scholarly journals Improved dryland carbon flux predictions with explicit consideration of water-carbon coupling

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Mallory L. Barnes ◽  
Martha M. Farella ◽  
Russell L. Scott ◽  
David J. P. Moore ◽  
Guillermo E. Ponce-Campos ◽  
...  
Keyword(s):  
Interannual Variability ◽  
Large Scale ◽  
Carbon Sink ◽  
American Southwest ◽  
Carbon Uptake ◽  
The North ◽  
Explicit Consideration ◽  
Dryland Ecosystems ◽  
Meteorological Observations ◽  
Terrestrial Carbon Sink

AbstractDryland ecosystems are dominant influences on both the trend and interannual variability of the terrestrial carbon sink. Despite their importance, dryland carbon dynamics are not well-characterized by current models. Here, we present DryFlux, an upscaled product built on a dense network of eddy covariance sites in the North American Southwest. To estimate dryland gross primary productivity, we fuse in situ fluxes with remote sensing and meteorological observations using machine learning. DryFlux explicitly accounts for intra-annual variation in water availability, and accurately predicts interannual and seasonal variability in carbon uptake. Applying DryFlux globally indicates existing products may underestimate impacts of large-scale climate patterns on the interannual variability of dryland carbon uptake. We anticipate DryFlux will be an improved benchmark for earth system models in drylands, and prompt a more sensitive accounting of water limitation on the carbon cycle.

scholarly journals Past megadroughts in central Europe were longer, more severe and less warm than modern droughts

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
M. Ionita ◽  
M. Dima ◽  
V. Nagavciuc ◽  
P. Scholz ◽  
G. Lohmann
Keyword(s):  
Central Europe ◽  
North Atlantic Ocean ◽  
Explosive Volcanism ◽  
American Southwest ◽  
The North ◽  
European Climate ◽  
Blocking Activity ◽  
Meteorological Observations ◽  
Dalton Minimum

AbstractMegadroughts are notable manifestations of the American Southwest, but not so much of the European climate. By using long-term hydrological and meteorological observations, as well as paleoclimate reconstructions, here we show that central Europe has experienced much longer and severe droughts during the Spörer Minimum (~AD 1400–1480) and Dalton Minimum (~AD 1770–1840), than the ones observed during the 21st century. These two megadroughts appear to be linked with a cold state of the North Atlantic Ocean and enhanced winter atmospheric blocking activity over the British Isles and western part of Europe, concurrent with reduced solar forcing and explosive volcanism. Moreover, we show that the recent drought events (e.g., 2003, 2015, and 2018), are within the range of natural variability and they are not unprecedented over the last millennium.

scholarly journals The South Atlantic Subtropical High: Climatology and Interannual Variability

2017 ◽  
Vol 30 (9) ◽  
pp. 3279-3296 ◽  
Author(s):  
Xiaoming Sun ◽  
Kerry H. Cook ◽  
Edward K. Vizy
Keyword(s):  
Interannual Variability ◽  
Annual Cycle ◽  
Large Scale ◽  
Austral Summer ◽  
Southern Annular Mode ◽  
South Atlantic ◽  
Subtropical High ◽  
Interannual Variations ◽  
The South ◽  
The North

ERA-Interim and JRA-55 reanalysis products are analyzed to document the annual cycle of the South Atlantic subtropical high (SASH) and examine how its interannual variability relates to regional and large-scale climate variability. The annual cycle of the SASH is found to have two peaks in both intensity and size. The SASH is strongest and largest during the solstitial months when its center is either closest to the equator and on the western side of the South Atlantic basin during austral winter or farthest poleward and in the center of the basin in late austral summer. Although interannual variations in the SASH’s position are larger in the zonal direction, the intensity of the high decreases when it is positioned to the north. This relationship is statistically significant in every month. Seasonal composites and EOF analysis indicate that meridional changes in the position of the SASH dominate interannual variations in austral summer. In particular, the anticyclone tends to be displaced poleward in La Niña years when the southern annular mode (SAM) is in its positive phase and vice versa. Wave activity flux vectors suggest that ENSO-related convective anomalies located in the central-eastern tropical Pacific act as a remote forcing for the meridional variability of the summertime SASH. In southern winter, multiple processes operate in concert to induce interannual variability, and none of them appears to dominate like ENSO does during the summer.

scholarly journals Drivers of 21<sup>st</sup> Century carbon cycle variability in the North Atlantic Ocean

