Observed spatio-temporal changes of winter snow albedo over the north-west Himalaya

2016 ◽  
Vol 37 (5) ◽  
pp. 2304-2317 ◽  
Author(s):  
H. S. Negi ◽  
P. Datt ◽  
N. K. Thakur ◽  
A. Ganju ◽  
V. K. Bhatia ◽  
...  
2021 ◽  
Author(s):  
Harry West ◽  
Nevil Quinn ◽  
Michael Horswell

<p>The North Atlantic Oscillation (NAO) is often cited as the primary atmospheric-oceanic circulation or teleconnection influencing regional climate in Great Britain. As our ability to predict the NAO several months in advance improves, it is important that we also continue to develop our spatial and temporal understanding of the rainfall signatures which the circulation produces.</p><p>We present a novel application of spatial statistics to explore variability in monthly NAO rainfall signatures using a 5km gridded monthly Standardised Precipitation Index (SPI) dataset. We first use the Getis-Ord Gi* statistic to map spatially significant hot and cold spots (clusters of high/wet and low/dry SPI values) in average monthly rainfall signatures under NAO Positive and Negative conditions over the period 1900-2015. We then look across the record and explore the temporal variability in these signatures, in other words how often a location is in a significant spatial hot/cold spot (high/low SPI) at a monthly scale under NAO Positive/Negative conditions.</p><p>The two phases of the NAO are typically more distinctive in the winter months, with stronger and more variable NAO Index values. The average monthly SPI analysis reveals a north-west/south-east ‘spatial divide’ in rainfall response. NAO Positive phases result in a southerly North Atlantic Jet Stream bringing warm and wet conditions from the tropics, increasing rainfall particularly in the north-western regions. However, under NAO Negative phases which result in a northerly Jet Stream, much drier conditions in the north-west prevail. Meanwhile in the south-eastern regions under both NAO phases a weaker and opposite wet/dry signal is observed. This north-west/south-east ‘spatial divide’ is marked by the location of spatially extensive hot/cold spots. The Getis-Ord Gi* result identifies that the spatial pattern we detect in average winter rainfall is statistically significant. Looking across the record, this NW/SE opposing response appears to have a relatively high degree of spatio-temporal consistency. This suggests that there is a high probability that NAO Positive and Negative phases will result in this NW/SE statistically significant spatial pattern.</p><p>Even though the phases of the NAO in the summer months are less distinctive they still produce rainfall responses which are evident in the monthly average SPI. However, the spatiality in wet/dry conditions is more homogenous across the country. In other words the ‘spatial divide’ observed in winter is diluted in summer. As a result, the occurrence of significant hot/cold spots is more variable in space and time.</p><p>Our analysis demonstrates a novel application of the Getis-Ord Gi* statistic which allows for spatially significant patterns in the monthly SPI data to be mapped for each NAO phase. In winter months particularly, this analysis reveals statistically significant opposing rainfall responses, which appear to have long-term spatio-temporal consistency. This is important because as winter NAO forecasting skill improves, the findings of our research enable a more spatially reliable estimate of the likely impacts of NAO-influenced rainfall distribution.</p>


2018 ◽  
Vol 187 ◽  
pp. 109-185 ◽  
Author(s):  
J. Craig ◽  
N. Hakhoo ◽  
G.M. Bhat ◽  
M. Hafiz ◽  
M.R. Khan ◽  
...  

Nature ◽  
1982 ◽  
Vol 298 (5873) ◽  
pp. 432-436 ◽  
Author(s):  
Douglas W. Burbank ◽  
Gary D. Johnson

2019 ◽  
Author(s):  
Alejandro Lome-Hurtado ◽  
Jacques Lartigue Mendoza ◽  
Juan Carlos Trujillo

Abstract Background: The number of death children at the international scale are still high, but with proper spatially-targeted health public policies this number could be reduced. In Mexico, children mortality is a particular health concern due to its alarming rate all throughout North America. The aims of this study are i) to model the change of children mortality risk at the municipality level, (ii) to identify municipalities with high, medium and low risk over time and (iii) to ascertain potential high-risk municipalities across time, using local trends of each municipality in Greater Mexico City. Methods: The study uses Bayesian spatio-temporal analysis to control for space-time patterns of data. This allow to model the geographical variation of the municipalities within the time span studied. Results: The analysis shows that most of the high-risk municipalities are in the north, west, and some in the east; some of such municipalities show an increasing children mortality risk over time. The outcomes highlight some municipalities which show a medium risk currently but are likely to become high risk along the study period. Finally, the odds of children mortality risk illustrate a decreasing tendency over the 7-year framework. Conclusions: Identification of high-risk municipalities may provide a useful input to policy-makers seeking out to reduce the incidence of children mortality, since it would provide evidence to support geographical targeting for policy interventions.


Author(s):  
Mike Searle

The Himalaya is the greatest mountain range on Earth: the highest, longest, youngest, the most tectonically active, and the most spectacular of all. Unimaginable geological forces created these spectacular peaks. Indeed, the crash of the Indian plate into Asia is the biggest known collision in geological history, giving birth to the Himalaya and Karakoram, one of the most remote and savage places on Earth. In this beautifully illustrated book, featuring spectacular color photographs throughout, one of the most experienced field geologists of our time presents a rich account of the geological forces that were involved in creating these monumental ranges. Over three decades, Mike Searle has transformed our understanding of this vast region. To gather his vital geological evidence, he has had to deploy his superb skills as a mountaineer, spending weeks at time in remote and dangerous locations. Searle weaves his own first-hand tales of discovery with an engaging explanation of the processes that formed these impressive peaks. His narrative roughly follows his career, from his early studies in the north west Himalaya of Ladakh, Zanskar and Kashmir, through several expeditions to the Karakoram ranges (including climbs on K2, Masherbrum, and the Trango Towers, and the crossing of Snow Lake, the world's largest ice cap outside polar regions), to his later explorations around Everest, Makalu, Sikkim and in Tibet and South East Asia. The book offers a fascinating first-hand account of a major geologist at work-the arduous labor, the eureka moments, and the days of sheer beauty, such as his trek to Kathmandu, over seven days through magnificent rhododendron forests ablaze in pinks, reds and white and through patches of bamboo jungle with hanging mosses. Filled with satellite images, aerial views, and the author's own photographs of expeditions, Colliding Continents offers a vivid account of the origins and present state of the greatest mountain range on Earth.


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