scholarly journals Time Series Analysis of MODIS-Derived NDVI for the Hluhluwe-Imfolozi Park, South Africa: Impact of Recent Intense Drought

Climate ◽  
2018 ◽  
Vol 6 (4) ◽  
pp. 95 ◽  
Author(s):  
Nkanyiso Mbatha ◽  
Sifiso Xulu
Keyword(s):  
El Niño ◽  
Vegetation Index ◽  
El Nino ◽  
Southern Oscillation ◽  
Climatic Variability ◽  
Phase Relationship ◽  
Google Earth ◽  
Area Index ◽  
Mk Test ◽  
Significant Downward Trend

The variability of temperature and precipitation influenced by El Niño-Southern Oscillation (ENSO) is potentially one of key factors contributing to vegetation product in southern Africa. Thus, understanding large-scale ocean–atmospheric phenomena like the ENSO and Indian Ocean Dipole/Dipole Mode Index (DMI) is important. In this study, 16 years (2002–2017) of Moderate Resolution Imaging Spectroradiometer (MODIS) Terra/Aqua 16-day normalized difference vegetation index (NDVI), extracted and processed using JavaScript code editor in the Google Earth Engine (GEE) platform was used to analyze the vegetation response pattern of the oldest proclaimed nature reserve in Africa, the Hluhluwe-iMfolozi Park (HiP) to climatic variability. The MODIS enhanced vegetation index (EVI), burned area index (BAI), and normalized difference infrared index (NDII) were also analyzed. The study used the Modern Retrospective Analysis for the Research Application (MERRA) model monthly mean soil temperature and precipitations. The Global Land Data Assimilation System (GLDAS) evapotranspiration (ET) data were used to investigate the HiP vegetation water stress. The region in the southern part of the HiP which has land cover dominated by savanna experienced the most impact of the strong El Niño. Both the HiP NDVI inter-annual Mann–Kendal trend test and sequential Mann–Kendall (SQ-MK) test indicated a significant downward trend during the El Niño years of 2003 and 2014–2015. The SQ-MK significant trend turning point which was thought to be associated with the 2014–2015 El Niño periods begun in November 2012. The wavelet coherence and coherence phase indicated a positive teleconnection/correlation between soil temperatures, precipitation, soil moisture (NDII), and ET. This was explained by a dominant in-phase relationship between the NDVI and climatic parameters especially at a period band of 8–16 months.

scholarly journals Drought risk in the Bolivian Altiplano associated with El Niño Southern Oscillation using satellite imagery data

2019 ◽  
Author(s):  
Claudia Canedo-Rosso ◽  
Stefan Hochrainer-Stigler ◽  
Georg Pflug ◽  
Bruno Condori ◽  
Ronny Berndtsson
Keyword(s):  
Satellite Imagery ◽  
El Niño ◽  
Crop Production ◽  
Vegetation Index ◽  
Crop Yields ◽  
El Nino ◽  
Southern Oscillation ◽  
Drought Risk ◽  
Bolivian Altiplano ◽  
Imagery Data

Abstract. Drought is a major natural hazard in the Bolivian Altiplano that causes large losses to farmers, especially during positive ENSO phases. However, empirical data for drought risk estimation purposes are scarce and spatially uneven distributed. Due to these limitations, similar to many other regions in the world, we tested the performance of satellite imagery data for providing precipitation and temperature data. The results show that droughts can be better predicted using a combination of satellite imagery and ground-based available data. Consequently, the satellite climate data were associated with the Normalized Difference Vegetation Index (NDVI) in order to evaluate the crop production variability. Moreover, NDVI was used to target specific drought hotspot regions. Furthermore, during positive ENSO phase (El Niño years), a significant decrease in crop yields can be expected and we indicate areas where losses will be most pronounced. The results can be used for emergency response operations and enable a pro-active approach to disaster risk management against droughts. This includes economic-related and risk reduction strategies such as insurance and irrigation.