2019 ◽  
Author(s):  
Matthew P. Couldrey ◽  
Kevin I. C. Oliver ◽  
Andrew Yool ◽  
Paul R. Halloran ◽  
Eric P. Achterberg
Keyword(s):  
Soft Tissue ◽  
Interannual Variability ◽  
North Atlantic ◽  
Decadal Variability ◽  
Dissolved Inorganic Carbon ◽  
Carbon Sink ◽  
Co2 Uptake ◽  
The North ◽  
Anthropogenic Carbon ◽  
The North Atlantic

Abstract. The North Atlantic carbon sink is a prominent component of global climate, storing large amounts of atmospheric carbon dioxide (CO2), but this basin’s CO2 uptake variability presents challenges for future climate prediction. A comprehensive mechanistic understanding of the processes that give rise to year-to-year (interannual) and decade-to-decade (decadal) variability in the North Atlantic’s dissolved inorganic carbon (DIC) inventory is lacking. Here, we numerically simulate the oceanic response to human-induced (anthropogenic) climate change from the industrial era to the year 2100. The model distinguishes how different physical, chemical, and biological processes modify the basin’s DIC inventory; the saturation, soft tissue, and carbonate pumps, anthropogenic emissions, and other processes causing air-sea disequilibria. There are four ‘natural’ pools (saturation, soft tissue, carbonate, and disequilibrium), and an ‘anthropogenic’ pool. Interannual variability of the North Atlantic DIC inventory arises primarily due to temperature- and alkalinity-induced changes in carbon solubility (saturation concentrations). A mixture of saturation and anthropogenic drivers cause decadal variability. Multidecadal variability results from the opposing effects of saturation versus soft tissue carbon, and anthropogenic carbon uptake. By the year 2100, the North Atlantic gains 66 Pg (1 Pg = 1015 grams) of anthropogenic carbon, and the natural carbon pools collectively decline by 4.8 Pg. The first order controls on interannual variability of the North Atlantic carbon sink size are therefore largely physical, and the biological pump emerges as an important driver of change on multidecadal timescales. Further work should identify specifically which physical processes underlie the interannual saturation-dominated DIC variability documented here.

scholarly journals The Interannual Variability of Tropical Cyclones

2007 ◽  
Vol 135 (10) ◽  
pp. 3587-3598 ◽  
Author(s):  
William M. Frank ◽  
George S. Young
Keyword(s):  
Tropical Cyclone ◽  
Interannual Variability ◽  
Tropical Cyclones ◽  
Large Scale ◽  
Storm Activity ◽  
Modes Of Variability ◽  
The North ◽  
Temporal And Spatial ◽  
Using Data ◽  
The North Atlantic Oscillation

Abstract This paper examines the interannual variability of tropical cyclones in each of the earth’s cyclone basins using data from 1985 to 2003. The data are first analyzed using a Monte Carlo technique to investigate the long-standing myth that the global number of tropical cyclones is less variable than would be expected from examination of the variability in each basin. This belief is found to be false. Variations in the global number of all tropical cyclones are indistinguishable from those that would be expected if each basin was examined independently of the others. Furthermore, the global number of the most intense storms (Saffir–Simpson categories 4–5) is actually more variable than would be expected because of an observed tendency for storm activity to be correlated between basins, and this raises important questions as to how and why these correlations arise. Interbasin correlations and factor analysis of patterns of tropical cyclone activity reveal that there are several significant modes of variability. The largest three factors together explain about 70% of the variance, and each of these factors shows significant correlation with ENSO, the North Atlantic Oscillation (NAO), or both, with ENSO producing the largest effects. The results suggest that patterns of tropical cyclone variability are strongly affected by large-scale modes of interannual variability. The temporal and spatial variations in storm activity are quite different for weaker tropical cyclones (tropical storm through category 2 strength) than for stronger storms (categories 3–5). The stronger storms tend to show stronger interbasin correlations and stronger relationships to ENSO and the NAO than do the weaker storms. This suggests that the factors that control tropical cyclone formation differ in important ways from those that ultimately determine storm intensity.

scholarly journals Climate-driven shifts in continental net primary production implicated as a driver of a recent abrupt increase in the land carbon sink

2016 ◽  
Vol 13 (5) ◽  
pp. 1597-1607 ◽  
Author(s):  
Wolfgang Buermann ◽  
Claudie Beaulieu ◽  
Bikash Parida ◽  
David Medvigy ◽  
George J. Collatz ◽  
...  
Keyword(s):  
Climate Variability ◽  
Primary Production ◽  
North Atlantic ◽  
Large Scale ◽  
Net Primary Production ◽  
Carbon Sink ◽  
Northern Eurasia ◽  
Sink Strength ◽  
Independent Evidence ◽  
The North

