scholarly journals Assessing the distribution and variation characteristics of marine primary productivity in the coastal marine area of Vietnam South Centre

2022 ◽  
Vol 964 (1) ◽  
pp. 012011
Author(s):  
Nguyen Trinh Duc Hieu ◽  
Nguyen Huu Huan ◽  
Tran Thi Van ◽  
Nguyen Phuong Lien
Keyword(s):  
Primary Productivity ◽  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Monsoon Season ◽  
Marine Ecosystem ◽  
Correlation Coefficients ◽  
Northeast Monsoon ◽  
Marine Area ◽  
Coastal Marine

Abstract Primary production (PP) of phytoplankton plays an essential role in food web dynamics, biogeochemical cycles and marine fisheries. It is used as one of the basic information for evaluating marine ecosystems. In this paper, monthly composite PP data on a 4 km x 4 km grid for the period 2003-2020 was used to evaluate the distributional characteristics of PP in the coastal marine area of Vietnam South Centre. The statistical results show that the climatological average of PP in 18 years reached 449.2 mgC/m2/day, ranged from 272.1 to 14,205.4 mgC/m2/day. The PP has seasonal and spatial variations. In time, the lowest value of PP was in spring, and the highest was in winter; in space, PP tended to decrease from shore to offshore, PP was higher in coastal areas than in the open sea areas. During the northeast monsoon season, PP increased by more than 1000 mgC/m2/day in the coastal area. Meanwhile, in the southwest monsoon season, due to the ecological influence of the upwelling phenomenon, PP increased with a value greater than 1500 mgC/m2/day, distributed along the coastline of Ninh Thuan - Binh Thuan. Primary productivity positively correlated with chlorophyll content but negatively correlated with sea surface temperature with correlation coefficients of 0.9 and -0.6, respectively. There was a weak correlation between PP and ONI with correlation coefficients of -0.23. The temporal-spatial variation of PP was affected by the ENSO (El Niño-Southern Oscillation) phenomenon, the positive phase of ENSO (El Niño conditions) corresponded to lower PP, and the negative phase of ENSO (La Niña conditions) corresponded to higher PP. The research results from this paper can be used as a reference in marine ecosystem management.

The role of El Niño Southern Oscillation on the patterns of cycling rates observed over India during the monsoon season

2014 ◽  
Vol 5 (4) ◽  
pp. 696-706 ◽  
Author(s):  
T. V. Lakshmi Kumar ◽  
K. Koteswara Rao ◽  
R. Uma ◽  
K. Aruna
Keyword(s):  
Water Vapor ◽  
El Niño ◽  
Hydrological Cycle ◽  
El Nino ◽  
Southern Oscillation ◽  
Monsoon Season ◽  
Precipitable Water ◽  
Spatiotemporal Variability ◽  
Monsoon Period ◽  
Sw Monsoon

Trend and interannual variability of total integrated precipitable water vapor (PWV) has been studied over India for the period 1979–2004 using NCEP/National Centre for Atmospheric Research reanalysis data with 2.5° × 2.5° resolution. The spatiotemporal variability of cycling rates (CR; units: per day), obtained from the ratio of rainfall to the PWV were presented not only for the long term (1979–2004) but also during El Niño (EN) and La Niña (LN) years of the study period to understand the intensity of hydrological cycle. The paper then dwells on obtaining the monthly atmospheric residences times over India to infer the stay of water vapor before it precipitates. The results of the present study are: all India PWV shows decreasing trend in association with the increasing/decreasing trends of Niño 3 SST/Southern Oscillation Index (SOI) for the southwest (SW) monsoon period of 1979–2004; the spatial pattern of temporal correlations of CR with SOI and Niño 3 SST displayed the significant positive and negative values in peninsular and central Indian portions of India respectively; all India atmospheric residence times varied from 9 to 2 days from premonsoon/post monsoon to SW monsoon over India.

scholarly journals Evolutions of sea level high and warm pool in the southeastern Arabian Sea and their association with Asian monsoons : A study on cause-and-effect relationships

MAUSAM ◽  
2021 ◽  
Vol 59 (1) ◽  
pp. 87-94
Author(s):  
O. P. SINGH
Keyword(s):  
Sea Level ◽  
Summer Monsoon ◽  
El Niño ◽  
Arabian Sea ◽  
El Nino ◽  
Southern Oscillation ◽  
Monsoon Season ◽  
Warm Pool ◽  
Sea Surface ◽  
Southeastern Arabian Sea

