Multiple hydroclimatic controls over recent sedimentation in proglacial Mirror Lake, southern Selwyn Mountains, Northwest Territories

2005 ◽  
Vol 42 (9) ◽  
pp. 1589-1599 ◽  
Author(s):  
Jessica D Tomkins ◽  
Scott F Lamoureux
Keyword(s):  
Northwest Territories ◽  
Summer Temperature ◽  
Sedimentary Record ◽  
Sediment Delivery ◽  
Late 20Th Century ◽  
Glacial Meltwater ◽  
Varve Thickness ◽  
Mirror Lake ◽  
Decadal Scale ◽  
The Impact

Varves from Mirror Lake, Northwest Territories (62°N, 128°W) reveal significant, but changing climatic influences on discharge and sedimentation on a decadal scale during the late 20th century. The complex hydroclimatic signal within the sediments indicates the difficulty in identifying a quantitative relationship between varve thickness and a single climatic variable. Regression of recent varve thickness with local meteorological data shows July temperature as the dominant control over sediment accumulation. In contrast, the dampening effects of increased snowfall on glacier ablation and resultant runoff reduce sediment delivery. Although the impact of snowfall does not appear to significantly weaken the relationship between summer temperature and varve formation, periods when multiple climatic factors control sediment delivery are characterized by distinctive varves containing two prominent silt units. Thus, the Mirror Lake hydrological system appears to shift between two general states. The first state involves a pronounced summer glacial meltwater phase due to dominant summer temperature influences on glacial melt, resulting in varves with one silt unit. This varve structure dominates the sedimentary record from A.D. 1670 to 1941, possibly reflecting a Little Ice Age influence in the study area. The second state operates in years when glacial meltwater discharge is delayed until August, due to increased snow cover, and the lake receives increased sediment-poor nival melt. These conditions lead to the formation of varves with two silt units corresponding to nival and glacial discharge phases and are common in the sedimentary record from A.D. 1390 to 1669 and A.D. 1942 to 1996.

A 1000-Year Record of Temperature and Precipitation in the Sierra Nevada

1993 ◽  
Vol 39 (2) ◽  
pp. 249-255 ◽  
Author(s):  
Lisa J. Graumlich
Keyword(s):  
20Th Century ◽  
Sierra Nevada ◽  
Response Surfaces ◽  
Summer Temperature ◽  
Ice Age ◽  
Late 20Th Century ◽  
Temperature And Precipitation ◽  
Decadal Scale ◽  
Tree Ring Data ◽  
Precipitation Variation

AbstractTree-ring data from subalpine conifers in the southern Sierra Nevada were used to reconstruct temperature and precipitation back to A.D. 800. Tree growth of foxtail pine (Pinus balfouriana) and western juniper (Juniperus occidentalis ssp. australis) is influenced by nonlinear interactions between summer temperature and winter precipitation. Reconstruction of the separate histories of temperature and precipitation is feasible by explicitly modeling species and site differences in climatic response using response surfaces. The summer temperature reconstruction shows fluctuations on centennial and longer time scales including a period with temperatures exceeding late 20th-century values from ca. 1100 to 1375 A.D., corresponding to the Medieval Warm Period identified in other proxy data sources, and a period of cold temperatures from ca. 1450 to 1850, corresponding to the Little Ice Age. Precipitation variation is dominated by shorter period, decadal-scale oscillations. The long-term record presented here indicates that the 20th century is anomalous with respect to precipitation variation. A tabulation of 20- and 50-yr means indicates that precipitation equaling or exceeding 20th-century levels occurred infrequently in the 1000+-yr record.

scholarly journals The Impact of Morphological Features on Summer Temperature Variations on the Example of Two Residential Neighborhoods in Ljubljana, Slovenia

2017 ◽  
Vol 9 (1) ◽  
pp. 122 ◽  
Author(s):  
Alenka Fikfak ◽  
Saja Kosanović ◽  
Miha Konjar ◽  
Janez Grom ◽  
Martina Zbašnik-Senegačnik
Keyword(s):  
Summer Temperature ◽  
Morphological Features ◽  
Temperature Variations ◽  
The Impact

scholarly journals Impact of satellite viewing swath width on global and regional aerosol optical thickness statistics and trends

