scholarly journals Glacier-climate interaction at low latitudes

2001 ◽  
Vol 47 (157) ◽  
pp. 195-204 ◽  
Author(s):  
Georg Kaser
Keyword(s):  
Air Temperature ◽  
Specific Mass ◽  
Irian Jaya ◽  
Global Circulation ◽  
Field Evidence ◽  
Circulation Patterns ◽  
Tropical Conditions ◽  
Low Latitudes ◽  
Seasonal Oscillation ◽  
Dry Seasons

AbstractIn the low latitudes there is an absence of major thermal seasonality, yet there are three different climate regimes related to global circulation patterns and their seasonal oscillation: the humid inner tropics, the dry subtropics and, intermediate between these two, the outer tropics. For the respective glacier regimes the vertical profiles of specific mass balance (VBPs) are modeled considering vertical gradients of accumulation, air temperature and albedo, the duration of the ablation period and a factor for the ratio between melting and sublimation. The model is first calibrated with data from Hintereisferner, Austrian Alps, and is then applied to tropical conditions. The simulated VBP matches well the measured profiles from Irian jaya and Mount Kenya. Due to lack of field evidence, the subtropical VBP cannot be verified directly. However, application of the respective model versions separately to the humid and dry seasons of the outer-tropical Glaciar Uruashraju, Cordillera Blanca, Peru, provides reasonable results. Glaciers in the humid inner tropics are considered to be most sensitive to variations in air temperature, while dry subtropical glaciers are most sensitive to changes in air humidity. The two seasons of the outer tropics have to be viewed from these different perspectives.

scholarly journals Relationships of surface air temperature anomalies over Europe to persistence of atmospheric circulation patterns conducive to heat waves

2008 ◽  
Vol 14 ◽  
pp. 243-249 ◽  
Author(s):  
J. Kyselý ◽  
R. Huth
Keyword(s):  
Atmospheric Circulation ◽  
Air Temperature ◽  
Heat Waves ◽  
Temperature Extremes ◽  
Human Society ◽  
Positive Temperature ◽  
Temperature Anomalies ◽  
Circulation Types ◽  
Circulation Patterns ◽  
Air Temperature Anomalies

Abstract. Heat waves are among natural hazards with the most severe consequences for human society, including pronounced mortality impacts in mid-latitudes. Recent studies have hypothesized that the enhanced persistence of atmospheric circulation may affect surface climatic extremes, mainly the frequency and severity of heat waves. In this paper we examine relationships between the persistence of the Hess-Brezowsky circulation types conducive to summer heat waves and air temperature anomalies at stations over most of the European continent. We also evaluate differences between temperature anomalies during late and early stages of warm circulation types in all seasons. Results show that more persistent circulation patterns tend to enhance the severity of heat waves and support more pronounced temperature anomalies. Recent sharply rising trends in positive temperature extremes over Europe may be related to the greater persistence of the circulation types, and if similar changes towards enhanced persistence affect other mid-latitudinal regions, analogous consequences and implications for temperature extremes may be expected.

Global circulation of Mars’ upper atmosphere

Science ◽  
2019 ◽  
Vol 366 (6471) ◽  
pp. 1363-1366 ◽  
Author(s):  
M. Benna ◽  
S. W. Bougher ◽  
Y. Lee ◽  
K. J. Roeten ◽  
E. Yiğit ◽  
...  
Keyword(s):  
Gravity Waves ◽  
Incident Energy ◽  
Upper Atmosphere ◽  
The Sun ◽  
Mars Atmosphere ◽  
Neutral Winds ◽  
Global Circulation ◽  
Structure And Dynamics ◽  
Circulation Patterns

The thermosphere of Mars is the interface through which the planet is continuously losing its reservoir of atmospheric volatiles to space. The structure and dynamics of the thermosphere is driven by a global circulation that redistributes the incident energy from the Sun. We report mapping of the global circulation in the thermosphere of Mars with the Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft. The measured neutral winds reveal circulation patterns simpler than those of Earth that persist over changing seasons. The winds exhibit pronounced correlation with the underlying topography owing to orographic gravity waves.

scholarly journals Projected Changes in Daily Variability and Seasonal Cycle of Near-Surface Air Temperature over the Globe during the Twenty-First Century

2019 ◽  
Vol 32 (24) ◽  
pp. 8537-8561 ◽  
Author(s):  
Jiao Chen ◽  
Aiguo Dai ◽  
Yaocun Zhang
Keyword(s):  
Sea Ice ◽  
Air Temperature ◽  
Seasonal Cycle ◽  
Surface Air Temperature ◽  
First Century ◽  
The Arctic ◽  
Boreal Summer ◽  
High Latitudes ◽  
Low Latitudes ◽  
Twenty First Century

