nasa-gesdisc/es-publications-researchareas huggingface dataset:
Magma accumulation underneath Laacher See volcano from detrital zircon in modern streams (2022)

The detrital zircon grains from two catchments in the East Eifel Volcanic Field consist of crystals sourced from proximal deposits of Quaternary trachyticphonolitic volcanic centres, Hocheifel Paleogene trachytic rocks and the Paleozoic basement. The outcrop patterns indicate the derivation of a significant detrital zircon population from deposits of the c. 13 ka Lower and Upper Laacher See Tephra. Intercalated Middle Laacher See Tephra, consisting of valley-filling ignimbrites, by contrast, is a minor zircon source despite thick ignimbrite deposits in one of the catchments. This reflects zircon undersaturation in the hotter and less evolved phonolite tapped from deeper parts of the magma reservoir as the eruption unfolded, as well as fewer antecrysts recycled from the plutonic carapace. A previously unrecognized zircon age population of c. 63 ka, mostly derived from Lower Laacher See Tephra, marks the onset of the presence of evolved magma at the top of the reservoir. Correlative Hf and O isotopic analysis reveals significant crustal interactions during phonolite differentiation in a shallow reservoir, with the assimilation of cogenetic, but hydrothermally modified, plutonic margins. Raman spectra indicate that magmatically heated crustal zircon xenocrysts are absent. Detrital zircon can thus provide more integrated insights into the evolution of Quaternary magma systems than the punctuated sampling of volcanic or cogenetic plutonic rocks.Supplementary material: Data tables presenting UTh, UPb, OHf and Raman geochronology results are available at https://doi.org/10.6084/m9.figshare.c.6123823

Research areas: Volcanic Eruptions
An oxidised intrusion-related origin in the controversial Jiaodong gold province (China) for the Shicheng Au-Cu deposit (2021)

The Shicheng Au-Cu deposit is hosted in the late Early Cretaceous Sanfoshan pluton within the Muping-Rushan (Mu-Ru) metallogenic belt, southeast Jiaodong. The deposit is characterised by Au-Cu bearing quartz-carbonate-sulphide veins that illustrate overprinting sheeted-like and breccia styles. Paragenetically-later veins contain Pb-Zn-(Cu) metal association, suggesting metal zonation at the deposit scale. Quartz from Shicheng shows the cathodoluminescence (CL) textures characteristic of hydrothermal systems with a magmatic influence and exhibits a similar quartz generations sequence. Moreover, this study presents a later overprinting mineralising event, characterised by quartz veins that contain As-rich pyrite, at the Jinqingding deposit in the middle part of the Mu-Ru belt. Jinqingding has a young mineralisation age that overlaps the emplacement age of the Sanfoshan pluton. Quartz from these veins at Jinqingding shows CL textures like those of the Shicheng deposit. The Sanfoshan pluton evolved from highly oxidised, high-K calc-alkaline, I-type magmatism. The early phases of the Sanfoshan pluton have K/Rb, Rb/Sr, and Fe2O3/FeO ratios that indicate moderately evolved, less fractionated, and highly oxidised magma, respectively, favouring Au-chalcophile metal association. Therefore, the Shicheng deposit and the overprinting mineralising event at Jinqingding may reasonably represent the products of an oxidised magmatic-hydrothermal system associated with the Sanfoshan-forming magmatism.

Research areas: Volcanic Eruptions
Volcanic SO2 effective layer height retrieval for the Ozone Monitoring Instrument (OMI) using a machine-learning approach (2021)

