Nina Southern Oscillation Research Articles

Statistical analysis of the relationship between climate-induced maize yield and rainy-season precipitation across Inner Mongolia, North China

Exploring possible relationships between climate-induced maize yield and rainy-season precipitation under climate change is fundamental to science-based decision for food security in Inner Mongolia Autonomous Region (IMAR). To determine the relationship of maize yield with precipitation variables across IMAR during 1960–2012, we selected 11 precipitation indices of rainy season and divided IMAR into four sub-regions—west, middle, east, and northeast using principal component analysis and K-means clustering methods. Results show that climate-induced maize yield is more sensitive to precipitation variability in the west and middle IMAR. The most important precipitation factor that limits maize yield is moderate precipitation days in these two sub-regions. Moreover, west and middle Inner Mongolia was dominated by decreasing precipitation during the rainy season. Furthermore, the El Nino/La Nina-Southern Oscillation cycle has the significant influence on the rainy-season precipitation in the west and middle IMAR.

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

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.

Water discharge variability of Changjiang (Yangtze) and Huanghe (Yellow) Rivers and its response to climatic changes

Infl uences of large-scale climatic phenomena, such as the El Nino/La Nina-Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO), on the temporal variations of the annual water discharge at the Lijin station in the Huanghe (Yellow) River and at the Datong station in the Changjiang (Yangtze) River were examined. Using the empirical mode decomposition-maximum entropy spectral analysis (EMDMESA) method, the 2- to 3-year, 8- to 14-year, and 23-year cyclical variations of the annual water discharge at the two stations were discovered. Based on the analysis results, the hydrological time series on the interannual to interdecadal scales were constructed. The results indicate that from 1950 to 2011, a significant downward trend occurred in the natural annual water discharge in Huanghe River. However, the changes in water discharge in Changjiang River basin exhibited a slightly upward trend. It indicated that the changes in the river discharge in the Huanghe basin were driven primarily by precipitation. Other factors, such as the precipitation over the Changjiang River tributaries, ice melt and evaporation contributed much more to the increase in the Changjiang River basin. Especially, the impacts of the inter-annual and inter-decadal climate oscillations such as ENSO and PDO could change the long-term patterns of precipitation over the basins of the two major rivers. Generally, low amounts of basin-wide precipitation on interannual to interdecadal scales over the two rivers corresponded to most of the warm ENSO events and the warm phases of the PDO, and vice versa. The positive phases of the PDO and ENSO could lead to reduced precipitation and consequently affect the long-term scale water discharges at the two rivers.

Spatiotemporal variations in suitable areas for Japanese scallop aquaculture in the Dalian coastal area from 2003 to 2012

Abstract The Japanese scallop ( Mizuhopecten yessoensis ) is an important commercial species in the Dalian coastal area. The present study employed a suitable aquaculture site-selection model (SASSM) and used satellite remote-sensing data to analyze the spatiotemporal distribution of suitable areas for Japanese scallop aquaculture in the Dalian coastal area from 2003 to 2012. The study area was divided into four marine zones. The results demonstrated that the suitability scores of scallop aquaculture areas were high in May and low in February. The Changhai County (Zone II) and Lushunkou areas (Zone III) exhibited high potential for Japanese scallop aquaculture development. The results of the suitability models were consistent with the existing scallop aquaculture in the study area. These zones, combined with climatic events [the winter East Asian Monsoon (EAM) and El Nino/La Nina–Southern Oscillation (ENSO) events], were used to examine the impact of climate variability on scallop aquaculture. Results suggest that the suitability scores in Zone III were more sensitive to changes in environmental factors ( e.g. , sea surface temperature, chlorophyll-a, and suspended sediment) and climate changes, whereas the correlations among these factors were not significant in Zone II. Adaptation to these changes should be considered when developing plans and management strategies for scallop aquaculture.

