea ◽  
Interannual Variability ◽  
Sea Level ◽  
Wind Stress ◽  
Southern Oscillation ◽  
Horizontal Resolution ◽  
Intrinsic Variability ◽  
Sea Level Variability ◽  
The Pacific ◽  
Regional Sea Level

Abstract. Strong regional sea-level trends, mainly related to basin-wide wind stress anomalies, have been observed in the western tropical Pacific over the last 3 decades. Analyses of regional sea level in the densely populated regions of the neighbouring Australasian Mediterranean Sea (AMS; also called tropical Asian seas) are hindered by its complex topography and respective studies are sparse. We used a series of global eddy-permitting ocean models, including a high-resolution configuration that resolves the AMS with 120∘ horizontal resolution, forced by a comprehensive atmospheric forcing product over 1958–2016 to characterize the patterns and magnitude of decadal sea-level variability in the AMS. The nature of this variability is elucidated further by sensitivity experiments with interannual variability restricted to either the momentum or buoyancy fluxes, building on an experiment employing a repeated-year forcing without interannual variability in all forcing components. Our results suggest that decadal fluctuations of the El Niño–Southern Oscillation (ENSO) account for over 80 % of the variability in all deep basins of the region, except for the central South China Sea (SCS). Changes related to the Pacific Decadal Oscillation (PDO) are most pronounced in the shallow Arafura and Timor seas and in the central SCS. On average, buoyancy fluxes account for less than 10 % of decadal SSH variability, but this ratio is highly variable over time and can reach values of up to 50 %. In particular, our results suggest that buoyancy flux forcing amplifies the dominant wind-stress-driven anomalies related to ENSO cycles. Intrinsic variability is mostly negligible except in the SCS, where it accounts for 25 % of the total decadal SSH variability.

scholarly journals Interannual Hydroclimatic Variability of the Lake Mweru Basin, Zambia

Water ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 1801 ◽  
Author(s):  
Peter Waylen ◽  
Christopher Annear ◽  
Erin Bunting
Keyword(s):  
Interannual Variability ◽  
Lake Level ◽  
Southern Oscillation ◽  
Breeding Habitat ◽  
Fish Populations ◽  
Annual Precipitation ◽  
Data Sets ◽  
Lake Levels ◽  
Wetland Complex ◽  
Hydroclimatic Variability

Annual precipitation inputs to the Lake Mweru basin, Zambia, were computed from historic data and recent gridded data sets to determine historic (1925–2013) changes in lake level and their potential impacts on the important fisheries of the lake. The results highlight a period from the early 1940s to the mid-1960s when interannual variability of inputs doubled. Existing lake level data did not capture this period but they did indicate that levels were positively correlated with precipitation one to three years previously, reflecting the hydrologic storage of the lake, the inflowing Luapula River and the upstream Bangweulu wetland complex. Lag cross-correlations of rainfall to El Niño-Southern Oscillation (ENSO) and the Indian Ocean Dipole were weak and spatially and temporally discontinuous. The two drivers were generally positively correlated and induced opposing effects upon annual precipitation and lagged lake levels. This correlation became non-significant during the time of high observed interannual variability and basin inputs were prone to the vagaries of either driver independently or reinforcing drought/excess conditions. During times of high flows and persistent elevated lake levels, breeding habitat for fish increased markedly, as did nutrition supplied from the upstream wetlands. High hydrologic storage ensures that lake levels change slowly, despite contemporary precipitation totals. Therefore, good conditions for the growth of fish populations persisted for several years and populations boomed. Statistical models of biological populations indicated that such temporally autocorrelated conditions, combined with abundant habitat and nutrition can lead the “boom and bust” of fish populations witnessed historically in Lake Mweru.

Parasitic Copepods of Sebastodes alutus Including Chondracanthus triventricosus sp.nov. and Colobomatus kyphosus sp.nov.

1970 ◽  
Vol 27 (11) ◽  
pp. 1943-1960 ◽  
Author(s):  
A. D. Sekerak
Keyword(s):  
British Columbia ◽  
New Species ◽  
Pacific Ocean ◽  
Eastern Pacific ◽  
Parasitic Copepods ◽  
Nasal Cavities ◽  
The Pacific ◽  
The Pacific Ocean ◽  
First Time

Sixty-six specimens of Sebastodes alutus, the Pacific ocean perch, collected from the coast of Oregon and British Columbia were examined for parasitic copepods. The six species identified are Chondracanthus pinguis Wilson, 1912, Chondracanthus triventricosus sp.nov., Clavella parva Wilson, 1912, Brachiella robusta (Wilson 1912) Kabata, 1970, Colobomatus kyphosus sp.nov., and Sarcotaces arcticus Collett 1874. Colobomatus kyphosus is the second species of the genus to be described from the eastern Pacific and Ch. triventricosus is the second chondracanthid to be found in nasal cavities. Sarcotaces arcticus is reported as a parasite of S. alutus for the first time. Details of the appendages of each new species are described and illustrated.