Monitoring Agricultural Drought Using El Niño and Southern Oscillation Data

2005 ◽  
Author(s):  
Lino Naranjo Díaz
Keyword(s):  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Climatic Variability ◽  
Past Century ◽  
Climatic Data ◽  
Weather Patterns ◽  
El Niño Events ◽  
Ring Analysis ◽  
El Nino Events

Almost all the studies performed during the past century have shown that drought is not the result of a single cause. Instead, it is the result of many factors varying in nature and scales. For this reason, researchers have been focusing their studies on the components of the climate system to explain a link between patterns (regional and global) of climatic variability and drought. Some drought patterns tend to recur frequently, particularly in the tropics. One such pattern is the El Niño and Southern Oscillation (ENSO). This chapter explains the main characteristics of the ENSO and its data forms, and how this phenomenon is related to the occurrence of drought in the world regions. Originally, the name El Niño was coined in the late 1800s by fishermen along the coast of Peru to refer to a seasonal invasion of south-flowing warm currents of the ocean that displaced the north-flowing cold currents in which they normally fished. The invasion of warm water disrupts both the marine food chain and the economies of coastal communities that are based on fishing and related industries. Because the phenomenon peaks around the Christmas season, the fishermen who first observed it named it “El Niño” (“the Christ Child”). In recent decades, scientists have recognized that El Niño is linked with other shifts in global weather patterns (Bjerknes, 1969; Wyrtki, 1975; Alexander, 1992; Trenberth, 1995; Nicholson and Kim, 1997). The recurring period of El Niño varies from two to seven years. The intensity and duration of the event vary too and are hard to predict. Typically, the duration of El Niño ranges from 14 to 22 months, but it can also be much longer or shorter. El Niño often begins early in the year and peaks in the following boreal winter. Although most El Niño events have many features in common, no two events are exactly the same. The presence of El Niño events during historical periods can be detected using climatic data interpreted from the tree ring analysis, sediment or ice cores, coral reef samples, and even historical accounts from early settlers.

scholarly journals El Niño Southern Oscillation (ENSO) and Health: An Overview for Climate and Health Researchers

Atmosphere ◽  
2018 ◽  
Vol 9 (7) ◽  
pp. 282 ◽  
Author(s):  
Glenn McGregor ◽  
Kristie Ebi
Keyword(s):  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Climatic Variability ◽  
Climate Impacts ◽  
Health Science ◽  
El Niño Southern Oscillation ◽  
El Nino Southern Oscillation ◽  
Major Mode ◽  
Climate And Health

The El Niño Southern Oscillation (ENSO) is an important mode of climatic variability that exerts a discernible impact on ecosystems and society through alterations in climate patterns. For this reason, ENSO has attracted much interest in the climate and health science community, with many analysts investigating ENSO health links through considering the degree of dependency of the incidence of a range of climate diseases on the occurrence of El Niño events. Because of the mounting interest in the relationship between ENSO as a major mode of climatic variability and health, this paper presents an overview of the basic characteristics of the ENSO phenomenon and its climate impacts, discusses the use of ENSO indices in climate and health research, and outlines the present understanding of ENSO health associations. Also touched upon are ENSO-based seasonal health forecasting and the possible impacts of climate change on ENSO and the implications this holds for future assessments of ENSO health associations. The review concludes that there is still some way to go before a thorough understanding of the association between ENSO and health is achieved, with a need to move beyond analyses undertaken through a purely statistical lens, with due acknowledgement that ENSO is a complex non-canonical phenomenon, and that simple ENSO health associations should not be expected.

Spatial Climatic Variability and Impact of El Niño–Southern Oscillation on Extreme Precipitation of River Catchment

2020 ◽  
Vol 37 (5) ◽  
pp. 346-364
Author(s):  
Muhammad Imran Azam ◽  
Jiali Guo ◽  
Xiaotao Shi ◽  
Muhammad Yaseen ◽  
Muhammad Tayyab ◽  
...  
Keyword(s):  
El Niño ◽  
Extreme Precipitation ◽  
El Nino ◽  
Southern Oscillation ◽  
Climatic Variability ◽  
El Niño Southern Oscillation ◽  
El Nino Southern Oscillation ◽  
River Catchment

scholarly journals Time Series Analysis of MODIS-Derived NDVI for the Hluhluwe-iMfolozi Park, South Africa: Impact of Recent Intense Drought