The present study aims at gaining more insight into the evolution of warm pool and associated sea level dome in the southeastern Arabian Sea before the summer monsoon onset.  The results show that the Sea Surface Temperature (SST) maximum in the warm pool region is found during April close to the southwest coast of India.  The Sea Surface Height (SSH) maximum over the same region is observed during December. The collapse of sea level dome begins well in advance during the pre-monsoon whereas the warm pool collapses after the onset of summer monsoon during June.  Therefore, there is a lag of about three to four months between the collapses of the sea level high and the warm pool.  Most interesting aspect is the dramatic increase of SST from September and SSH from October which is continued throughout the post monsoon season (October - December). Therefore, both the collapse and evolution of warm pool are dramatic events before and after the summer monsoon.                    There are considerable variations in the intensity of warm pool and the height of sea level dome on interannual scale.  The variation during El-Nino Southern Oscillation (ENSO) epoch of 1987-88 has revealed many interesting features.  During El-Nino year 1987 the warm pool intensity reached its peak in June whereas during La Nina year 1988 the warm pool attained its maximum intensity much earlier, i.e., in April. 

scholarly journals Study of rainfall departure over catchments of Bihar plains

MAUSAM ◽  
2021 ◽  
Vol 61 (2) ◽  
pp. 187-196
Author(s):  
T. N. JHA ◽  
R. D. RAM
Keyword(s):  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Monsoon Season ◽  
Daily Rainfall ◽  
La Niña ◽  
Rainfall Time Series ◽  
La Nina ◽  
Multivariate Enso Index ◽  
Rainfall Departure

Station wise daily rainfall data of sixty years is used to study rainfall departure and variability  in  Kosi, Kamala/Bagmati/Adhwara and  Gandak/Burhi Gandak catchments during  monsoon  season. Station and catchment wise rainfall time series have been made to compute rainfall departure and Coefficient of Variation (CV). Southern Oscillation Index (SOI), Multivariate ENSO Index (MEI) and ENSO strength based on percentile analysis are used to ascertain their impact on rainfall distribution in the category as excess, normal, deficient and scanty. Results indicate that the variability is greater over Kosi as compared to the other catchments. Probability of normal rainfall is found 0.75 and there is no possibility of scanty rain over the catchments during El Nino and La Nina year. Similarly probabilities of normal, deficient, excess rainfall are found as 0.67, 0.18 and 0.15 respectively during mixed year. SOI has emerged as principal parameter which modifies the departure during El Nino and La Nina year. MEI along with ENSO strength  are more prominent  during  mixed year  particularly to ascertain deficient and excess rain in weak and strong- moderate La Nina  respectively .   

scholarly journals Reconstructing past variations in environmental conditions and paleoproductivity over the last ~ 8000 years off Central Chile (30° S)

2018 ◽  
Author(s):  
Práxedes Muñoz ◽  
Lorena Rebolledo ◽  
Laurent Dezileau ◽  
Antonio Maldonado ◽  
Christoph Mayr ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Primary Productivity ◽  
El Niño ◽  
Arid Zone ◽  
El Nino ◽  
Southern Oscillation ◽  
Coastal Zones ◽  
Winter Climate ◽  
Continuous Increase ◽  
Semi Arid

Abstract. This study aims at establishing past variations of the main oceanographic and climatic features in the Central Chilean coast, using recent sedimentary records of a transitional semi-arid ecosystem susceptible to environmental forcing conditions. Coquimbo (30° S) region is characterized by dry summers and short rainfall periods during winter. The relatively wet-winter climate results from the interactions between the southern westerly winds and the South Pacific Anticyclone (SPA); in summer, the SPA moves southwards while in winter it returns to the north, allowing the passage of storm fronts. This semi-arid zone is strongly affected by variations associated with El Niño-Southern Oscillation (ENSO), caused by seasonal latitudinal changes in the SPA that produce high variability and precipitation in Chilean mid-latitudes. Sediment cores were retrieved in two bays, Guanaqueros and Tongoy, for geochemical analyses including: sensitive redox trace elements, biogenic opal, total organic carbon (TOC), diatoms, stable isotopes of organic carbon and nitrogen. The results suggest a main dry phase of high primary productivity concomitant with high fluxes of organic compounds to the bottom and suboxic-anoxic conditions in the sediments. This period reached a maximum at cal BC ~ 4500, followed by a continuous increase in wet conditions, low primary productivity and a more oxygenated environment towards the present, being remarkably stronger in the last 2000 years. We suggest that this might be associated with greater El Niño frequencies or similar conditions that increase precipitation, concomitantly with the introduction of oxygenated waters to coastal zones by the propagation of equatorial origin waves.

scholarly journals Influence of Asian Summer Monsoon Anticyclone on the Trace gases and Aerosols over Indian region

