scholarly journals Coastal Wave Extremes around the Pacific and Their Remote Seasonal Connection to Climate Modes

Climate ◽  
2021 ◽  
Vol 9 (12) ◽  
pp. 168
Author(s):  
Julien Boucharel ◽  
Loane Santiago ◽  
Rafael Almar ◽  
Elodie Kestenare
Keyword(s):  
Large Scale ◽  
Wind Wave ◽  
Boreal Summer ◽  
Opposite Hemisphere ◽  
Ocean Surface Waves ◽  
First Order ◽  
Coastal Waves ◽  
The Pacific ◽  
Wide Range ◽  
The Tropics

At first order, wind-generated ocean surface waves represent the dominant forcing of open-coast morpho-dynamics and associated vulnerability over a wide range of time scales. It is therefore paramount to improve our understanding of the regional coastal wave variability, particularly the occurrence of extremes, and to evaluate how they are connected to large-scale atmospheric regimes. Here, we propose a new “2-ways wave tracking algorithm” to evaluate and quantify the open-ocean origins and associated atmospheric forcing patterns of coastal wave extremes all around the Pacific basin for the 1979–2020 period. Interestingly, the results showed that while extreme coastal events tend to originate mostly from their closest wind-forcing regime, the combined influence from all other remote atmospheric drivers is similar (55% local vs. 45% remote) with, in particular, ~22% coming from waves generated remotely in the opposite hemisphere. We found a strong interconnection between the tropical and extratropical regions with around 30% of coastal extremes in the tropics originating at higher latitudes and vice-versa. This occurs mostly in the boreal summer through the increased seasonal activity of the southern jet-stream and the northern tropical cyclone basins. At interannual timescales, we evidenced alternatingly increased coastal wave extremes between the western and eastern Pacific that emerge from the distinct seasonal influence of ENSO in the Northern and SAM in the Southern Hemisphere on their respective paired wind-wave regimes. Together these results pave the way for a better understanding of the climate connection to wave extremes, which represents the preliminary step toward better regional projections and forecasts of coastal waves.

Blueprints for Tropical Dairy Farming

2017 ◽  
Author(s):  
John Moran ◽  
Philip Chamberlain
Keyword(s):  
Developing Countries ◽  
Best Management Practices ◽  
Large Scale ◽  
Management Practices ◽  
Production Systems ◽  
Dairy Farming ◽  
Dairy Herds ◽  
Dairy Production ◽  
Wide Range ◽  
The Tropics

Blueprints for Tropical Dairy Farming provides insight into the logistics, infrastructure and management required for the development of small and large dairy farms in tropical developing countries. Farmers will learn how to improve the welfare, milk quality and productivity of their dairy herds. This book complements author John Moran’s five previous books on the principles of tropical dairy farming. The manual covers a wide range of topics related to ensuring the sustainability of dairy production systems in tropical developing countries, such as South and East Asia, Africa and Central America. It also provides guidelines for the best management practices of large-scale, more intensive dairy systems. While smallholder farms are the major suppliers of milk in the tropics, many larger farms are becoming established throughout the tropics to satisfy the increasing demands for fresh milk. Blueprints for Tropical Dairy Farming will be a valuable resource for farmers and stockpeople who want to improve the productive performance of their dairy herds, farm advisers who can assist farmers to achieve this aim, educators who develop training programs for farmers or who train dairy advisers in the basics of dairy production technology, and other stakeholders in tropical dairy production, such as local agribusiness, policy makers and research scientists. National and international agencies will learn new insights into the required long-term logistics for regional dairy development, while potential investors will acquire knowledge into intensive tropical dairy farming.

scholarly journals The Climatological Analysis of Typhoon Tracks, Steering Flow, and the Pacific Subtropical High in the Vicinity of Taiwan and the Western North Pacific

Atmosphere ◽  
2020 ◽  
Vol 11 (5) ◽  
pp. 543
Author(s):  
Chih-wen Hung ◽  
Ming-Fu Shih ◽  
Te-Yuan Lin
Keyword(s):  
Tropical Cyclones ◽  
Large Scale ◽  
Subtropical High ◽  
Boreal Summer ◽  
The South ◽  
The West ◽  
Steering Flow ◽  
The Pacific ◽  
Typhoon Season ◽  
Typhoon Tracks

Taiwan frequently suffers from typhoon hits in the boreal summer and fall. The location of Taiwan makes it vulnerable to the pathways of typhoons mainly determined by the position of the Pacific subtropical high. In order to clarify the linkage between typhoon invasion and associated large-scale environments from a climatological perspective, this study counts the historical typhoon invasion days for each month in the typhoon season to establish analyzed cases and then categorizes them with statistical thresholds. Besides, the categorized cases with less typhoon invasion are further sorted to distinguish different movements of tropical cyclones. Therefore, corresponding composites are applied for each category. The results reveal that when the subtropical high retreats eastward, the accompanying steering flow guides typhoons to make an early recurvature toward Japan and South Korea. While the subtropical high further extends its property to the west covering Taiwan, the steering flow on the south transfers typhoons moving westward to the South China Sea. However, when the subtropical high lies in areas between the above two scenarios, the steering flow along the periphery of the subtropical high continuously sends typhoons toward Taiwan and the vicinity, which greatly increases the threat to the island.