2013 ◽  
Vol 6 (6) ◽  
pp. 10117-10163 ◽  
Author(s):  
P. R. Colarco ◽  
R. A. Kahn ◽  
L. A. Remer ◽  
R. C. Levy
Keyword(s):  
Optical Thickness ◽  
Statistical Significance ◽  
Sampling Strategy ◽  
Aerosol Optical Thickness ◽  
Mean Values ◽  
Sampling Artifacts ◽  
Aerosol Loading ◽  
Decadal Scale ◽  
Along Track ◽  
The Impact

Abstract. We use the Moderate Resolution Imaging Spectroradiometer (MODIS) satellite aerosol optical thickness (AOT) product to assess the impact of reduced swath width on global and regional AOT statistics and trends. Ten different sampling strategies are employed, in which the full MODIS dataset is sub-sampled with various narrow-swath (~400–800 km) and curtain-like (~10 km) along-track configurations. Although view-angle artifacts in the MODIS AOT retrieval confound direct comparisons between averages derived from different sub-samples, careful analysis shows that with many portions of the Earth essentially unobserved, the AOT statistics of these sub-samples exhibit significant regional and seasonal biases. These AOT spatial sampling artifacts comprise up to 60% of the full-swath AOT value under moderate aerosol loading, and can be as large as 0.1 in some regions under high aerosol loading. Compared to full-swath observations, narrower swaths exhibit a reduced ability to detect AOT trends with statistical significance, and for curtain-like sampling we do not find any statistically significant decadal-scale trends at all. An across-track sampling strategy obviates the MODIS view angle artifact, and its mean AOT converges to the full-swath mean values for sufficiently coarse spatial and temporal aggregation. Nevertheless, across-track sampling has significant seasonal-regional sampling artifacts, leading to biases comparable to the curtain-like along-track sampling, lacks sufficient coverage to assign statistical significance to aerosol trends, and is not achievable with an actual narrow-swath or curtain-like instrument. These results suggest that future aerosol satellite missions having significantly less than full-swath viewing are unlikely to sample the true AOT distribution well enough to determine decadal-scale trends or to obtain the statistics needed to reduce uncertainty in aerosol direct forcing of climate.

scholarly journals Impak Pemikiran Islah dan Tajdid Terhadap Pendidikan Tinggi Wanita Islam di Malaysia Selepas Merdeka

2018 ◽  
Vol 10 (3-4) ◽  
Author(s):  
Wahibah Twahir@Hj Tahir ◽  
Kamaruzzaman Yusof ◽  
Abu Hassan Abdul
Keyword(s):  
20Th Century ◽  
Women's Education ◽  
Muslim Women ◽  
Female Students ◽  
Islamic Education ◽  
Late 20Th Century ◽  
Secondary Sources ◽  
Education Network ◽  
High Level ◽  
The Impact

The study aims to identify the development of the Islah and Tajdid movements in Malaya and the impact on Islamic education for women starting at the madrasah level to the high level in the late 20th century. This study discusses the movement of Islah and Tajdid which appeared at the beginning of the 20th century in Malaya and analyzed the influence of thinking on Islamic women's education. This study was conducted using a qualitative study, where all data information from primary and secondary sources was scrutinized and analyzed by taking an inductive approach. The study found that the characters involved in this movement in Malaya since the very beginning of their return from their studies in Egypt have supported the thought of Sheikh Muhammad Abduh and Sheikh Rasyid Ridha in the case of women's education. They wrote and worked on publications through newspapers and magazines that voiced the importance of Muslim women to be given freedom of education to engage in society. In order to realize these thoughts and awareness, they also set up special madrasah for female students in Penang, Melaka and Singapore. The influence of their thinking has led to the awareness of the Malay community with the establishment of madrasah in the states of Kelantan, Kedah, Perlis, and Johor and opened the widest opportunities for female students to receive education. Until the Independence era of Malaya, these madrasah have expanded to whole land of Malay as the efforts and awareness of group of religionist that support the thinking of Islah and Tajdid. In 1952 Malaya Islamic College was established and followed by Yayasan Pengajian Tinggi Islam Kelantan (YPTIK) in 1956 as a result of this group's efforts. Women's students also have the opportunity to pursue higher levels of education until there is an Islamic women's education network between Malaysia, Indonesia and Egypt. At the end of the 20th century, Muslim women had succeeded in occupying various career fields, especially in Islamic education as teachers in schools, as a lecturer at higher learning centers that offering various fields of Islamic studies and as civil servants in government departments.