2018 ◽  
Author(s):  
Nkanyiso Mbatha ◽  
Sifiso Xulu
Keyword(s):  
Time Series ◽  
Vegetation Index ◽  
Southern Oscillation ◽  
Kendall Test ◽  
Google Earth ◽  
Maximum Temperature ◽  
Sudden Increase ◽  
Area Index ◽  
Enhanced Vegetation Index ◽  
Temperature And Precipitation

The variability of meteorological parameters such as temperature and precipitation, and climatic conditions such as intense droughts, are known to impact vegetation health over southern Africa. Thus, understanding large-scale ocean–atmospheric phenomena like the El Niño/Southern Oscillation (ENSO) and Indian Ocean Dipole/Dipole Mode Index (DMI) is important as these factors drive the variability of temperature and precipitation. In this study, 16 years (2002–2017) of Moderate Resolution Imaging Spectroradiometer (MODIS) Terra/Aqua 16-day normalized difference vegetation index (NDVI), extracted and processed using JavaScript code editor in the Google Earth Engine (GEE) platform in order to analyze the response pattern of the oldest proclaimed nature reserve in Africa, the Hluhluwe-iMfolozi Park (HiP), during the study period. The MODIS-enhanced vegetation index and burned area index were also analyzed for this period. The area-averaged Modern Retrospective Analysis for Research Application (MERRA) model maximum temperature and precipitation were also extracted using the JavaScript code editor in the GEE platform. This procedure demonstrated a strong reversal of both the NDVI and Enhanced Vegetation Index (EVI), leading to signs of a sudden increase of burned areas (strong BAI) during the strongest El Niño period. Both the Theilsen method and the Mann–Kendall test showed no significant greening or browning trends over the whole time series, although the annual Mann–Kendall test, in 2003 and 2014–2015, indicated significant browning trends due to the most recent strongest El Niño. Moreover, a multi-linear regression model seems to indicate a significant influence of both ENSO activity and precipitation. Our results indicate that the recent 2014–2016 drought altered the vegetation condition in the HiP. We conclude that it is vital to exploit freely available GEE resources to develop drought monitoring vegetation systems, and to integrate climate information for analyzing its influence on protected areas, especially in data-poor counties.

scholarly journals Statistical Analysis of Tropical Cyclones in the Solomon Islands

2018 ◽  
Author(s):  
Edward Maru ◽  
Taiga Shibata ◽  
Kosuke Ito
Keyword(s):  
Tropical Cyclone ◽  
El Niño ◽  
Large Scale ◽  
El Nino ◽  
Southern Oscillation ◽  
Solomon Islands ◽  
Climatic Variability ◽  
Vertical Wind Shear ◽  
Longwave Radiation ◽  
Relative Vorticity

This paper examines the tropical cyclone (TC) activity in Solomon Islands (SI) using the best track data from Tropical Cyclone Warning Centre Brisbane and Regional Specialized Meteorological Centre Nadi. The long-term trend analysis showed that the frequency of TCs has been decreasing in this region while average TC intensity becomes strong. Then, the datasets were classified according to the phase of Madden-Julian Oscillation (MJO) and the index of El Nino Southern Oscillation (ENSO) provided by Bureau of Meteorology. The MJO has sufficiently influenced TC activity in the SI region with more genesis occurring in phases 6-8, in which the lower outgoing longwave radiation indicates enhanced convective activity. In contrast, TC genesis occurs less frequently in phases 1, 2, and 5. As for the influence of ENSO, more TCs are generated in El Nino period. The TC genesis locations during El Nino (La Nina) period were significantly displaced to the north (south) over SI region. TCs generated during El Nino condition tended to be strong. This paper also argues the modulation in terms of seasonal climatic variability of large-scale environmental conditions such as sea surface temperature, low level relative vorticity, vertical wind shear, and upper level divergence.

