scholarly journals Pemodelan Sistem Karbonat di Laut Jawa

2021 ◽  
Vol 6 (3) ◽  
pp. 149
Author(s):  
Alan Frendy Koropitan
Keyword(s):  
Carbon Source ◽  
Forest Fires ◽  
Carbon Sink ◽  
Marine Ecosystem ◽  
Carbonate System ◽  
Carbon Cycle Model ◽  
Wind Speeds ◽  
Marine Carbonate ◽  
Marine Ecosystem Model ◽  
Java Sea

<p class="Papertext"><strong>Modeling Carbonate System in the Java Sea</strong>. Besides the global fossil fuel burning activities, forest fires in Kalimantan could potentially increase atmospheric CO<sub>2</sub> concentrations, impacting air-sea CO<sub>2</sub> gas exchange in the Java Sea and changing the balance of the marine carbonate system. This study uses a marine carbonate model to examine the processes that control CO<sub>2</sub> flux in the Java Sea and their relationship to CO<sub>2</sub> increase in the atmosphere. OCMIP-2 (<em>Ocean Carbon-Cycle Model Intercomparison Model Project, Phase-2</em>) is performed in this marine carbonate model coupled with the marine ecosystem model. The model results show that the quantity of carbon air flux differs during February and October 2000. More considerable flux is produced during February 2000, where the wind speeds are higher than in October 2000. However, the wind speeds have less impact when the CO<sub>2</sub> level in the atmosphere rises significantly. Due to the influence of a relatively high surface temperature in the tropical Java sea, the Java Sea functions as a carbon source to the atmosphere in general. In this case, the role of the <em>solubility pump</em> is more significant than that of biological processes in carbon absorption. Moreover, increased CO<sub>2</sub> in the atmosphere could alter the partial pressure equilibrium. In the case of 2002 forest fires (atmospheric CO<sub>2</sub> = 460 ppm), the carbon source of the Java Sea was less than before forest fires and even became carbon sink when atmospheric CO<sub>2</sub> rose to 1135.2 ppm based on the highest SSP scenario in 2100. This modeling also reveals marine acidification issues and could rapidly assess the future changes in marine ecosystems due to CO<sub>2</sub> levels rising in the atmosphere.</p>

scholarly journals The Sensitivity of the Marine Carbonate System to Regional Ocean Alkalinity Enhancement

2021 ◽  
Vol 3 ◽  
Author(s):  
Daniel J. Burt ◽  
Friederike Fröb ◽  
Tatiana Ilyina
Keyword(s):  
Southern Ocean ◽  
Dissolved Inorganic Carbon ◽  
Ocean Model ◽  
Total Alkalinity ◽  
Surface Pattern ◽  
Carbon Uptake ◽  
Max Planck ◽  
Carbonate System ◽  
Carbon Cycle Model ◽  
Marine Carbonate

Ocean Alkalinity Enhancement (OAE) simultaneously mitigates atmospheric concentrations of CO2 and ocean acidification; however, no previous studies have investigated the response of the non-linear marine carbonate system sensitivity to alkalinity enhancement on regional scales. We hypothesise that regional implementations of OAE can sequester more atmospheric CO2 than a global implementation. To address this, we investigate physical regimes and alkalinity sensitivity as drivers of the carbon-uptake potential response to global and different regional simulations of OAE. In this idealised ocean-only set-up, total alkalinity is enhanced at a rate of 0.25 Pmol a-1 in 75-year simulations using the Max Planck Institute Ocean Model coupled to the HAMburg Ocean Carbon Cycle model with pre-industrial atmospheric forcing. Alkalinity is enhanced globally and in eight regions: the Subpolar and Subtropical Atlantic and Pacific gyres, the Indian Ocean and the Southern Ocean. This study reveals that regional alkalinity enhancement has the capacity to exceed carbon uptake by global OAE. We find that 82–175 Pg more carbon is sequestered into the ocean when alkalinity is enhanced regionally and 156 PgC when enhanced globally, compared with the background-state. The Southern Ocean application is most efficient, sequestering 12% more carbon than the Global experiment despite OAE being applied across a surface area 40 times smaller. For the first time, we find that different carbon-uptake potentials are driven by the surface pattern of total alkalinity redistributed by physical regimes across areas of different carbon-uptake efficiencies. We also show that, while the marine carbonate system becomes less sensitive to alkalinity enhancement in all experiments globally, regional responses to enhanced alkalinity vary depending upon the background concentrations of dissolved inorganic carbon and total alkalinity. Furthermore, the Subpolar North Atlantic displays a previously unexpected alkalinity sensitivity increase in response to high total alkalinity concentrations.