scholarly journals The Impact of Possible Decadal-Scale Cold Waves on Viticulture over Europe in a Context of Global Warming

Agronomy ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 397 ◽  
Author(s):  
Giovanni Sgubin ◽  
Didier Swingedouw ◽  
Iñaki García de Cortázar-Atauri ◽  
Nathalie Ollat ◽  
Cornelis van Leeuwen
Keyword(s):  
Climate Change ◽  
21St Century ◽  
Developmental Stages ◽  
Future Climate ◽  
Future Climate Change ◽  
Cold Waves ◽  
Decadal Scale ◽  
Ensemble Mean ◽  
The Impact

A comprehensive analysis of all the possible impacts of future climate change is crucial for strategic plans of adaptation for viticulture. Assessments of future climate are generally based on the ensemble mean of state-of-the-art climate model projections, which prefigures a gradual warming over Europe for the 21st century. However, a few models project single or multiple O(10) year temperature drops over the North Atlantic due to a collapsing subpolar gyre (SPG) oceanic convection. The occurrence of these decadal-scale “cold waves” may have strong repercussions over the continent, yet their actual impact is ruled out in a multi-model ensemble mean analysis. Here, we investigate these potential implications for viticulture over Europe by coupling dynamical downscaled EUR-CORDEX temperature projections for the representative concentration pathways (RCP)4.5 scenario from seven different climate models—including CSIRO-Mk3-6-0 exhibiting a SPG convection collapse—with three different phenological models simulating the main developmental stages of the grapevine. The 21st century temperature increase projected by all the models leads to an anticipation of all the developmental stages of the grapevine, shifting the optimal region for a given grapevine variety northward, and making climatic conditions suitable for high-quality wine production in some European regions that are currently not. However, in the CSIRO-Mk3-6-0 model, this long-term warming trend is suddenly interrupted by decadal-scale cold waves, abruptly pushing the suitability pattern back to conditions that are very similar to the present. These findings are crucial for winemakers in the evaluation of proper strategies to face climate change, and, overall, provide additional information for long-term plans of adaptation, which, so far, are mainly oriented towards the possibility of continuous warming conditions.

scholarly journals Effect of Drought on Outbreaks of Major Forest Pests, Pine Caterpillars (Dendrolimus spp.), in Shandong Province, China

Forests ◽  
2019 ◽  
Vol 10 (3) ◽  
pp. 264 ◽  
Author(s):  
Yongbin Bao ◽  
Fei Wang ◽  
Siqin Tong ◽  
Li Na ◽  
Aru Han ◽  
...  
Keyword(s):  
Positive Impact ◽  
Shandong Province ◽  
Forest Damage ◽  
Decadal Scale ◽  
Effects Of Drought ◽  
Forestry Production ◽  
Ecological Reconstruction ◽  
The Impact ◽  
The Relationship

As the main defoliators of coniferous forests in Shandong Province, China, pine caterpillars (including Dendrolimus suffuscus suffuscus Lajonquiere, D. spectabilis Butler, and D. tabulaeformis Tsai et Liu) have caused substantial forest damage, adverse economic impacts, and losses of ecosystem resources. Therefore, elucidating the effects of drought on the outbreak of these pests is important for promoting forestry production and ecological reconstruction. Accordingly, the aim of the present study was to analyse the spatiotemporal variation of drought in Shandong Province, using the Standard Precipitation Index, and to investigate the impact of drought on the outbreak of pine caterpillar infestations. Future trends in drought and pine caterpillar populations were then estimated using the Hurst exponent. The results showed that: (1) Drought decreased gradually and showed a wetting trend from 1981 to 2012, with frequency decreasing on a decadal scale as follows: 1980s > 1990s > 2000s > 2010s; (2) The total area of pine caterpillar occurrence decreased strongly from 1992 to 2012; (3) Long-term or prolonged drought had a greater positive impact on pine caterpillar outbreak than short-term drought; (4) In the future, a greater portion of the province’s area will experience increased wetting conditions (57%) than increased drought (43%), and the area of pine caterpillar outbreak is estimated to decrease overall. These findings help elucidate the relationship between drought and pine caterpillar outbreak in Shandong Province and, hence, provide a basis for developing preventive measures and plans.

