scholarly journals Long-term changes in the snow–firn pack stratigraphy on Ürümqi glacier No. 1, eastern Tien Shan, China

2007 ◽  
Vol 46 ◽  
pp. 331-334 ◽  
Author(s):  
Feiteng Wang ◽  
Zhongqin Li ◽  
R. Edwards ◽  
Huilin Li
Keyword(s):  
Ablation Rate ◽  
Tien Shan ◽  
Coarse Grained ◽  
Climatic Warming ◽  
The West ◽  
Branch Site ◽  
Snow Stratigraphy ◽  
Long Term Changes ◽  
The Mean

AbstractWe report on changes to the snowpack of Ürümqi glacier No. 1, eastern Tien Shan, China, resulting from climate change between 1961 and 2005. Data from more than 120 snow pits were used to investigate temporal changes in the snow stratigraphy for three periods 1961–62, 1980–83 and 2002–05. Both the thickness and structure of the snow were found to be significantly altered by climatic warming. The proportion of coarse-grained firn, which is usually formed by infiltration water, was found to have increased from 40% to 65% over the period 1961–2005, and the distribution of the glacier zones also changed significantly, with all boundaries moving up-slope. The recrystallization–infiltration zone disappeared in 1989. The mean ablation rate over the melt season increased by ~26% from 1962 to 1980 at the west branch site and by ~75% from 1980 to 2004 at the east branch site.

scholarly journals Long-term changes of the ice regime of rivers in Latvia

2016 ◽  
Vol 47 (4) ◽  
pp. 782-798
Author(s):  
Inese Latkovska ◽  
Elga Apsīte ◽  
Didzis Elferts
Keyword(s):  
Regional Differences ◽  
Severity Index ◽  
Ice Cover ◽  
Ice Thickness ◽  
Positive Trend ◽  
The West ◽  
Climate Conditions ◽  
Long Term Changes ◽  
Ice Regime

The ice regime of rivers is considered a sensitive indicator of climate change. This paper summarises the results of research on the long-term changes in the ice regime parameters under changing climate conditions and their regional peculiarities in Latvia from 1945 to 2012. The ice cover duration on Latvian rivers has decreased during recent decades. The research results demonstrated that there is a positive trend as regards the formation of the ice cover and in 31.8% of the cases the trend is statistically significant at p < 0.05. As regards the breaking up of ice, there is a statistically significant negative trend in 93.2% of the cases at p < 0.05. This indicates an earlier ice break-up date, which in turn, displays a strong correlation with the increase of the air temperature. The same pattern applies to the reduction of the length of ice cover (a statistically significant trend in 86.4% of the cases at p < 0.05). In approximately 60% of the cases, there is a statistically significant reduction of the ice thickness. The estimated winter severity index indicates warmer winters over the last 20 years as well as regional differences in the west–east direction.

scholarly journals Variability and past long-term changes of brominated very short-lived substances at the tropical tropopause

2020 ◽  
Vol 20 (11) ◽  
pp. 7103-7123
Author(s):  
Susann Tegtmeier ◽  
Elliot Atlas ◽  
Birgit Quack ◽  
Franziska Ziska ◽  
Kirstin Krüger
Keyword(s):  
Central America ◽  
Temporal Variability ◽  
Spatial And Temporal Variability ◽  
Positive Trend ◽  
The West ◽  
West Pacific ◽  
Mixing Ratios ◽  
Long Term Changes ◽  
Averaged Model