Abstract. Information about the height and loading of sulfur dioxide (SO2) plumes from volcanic eruptions is crucial for aviation safety and for assessing the effect of sulfate aerosols on climate. While SO2 layer height has been successfully retrieved from backscattered Earthshine ultraviolet (UV) radiances measured by the Ozone Monitoring Instrument (OMI), previously demonstrated techniques are computationally intensive and not suitable for near-real-time applications. In this study, we introduce a new OMI algorithm for fast retrievals of effective volcanic SO2 layer height. We apply the Full-Physics Inverse Learning Machine (FP_ILM) algorithm to OMI radiances in the spectral range of 310330 nm. This approach consists of a training phase that utilizes extensive radiative transfer calculations to generate a large dataset of synthetic radiance spectra for geophysical parameters representing the OMI measurement conditions. The principal components of the spectra from this dataset in addition to a few geophysical parameters are used to train a neural network to solve the inverse problem and predict the SO2 layer height. This is followed by applying the trained inverse model to real OMI measurements to retrieve the effective SO2 plume heights. The algorithm has been tested on several major eruptions during the OMI data record. The results for the 2008 Kasatochi, 2014 Kelud, 2015 Calbuco, and 2019 Raikoke eruption cases are presented here and compared with volcanic plume heights estimated with other satellite sensors. For the most part, OMI-retrieved effective SO2 heights agree well with the lidar measurements of aerosol layer height from CloudAerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) and thermal infrared retrievals of SO2 heights from the infrared atmospheric sounding interferometer (IASI). The errors in OMI-retrieved SO2 heights are estimated to be 11.5 km for plumes with relatively large SO2 signals (>40 DU). The algorithm is very fast and retrieves plume height in less than 10 min for an entire OMI orbit.

Research areas: Volcanic Eruptions
Stratospheric Circulation Changes Associated With the Hunga Tonga‐Hunga Ha'apai Eruption (2022)

The 15 January 2022 eruption of the Hunga Tonga-Hunga Ha'apai underwater volcano (20.5°S, 175.4°W) injected a record amount of water directly into the stratosphere. This study attempts to quantify this impact on the temperature, as well as the subsequent changes to the stratospheric circulation, during the months following the eruption based on reanalysis fields. The extreme nature of the temperature, wind, and circulation changes are tracked through comparisons of the first six months of 2022 with the previous 42 years. Examination of the data assimilation process shows that at 20 hPa the thermal observations are forcing significant cooling, compensating for the absence of the excess stratospheric moisture in the model used for the reanalysis. In response to this cooling the atmosphere adjusts by creating strong westerly winds above the temperature anomaly and large changes to the downward and poleward mean meridional circulation.

Research areas: Volcanic Eruptions
Extreme rainfall triggered the 2018 rift eruption at Kīlauea Volcano (2020)

The May 2018 rift intrusion and eruption of Kilauea Volcano, Hawaii, represented one of its most extraordinary eruptive sequences in at least 200 years, yet the trigger mechanism remains elusive1. The event was preceded by several months of anomalously high precipitation. It has been proposed that rainfall can modulate shallow volcanic activity2,3, but it remains unknown whether it can have impacts at the greater depths associated with magma transport. Here we show that immediately before and during the eruption, infiltration of rainfall into Kilauea Volcanos subsurface increased pore pressure at depths of 1 to 3 kilometres by 0.1 to 1 kilopascals, to its highest pressure in almost 50 years. We propose that weakening and mechanical failure of the edifice was driven by changes in pore pressure within the rift zone, prompting opportunistic dyke intrusion and ultimately facilitating the eruption. A precipitation-induced eruption trigger is consistent with the lack of substantial precursory summit inflation, showing that this intrusionunlike otherswas not caused by the forceful intrusion of new magma into the rift zone. Moreover, statistical analysis of historic eruption occurrence suggests that rainfall patterns contribute substantially to the timing and frequency of Kilaueas eruptions and intrusions. Thus, volcanic activity can be modulated by extreme rainfall triggering edifice rock failurea factor that should be considered when assessing volcanic hazards. Notably, the increasingly extreme weather patterns associated with ongoing anthropogenic climate change could increase the potential for rainfall-triggered volcanic phenomena worldwide.