Employment Conditions in Journalism

2019 ◽  
Author(s):  
Mirjam Gollmitzer
Keyword(s):  
Public Relations ◽  
Work Experience ◽  
The United States ◽  
Economic Sectors ◽  
Late 20Th Century ◽  
Budget Planning ◽  
Employment Conditions ◽  
Ongoing Work ◽  
News Organizations ◽  
The Impact

Amid the rise of atypical and casual employment across economic sectors and the decline in profits taking place in media organizations internationally, the conditions under which journalists work are changing and, for many, worsening. The number of employed journalists has declined significantly since the late 20th century, and the real salaries of the remaining journalists have decreased or remained mostly stagnant. Female journalists, freelancers, and online journalists are paid (often significantly) less than male employees working for traditional media. These trends are particularly well documented for the United States, but they are international in scope. Although job satisfaction is traditionally robust among journalists, it is starting to decline, as some studies have indicated, together with the perceived level of autonomy over the labor process. Although those who continue to hold permanent jobs in news organizations do journalism from a position of having a steady income and social security, a growing number of freelancers work for multiple clients, experience fluctuating incomes, and must shoulder greater risks (such as legal challenges potentially arising from their reporting). Staff journalists encounter increased workloads in newsrooms as they take on the tasks of laid-off colleagues. Freelancers, on the other hand, find it increasingly difficult to earn enough from doing journalism alone and take on secondary jobs or assignments, including in public relations. Their stress is more related to ensuring that they have ongoing work; juggling multiple jobs; and doing self-promotion, administrative work, and budget planning on top of journalism. Despite this, freelancers consistently report enjoying the flexibility and autonomy their employment status affords, pointing to a complex interlinking of freedom and constraint at the core of their work experience. It is not yet clear whether emerging ways of organizing and financing journalistic labor, such as journalism cooperatives, news start-ups, and crowdfunding, offer sustainable alternatives to the waning employment opportunities in the big news organizations or to the model of the lone freelancer. So-called entrepreneurial journalism does not only tend to emphasize teamwork across professional boundaries; it also assigns a defining importance to digital technologies. The impact of the latter on journalistic labor overall varies; some research foregrounds the increased mobility and autonomy of multiskilled reporters, and other research mentions deskilling, labor rationalization, and the increased monitoring and measuring of journalistic performance.

scholarly journals Near East Desertification: impact of Dead Sea drying on convective rainfall

2019 ◽  
Author(s):  
Samiro Khodayar ◽  
Johannes Hoerner
Keyword(s):  
Lake Level ◽  
Weather Prediction ◽  
Regional Climate ◽  
Atmospheric Stability ◽  
Lower Boundary ◽  
Heavy Precipitation ◽  
Dead Sea ◽  
Decadal Scale ◽  
The Dead ◽  
The Impact

Abstract. The Dead Sea desertification-threatened region is affected by continual lake level decline and occasional, but life-endangering flash-floods. Climate change has aggravated such issues in the past decades. In this study, the impact of the Dead Sea drying on the severe convection generating heavy precipitation in the region is investigated. Perturbation simulations with the high-resolution convection-permitting regional climate model COSMO-CLM and several numerical weather prediction (NWP) runs on an event time scale are performed over the Dead Sea area. A reference simulation covering the 2003 to 2013 period and a twin sensitivity experiment, in which the Dead Sea is dried out and set to bare soil, are compared. NWP simulations focus on heavy precipitation events exhibiting relevant differences between the reference and the sensitivity decadal realization to assess the impact on the underlying convection-related processes. On a decadal scale, the difference between the simulations points out that in future regional climate, under ongoing lake level decline, a decrease in evaporation, higher air temperatures and less precipitation is to expect. Particularly, an increase in the number of dry days and in the intensity of heavy precipitation is foreseen. The drying of the Dead Sea is seen to affect the atmospheric conditions leading to convection in two ways: (a) the local decrease in evaporation reduces moisture availability in the lower boundary layer locally and in the neighbouring, directly affecting atmospheric stability. Weaker updrafts characterize the drier and more stable atmosphere of the simulations where the Dead Sea has been dried out. (b) Thermally driven wind system circulations and resulting divergence/convergence fields are altered preventing in many occasions convection initiation because of the omission of convergence lines.

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