Evidence of El Niño/La Niña–Southern Oscillation Variability in the Neogene-Pleistocene of Panama Revealed by a New Bryozoan Assemblage-Based Proxy

Here we explore how fossil cheilostome bryozoans can demonstrate El Nino/La Nina-Southern Oscillation (ENSO) variability in ancient tropical environments of the tropical eastern Pacific and southwestern caribbean when used collectively to produce frequency distributions of estimates of mean annual ranges in temperature (MARTs) via zooid-size MART analysis (zs-MART). The approach is based on linking variation in the sizes of constituent zooids in bryozoan colonies with the temperature regimes in which the zooids developed. The shapes of frequency distributions of zs-MART estimates from modern environments are consistent with known upwelling and non-upwelling environments and ENSO variability. Data from fossil colonies provide evidence that ENSO variability characterized caribbean environments in what is now present-day Panama during the miocene and Pliocene (thus supporting neither a permanent El nino nor a permanent la nina in the Pliocene), but not the Pleistocene after the isthmus of Panama closed. Western atlantic data provide further evidence for ENSO variability in the Pliocene of florida but not virginia. Our study shows the potential of bryozoan assemblages to infer variation in seasonal regimes thus encouraging the further development of this proxy for inferring ENSO variability.

Connections of ENSO/IOD and aerosols with Thai rainfall anomalies and associated implications for local rainfall forecasts

El Nino/La Nina Southern Oscillation (ENSO), Indian Ocean Dipole (IOD) and aerosols have important roles to play in relation to Southeast Asian rainfall anomalies. This study investigates connections between these factors and local seasonal rainfall anomalies at 17 locations throughout Thailand using ground measurements and satellite observations available from 1980 to October 2011. This research investigates further the usefulness of incorporating these factors into rainfall forecasts. Results from canonical correlation analysis indicate that strong ENSO signals from October to March may affect rainfall anomalies in the nonsummer monsoon months, whereas IOD signals in the previous summer monsoon months were deemed to be of greater responsibility for current summer monsoon rainfall. Comparison of rainfall levels with different aerosol loadings suggests rainfall-decreasing aerosol from December to February for the South East Coast and in pre-summer monsoon months for deeper inland areas having less coastal influences. Rainfall-increasing aerosol was observed in post-summer monsoon months at the inland stations. The use of ENSO/IOD signals as predictors yielded better rainfall forecast model performance than that of the aerosol loading. However, model performance significantly improved when both ENSO/IOD signals and seasonal aerosol loadings were introduced.

How well do the GCMs/RCMs capture the multi-scale temporal variability of precipitation in the Southwestern United States?

Summary Multi-scale temporal variability of precipitation has an established relationship with floods and droughts. In this paper, we present the diagnostics on the ability of 16 General Circulation Models (GCMs) from Bias Corrected and Downscaled (BCSD) World Climate Research Program’s (WCRP’s) Coupled Model Inter-comparison Project Phase 3 (CMIP3) projections and 10 Regional Climate Models (RCMs) that participated in the North American Regional Climate Change Assessment Program (NARCCAP) to represent multi-scale temporal variability determined from the observed station data. Four regions (Los Angeles, Las Vegas, Tucson, and Cimarron) in the Southwest United States are selected as they represent four different precipitation regions classified by clustering method. We investigate how storm properties and seasonal, inter-annual, and decadal precipitation variabilities differed between GCMs/RCMs and observed records in these regions. We find that current GCMs/RCMs tend to simulate longer storm duration and lower storm intensity compared to those from observed records. Most GCMs/RCMs fail to produce the high-intensity summer storms caused by local convective heat transport associated with the summer monsoon. Both inter-annual and decadal bands are present in the GCM/RCM-simulated precipitation time series; however, these do not line up to the patterns of large-scale ocean oscillations such as El Nino/La Nina Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO). Our results show that the studied GCMs/RCMs can capture long-term monthly mean as the examined data is bias-corrected and downscaled, but fail to simulate the multi-scale precipitation variability including flood generating extreme events, which suggests their inadequacy for studies on floods and droughts that are strongly associated with multi-scale temporal precipitation variability.