Research areas: Volcanic Eruptions
Life cycle of bamboo in the southwestern Amazon and its relation to fire events (2018)

Abstract. Bamboo-dominated forests comprise 1 % of the world's forests and 3 % of the Amazon forests. The Guadua spp. bamboos that dominate the southwest Amazon are semelparous; thus flowering and fruiting occur once in a lifetime before death. These events occur in massive spatially organized patches every 28 years and produce huge quantities of necromass. The bamboofire hypothesis argues that increased dry fuel after die-off enhances fire probability, creating opportunities that favor bamboo growth. In this study, our aim is to map the bamboo-dominated forests and test the bamboofire hypothesis using satellite imagery. Specifically, we developed and validated a method to map the bamboo die-off and its spatial distribution using satellite-derived reflectance time series from the Moderate Resolution Imaging Spectroradiometer (MODIS) and explored the bamboofire hypothesis by evaluating the relationship between bamboo die-off and fires detected by the MODIS thermal anomalies product in the southwest Amazon. Our findings show that the near-infrared (NIR) is the most sensitive spectral interval to characterize bamboo growth and cohort age. Automatic detection of historical bamboo die-off achieved an accuracy above 79 %. We mapped and estimated 15.5 million ha of bamboo-dominated forests in the region. The bamboofire hypothesis was not supported because only a small fraction of bamboo areas burned during the analysis timescale, and, in general, bamboo did not show higher fire probability after the die-off. Nonetheless, fire occurrence was 45 % higher in dead than live bamboo in drought years, associated with ignition sources from land use, suggesting a bamboohumanfire association. Although our findings show that the observed fire was not sufficient to drive bamboo dominance, the increased fire occurrence in dead bamboo in drought years may contribute to the maintenance of bamboo and potential expansion into adjacent bamboo-free forests. Fire can even bring deadly consequences to these adjacent forests under climate change effects.

Research areas: Wildfires
Quantifying spatial-temporal changes of tea plantations in complex landscapes through integrative analyses of optical and microwave imagery (2018)

High demand for tea has driven the expansion of tea plantations in the tropical and subtropical regions over the past few decades. Tea plant cultivation promotes economic development and creates job opportunities, but tea plantation expansion has significant impacts on biodiversity, carbon and water cycles, and ecosystem services. Mapping the spatial distribution and extent of tea plantations in a timely fashion is crucial for land use management and policy making. In this study, we mapped tea plantation expansion in Menghai County, Yunnan Province, China. We analyzed the structure and features of major land cover types in this tropical and subtropical region using (1) the HH and HV gamma-naught imagery from the Advanced Land Observation Satellite (ALOS) Phased Array L-band Synthetic Aperture Radar (PALSAR) and (2) time series Landsat TM/ETM+/OLI imagery. Tea plantation maps for 2010 and 2015 were generated using the pixel-based support vector machine (SVM) approach at 30 m resolution, which had high user/producer accuracies of 83.58%/91.67% and 87.50%/90.83%, respectively. The resultant maps show that tea plantation area increased by 33.56% (9335 ha), from 27,817 ha in 2010 to 37,152 ha in 2015. The additional tea plantation area was mainly converted from forest (32.50%) and cropland (67.50%). The results showed that the combination of PALSAR and optical data performed better in tea plantation mapping than using optical data only. This study provides a promising new approach to identify and map tea plantations in complex tropical landscapes at high spatial resolution.

Research areas: Agriculture
Aerosol size distribution changes in FIREX-AQ biomass burning plumes: the impact of plume concentration on coagulation and OA condensation/evaporation (2022)

Abstract. The evolution of organic aerosol (OA) and aerosol size
distributions within smoke plumes is uncertain due to the variability in
rates of coagulation and OA condensation/evaporation between different smoke
plumes and at different locations within a single plume. We use aircraft
data from the FIREX-AQ campaign to evaluate differences in evolving aerosol
size distributions, OA, and oxygen to carbon ratios (O:C) between and within
smoke plumes during the first several hours of aging as a function of smoke
concentration. The observations show that the median particle diameter
increases faster in smoke of a higher initial OA concentration (>1000 g m3), with diameter growth of over 100 nm in 8 h  despite generally having a net decrease in OA enhancement
ratios  than smoke of a lower initial OA concentration (<100 g m3), which had net increases in OA. Observations of OA and O:C
suggest that evaporation and/or secondary OA formation was greater in less
concentrated smoke prior to the first measurement (557 min after
emission). We simulate the size changes due to coagulation and dilution and
adjust for OA condensation/evaporation based on the observed changes in OA.
We found that coagulation explains the majority of the diameter growth, with
OA evaporation/condensation having a relatively minor impact. We found that
mixing between the core and edges of the plume generally occurred on
timescales of hours, slow enough to maintain differences in aging between
core and edge but too fast to ignore the role of mixing for most of our cases.