scholarly journals Seamless Precipitation Prediction Skill in the Tropics and Extratropics from a Global Model

2014 ◽  
Vol 142 (4) ◽  
pp. 1556-1569 ◽  
Author(s):  
Hongyan Zhu ◽  
Matthew C. Wheeler ◽  
Adam H. Sobel ◽  
Debra Hudson
Keyword(s):  
Lead Time ◽  
Southern Oscillation ◽  
Time Windows ◽  
Austral Summer ◽  
Local Maximum ◽  
Boreal Summer ◽  
Moist Convection ◽  
The Pacific ◽  
Using Data ◽  
The Tropics

Abstract The skill with which a coupled ocean–atmosphere model is able to predict precipitation over a range of time scales (days to months) is analyzed. For a fair comparison across the seamless range of scales, the verification is performed using data averaged over time windows equal in length to the lead time. At a lead time of 1 day, skill is greatest in the extratropics around 40°–60° latitude and lowest around 20°, and has a secondary local maximum close to the equator. The extratropical skill at this short range is highest in the winter hemisphere, presumably due to the higher predictability of winter baroclinic systems. The local equatorial maximum comes mostly from the Pacific Ocean, and thus appears to be mostly from El Niño–Southern Oscillation (ENSO). As both the lead time and averaging window are simultaneously increased, the extratropical skill drops rapidly with lead time, while the equatorial maximum remains approximately constant, causing the equatorial skill to exceed the extratropical at leads of greater than 4 days in austral summer and 1 week in boreal summer. At leads longer than 2 weeks, the extratropical skill flattens out or increases, but remains below the equatorial values. Comparisons with persistence confirm that the model beats persistence for most leads and latitudes, including for the equatorial Pacific where persistence is high. The results are consistent with the view that extratropical predictability is mostly derived from synoptic-scale atmospheric dynamics, while tropical predictability is primarily derived from the response of moist convection to slowly varying forcing such as from ENSO.

scholarly journals Impact of the Indonesian Throughflow on Agulhas leakage

Ocean Science ◽  
2013 ◽  
Vol 9 (5) ◽  
pp. 773-785 ◽  
Author(s):  
D. Le Bars ◽  
H. A. Dijkstra ◽  
W. P. M. De Ruijter
Keyword(s):  
Large Scale ◽  
Ocean Model ◽  
Global Ocean ◽  
Momentum Balance ◽  
Indonesian Throughflow ◽  
Current Transport ◽  
Flat Bottom ◽  
Agulhas Current ◽  
The Pacific ◽  
Wide Range

Abstract. Using ocean models of different complexity we show that opening the Indonesian Passage between the Pacific and the Indian oceans increases the input of Indian Ocean water into the South Atlantic via the Agulhas leakage. In a strongly eddying global ocean model this response results from an increased Agulhas Current transport and a constant proportion of Agulhas retroflection south of Africa. The leakage increases through an increased frequency of ring shedding events. In an idealized two-layer and flat-bottom eddy resolving model, the proportion of the Agulhas Current transport that retroflects is (for a wide range of wind stress forcing) not affected by an opening of the Indonesian Passage. Using a comparison with a linear model and previous work on the retroflection problem, the result is explained as a balance between two mechanisms: decrease retroflection due to large-scale momentum balance and increase due to local barotropic/baroclinic instabilities.

scholarly journals A Simple Model of the Life Cycle of Mesoscale Convective Systems Cloud Shield in the Tropics

2017 ◽  
Vol 30 (11) ◽  
pp. 4283-4298 ◽  
Author(s):  
R. Roca ◽  
T. Fiolleau ◽  
D. Bouniol
Keyword(s):  
Life Cycle ◽  
Simple Model ◽  
Large Scale ◽  
Morphological Characteristics ◽  
Mesoscale Convective Systems ◽  
Boreal Summer ◽  
Maximum Extent ◽  
Convective Systems ◽  
Mesoscale Convective ◽  
The Tropics