2019 ◽  
Author(s):  
Ghouse Basha ◽  
M. Venkat Ratnam ◽  
Pangaluru Kishore ◽  
S. Ravindrababu ◽  
Isabella Velicogna
Keyword(s):  
Summer Monsoon ◽  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Asian Summer Monsoon ◽  
Monsoon Season ◽  
Trace Gases ◽  
La Niña ◽  
La Nina ◽  
Asian Summer

Abstract. The Asian Summer Monsoon Anticyclone (ASMA) persisting during monsoon season in the upper troposphere and lower stratosphere (UTLS) region play an important role in confining the trace gases and aerosols for a longer period thus affects regional and global climate. Our understanding on these trace gases and aerosols variability in the ASMA is limited. In this study, the effect of the ASMA on the trace gases (Water Vapour (WV), Ozone (O3), Carbon Monoxide (CO)) and aerosols (Attenuated Scattering Ratio (ASR)) obtained from long-term (2006–2016) satellite measurements is investigated. Since the ASMA is present in the UTLS region, its influence on the tropopause characteristics is also explored. Higher tropopause altitude, WV, CO and ASR confining to the ASMA region is observed, whereas tropopause temperatures and O3 are found low. There exists large inter-annual variation in the ASMA and hence its effect on these trace gases and aerosols are also seen clearly. A significant relationship is also observed between the phases of Quasi-Biannual Oscillation (QBO) and El Niño Southern Oscillation (ENSO) on the trace gases and ASR, including the tropopause when measurements in the ASMA region are subject to multivariate regression analysis. Further, the influence of the Indian summer monsoon (ISM) activity on the ASMA trace gases and aerosols is studied with respect to active and break spells of monsoon, strong and weak monsoon years, strong La Niña, El Niño years. Results show a significant increase in WV, CO and decrease in O3 during the active phase of the ISM, strong monsoon years and strong La Niña years in the ASMA. Enhancement in the ASR values during the strong monsoon years and strong La Niña years is observed. Thus, it is prudent to conclude that the dynamics of the ASMA play an important role in the confinement of several trace gases and aerosols and suggested to consider the activity of summer monsoon while dealing with them at sub-seasonal scales.

Variations of Sea Level and Tidal Behaviour during El Nino/La Nina: An Example of Malaysian Coastline

2015 ◽  
Vol 73 (5) ◽  
Author(s):  
Mohd Hilmi Abdullah ◽  
Mohd Razali Mahmud ◽  
Nor Ainah Amat
Keyword(s):  
Sea Level ◽  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Enso Event ◽  
La Niña ◽  
Observation Data ◽  
Northeast Monsoon ◽  
Tidal Variation ◽  
La Nina

The El Nino/La Nina Southern Oscillation (ENSO) phenomenon indirectly provides dramatic changes to tidal that can cause floods, drought and affect various marine activities. Tidal observation data plays important role in determining the characteristic or behaviour of tide along the coastal area especially during sudden climate change such as the phenomenon of El Nino/La Nina, the Northeast Monsoon, Northwest Monsoon and Tsunami. It is important to study the occurrence of the ENSO event and it characteristic so that it can be used for prediction and monitoring the land and water ecosystem. This research is to identify the variations of sea level and tidal behaviour in Malaysian coastline during El Nino/La Nina. The tidal observation data, meteorology data (temperature and mean sea level pressure), and Southern Oscillation Index (SOI) calculation are used to look on the changes of the tidal variation during the ENSO phenomenon. The results of this research will specially benefit in the determination of tidal level in Malaysia and to the professionals who have responsibilities in policy making, agriculture, environmental planning, economics and marine engineering.

scholarly journals A Verified Estimation of the El Niño Index Niño-3.4 since 1877

2009 ◽  
Vol 22 (14) ◽  
pp. 3979-3992 ◽  
Author(s):  
Lucia Bunge ◽  
Allan J. Clarke
Keyword(s):  
Time Series ◽  
Surface Temperature ◽  
Sea Surface Temperature ◽  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Correlation Coefficients ◽  
Sea Surface ◽  
Monthly Time Series ◽  
Sst Anomaly