Effects of ENSO-linked climate and vegetation on population dynamics of sympatric rodent species in semiarid grasslands of Inner Mongolia, China

2011 ◽  
Vol 89 (8) ◽  
pp. 678-691 ◽  
Author(s):  
G. Jiang ◽  
T. Zhao ◽  
J. Liu ◽  
L. Xu ◽  
G. Yu ◽  
...  
Keyword(s):  
El Niño ◽  
Inner Mongolia ◽  
Vegetation Index ◽  
El Nino ◽  
Southern Oscillation ◽  
Time Lag ◽  
Rodent Species ◽  
Bottom Up ◽  
Precipitation Temperature ◽  
Rodent Abundance

El Niño Southern Oscillation (ENSO) linked climate has been known to be associated with several rodent species, but its effects on rodent community at both spatial and temporal scales are not well studied. In this study, we investigated the possible causal chain relating ENSO, precipitation, temperature, and vegetation index (normalized difference vegetation index, NDVI) to rodent abundance for 14 sympatric rodent species in 21 counties of semiarid grasslands in Inner Mongolia, China, from 1982 to 2006. We found that both precipitation and temperature showed a generally direct positive effect on rodent abundance in many species in the current year, but indirect effects that operate through NDVI in the current or following year could have a reverse effect on abundance. We described one ENSO-linked precipitation bottom-up chain and three ENSO-linked temperature bottom-up chains. These observed bottom-up links reveal that in El Niño years, or 1 year after La Niña years, or 2 years after El Niño years, ENSO-driven climate or vegetation factors tend to increase population abundances of many sympatric rodent species in this region. We also found time-lag effects and the life-history strategy (i.e., functional groups of hibernating behavior, activity rhythm, or food habits) also contribute to the observed complicated effects of SOI on precipitation, temperature, NDVI, and ultimately rodent abundance.

scholarly journals Fenómenos meteorológicos y su efecto sobre la producción de café en la Zona Central de Veracruz

UVserva ◽  
2020 ◽  
pp. 47-58
Author(s):  
Paulo César Parada Molina ◽  
Mario Javier Gómez Martínez ◽  
Gustavo Celestino Ortiz Ceballos ◽  
Carlos Roberto Cerdán Cabrera ◽  
Juan Cervantes Pérez
Keyword(s):  
El Niño ◽  
Negative Impact ◽  
El Nino ◽  
Southern Oscillation ◽  
Climatic Variability ◽  
Agroforestry Systems ◽  
Mitigation Strategies ◽  
Negative Effects ◽  
Phenological Stages ◽  
Positive Effects

La producción de café se está viendo afectada por cambios en los patrones climáticos y por la aparición de fenómenos meteorológicos que coinciden con importantes etapas fenológicas para este cultivo. El café es más sensible a variaciones del clima cuando se encuentra en las etapas de floración y el inicio del crecimiento del fruto, en este periodo cuatro fenómenos están presentes, que de acuerdo con su intensidad podría incidir de manera negativa. La etapa de maduración y cosecha es impactada por cinco fenómenos mientras que durante la etapa de crecimiento y llenado del grano sólo dos fenómenos la afectan. El Niño Oscilación del Sur (ENSO), en su fase negativa, intensificaría los efectos negativos. Sin embargo, no debe pasar inadvertido los efectos positivos del ENSO, en fase fría, en la temporada seca (diciembre-abril). Se deben buscar y estudiar estrategias de mitigación a la variación climática producto de los fenómenos meteorológicos, donde los sistemas agroforestales pueden ser una alternativa para enfrentar esta problemática.Palabras clave: Desarrollo reproductivo; ENSO; etapas fenológicas; eventos climáticos; regiones cafetaleras; variabilidad climática. Abstract: Coffee production is being affected by changes in weather patterns and the appearance of meteorological phenomena that coincide with important phenological stages for coffee cultivation. The coffee is more sensitive to the variations of the climate when it is in the stages of flowering and the beginning of the growth of the product, in this period four phenomena are present, and according to its intensity it could have a negative impact. The stage of maturation and harvest is shocking by five phenomena while during the growth stage and the grain volumes only two phenomena stress. El Niño-Southern Oscillation (ENSO), in its negative phase, would intensify the negative effects. However, the positive effects of the ENSO, in the cold phase, during dry season (December-April) should not go unnoticed. Mitigation strategies for climate variation due to meteorological phenomena must be sought and studied, where agroforestry systems can be an alternative to address this problem.Keywords: Reproductive Development; ENSO; Phenological Stages; Climatic Events; Coffee Regions; Climatic Variability.

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