scholarly journals Interannual Variability of the Global Meridional Overturning Circulation Dominated by Pacific Variability

2020 ◽  
Vol 50 (3) ◽  
pp. 559-574
Author(s):  
Neil F. Tandon ◽  
Oleg A. Saenko ◽  
Mark A. Cane ◽  
Paul J. Kushner
Keyword(s):  
Interannual Variability ◽  
Large Scale ◽  
Southern Oscillation ◽  
Meridional Overturning Circulation ◽  
Ekman Transport ◽  
Prominent Feature ◽  
Overturning Circulation ◽  
Near Surface ◽  
The Pacific ◽  
Meridional Overturning

AbstractThe most prominent feature of the time-mean global meridional overturning circulation (MOC) is the Atlantic MOC (AMOC). However, interannual variability of the global MOC is shown here to be dominated by Pacific MOC (PMOC) variability over the full depth of the ocean at most latitudes. This dominance of interannual PMOC variability is robust across modern climate models and an observational state estimate. PMOC interannual variability has large-scale organization, its most prominent feature being a cross-equatorial cell spanning the tropics. Idealized experiments show that this variability is almost entirely wind driven. Interannual anomalies of zonal mean zonal wind stress produce zonally integrated Ekman transport anomalies that are larger in the Pacific Ocean than in the Atlantic Ocean, simply because the Pacific is wider than the Atlantic at most latitudes. This contrast in Ekman transport variability implies greater variability in the near-surface branch of the PMOC when compared with the near-surface branch of the AMOC. These near-surface variations in turn drive compensating flow anomalies below the Ekman layer. Because the baroclinic adjustment time is longer than a year at most latitudes, these compensating flow anomalies have baroclinic structure spanning the full depth of the ocean. Additional analysis reveals that interannual PMOC variations are the dominant contribution to interannual variations of the global meridional heat transport. There is also evidence of interaction between interannual PMOC variability and El Niño–Southern Oscillation.

scholarly journals Interannual variability of the frequency of MJO phases and its association with two types of ENSO

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Panini Dasgupta ◽  
M. K. Roxy ◽  
Rajib Chattopadhyay ◽  
C. V. Naidu ◽  
Abirlal Metya
Keyword(s):  
Indian Ocean ◽  
Interannual Variability ◽  
Southern Oscillation ◽  
Regional Scale ◽  
Moisture Distribution ◽  
Eastern Pacific ◽  
Central Pacific ◽  
Frequency Pattern ◽  
Enso Events ◽  
Enso Phases

AbstractIn this study, we reexamine the effect of two types of El Niño Southern Oscillation (ENSO) modes on Madden Julian Oscillation (MJO) activity in terms of the frequency of MJO phases. Evaluating all-season data, we identify two dominant zonal patterns of MJO frequency exhibiting prominent interannual variability. These patterns are structurally similar to the Wheeler and Hendon (Mon. Weather Rev. 132:1917–1932, 2004) RMM1 and RMM2 spatial patterns. The first pattern explains a higher frequency of MJO activity over the Maritime Continent and a lower frequency over the central Pacific Ocean and the western Indian Ocean, or vice versa. The second pattern is associated with a higher frequency of MJO active days over the eastern Indian Ocean and a lower frequency over the western Pacific, or vice versa. We find that these two types of MJO frequency patterns are related to the central Pacific and eastern Pacific ENSO modes. From the positive to the negative ENSO (central Pacific or eastern Pacific) phases, the respective MJO frequency patterns change their sign. The MJO frequency patterns are the lag response of the underlying ocean state. The coupling between ocean and atmosphere is exceedingly complex. The first MJO frequency pattern is most prominent during the negative central-Pacific (CP-type) ENSO phases (specifically during September–November and December-February seasons). The second MJO frequency pattern is most evident during the positive eastern-Pacific (EP-type) ENSO phases (specifically during March–May, June–August and September–November). Different zonal circulation patterns during CP-type and EP-type ENSO phases alter the mean moisture distribution throughout the tropics. The horizontal convergence of mean background moisture through intraseasonal winds are responsible for the MJO frequency anomalies during the two types of ENSO phases. The results here show how the MJO activity gets modulated on a regional scale in the presence of two types of ENSO events and can be useful in anticipating the seasonal MJO conditions from a predicted ENSO state.

Sign in / Sign up

Export Citation Format

Share Document