Abstract. The world's ocean and land ecosystems act as sinks for anthropogenic CO2, and over the last half century their combined sink strength grew steadily with increasing CO2 emissions. Recent analyses of the global carbon budget, however, have uncovered an abrupt, substantial ( ∼  1 PgC yr−1) and sustained increase in the land sink in the late 1980s whose origin remains unclear. In the absence of this prominent shift in the land sink, increases in atmospheric CO2 concentrations since the late 1980s would have been  ∼  30 % larger than observed (or  ∼  12 ppm above current levels). Global data analyses are limited in regards to attributing causes to changes in the land sink because different regions are likely responding to different drivers. Here, we address this challenge by using terrestrial biosphere models constrained by observations to determine if there is independent evidence for the abrupt strengthening of the land sink. We find that net primary production significantly increased in the late 1980s (more so than heterotrophic respiration), consistent with the inferred increase in the global land sink, and that large-scale climate anomalies are responsible for this shift. We identify two key regions in which climatic constraints on plant growth have eased: northern Eurasia experienced warming, and northern Africa received increased precipitation. Whether these changes in continental climates are connected is uncertain, but North Atlantic climate variability is important. Our findings suggest that improved understanding of climate variability in the North Atlantic may be essential for more credible projections of the land sink under climate change.

High-Resolution Climatic Analysis and Southwest Biogeography

Science ◽  
1986 ◽  
Vol 232 (4746) ◽  
pp. 27-34 ◽  
Author(s):  
RONALD P. NEILSON
Keyword(s):  
Large Scale ◽  
Ecological Monitoring ◽  
American Southwest ◽  
Photosynthetic Pathway ◽  
Desert Shrubs ◽  
The North ◽  
High Frequency Variability ◽  
Effect Relation ◽  
Effect Hypothesis

Meteorologists and climatologists have produced significant new data on the fluid dynamics of the atmosphere, thus allowing biologists to examine more closely the cause-effect relation between the large-scale structure of the atmosphere and the dominant patterns of global biogeography. The inability to characterize the high-frequency variability of the weather has constrained such efforts. A method that allows year-to-year patterns of weather variability to be characterized in the contexts of global warming and cooling trends is applied in a combined analysis of long-term monthly weather records and data from an ecological monitoring project in southern New Mexico. The analysis suggests a cause-effect hypothesis of recent desertification in the North American Southwest. The links between the atmosphere and the biosphere are based on the fundamentally different responses to specific weather regimes of semidesert grasses with a C4photosynthetic pathway and desert shrubs with a C3photosynthetic pathway. The hypothesis appears to be of sufficient generality to explain the complex, but well-documented, floristic changes that have occurred in the same region since the last glacial maximum.

scholarly journals Forests dominate the interannual variability of the North American carbon sink

2018 ◽  
Vol 13 (8) ◽  
pp. 084015 ◽  
Author(s):  
Yoichi P Shiga ◽  
Anna M Michalak ◽  
Yuanyuan Fang ◽  
Kevin Schaefer ◽  
Arlyn E Andrews ◽  
...  
Keyword(s):  
Interannual Variability ◽  
North American ◽  
Carbon Sink ◽  
The North

scholarly journals Global evaluation of nutrient enabled version land surface model ORCHIDEE-CNP v1.2 (r5986)

2020 ◽  
Author(s):  
Yan Sun ◽  
Daniel S. Goll ◽  
Jinfeng Chang ◽  
Philippe Ciais ◽  
Betrand Guenet ◽  
...  
Keyword(s):  
Land Surface ◽  
Large Scale ◽  
Production Efficiency ◽  
Carbon Sink ◽  
A Priori ◽  
Land Surface Model ◽  
Terrestrial Ecosystems ◽  
Surface Model ◽  
Global Evaluation ◽  
The North