Large-scale spheroidal redoximorphic features around plinthite nuclei in Orinoco River sediments reflect mean seasonal fluctuation in river stage and ENSO-related anomalies

In sediments emerging on the scarp of Lower Orinoco River, Venezuela, we have discovered and studied large (0.5 m) features formed by a plinthite nucleus surrounded by evenly spaced concentric spheroidal structures of iron oxides separated by depletion zones. These features are located in sediments subjected to the mean annual river fluctuation (approx. 14 m) and hence are submerged for several months each year. To the best of our knowledge, structures like these have never been reported or studied. The nuclei and concentric ring formations found in the Orinoco sediments represent an extreme case of regular currently alternating redox conditions. Here we show that the concentric ferric rings surrounding the nuclei could be the result of repeated cycles of diffusion of ferrous ions during flood and subsequent precipitation as ferric oxide during the dry period, thus reflecting the seasonal fluctuation in river level. Our results are consistent with a simple proposed model of ferrous iron diffusion/oxidation according to the flood/dry intervals imposed by river dynamics. This paper is a contribution toward understanding these redoximorphic features (RFs) by: (1) describing their composition and mineralogy; (2) suggesting a possible mode of their formation using the switch to reducing conditions and diffusion of soluble Fe during flood, and its subsequent oxidation and hence immobilization and partial crystallization once exposed to the air; (3) by confirming how this theoretical approach fits the actual pattern of river hydrology in Orinoco, both under average conditions, and as modified by climatic extreme conditions influenced by the El Nino/La Nina Southern Oscillation (ENSO) affecting the ratio of flood/emergence.

Uncertainty estimation of the global temperature trends for multiple radiosondes, reanalyses, and CMIP3/IPCC climate model simulations

Based on three groups of datasets that include radiosondes, reanalyses, and climate model simulations (e.g., Coupled Model Intercomparison Project, CMIP3) from 1979 to 2008, the interannual variability, global temperature trends, and their uncertainty using ensemble spread among intra-group and inter-group datasets have been discussed. The results show that the interannual temperature variability increased from the troposphere to stratosphere, and the maximum occurs around 50 hPa. The CMIP3 climate models have the largest discrepancy in the stratosphere. The intra-group correlations at 500 hPa generally show high similarity within each data group while the inter-group correlations between reanalyses and the CMIP3 climate model simulations indicate lesser similarity. In contrast, the inter-group correlation at 50 hPa is improved except with the Japanese 25-year Reanalysis Project (JRA-25) dataset, and the Twentieth Century Reanalysis (20CR) reanalysis shows a weak cross correlation. The global temperature trends are highly dependent on the individual data sources. Compared to the radiosondes, the reanalyses show a large ensemble spread of trends in the stratosphere, and the CMIP3 climate model simulations have a large ensemble spread in the height of the crossover point where tropospheric warming changes into stratospheric cooling. The largest ensemble spread among the reanalyses in the stratosphere is mainly from the large discrepancy in the JRA-25 reanalysis after 1998 and a relatively weak anomaly in the 20CR before 1986. The largest ensemble spread among the CMIP3 climate models in the troposphere is related to the influence of both volcanic eruptions and El Nino/La Nina–Southern Oscillation events. The strong anomalies corresponding to the volcanic eruptions of El Chichon in 1982 and Mt Pinatubo in 1991 are clearly identified in the stratosphere. These volcanic eruptions reduced the warming in the troposphere and strengthened the cooling in the stratosphere during the most recent 30 years.

Western Indian Ocean SST signal and anomalous Antarctic sea-ice concentration variation

Teleconnection between El Nino/La Nina-Southern Oscillation (ENSO) phenomenon and anomalous Antarctic sea-ice variation has been studied extensively. In this study, impacts of sea surface temperature in the Indian Ocean on Antarctic sea-ice change were investigated during Janaury 1979 and October 2009. Based on previous research results, sea areas in the western Indian Ocean (WIO; 50°-70°E, 10°-20°S) are selected for the resreach. All variables showed 1–10 year interannual timescales by Fast Founer Tranaform (FFT) transformation. Results show that i) strong WIO signals emerged in the anomalous changes of Antarctic sea-ice concentration; ii) significant positive correlations occurred around the Antarctic Peninsula, Ross Sea and its northwest peripheral sea region iii) negative correlation occurred in the Indian Ocean section of the Southern Ocean, Amundsen Seas, and the sea area over northern Ross Sea; and iv) the atmospheric anomalies associated with the WIO including wind, meridional heat flux, and surface air temperature over southern high latitudes were the possible factors for the teleconnection.