scholarly journals The mineralogic and isotopic fingerprint of equatorial carbonates: Kepulauan Seribu, Indonesia

2021 ◽  
Author(s):  
Dwi Amanda Utami ◽  
Lars Reuning ◽  
Maximillian Hallenberger ◽  
Sri Yudawati Cahyarini
Keyword(s):  
River Runoff ◽  
Patch Reef ◽  
High Water ◽  
Sem Analysis ◽  
Shallow Waters ◽  
Carbonate System ◽  
Riverine Water ◽  
High Turbidity ◽  
Java Sea ◽  
River Catchments

AbstractKepulauan Seribu is an isolated patch reef complex situated in the Java Sea (Indonesia) and is a typical example for a humid, equatorial carbonate system. We investigate the mineralogical and isotopic fingerprint of Panggang, one of the reef platforms of Kepulauan Seribu, to evaluate differences to other carbonate systems, using isotope in combination with XRD and SEM analysis. A characteristic property of shallow water (< 20 m) sediments from Kepulauan Seribu is their increased LMC content (~ 10%) derived from some genera of rotaliid foraminifers and bivalves. The relative abundance of these faunal elements in shallow waters might be related to at least temporary turbid conditions caused by sediment-laden river runoff. This influence is also evidenced by the presence of low amounts of siliciclastic minerals below the regional wave base. Kepulauan Seribu carbonates are characterized by very low δ13C and δ18O values. This is related to the isotopically depleted riverine input. The δ13CDIC in riverine water is reduced by the contribution of 12C from riverside mangroves. Deep atmospheric convection and intensive rains contribute 18O-depleted freshwater in the river catchments, finally reducing salinity in the Java Sea. The depleted δ13C signature in carbonates is further enhanced by the lack of green algae and inorganic carbonates and abundance of coral debris. Low δ18O values in carbonates are favored by the high water temperatures in the equatorial setting. Since equatorial carbonates in SE Asia, including the Java Sea, are typically influenced by high turbidity and/or river runoff, the observed distinctively low isotope values likely are characteristic for equatorial carbonate systems in the region.

scholarly journals Different climate sensitivity for radial growth, but uniform for tree-ring stable isotopes along an aridity gradient in Polylepis tarapacana, the world’s highest elevation tree-species

2021 ◽  
Author(s):  
Milagros Rodriguez-Caton ◽  
Laia Andreu-Hayles ◽  
Mariano S Morales ◽  
Valérie Daux ◽  
Duncan A Christie ◽  
...  
Keyword(s):  
Stable Isotopes ◽  
Carbon Source ◽  
Tree Ring ◽  
Tree Growth ◽  
Carbon Sink ◽  
Growing Season ◽  
Wood Formation ◽  
Aridity Gradient ◽  
Leaf Level ◽  
Δ13c And Δ18o