Abstract Mesoscale convective systems (MCSs) are important to the water and energy budget of the tropical climate and are essential ingredients of the tropical circulation. MCSs are readily observed in satellite infrared geostationary imagery as cloud clusters that evolve in time from small structures to well-organized large patches of cloud shield before dissipating. The MCS cloud shield is the result of a large ensemble of mesoscale dynamical, thermodynamical, and microphysical processes. This study shows that a simple parametric model can summarize the time evolution of the morphological characteristics of the cloud shield during the life cycle of the MCS. It consists of a growth–decay linear model of the cloud shield and is based on three parameters: the time of maximum extent, the maximum extent, and the duration of the MCS. It is shown that the time of maximum is frequently close to the middle of the life cycle and that the correlation between maximum extent and duration is strong all over the tropics. This suggests that 1 degree of freedom is left to summarize the life cycle of the MCS cloud shield. Such a model fits the observed MCS equally well, independent of the duration, size, location, and propagation characteristics, and its relevance is assessed for a large number of MCSs over three boreal summer periods over the whole tropical belt. The scaling of this simple model exhibits weak (strong) regional variability for the short- (long-) lived systems indicative of the primary importance of the internal dynamics of the systems to the large-scale environment for MCS sustainability.

scholarly journals Large-scale transport into the Arctic: the roles of the midlatitude jet and the Hadley Cell

2018 ◽  
Author(s):  
Huang Yang ◽  
Darryn W. Waugh ◽  
Clara Orbe ◽  
Guang Zeng ◽  
Olaf Morgenstern ◽  
...  
Keyword(s):  
Large Scale ◽  
Climate Model ◽  
Source Region ◽  
Underlying Mechanism ◽  
Meridional Flow ◽  
Hadley Cell ◽  
The Arctic ◽  
Boreal Summer ◽  
The Pacific ◽  
Fixed Lifetime

Abstract. Transport from the Northern Hemisphere (NH) midlatitudes to the Arctic plays a crucial role in determining the abundance of trace gases and aerosols that are important to Arctic climate via impacts on radiation and chemistry. Here we examine this transport using an idealized tracer with fixed lifetime and predominantly midlatitude land-based sources in models participating in the Chemistry Climate Model Initiative (CCMI). We show that there is a 20 %–40 % difference in the Arctic concentrations of this tracer among the models. This spread is found to be generally related to the spread in location of the Pacific jet, with lower Arctic tracer concentrations occurring in models with a more northern jet, during both winter and summer. However, the underlying mechanism for this relationship does not involve the jet directly, but instead involves differences in the surface meridional flow over the tracer source region, that vary with jet latitude. Specifically, in models with a more northern jet, the Hadley Cell (HC) generally extends further north and the tracer source region is mostly covered by surface southward flow associated with the lower branch of the HC, resulting in less efficient transport poleward to the Arctic. During boreal summer, there are poleward biases in jet location in free-running models, and these models likely underestimate the rate of transport into the Arctic. Models using specified dynamics do not have biases in the jet location, but do have biases in the surface meridional flow, which results in differences in the transport into the Arctic. In addition to the land-based tracer, the midlatitude-to-Arctic transport is further examined by another idealized tracer with zonally uniform sources. With equal sources from lands and oceans, the intermodel spread of this zonally uniform tracer is more related to variations of parameterized convection over oceans than variations of HC extent particularly during boreal summer. This suggests that transport of land-based and oceanic tracers or aerosols towards the Arctic differ in pathways and therefore their corresponding intermodel variabilities result from different physical processes.

scholarly journals A Transbasin Mode of Interannual Variability of the Central American Gap Winds: Seasonality and Large-Scale Forcing

2017 ◽  
Vol 30 (20) ◽  
pp. 8223-8235
Author(s):  
Jun-Chao Yang ◽  
Xiaopei Lin ◽  
Shang-Ping Xie
Keyword(s):  
Central America ◽  
Large Scale ◽  
Southern Oscillation ◽  
Function Analysis ◽  
Walker Circulation ◽  
Central American ◽  
Boreal Summer ◽  
Wind Variability ◽  
The Pacific ◽  
Gap Winds

Abstract A transbasin mode (TBM) is identified as the leading mode of interannual surface wind variability over the Intra-Americas Seas across Central America based on empirical orthogonal function analysis. The TBM is associated with variability in Central American gap winds, most closely with the Papagayo jet but with considerable signals over the Gulfs of Tehuantepec and Panama. Although El Niño–Southern Oscillation (ENSO) is the main large-scale forcing, the TBM features a distinct seasonality due to sea level pressure (SLP) adjustments across the Pacific and Atlantic. During July–September, ENSO causes meridional SLP gradient anomalies across Central America, intensifying anomalous geostrophic winds funneling through Papagayo to form the TBM. During wintertime, ENSO peaks but imparts little anomalous SLP gradient across Central America with a weak projection on the TBM because of the competing effects of the Pacific–North American teleconnection and tropospheric Kelvin waves. Besides ENSO, tropical Atlantic sea surface temperature anomalies make a weak contribution to the TBM in boreal summer by strengthening the cross-basin gradient. ENSO and the Atlantic forcing constitute a cross-basin seesaw pattern in SLP, manifested as an anomalous Walker circulation across the tropical Americas. The TBM appears to be part of the low-level branch of the anomalous Walker circulation, which modulates Central American wind jets by orographic effect. This study highlights the seasonality of gap wind variability, and calls for further research into its influence on regional climate.