Abstract Decadal and longer time-scale variabilities of the best known El Niño–Southern Oscillation (ENSO) indexes are poorly correlated before 1950, and so knowledge of interdecadal variability and trend in ENSO indexes is dubious, especially before 1950. To address this problem, the authors constructed and compared physically related monthly ENSO indexes. The base index was El Niño index Niño-3.4, the sea surface temperature (SST) anomaly averaged over the equatorial box bounded by 5°N, 5°S, 170°W, and 120°W; the authors also constructed indexes based on the nighttime marine air temperature over the Niño-3.4 region (NMAT3.4) and an equatorial Southern Oscillation index (ESOI). The Niño-3.4 index used the “uninterpolated” sea surface temperature data from the Second Hadley Centre Sea Surface Temperature dataset (HadSST2), a dataset with smaller uncertainty and better geographical coverage than others. In constructing the index, data at each point for a given month were weighted to take into account the typical considerable spatial variation of the SST anomaly over the Niño-3.4 box as well as the number of observations at that point for that month. Missing monthly data were interpolated and “noise” was reduced by using the result that Niño-3.4 has essentially the same calendar month amplitude structure every year. This 12-point calendar month structure from April to March was obtained by an EOF analysis over the last 58 yr and then was fitted to the entire monthly time series using a least squares approach. Equivalent procedures were followed for NMAT3.4 and ESOI. The new ESOI uses Darwin atmospheric pressure in the west and is based on theory that allows for variations of the atmospheric boundary layer depth across the Pacific. The new Niño-3.4 index was compared with NMAT3.4, the new ESOI, and with a record of δ18O from a coral at Palmyra, an atoll inside the region Niño-3.4 (Cobb et al.). Correlation coefficients between Niño-3.4 and the three monthly indexes mentioned above before 1950 are 0.84, 0.87, 0.73 and 0.93, 0.86, 0.73 for decadal time scales. These relatively high correlation coefficients between physically related but independent monthly time series suggest that this study has improved knowledge of low-frequency variability. All four indexes are consistent with a rise in Niño-3.4 SST and the weakening of the equatorial Pacific winds since about 1970.

scholarly journals ENSO effects on primary productivity in Southern Atacama desert

2006 ◽  
Vol 6 ◽  
pp. 273-277 ◽  
Author(s):  
F. A. Squeo ◽  
Y. Tracol ◽  
D. López ◽  
J. R. Gutiérrez ◽  
A. M. Cordova ◽  
...  
Keyword(s):  
Primary Productivity ◽  
El Niño ◽  
Net Primary Productivity ◽  
El Nino ◽  
Southern Oscillation ◽  
Atacama Desert ◽  
Limiting Factors ◽  
Landsat Images ◽  
Enso Events ◽  
Main Factor

Abstract. In the winter-rain southern Atacama Desert of the Coquimbo Region of Chile, El Niño - Southern Oscillation (ENSO) events modulate primary productivity. In this region, there are important changes in water availability between La Niña (dry) and El Niño (rainy) years. Using inter-annual comparisons of LANDSAT images from 30° to 31° S latitude, we observed changes in primary productivity between dry and rainy years at the regional level. There were also significant, negative correlations between productivity and elevation, with changes occurring first at low elevation during rainy years. The limiting factors to dryland vegetation primary productivity is different in regard to elevation. Rain during an El Niño year is the main factor that explains the increase in primary productivity at low elevation, while lower temperatures reduce and delay the net primary productivity at mid elevation.

scholarly journals Effects of ENSO on Temperature, Precipitation, and Potential Evapotranspiration of North India’s Monsoon: An Analysis of Trend and Entropy

Water ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 189 ◽  
Author(s):  
Kazi Ali Tamaddun ◽  
Ajay Kalra ◽  
Miguel Bernardez ◽  
Sajjad Ahmad
Keyword(s):  
El Niño ◽  
Potential Evapotranspiration ◽  
El Nino ◽  
Southern Oscillation ◽  
Statistical Tests ◽  
Monsoon Season ◽  
Climate Extremes ◽  
Precipitation Pattern ◽  
The North ◽  
And Shifts

The influence of El Niño Southern Oscillation (ENSO) on the north Indian temperature, precipitation, and potential evapotranspiration (PET) change patterns were evaluated during the monsoon season across the last century. Trends and shifts in 146 districts were assessed using nonparametric statistical tests. To quantify their temporal variation, the concept of apportionment entropy was applied to both the annual and seasonal scales. Results suggest that the El Niño years played a greater role in causing hydro-climatological changes compared to the La Niña or neutral years. El Niño was more influential in causing shifts compared to trends. For certain districts, a phase change in ENSO reversed the trend/shift direction. The century-wide analysis suggested that the vast majority of the districts experienced significant decreasing trends/shifts in temperature and PET. However, precipitation experienced both increasing and decreasing trends/shifts based on the location of the districts. Entropy results suggested a lower apportionment of precipitation compared to the other variables, indicating an intermittent deviation of precipitation pattern from the generic trend. The findings may help understand the effects of ENSO on the hydro-climatological variables during the monsoon season. Practitioners may find the results useful as monsoon is the most important season for India causing climate extremes.

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