scholarly journals Dipole patterns in tropical precipitation were pervasive across landmasses throughout Marine Isotope Stage 5

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Katrina Nilsson-Kerr ◽  
Pallavi Anand ◽  
Philip B. Holden ◽  
Steven C. Clemens ◽  
Melanie J. Leng
Keyword(s):  
Large Scale ◽  
Marine Isotope Stage ◽  
Convergence Zone ◽  
Inter Tropical Convergence Zone ◽  
Tropical Regions ◽  
Tropical Precipitation ◽  
Rainfall Patterns ◽  
Marine Isotope Stage 5 ◽  
Climate Cooling ◽  
The Tropics

AbstractMost of Earth’s rain falls in the tropics, often in highly seasonal monsoon rains, which are thought to be coupled to the inter-hemispheric migrations of the Inter-Tropical Convergence Zone in response to the seasonal cycle of insolation. Yet characterization of tropical rainfall behaviour in the geologic past is poor. Here we combine new and existing hydroclimate records from six large-scale tropical regions with fully independent model-based rainfall reconstructions across the last interval of sustained warmth and ensuing climate cooling between 130 to 70 thousand years ago (Marine Isotope Stage 5). Our data-model approach reveals large-scale heterogeneous rainfall patterns in response to changes in climate. We note pervasive dipole-like tropical precipitation patterns, as well as different loci of precipitation throughout Marine Isotope Stage 5 than recorded in the Holocene. These rainfall patterns cannot be solely attributed to meridional shifts in the Inter-Tropical Convergence Zone.

scholarly journals Detecting and Tracking Coastal Precipitation in the Tropics: Methods and Insights into Multiscale Variability of Tropical Precipitation

2020 ◽  
Vol 33 (15) ◽  
pp. 6689-6705
Author(s):  
David Coppin ◽  
Gilles Bellon ◽  
Alexander Pletzer ◽  
Chris Scott
Keyword(s):  
Diurnal Cycle ◽  
Large Scale ◽  
Madden Julian Oscillation ◽  
Maritime Continent ◽  
Total Rainfall ◽  
Tropical Precipitation ◽  
Precipitation Estimates ◽  
Summer Hemisphere ◽  
The Tropics ◽  
Climate Prediction Center

AbstractWe propose an algorithm to detect and track coastal precipitation systems and we apply it to 18 years of the high-resolution (8 km and 30 min) Climate Prediction Center CMORPH precipitation estimates in the tropics. Coastal precipitation in the Maritime Continent and Central America contributes to up to 80% of the total rainfall. It also contributes strongly to the diurnal cycle over land with the largest contribution from systems lasting between 6 and 12 h and contributions from longer-lived systems peaking later in the day. While the diurnal cycle of coastal precipitation is more intense over land in the summer hemisphere, its timing is independent of seasons over both land and ocean because the relative contributions from systems of different lifespans are insensitive to the seasonal cycle. We investigate the hypothesis that coastal precipitation is enhanced prior to the arrival of the Madden–Julian oscillation (MJO) envelope over the Maritime Continent. Our results support this hypothesis and show that, when considering only coastal precipitation, the diurnal cycle appears reinforced even earlier over islands than previously reported. We discuss the respective roles of coastal and large-scale precipitation in the propagation of the MJO over the Maritime Continent. We also document a shift in diurnal cycle with the phases of the MJO, which results from changes in the relative contributions of short-lived versus long-lived coastal systems.

scholarly journals Large-scale phylogenetic analyses reveal the causes of high tropical amphibian diversity

2013 ◽  
Vol 280 (1770) ◽  
pp. 20131622 ◽  
Author(s):  
R. Alexander Pyron ◽  
John J. Wiens
Keyword(s):  
Species Richness ◽  
Time Scales ◽  
Large Scale ◽  
Phylogenetic Analyses ◽  
Geological Time ◽  
Tropical Regions ◽  
Extinction Rates ◽  
Tropical Diversity ◽  
Limited Dispersal ◽  
The Tropics