Abstract Increases in atmospheric greenhouse gases will not only raise Earth’s temperature but may also change its variability and seasonal cycle. Here CMIP5 model data are analyzed to quantify these changes in surface air temperature (Tas) and investigate the underlying processes. The models capture well the mean Tas seasonal cycle and variability and their changes in reanalysis, which shows decreasing Tas seasonal amplitudes and variability over the Arctic and Southern Ocean from 1979 to 2017. Daily Tas variability and seasonal amplitude are projected to decrease in the twenty-first century at high latitudes (except for boreal summer when Tas variability increases) but increase at low latitudes. The day of the maximum or minimum Tas shows large delays over high-latitude oceans, while it changes little at low latitudes. These Tas changes at high latitudes are linked to the polar amplification of warming and sea ice loss, which cause larger warming in winter than summer due to extra heating from the ocean during the cold season. Reduced sea ice cover also decreases its ability to cause Tas variations, contributing to the decreased Tas variability at high latitudes. Over low–midlatitude oceans, larger increases in surface evaporation in winter than summer (due to strong winter winds, strengthened winter winds in the Southern Hemisphere, and increased winter surface humidity gradients over the Northern Hemisphere low latitudes), coupled with strong ocean mixing in winter, lead to smaller surface warming in winter than summer and thus increased seasonal amplitudes there. These changes result in narrower (wider) Tas distributions over the high (low) latitudes, which may have important implications for other related fields.

scholarly journals Genetic diversity of Salmonella Paratyphi A isolated from enteric fever patients in Bangladesh from 2008 to 2018

2021 ◽  
Vol 15 (10) ◽  
pp. e0009748
Author(s):  
Sadia Isfat Ara Rahman ◽  
To Nguyen Thi Nguyen ◽  
Farhana Khanam ◽  
Nicholas R. Thomson ◽  
Zoe A. Dyson ◽  
...  
Keyword(s):  
Disease Surveillance ◽  
Enteric Fever ◽  
Sequence Data ◽  
Single Point ◽  
Point Mutations ◽  
Genomic Epidemiology ◽  
Global Circulation ◽  
Circulation Patterns ◽  
Genomic Studies ◽  
Study Sites

Background The proportion of enteric fever cases caused by Salmonella Paratyphi A is increasing and may increase further as we begin to introduce typhoid conjugate vaccines (TCVs). While numerous epidemiological and genomic studies have been conducted for S. Typhi, there are limited data describing the genomic epidemiology of S. Paratyphi A in especially in endemic settings, such as Bangladesh. Principal findings We conducted whole genome sequencing (WGS) of 67 S. Paratyphi A isolated between 2008 and 2018 from eight enteric disease surveillance sites across Bangladesh. We performed a detailed phylogenetic analysis of these sequence data incorporating sequences from 242 previously sequenced S. Paratyphi A isolates from a global collection and provided evidence of lineage migration from neighboring countries in South Asia. The data revealed that the majority of the Bangladeshi S. Paratyphi A isolates belonged to the dominant global lineage A (67.2%), while the remainder were either lineage C (19.4%) or F (13.4%). The population structure was relatively homogenous across the country as we did not find any significant lineage distributions between study sites inside or outside Dhaka. Our genomic data showed presence of single point mutations in gyrA gene either at codon 83 or 87 associated with decreased fluoroquinolone susceptibility in all Bangladeshi S. Paratyphi A isolates. Notably, we identified the pHCM2- like cryptic plasmid which was highly similar to S. Typhi plasmids circulating in Bangladesh and has not been previously identified in S. Paratyphi A organisms. Significance This study demonstrates the utility of WGS to monitor the ongoing evolution of this emerging enteric pathogen. Novel insights into the genetic structure of S. Paratyphi A will aid the understanding of both regional and global circulation patterns of this emerging pathogen and provide a framework for future genomic surveillance studies.

scholarly journals Assessing and Projecting Surface Air Temperature Conditions Required To Sustain Permafrost in Japan

2021 ◽  
Author(s):  
Tokuta Yokohata ◽  
Go IWAHANA ◽  
Kazuyuki Saito ◽  
Noriko Ishizaki ◽  
Taiga Matsushita ◽  
...  
Keyword(s):  
Air Temperature ◽  
Surface Air Temperature ◽  
Slope Instability ◽  
Alpine Ecosystems ◽  
Mountainous Areas ◽  
Mountain Environments ◽  
Low Latitudes ◽  
Mountain Permafrost ◽  
Considerable Impact ◽  
Mountain Environment

Abstract Permafrost covers a wide area of the Northern Hemisphere, including high-altitude mountainous areas even at mid-low latitudes. There is concern that the thawing of mountain permafrost can cause slope instability and substantially impact alpine ecosystems. However, permafrost in mountainous areas is difficult to observe, and detailed analyses have not been performed on its current distribution and future changes. Here, we show that the surface air temperature required to sustain Japan's mountain permafrost is estimated to decrease rapidly at present; most mountain permafrost in Japan is projected to disappear by the second half of the 21st century, and disappear very quickly in some places from approximately 2020–2030, regardless of climate scenarios. Our projections indicate that climate change has a considerable impact on mountain environments and that even if climate stabilization is achieved, Japan's mountain permafrost may almost disappear. It is important to consider measures to adapt to the changing mountain environment.

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