A seasonal scale analysis correlating total cloud amount anomalies with ENSO over the tropical Pacific

The seasonal patterns of total cloud amount (TCA) responsible for El Nino/La Nina-Southern Oscillation (ENSO) Sea Surface Temperature (SST) anomalies were investigated using the ISCCP-D2 cloud and NOAA OI.v2 SST datasets for the period of July 1983 to June 2008. The results show three main ENSO-sensitive regions obtained by spatial overlapping of seasonal correlations, two in the western tropical Pacific and one in the central tropical Pacific. These regions were named WTP1, WTP2, and CTP. In all three regions, except the JJA (June–August) WTP2, the TCA changes were significantly correlated with the Nino 3.4 anomalies during the four seasons (December–January–February (DJF), March–April–May, JJA, and September–October–November (SON)). Remarkable differences in the seasonal variability of TCA were observed in these regions. In the WTP1, the DJF TCA always remained the highest value among the four seasons in all years. In the WTP2, the maximum TCA occurred during JJA in most years. In the CTP, the extreme value of TCA was mainly observed in DJF or SON near the peak time of ENSO. Seasonal cross-correlation analyses also showed significant relations between TCA and Nino 3.4 SST in these regions, which may be helpful for forecasting the evolution of ENSO.

The tropical circulation in the Australian and Asian region - May to October 2008

A summary of the broadscale tropical circulation from 70o E to 180o, for the six months May to October 2010, is presented. During this period the El Nino/La Nina-Southern Oscillation (ENSO) state shifted gradually from neutral conditions to La Nina conditions by July 2010. The Southern Oscillation Index (SOI) remained mostly above +10 during the season and reached a peak value of +25 in September. The mean SOI for the season was +15.8. Above average convection persisted throughout the season south of the equator between 90°E and 140°E and the South Pacific Convergence Zone (SPCZ). Mostly weak mean sealevel pressure (MSLP) anomalies persisted in the Darwin Regional Specialised Meteorological Centre (RSMC) analysis area except over parts of Australia, where it remained higher than normal. Easterlies in the tropical western Pacific remained stronger than normal. Sea Surface Temperatures in the tropical western Pacific gradually shifted from a warm to cooler pattern during the season and in the tropical Indian Ocean were warmer than their long-term mean. Weak active convective phases of the Madden-Julian Oscillation (MJO) were observed in the the beginning of each month during the season with a periodicity of 30 to 35 days. However, it was difficult to analyse the eastward propagation of the MJO signal mainly due to the developing La Nina conditions. A total of sixteen tropical cyclones (including eight typhoons/severe cyclones) were analysed during the period, less than the mean of 30 for the Darwin RSMC analysis area.

Asymptotic solution of a sea–air oscillator for ENSO mechanism

The EI Nino/La Nina–Southern Oscillation (ENSO) is an interannual phenomenon involved in the tropical Pacific ocean–atmosphere interactions. In this paper, a class of coupled system of the ENSO mechanism is considered. Based on a class of oscillator of ENSO model, the asymptotic solution of a corresponding problem is studied by employing the approximate method. It is proved from the results that the perturbation method can be used for analysing the sea surface temperature anomaly in the equatorial eastern Pacific and the thermocline depth anomaly of the atmosphere–ocean oscillation for the ENSO model.

Homotopic method of solving a class of EI Niño/La Niña-Southern Oscillation sea–air oscillator

The EI Nino/La Nina-Southern Oscillation (ENSO) is an interannual phenomenon involved in the tropical Pacific Ocean–atmosphere interactions. In this paper, an asymptotic method of solving the nonlinear equation for the ENSO model is created. And based on a class of oscillator of the ENSO model, the approximate solution of a corresponding problem is studied by employing the method of homotopic mapping. It is proved from the results that the homotopic method can be used for analysing the sea surface temperature anomaly in the equatorial eastern Pacific and the thermocline depth anomaly of the atmosphere–ocean oscillation for the ENSO model.

The homotopic mapping method for sea–air oscillator model of interdecadal climate fluctuations

The El Nino/La Nina Southern Oscillation (ENSO) is an interannual phenomenon involved in the tropical Pacific ocean–atmosphere interactions. In this paper, a coupled system of sea–air oscillator model is studied. The aim is to create an asymptotic solving method of nonlinear equation for the ENSO model. And based on a class of oscillators of ENSO model, employing the method of homotopic mapping, the approximate solution of corresponding problem is studied. It is proven from the results that the homotopic method can be used for analysing the sea surface temperature anomaly in the equatorial eastern Pacific and the thermocline depth anomaly of the atmosphere–ocean oscillation for ENSO model.