Many groups show higher species richness in tropical regions but the underlying causes remain unclear. Despite many competing hypotheses to explain latitudinal diversity gradients, only three processes can directly change species richness across regions: speciation, extinction and dispersal. These processes can be addressed most powerfully using large-scale phylogenetic approaches, but most previous studies have focused on small groups and recent time scales, or did not separate speciation and extinction rates. We investigate the origins of high tropical diversity in amphibians, applying new phylogenetic comparative methods to a tree of 2871 species. Our results show that high tropical diversity is explained by higher speciation in the tropics, higher extinction in temperate regions and limited dispersal out of the tropics compared with colonization of the tropics from temperate regions. These patterns are strongly associated with climate-related variables such as temperature, precipitation and ecosystem energy. Results from models of diversity dependence in speciation rate suggest that temperate clades may have lower carrying capacities and may be more saturated (closer to carrying capacity) than tropical clades. Furthermore, we estimate strikingly low tropical extinction rates over geological time scales, in stark contrast to the dramatic losses of diversity occurring in tropical regions presently.

Convective Entrainment and Large-Scale Organization of Tropical Precipitation: Sensitivity of the CNRM-CM5 Hierarchy of Models

2013 ◽  
Vol 26 (9) ◽  
pp. 2931-2946 ◽  
Author(s):  
Boutheina Oueslati ◽  
Gilles Bellon
Keyword(s):  
Large Scale ◽  
Global Climate Model ◽  
South Pacific Convergence Zone ◽  
Convective Heating ◽  
Convergence Zone ◽  
Systematic Bias ◽  
Moist Convection ◽  
Tropical Precipitation ◽  
Double Itcz ◽  
Hierarchy Of Models

Abstract The spurious double intertropical convergence zone (ITCZ) is a systematic bias affecting state-of-the-art coupled general circulation models (GCMs). Modeling studies show that the ITCZ structure is very sensitive to moist convection parameterization and in particular, to the vertical profile of convective heating and free-tropospheric moistening. To further explore this sensitivity, the authors focus in this study on the influence of lateral entrainment in convective plumes on the simulated tropical precipitation and large-scale circulation. Sensitivity studies to the entrainment parameter were performed in a hierarchy of models (coupled ocean–atmosphere GCM, atmospheric GCM, and aquaplanet GCM), in order to mitigate the double ITCZ problem in the Centre National de Recherches Météorologiques Coupled Global Climate Model, version 5 (CNRM-CM5). The sensitivity of the ITCZ structure to lateral entrainment is robust across our hierarchy of models. In response to increased entrainment, the realistic simulations exhibit a weakening of the southern side of the double ITCZ over the southeastern Pacific Ocean and a better representation of the South Pacific convergence zone (SPCZ). However, as a result of stronger moisture–convection feedbacks, precipitation is overestimated in the center of convergence zones. The change in ITCZ configuration is associated with a more realistic representation of the large-scale vertical regimes, explained by a decreased frequency of weak-to-moderate ascending regimes and an enhanced frequency of subsidence regimes. Mechanisms at play in this circulation change are examined by analyzing the vertically integrated dry static energy budget. This energetic analysis suggests that the feedback between large-scale dynamics and deep convection is crucial in controlling the probability distribution function (PDF) of midtropospheric vertical wind. This PDF, in turn, controls the precipitation distribution and, in particular, the double ITCZ bias.

scholarly journals Southward Intertropical Convergence Zone Shifts and Implications for an Atmospheric Bipolar Seesaw

2013 ◽  
Vol 26 (12) ◽  
pp. 4121-4137 ◽  
Author(s):  
Ivana Cvijanovic ◽  
Peter L. Langen ◽  
Eigil Kaas ◽  
Peter D. Ditlevsen
Keyword(s):  
Water Vapor ◽  
High Latitude ◽  
Intertropical Convergence Zone ◽  
Hadley Cell ◽  
Convergence Zone ◽  
Two Phase ◽  
High Northern Latitude ◽  
Tropical Precipitation ◽  
The Tropics ◽  
Southern High Latitude

