Exploring Connections between Global Climate Indices and African Vegetation Phenology

Variations in agricultural production due to rainfall and temperature fluctuations are a primary cause of food insecurity on the continent in Africa. Agriculturally destructive droughts and floods are monitored from space using satellite remote sensing by organizations seeking to provide quantitative and predictive information about food security crises. Better knowledge on the relation between climate indices and food production may increase the use of these indices in famine early warning systems and climate outlook forums on the continent. Here we explore the relationship between phenology metrics derived from the 26 year AVHRR NDVI record and the North Atlantic Oscillation index (NAO), the Indian Ocean Dipole (IOD), the Pacific Decadal Oscillation (PDO), the Multivariate ENSO Index (MEI) and the Southern Oscillation Index (SOI). We explore spatial relationships between growing conditions as measured by the NDVI and the five climate indices in Eastern, Western and Southern Africa to determine the regions and periods when they have a significant impact. The focus is to provide a clear indication as to which climate index has the most impact on the three regions during the past quarter century. We found that the start of season and cumulative NDVI were significantly affected by variations in the climate indices. The particular climate index and the timing showing highest correlation depended heavily on the region examined. The research shows that climate indices can contribute to understanding growing season variability in Eastern, Western and Southern Africa

Spatial-Temporal Distribution of Malaria Risk and Its Association With El Niño Southern Oscillation (ENSO)

Sarawak recorded the second-highest number of cases since 2013 until 2017 after Sabah. Sarawak is the largest state in Malaysia and needs to provide spatial information, especially to the ministry of health. The objective of this study was to examine the impact of El Niño-Southern Oscillation (ENSO) on the distribution of malaria risk maps. To achieve the objectives of this study requires Oceanic Niño Index (ONI) data, Visible Infrared Imaging Radiometer Suite (VIIRS), daily temperature, and secondary data on the number of malaria cases in Sarawak. The results of the study clearly show that the occurrence of La Niña and El Niño affects the total distribution of Malaria risk maps. The number of malaria cases is also related to the ONI value. The lower the ONI value causes the malaria case value to decrease. The results of this study suggest that most of the hot spots in the forest, forest fringe, and inland areas of Sarawak. This clearly shows the lack of knowledge and knowledge causing the rural population to be prone to malaria. The Ministry of Health needs to focus on the interior in disseminating teachings and knowledge in dealing with malaria mosquitoes

Anthropogenic and climatic control upon vegetation fires: new insights from satelite observations to assess current and future impacts

Doutoramento em Engenharia Florestal - Instituto Superior de AgronomiaVegetation fires actively participate in ecosystem dynamics and atmospheric composition. Their contemporaneous occurrence and impacts – described under the concept of “fire regimes” – is driven by climate, vegetation, and human activities – the components of the “fire triangle”. The gaps in our understanding of those drivers hamper the proper consideration of fires in various domains, including ecosystems management, vegetation modeling, and climate change investigation. This thesis capitalizes on satellite observations to depict the anthropogenic and climatic influence on fire regimes. Fire inter-annual variability is shown to be dominated by large scale climatic patterns, of which the El Niño-Southern Oscillation has the most widespread and long term footprint. Fire frequency and seasonality are more complex, being determined by the interaction of all three factors of the fire triangle. The evaluation of a vegetation-fire model thus reveals significant discrepancies. It suggests a great margin of progress on representing of the anthropogenic factor, supported by the wide range of fire practices identified from fire season dynamics. A model specific to tropical deforestation fires is developed, as a regional application of this thesis contributions. Climate is a forceful safeguard against forest conversion progress, but ongoing environmental changes could revert the situation

Remote Sensing of Hydro-Meteorology

Flood/drought, risk management, and policy: decision-making under uncertainty. Hydrometeorological extremes and their impact on human–environment systems. Regional and nonstationary frequency analysis of extreme events. Detection and prediction of hydrometeorological extremes with observational and model-based approaches. Vulnerability and impact assessment for adaptation to climate change

Global fire activity patterns (1996-2006) and climatic influence: an analysis using World Fire Atlas