Abstract Tree growth is generally considered to be temperature-limited at upper elevation treelines. Yet, climate factors controlling tree growth at semiarid treelines are poorly understood. We explored the influence of climate on stem growth and stable isotopes for Polyepis tarapacana, the world’s highest elevation tree-species found only in the South American Altiplano. We developed tree-ring width index (RWI), oxygen (δ18O) and carbon (δ13C) chronologies for the last 60 years at four P. tarapacana stands located above 4,400 meters in elevation, along a 500-km latitude-aridity gradient. Total annual precipitation decreased from 300 to 200 mm from the northern to the southern sites. We used RWI as a proxy of wood formation (carbon sink) and isotopic tree-ring signatures as proxies of leaf-level gas exchange processes (carbon source). We found distinct climatic conditions regulating carbon-sink processes along the gradient. Current-growing season temperature regulated RWI at wetter-northern sites, while prior-growing season precipitation determined RWI at arid-southern sites. This suggests that the relative importance of temperature to precipitation in regulating tree growth is driven by site-water availability. In contrast, warm and dry growing-seasons resulted in enriched tree-ring δ13C and δ18O at all study sites, suggesting that similar climate conditions control carbon-source processes. Site-level δ13C and δ18O chronologies were significantly and positively related at all sites, with the strongest relationships among the southern-drier stands. This indicates an overall regulation of intercellular carbon dioxide via stomatal conductance for the entire P. tarapacana network, with greater stomatal control when aridity increases. The manuscript also highlights a coupling and decoupling of physiological processes at leaf level versus wood formation depending on their respectively uniform and distinct sensitivity to climate. This study contributes to better understand and predict the response of high-elevation Polylepis woodlands to rapid climate changes and projected drying in the Altiplano.

scholarly journals Wavelet-based spatial comparison technique for analysing and evaluating two-dimensional geophysical model fields

2012 ◽  
Vol 5 (1) ◽  
pp. 223-230 ◽  
Author(s):  
S. Saux Picart ◽  
M. Butenschön ◽  
J. D. Shutler
Keyword(s):  
Satellite Data ◽  
Fishery Management ◽  
Numerical Models ◽  
Spatial Scales ◽  
Marine Ecosystem ◽  
Original Method ◽  
Precipitation Forecast ◽  
Spatial And Temporal Scales ◽  
Geographical Patterns ◽  
Marine Ecosystem Model

Abstract. Complex numerical models of the Earth's environment, based around 3-D or 4-D time and space domains are routinely used for applications including climate predictions, weather forecasts, fishery management and environmental impact assessments. Quantitatively assessing the ability of these models to accurately reproduce geographical patterns at a range of spatial and temporal scales has always been a difficult problem to address. However, this is crucial if we are to rely on these models for decision making. Satellite data are potentially the only observational dataset able to cover the large spatial domains analysed by many types of geophysical models. Consequently optical wavelength satellite data is beginning to be used to evaluate model hindcast fields of terrestrial and marine environments. However, these satellite data invariably contain regions of occluded or missing data due to clouds, further complicating or impacting on any comparisons with the model. This work builds on a published methodology, that evaluates precipitation forecast using radar observations based on predefined absolute thresholds. It allows model skill to be evaluated at a range of spatial scales and rain intensities. Here we extend the original method to allow its generic application to a range of continuous and discontinuous geophysical data fields, and therefore allowing its use with optical satellite data. This is achieved through two major improvements to the original method: (i) all thresholds are determined based on the statistical distribution of the input data, so no a priori knowledge about the model fields being analysed is required and (ii) occluded data can be analysed without impacting on the metric results. The method can be used to assess a model's ability to simulate geographical patterns over a range of spatial scales. We illustrate how the method provides a compact and concise way of visualising the degree of agreement between spatial features in two datasets. The application of the new method, its handling of bias and occlusion and the advantages of the novel method are demonstrated through the analysis of model fields from a marine ecosystem model.

scholarly journals Skillful prediction of tropical Pacific fisheries provided by Atlantic Niños

2021 ◽  
Author(s):  
Iñigo Gómara ◽  
Belén Rodríguez-Fonseca ◽  
Elsa Mohino ◽  
Teresa Losada ◽  
Irene Polo ◽  
...  
Keyword(s):  
Large Scale ◽  
Southern Oscillation ◽  
Marine Ecosystem ◽  
Ecosystem Model ◽  
Tropical Pacific ◽  
Equatorial Atlantic ◽  
Climate Conditions ◽  
Marine Food Web ◽  
Marine Ecosystem Model ◽  
The Tropical Pacific