Abstract In this study, southward intertropical convergence zone (ITCZ) shifts are investigated in three different scenarios: Northern Hemispheric cooling, Southern Hemispheric warming, and a bipolar seesaw-like forcing that combines the latter two. The experiments demonstrate the mutual effects that northern- and southern-high-latitude forcings exert on tropical precipitation, suggesting a time-scale-dependent dominance of northern versus southern forcings. In accordance with this, two-phase tropical precipitation shifts are suggested, involving a fast component dominated by the high-northern-latitude forcing and a slower component due to the southern-high-latitude forcing. The results may thus be useful for the future understanding and interpretation of high-resolution tropical paleoprecipitation proxies and their relation to high-latitude records (e.g., ice core data). The experiments also show that Southern Ocean warming has a global impact, affecting both the tropics and northern extratropics, as seen in a southward ITCZ shift and mid- and high-latitude North Atlantic surface temperature and wind changes. In terms of dynamical considerations, the tropical circulation response to high-latitude forcing is found to be nonlinear: the atmospheric heat transport and Hadley cell anomalies differ significantly (in magnitude) when comparing the warming and cooling experiments. These are related to different interhemispheric temperature gradients that are altered mainly by nonlinearities in water vapor response. Decomposition of the top-of-the-atmosphere flux response into atmospheric feedback effects shows the dominance of water vapor and cloud feedbacks in the tropics, with the longwave cloud feedback effect governing the overall cloud response.

scholarly journals Projected impacts of climate change and ocean acidification on the global biogeography of planktonic foraminifera

2014 ◽  
Vol 11 (6) ◽  
pp. 10083-10121
Author(s):  
T. Roy ◽  
F. Lombard ◽  
L. Bopp ◽  
M. Gehlen
Keyword(s):  
Climate Change ◽  
Ocean Acidification ◽  
Food Availability ◽  
Large Scale ◽  
Planktonic Foraminifera ◽  
Global Ocean ◽  
Tropical Regions ◽  
Carbonate Concentration ◽  
Calcite Saturation ◽  
The Tropics

Abstract. Planktonic foraminifera are a major contributor to the deep carbonate-flux and the planktonic biomass of the global ocean. Their microfossil deposits form one of the richest databases for reconstructing paleoenvironments, particularly through changes in their taxonomic and shell composition. Using an empirically-based foraminifer model that incorporates three known major physiological drivers of foraminifer biogeography – temperature, food and light – we investigate (i) the global redistribution of planktonic foraminifera under anthropogenic climate change, and (ii) the alteration of the carbonate chemistry of foraminifer habitat with ocean acidification. The present-day and future (2090–2100) 3-D distributions of foraminifera are simulated using temperature, plankton biomass, and light from an Earth system model forced with historical and a future (IPCC A2) high CO2 emission scenario. The broadscale patterns of present day foraminifer biogeography are well reproduced. Foraminifer abundance and diversity are projected to decrease in the tropics and subpolar regions and increase in the subtropics and around the poles. In the tropics, the geographical shifts are driven by temperature, while the vertical shifts are driven by both temperature and food availability. In the high-latitudes, vertical shifts are driven by food availability, while geographical shifts are driven by both food availability and temperature. Changes in the marine carbon cycle would be expected in response to (i) the large-scale rearrangements in foraminifer abundance, and (ii) the reduction of the carbonate concentration in the habitat range of planktonic foraminifers: from 10–30 μmol kg−1 in the polar/subpolar regions to 30–70 μmol kg−1 in the subtropical/tropical regions. High-latitude species are most vulnerable to anthropogenic change: their abundance and available habitat decrease and up to 10% of their habitat drops below the calcite saturation horizon.