Vegetation fires have been acknowledged as an environmental process of global scale, which affects the chemical composition of the troposphere, and has profound ecological and climatic impacts. However, considerable uncertainty remains, especially concerning intra and inter-annual variability of fire incidence. The main goals of our globalscale study were to characterise spatial-temporal patterns of fire activity, to identify broad geographical areas with similar vegetation fire dynamics, and to analyse the relationship between fire activity and the El Ni˜no-Southern Oscillation. This study relies on 10 years (mid 1996–mid 2006) of screened European Space Agency World Fire Atlas (WFA) data, obtained from Along Track Scanning Radiometer (ATSR) and Advanced ATSR (AATSR) imagery. Empirical Orthogonal Function analysis was used to reduce the dimensionality of the dataset. Regions of homogeneous fire dynamics were identified with cluster analysis, and interpreted based on their eco-climatic characteristics. The impact of 1997–1998 El Ni˜no is clearly dominant over the study period, causing increased fire activity in a variety of regions and ecosystems, with variable timing. Overall, this study provides the first global decadal assessment of spatialtemporal fire variability and confirms the usefulness of the screened WFA for global fire ecoclimatology researc

Observationally based analysis of land–atmosphere coupling

Abstract. The temporal variance of soil moisture, vegetation and evapotranspiration over land has been recognized to be strongly connected to the temporal variance of precipitation. However, the feedbacks and couplings between these variables are still not well understood and quantified. Furthermore, soil moisture and vegetation processes are associated with a memory and therefore they may have important implications for predictability. In this study we apply a generalized linear method, specifically designed to assess the reciprocal forcing between connected fields, to the latest available observational data sets of global precipitation, evapotranspiration, vegetation and soil moisture content. For the first time a long global observational data set is used to investigate the spatial and temporal land variability and to characterize the relationships and feedbacks between land and precipitation. The variables considered show a significant coupling among each other. The analysis of the response of precipitation to soil moisture evidences a robust coupling between these two variables. In particular, the first two modes of variability in the precipitation forced by soil moisture appear to have a strong link with volcanic eruptions and El Niño–Southern Oscillation (ENSO) cycles, respectively, and these links are modulated by the effects of evapotranspiration and vegetation. It is suggested that vegetation state and soil moisture provide a biophysical memory of ENSO and major volcanic eruptions, revealed through delayed feedbacks on rainfall patterns. The third mode of variability reveals a trend very similar to the trend of the inter-hemispheric contrast in sea surface temperature (SST) and appears to be connected to greening/browning trends of vegetation over the last three decades

A Review of Earth Observation-Based Drought Studies in Southeast Asia

Drought is a recurring natural climatic hazard event over terrestrial land; it poses devastating threats to human health, the economy, and the environment. Given the increasing climate crisis, it is likely that extreme drought phenomena will become more frequent, and their impacts will probably be more devastating. Drought observations from space, therefore, play a key role in dissimilating timely and accurate information to support early warning drought management and mitigation planning, particularly in sparse in-situ data regions. In this paper, we reviewed drought-related studies based on Earth observation (EO) products in Southeast Asia between 2000 and 2021. The results of this review indicated that drought publications in the region are on the increase, with a majority (70%) of the studies being undertaken in Vietnam, Thailand, Malaysia and Indonesia. These countries also accounted for nearly 97% of the economic losses due to drought extremes. Vegetation indices from multispectral optical remote sensing sensors remained a primary source of data for drought monitoring in the region. Many studies (~21%) did not provide accuracy assessment on drought mapping products, while precipitation was the main data source for validation. We observed a positive association between spatial extent and spatial resolution, suggesting that nearly 81% of the articles focused on the local and national scales. Although there was an increase in drought research interest in the region, challenges remain regarding large-area and long time-series drought measurements, the combined drought approach, machine learning-based drought prediction, and the integration of multi-sensor remote sensing products (e.g., Landsat and Sentinel-2). Satellite EO data could be a substantial part of the future efforts that are necessary for mitigating drought-related challenges, ensuring food security, establishing a more sustainable economy, and the preservation of the natural environment in the region

Precipitation and Land Cover Change in Komodo National Park During El Nino and La Nina

Komodo National Park is located in East Nusa Tenggara province which has a dry tropical climate. Air temperature in this area is relatively high with a lower rainfall compared to most of other Indonesian regions. This condition causes ecosystem in Komodo National Park to be unique with a wide area of savannah and dryland forest. This study aims to identify the change of rainfall and land cover in Komodo National Park in 2018-2020. The analysis was conducted using secondary data from observations and satellite products. The result shows that West Manggarai is classified in Aw climate type. The value of rainfall follows the pattern of ENSO events with a correlation between tree-month data of rainfall and the Ocean Nino Index (ONI) is 42% in average of June-December. The land cover of vegetation in March/April has decreased by 2,240 Ha (2018-2019) and 2,517 Ha (2019-2020) or around 4% and 5%​​ of total area. La Nina has occurred during wet season 2017/2018 followed by El Nino in the coming years. There was decreasing of rainfall during November-February period in 2019 and 2020, which was 17% and 37% lower compared to 2018