Research areas: Air Quality
Identification of advantageous electricity generation options in sub-Saharan Africa integrating existing resources (2016)

Pioneering approaches are needed to accelerate universal access to electricity while simultaneously transitioning to reliable, sustainable and affordable energy systems. In sub-Saharan Africa (SSA), the challenges lie in attracting the private sector to complement public investments. Here, we present an integrated ‘low-hanging-fruit’ approach aimed at boosting private investment and speeding up the deployment of renewable energy systems in SSA. We analyse the potential of existing energy infrastructure, where a significant upfront investment has already been made, to be exploited for electricity generation. We develop a comprehensive methodology to identify and select suitable locations in SSA and estimate their potential for exploitation. These locations have been further analysed in terms of power capacity potential, electricity output, investments needed and population to be benefited. This strategy to attract additional finance can easily be reproduced, engaging private investors while simultaneously helping to achieve the United Nations (UN) Sustainable Development Goals on energy.

Research areas: Energy Production/Use
Cloud processing and weeklong ageing affect biomass burning aerosol properties over the south-eastern Atlantic (2022)

Southern Africa produces a third of global biomass burning emissions, which have a long atmospheric lifetime and influence regional radiation balance and climate. Here, we use airmass trajectories to link different aircraft observations to investigate the evolution of biomass-burning aerosols during their westward transport from Southern Africa over the south-eastern Atlantic, where a semi-permanent stratocumulus cloud deck is located. Our results show secondary organic aerosol formation during the initial 3 days of transport, followed by decreases in organic aerosol via photolysis before reaching equilibrium. Aerosol absorption wavelength dependency decreases with ageing, due to an increase in particle size and photochemical bleaching of brown carbon. Cloud processing, including aqueous-phase reaction and scavenging, contributes to the oxidation of organic aerosols, while it strongly reduces large diameter particles and single-scattering albedo of biomass burning aerosols. Together, these processes resulted in a marine boundary layer with fewer yet more oxidized and absorbing aerosols.

Research areas: Environmental Impacts
Australian Fire Emissions of Carbon Monoxide Estimated by Global Biomass (2022)

Australian fires are a primary driver of variability in Australian atmospheric composition and contribute significantly to regional and global carbon budgets. However, biomass burning emissions from Australia remain highly uncertain. In this work, we use surface in situ, ground-based total column and satellite total column observations to evaluate the ability of two global models (GEOS-Chem and ACCESS-UKCA) and three global biomass burning emission inventories (FINN1.5, GFED4s, and QFED2.4) to simulate carbon monoxide (CO) in the Australian atmosphere. We find that emissions from northern Australia savanna fires are substantially lower in FINN1.5 than in the other inventories. Model simulations driven by FINN1.5 are unable to reproduce either the magnitude or the variability of observed CO in northern Australia. The remaining two inventories perform similarly in reproducing the observed variability, although the larger emissions in QFED2.4 combined with an existing high bias in the southern hemisphere background lead to large CO biases. We therefore recommend GFED4s as the best option of the three for global modeling studies with focus on Australia or the Southern Hemisphere. Near fresh fire emissions, the higher resolution ACCESS-UKCA model is better able to simulate surface CO than GEOS-Chem, while GEOS-Chem captures more of the observed variability in the total column and remote surface air measurements. We also show that existing observations in Australia can only partially constrain global model estimates of biomass burning. Continuous measurements in fire-prone parts of Australia are needed, along with updates to global biomass burning inventories that are validated with Australian data.