Abstract. The availability of phosphorus (P) and nitrogen (N) constrain the ability of ecosystems to use resources such as light, water and carbon. In turn, nutrients impact the distribution of productivity, ecosystem carbon turnovers and their net exchange of CO2 with the atmosphere in response to variation of environmental conditions both in space and in time. In this study, we evaluated the performance of the global version of the land surface model ORCHIDEE-CNP (v1.2) which explicitly simulates N and P biogeochemistry in terrestrial ecosystems coupled with carbon, water and energy transfers. We used data from remote-sensing, ground-based measurement networks and ecological databases. Components of the N and P cycle at different levels of aggregation (from local to global) are in good agreement with data-driven estimates. When integrated for the period 1850 to 2017 forced with variable climate, rising CO2 and land use change, we show that ORCHIDEE-CNP underestimates the land carbon sink in the North Hemisphere (NH) during the recent decades, despite an a priori realistic GPP response to rising CO2. This result suggests either that other processes than CO2 fertilization which are omitted in ORCHIDEE-CNP, such as changes in biomass turnover, are predominant drivers of the northern land sink, and/or that the model parameterizations produce too strict emerging nutrient limitations on biomass growth in northern areas. In line with the latter, we identified biases in the simulated large-scale patterns of leaf and soil stoichiometry and plant P use efficiency pointing towards a too severe P limitations towards the poles. Based on our analysis of ecosystem resource use efficiencies and nutrient cycling, we propose ways to address the model biases by giving priority to better representing processes of soil organic P mineralization and soil inorganic P transformation, followed by refining the biomass production efficiency under increasing atmospheric CO2, phenology dynamics and canopy light absorption.

Projecting long-term soil organic dynamics in Australia's rangelands

2021 ◽  
Author(s):  
Mingxi Zhang ◽  
Raphael Viscarra Rossel
Keyword(s):  
Short Term Memory ◽  
Carbon Sink ◽  
Soil C ◽  
Tropical Regions ◽  
Explanatory Variables ◽  
The North ◽  
Terrestrial Carbon Sink ◽  
Organic Carbon Stock ◽  
Trees And Shrubs

&lt;p&gt;Rangelands in Australia are vast and occupy more than 80% of the continental land area. They extend across arid, semi-arid, and the tropical regions with seasonal, variable rainfall in the north. They include diverse, relatively undisturbed grasslands, shrublands, woodlands and tropical savanna ecosystems. They represent Australia&amp;#8217;s largest terrestrial carbon sink as they account for almost 70% of Australia's total soil organic carbon stock (Viscarra Rossel et al., 2014), more than all above-ground sources of carbon (native grasses, trees and shrubs) in these regions (Gifford et al., 1992). Here we have developed a novel space-time approach for projecting the long-term C dynamics of rangelands soils using Long Short-Term Memory (LSTM) deep learning neural networks. We further demonstrate how the networks might be interpreted and quantified the influence of explanatory variables on the spatiotemporal dynamics of soil C in these regions. Our results provide an improved ability to accurately model long-term carbon dynamics, which is needed to confidently predict changes in soil C from change in climate or anthropogenic disturbance. The information is critical for improving our understanding of soil C in these regions and for understanding the potential for sequestering C in the rangelands.&lt;/p&gt;

scholarly journals Interannual variability of winter precipitation in the European Alps: relations with the North Atlantic Oscillation

2008 ◽  
Vol 5 (4) ◽  
pp. 2045-2065 ◽  
Author(s):  
E. Bartolini ◽  
P. Claps ◽  
P. D'Odorico
Keyword(s):  
Water Resources ◽  
Interannual Variability ◽  
Large Scale ◽  
Mechanistic Explanation ◽  
Winter Precipitation ◽  
European Alps ◽  
Small Areas ◽  
The North ◽  
The Alps ◽  
The North Atlantic Oscillation

Abstract. The European Alps rely on winter precipitation for various needs in terms of hydropower and other water uses. Major European rivers originate from the Alps and rely on winter precipitation and the consequent spring snow melt for their summer base flows. Understanding the fluctuations in winter rainfall in this region is crucially important to the study of changes in hydrologic regime in streams and rivers, as well as to the management of their water resources. Despite the recognized relevance of winter precipitation to the water resources of the Alps and surrounding regions, the magnitude and mechanistic explanation of interannual precipitation variability in the Alpine region remain unclear and poorly investigated. Here we use gridded precipitation data from the CRU TS 1.2 to study the interannual variability of winter alpine precipitation. We found that the Alps are the region with the highest interannual variability in winter precipitation in Europe. This variability cannot be completely explained by large scale climate patterns such as the AO, NAO or the EA-WR, even though regions below and above the Alps demonstrate connections with these patterns. Significant trends were detected only in small areas within this region, and were of opposite sign between the eastern and western part of the Alps.

Sign in / Sign up

Export Citation Format

Share Document