ICE-CORED ROCK GLACIERS IN ANTARCTICA: RECORDING GLACIAL ADVANCES FROM MARINE ISOTOPE STAGE 5 TO THE HOLOCENE

2019 ◽  
Author(s):  
Kate M. Swanger ◽  
◽  
Kelsey Winsor ◽  
Esther Babcock ◽  
Rachel D. Valletta ◽  
...  
Keyword(s):  
Marine Isotope Stage ◽  
The Holocene ◽  
Rock Glaciers ◽  
Marine Isotope Stage 5

Beyond arrows on a map: The dynamics of Homo sapiens dispersal and occupation of Arabia during Marine Isotope Stage 5

2021 ◽  
Vol 62 ◽  
pp. 101269
Author(s):  
Samuel Luke Nicholson ◽  
Rob Hosfield ◽  
Huw S. Groucutt ◽  
Alistair W.G. Pike ◽  
Dominik Fleitmann
Keyword(s):  
Homo Sapiens ◽  
Marine Isotope Stage ◽  
Marine Isotope Stage 5

scholarly journals Global climatology and trends in convective environments from ERA5 and rawinsonde data

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Mateusz Taszarek ◽  
John T. Allen ◽  
Mattia Marchio ◽  
Harold E. Brooks
Keyword(s):  
Large Scale ◽  
Climate Models ◽  
Global Climate ◽  
Convective Available Potential Energy ◽  
Global Climate Models ◽  
Convective Precipitation ◽  
The Past ◽  
The Tropics ◽  
Rawinsonde Data

AbstractGlobally, thunderstorms are responsible for a significant fraction of rainfall, and in the mid-latitudes often produce extreme weather, including large hail, tornadoes and damaging winds. Despite this importance, how the global frequency of thunderstorms and their accompanying hazards has changed over the past 4 decades remains unclear. Large-scale diagnostics applied to global climate models have suggested that the frequency of thunderstorms and their intensity is likely to increase in the future. Here, we show that according to ERA5 convective available potential energy (CAPE) and convective precipitation (CP) have decreased over the tropics and subtropics with simultaneous increases in 0–6 km wind shear (BS06). Conversely, rawinsonde observations paint a different picture across the mid-latitudes with increasing CAPE and significant decreases to BS06. Differing trends and disagreement between ERA5 and rawinsondes observed over some regions suggest that results should be interpreted with caution, especially for CAPE and CP across tropics where uncertainty is the highest and reliable long-term rawinsonde observations are missing.

scholarly journals Large-scale screening of natural genetic resource in the hydrocarbon-producing microalga Botrycoccus braunii identified novel fast-growing strains

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Koji Kawamura ◽  
Suzune Nishikawa ◽  
Kotaro Hirano ◽  
Ardianor Ardianor ◽  
Rudy Agung Nugroho ◽  
...  
Keyword(s):  
Large Scale ◽  
Biomass Productivity ◽  
Botryococcus Braunii ◽  
Algal Biofuel ◽  
Fast Growing ◽  
Wild Strains ◽  
Glass Tubes ◽  
The Tropics ◽  
Large Scale Screening ◽  
Hydrocarbon Productivity

AbstractAlgal biofuel research aims to make a renewable, carbon–neutral biofuel by using oil-producing microalgae. The freshwater microalga Botryococcus braunii has received much attention due to its ability to accumulate large amounts of petroleum-like hydrocarbons but suffers from slow growth. We performed a large-scale screening of fast-growing strains with 180 strains isolated from 22 ponds located in a wide geographic range from the tropics to cool-temperate. A fast-growing strain, Showa, which recorded the highest productivities of algal hydrocarbons to date, was used as a benchmark. The initial screening was performed by monitoring optical densities in glass tubes and identified 9 wild strains with faster or equivalent growth rates to Showa. The biomass-based assessments showed that biomass and hydrocarbon productivities of these strains were 12–37% and 11–88% higher than that of Showa, respectively. One strain, OIT-678 established a new record of the fastest growth rate in the race B strains with a doubling time of 1.2 days. The OIT-678 had 36% higher biomass productivity, 34% higher hydrocarbon productivity, and 20% higher biomass density than Showa at the same cultivation conditions, suggesting the potential of the new strain to break the record for the highest productivities of hydrocarbons.

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