Research areas: Wildfires
Biomass burning aerosol transport and vertical distribution over the South AfricanAtlantic region (2017)

Optically thick smoke aerosol plumes originating from biomass burning (BB) in the southwestern African Savanna during the austral spring are transported westward by the free tropospheric winds to primarily overlie vast stretches of stratocumulus cloud decks in the southeast Atlantic. We evaluated the simulations of long-range transport of BB aerosol by the Goddard Earth Observing System (GEOS-5) and four other global aerosol models over the complete South African-Atlantic region using Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) observations to find any distinguishing or common model biases. Models, in general, captured the vertical distribution of aerosol over land but exhibited some common features after long-range transport of smoke plumes that were distinct from that of CALIOP. Most importantly, the model-simulated BB aerosol plumes quickly descend to lower levels just off the western coast of the continent, while CALIOP data suggest that smoke plumes continue their horizontal transport at elevated levels above the marine boundary layer. This is crucial because the sign of simulated aerosol semidirect effect can change depending on whether the bulk of the absorbing aerosols is present within or above the cloud levels in a model. The levels to which the aerosol plumes get subsided and the steepness of their descent vary amongst the models and amongst the different subregions of the domain. Investigations into possible causes of differences between GEOS-5 and CALIOP aerosol transport over the ocean revealed a minimal role of aerosol removal process representation in the model as opposed to model dynamics.

Research areas: Environmental Impacts
Unintended consequences of Indian groundwater preservation law on crop residue burning (2022)

This paper examines the unintended consequences of a policy aimed at improving the groundwater level on crop residue burning in India. The Preservation of Subsoil Water Act, 2009 implemented in two Indian states bans the transplantation of paddy before mid-June to preserve groundwater. Theoretically, this leaves a short window of time for clearing the field before the next crop and thus increases the likelihood of farmers adopting time-saving methods like crop residue burning. Using a difference-in-difference framework we find that the ban results in both delay and an increase in crop residue burning in the winter months.

Research areas: Environmental Impacts
Estimation of emissions from biomass burning in China (2003–2017) based on MODIS fire radiative energy data (2019)

Abstract. Biomass burning plays a significant role in air pollution and climate change. In this study, we used a method based on fire radiative energy (FRE) to develop a biomass burning emission inventory for China from 2003 to 2017. Daily fire radiative power (FRP) data derived from 1 km MODIS Thermal Anomalies/Fire products (MOD14/MYD14) were used to calculate FRE and combusted biomass. Available emission factors were assigned to four biomass burning types: forest, cropland, grassland, and shrubland fires. The farming system and crop types in different temperate zones were taken into account in this research. Compared with traditional methods, the FRE method was found to provide a more reasonable estimate of emissions from small fires. The estimated average annual emission ranges, with a 90 % confidence interval, were 91.4 (72.7108.8) Tg CO2 yr1, 5.0 (2.37.8)  Tg CO yr1, 0.24 (0.050.48) Tg CH4 yr1, 1.43 (0.532.35) Tg NMHC yr1, 0.23 (0.050.45) Tg NOx yr1, 0.09 (0.020.17) Tg NH3 yr1, 0.03 (0.010.05) Tg SO2 yr1, 0.04 (0.010.08) Tg BC yr1, 0.27 (0.070.49) Tg OC yr1, 0.51 (0.190.84) Tg PM2.5 yr1, 0.57 (0.151.05) Tg PM10 yr1, where NMHC, BC, and OC are nonmethane hydrocarbons, black carbon, and organic carbon, respectively. Forest fires are determined to be the primary contributor to open fire emissions, accounting for 45 % of the total CO2 emissions (average 40.8 Tg yr1). Crop residue burning ranked second place with a large portion of 39 % (average 35.3 Tg yr1). During the study period, emissions from forest and grassland fires showed a significant downward trend. Crop residue emissions continued to rise during 20032015 but dropped by 42 % in 20152016. Emissions from shrubland were negligible and little changed. Forest and grassland fires are concentrated in northeastern China and southern China, especially in the dry season (from October to March of the following year). Plain areas with high crop yields, such as the North China Plain, experienced high agricultural fire emissions in harvest seasons. Most shrubland fires were located in Yunnan and Guangdong provinces. The resolution of our inventory (daily, 1 km) is much higher than previous inventories, such as GFED4s and GFASv1.0. It could be used in global and regional air quality modeling.

Research areas: Environmental Impacts, Wildfires