AbstractTropical Pacific upwelling-dependent ecosystems are the most productive and variable worldwide, mainly due to the influence of El Niño Southern Oscillation (ENSO). ENSO can be forecasted seasons ahead thanks to assorted climate precursors (local-Pacific processes, pantropical interactions). However, owing to observational data scarcity and bias-related issues in earth system models, little is known about the importance of these precursors for marine ecosystem prediction. With recently released reanalysis-nudged global marine ecosystem simulations, these constraints can be sidestepped, allowing full examination of tropical Pacific ecosystem predictability. By complementing historical fishing records with marine ecosystem model data, we show herein that equatorial Atlantic Sea Surface Temperatures (SSTs) constitute a superlative predictability source for tropical Pacific marine yields, which can be forecasted over large-scale areas up to 2 years in advance. A detailed physical-biological mechanism is proposed whereby Atlantic SSTs modulate upwelling of nutrient-rich waters in the tropical Pacific, leading to a bottom-up propagation of the climate-related signal across the marine food web. Our results represent historical and near-future climate conditions and provide a useful springboard for implementing a marine ecosystem prediction system in the tropical Pacific.

scholarly journals Global to local impacts on atmospheric CO2 caused by COVID-19 lockdown

2021 ◽  
Author(s):  
Ning Zeng
Keyword(s):  
Fossil Fuel ◽  
Transport Model ◽  
Atmospheric Transport ◽  
Carbon Sink ◽  
Co2 Concentration ◽  
Atmospheric Co2 ◽  
Monitoring Systems ◽  
Carbon Cycle Model ◽  
Safe Level ◽  
Small Change

&lt;p&gt;&lt;span&gt;The world-wide lockdown in response to the COVID-19 pandemic in year 2020 led to economic slowdown and large reduction of fossil fuel CO2 emissions 1,2, but it is unclear how much it would reduce atmospheric CO2 concentration, the main driver of climate change, and whether it can be observed. We estimated that a 7.9% reduction in emissions for 4 months would result in a 0.25 ppm decrease in the Northern Hemisphere CO2, an increment that is within the capability of current CO2 analyzers, but is a few times smaller than natural CO2 variabilities caused by weather and the biosphere such as El Nino. We used a state-of-the-art atmospheric transport model to simulate CO2, driven by a new daily fossil fuel emissions dataset and hourly biospheric fluxes from a carbon cycle model forced with observed climate variability. Our results show a 0.13 ppm decrease in atmospheric column CO2 anomaly averaged over 50S-50N for the period February-April 2020 relative to a 10-year climatology. A similar decrease was observed by the carbon satellite GOSAT3. Using model sensitivity experiments, we further found that COVID, the biosphere and weather contributed 54%, 23%, and 23% respectively. In May 2020, the CO2 anomaly continued to decrease and was 0.36 ppm below climatology, mostly due to the COVID reduction and a biosphere that turned from a relative carbon source to carbon sink, while weather impact fluctuated. This seemingly small change stands out as the largest sub-annual anomaly in the last 10 years. Measurements from global ground stations were analyzed. At city scale, on-road CO2 enhancement measured in Beijing shows reduction of 20-30 ppm, consistent with drastically reduced traffic during the lockdown, while station data suggest that the expected COVID signal of 5-10 ppm was swamped by weather-driven variability on multi-day time scales. The ability of our current carbon monitoring systems in detecting the small and short-lasting COVID signal on the background of fossil fuel CO2 accumulated over the last two centuries is encouraging. The COVID-19 pandemic is an unintended experiment whose impact suggests that to keep atmospheric CO2 at a climate-safe level will require sustained effort of similar magnitude and improved accuracy and expanded spatiotemporal coverage of our monitoring systems.&lt;/span&gt;&lt;/p&gt;

Sign in / Sign up

Export Citation Format

Share Document