scholarly journals Measuring air–sea gas-exchange velocities in a large-scale annular wind–wave tank

Ocean Science ◽  
2015 ◽  
Vol 11 (1) ◽  
pp. 121-138 ◽  
Author(s):  
E. Mesarchaki ◽  
C. Kräuter ◽  
K. E. Krall ◽  
M. Bopp ◽  
F. Helleis ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Large Scale ◽  
Wind Wave ◽  
Chemical Species ◽  
Surface States ◽  
Gas Transfer ◽  
Transfer Velocity ◽  
Wave Tank ◽  
Wide Range ◽  
Triton X

Abstract. In this study we present gas-exchange measurements conducted in a large-scale wind–wave tank. Fourteen chemical species spanning a wide range of solubility (dimensionless solubility, α = 0.4 to 5470) and diffusivity (Schmidt number in water, Scw = 594 to 1194) were examined under various turbulent (u10 = 0.73 to 13.2 m s−1) conditions. Additional experiments were performed under different surfactant modulated (two different concentration levels of Triton X-100) surface states. This paper details the complete methodology, experimental procedure and instrumentation used to derive the total transfer velocity for all examined tracers. The results presented here demonstrate the efficacy of the proposed method, and the derived gas-exchange velocities are shown to be comparable to previous investigations. The gas transfer behaviour is exemplified by contrasting two species at the two solubility extremes, namely nitrous oxide (N2O) and methanol (CH3OH). Interestingly, a strong transfer velocity reduction (up to a factor of 3) was observed for the relatively insoluble N2O under a surfactant covered water surface. In contrast, the surfactant effect for CH3OH, the high solubility tracer, was significantly weaker.

scholarly journals Nonlinear Zonal Propagation of Organized Convection in the Tropics

2019 ◽  
Vol 76 (9) ◽  
pp. 2837-2867
Author(s):  
Joaquin E. Blanco ◽  
David S. Nolan ◽  
Brian E. Mapes
Keyword(s):  
Large Scale ◽  
Water Model ◽  
Local Approach ◽  
Time Space ◽  
Cloud Clusters ◽  
Wide Range ◽  
Westerly Wind Burst ◽  
Large Scale Flow ◽  
The Tropics ◽  
Zonal Propagation

Abstract A wide range of the observed variability in the ITCZ is frequently explained in terms of equatorially trapped modes arising from Matsuno’s linear shallow-water model. Here, a series of zonally constant, meridionally symmetric aquachannel WRF simulations are used to study the propagation of tropical cloud clusters (CCs; patches of deep cloudiness and precipitation) in association with eastward-moving super cloud clusters (SCCs), also called convectively coupled Kelvin waves (CCKWs). Two independent but complementary methods are used: the first, from a local approach, involves a CC-tracking algorithm, while the second uses Lagrangian trajectories in a nonlocal framework. We show that the large-scale flow in low to midlevels advects the CCs either eastward or westward depending on model climatology, proximity to the CCKW axis, and latitude. Moreover, for most analyzed cases, sequences of CCs oscillate, describing qualitatively sinusoidal-like paths in longitude–time space, although with sharp transitions from westward to eastward motion due to westerly wind burst activity associated with the CCKWs. We also find that the discrete precipitation elements (CCs) are embedded in continuous tracks of positive moisture anomalies, which are parallel to the Lagrangian trajectories themselves. A conceptual model of the nonlinear SCC–CC interaction is presented.

Mimosa pudica (sensitive plant).

2021 ◽  
Author(s):  
Chris Parker
Keyword(s):  
Woody Plant ◽  
Ground Cover ◽  
Mimosa Pudica ◽  
Native Range ◽  
Disturbed Areas ◽  
Tropical Crops ◽  
The Pacific ◽  
Wide Range ◽  
The Tropics ◽  
Ornamental Species

Abstract M. pudica is an annual or biannual sub-woody plant native to South America. It was introduced outside of its native range as an ornamental species, and is still available for sale today. This species is typically present in disturbed areas in much of the tropics where it has naturalized. It can be readily and accidentally dispersed thanks to its propagules that stick to mammals' hairs and human clothing. M. pudica can become extremely weedy in disturbed sites, often forming monotypic ground cover, and is a major weed of many tropical crops. It is classified as invasive in a wide range of countries in Asia and the Pacific and is regarded as an undesirable import in to Florida, USA and Australia (ISSG, 2017). It is also reported as invasive in Burundi, Kenya, Malawi, Tanzania and Uganda.

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