Abstract. Halogenated very short-lived substances (VSLSs), such as bromoform (CHBr3), can be transported to the stratosphere and contribute to the halogen loading and ozone depletion. Given their highly variable emission rates and their short atmospheric lifetimes, the exact amount as well as the spatio-temporal variability of their contribution to the stratospheric halogen loading are still uncertain. We combine observational data sets with Lagrangian atmospheric modelling in order to analyse the spatial and temporal variability of the CHBr3 injection into the stratosphere for the time period 1979–2013. Regional maxima with mixing ratios of up to 0.4–0.5 ppt at 17 km altitude are diagnosed to be over Central America (1) and over the Maritime Continent–west Pacific (2), both of which are confirmed by high-altitude aircraft campaigns. The CHBr3 maximum over Central America is caused by the co-occurrence of convectively driven short transport timescales and strong regional sources, which in conjunction drive the seasonality of CHBr3 injection. Model results at a daily resolution reveal isolated, exceptionally high CHBr3 values in this region which are confirmed by aircraft measurements during the ACCENT campaign and do not occur in spatially or temporally averaged model fields. CHBr3 injection over the west Pacific is centred south of the Equator due to strong oceanic sources underneath prescribed by the here-applied bottom-up emission inventory. The globally largest CHBr3 mixing ratios at the cold point level of up to 0.6 ppt are diagnosed to occur over the region of India, Bay of Bengal, and Arabian Sea (3); however, no data from aircraft campaigns are available to confirm this finding. Inter-annual variability of stratospheric CHBr3 injection of 10 %–20 % is to a large part driven by the variability of coupled ocean–atmosphere circulation systems. Long-term changes, on the other hand, correlate with the regional sea surface temperature trends resulting in positive trends of stratospheric CHBr3 injection over the west Pacific and Asian monsoon region and negative trends over the east Pacific. For the tropical mean, these opposite regional trends balance each other out, resulting in a relatively weak positive trend of 0.017±0.012 ppt Br per decade for 1979–2013, corresponding to 3 % Br per decade. The overall contribution of CHBr3 together with CH2Br2 to the stratospheric halogen loading accounts for 4.7 ppt Br, in good agreement with existing studies, with 50 % and 50 % being injected in the form of source and product gases, respectively.

scholarly journals Variability and long-term changes of brominated VSLS at the tropical tropopause

2019 ◽  
Author(s):  
Susann Tegtmeier ◽  
Elliot Atlas ◽  
Birgit Quack ◽  
Franziska Ziska ◽  
Kirstin Krüger
Keyword(s):  
Central America ◽  
Spatial And Temporal Variability ◽  
Positive Trend ◽  
The West ◽  
Asian Monsoon Region ◽  
West Pacific ◽  
Mixing Ratios ◽  
Long Term Changes ◽  
Averaged Model

Abstract. We combine available observational data sets with Lagrangian atmospheric modelling in order to analyze the spatial and temporal variability of the CHBr3 injection into the stratosphere. Regional maxima with mixing ratios of up to 0.4–0.5 ppt at 17 km altitude are diagnosed to be over Central America (1) and over the Maritime Continent/West Pacific (2), both of which are confirmed by high-altitude aircraft campaigns. The CHBr3 maximum over Central America is caused by the co-occurrence of convectively-driven short transport time scales and strong regional sources, which in conjunction drive the seasonality of CHBr3 injection. Model results at a daily resolution reveal isolated, exceptionally high CHBr3 values in this region which are confirmed by measurements during the ACCENT campaign and do not occur in spatially or temporally averaged model fields. CHBr3 injection over the West Pacific is centered south of the equator due to strong oceanic sources underneath prescribed by the here applied bottom-up emission inventory. The globally strongest stratospheric CHBr3 injection of up to 0.6 ppt is diagnosed to occur over the region of India, Bay of Bengal and Arabian Sea (3), however, no data from aircraft campaigns are available to confirm this finding. Interannual variability of stratospheric CHBr3 injection of 10–20 % is to a large part driven by the variability of coupled ocean-atmosphere circulation systems. Long-term changes, on the other hand, correlate with the regional SST trends resulting in positive trends of stratospheric CHBr3 injection over the West Pacific and Asian monsoon region and negative trends over the East Pacific. For the tropical mean, these opposite regional trends balance each other out resulting in a relatively weak positive trend of 0.017 ± 0.012 ppt Br/dec for 1979–2013, corresponding 3 % Br/dec. The overall contribution of CHBr3 together with CH2Br2 to the stratospheric halogen loading accounts for 4.7 ppt Br, in good agreement with existing studies, with 50 %/50 % being injected in form of source and product gases, respectively.

scholarly journals Climatologies and long-term changes in mesospheric wind and wave measurements based on radar observations at high and mid latitudes

2019 ◽  
Vol 37 (5) ◽  
pp. 851-875 ◽  
Author(s):  
Sven Wilhelm ◽  
Gunter Stober ◽  
Peter Brown
Keyword(s):  
Kinetic Energy ◽  
Gravity Waves ◽  
Lower Thermosphere ◽  
Atmospheric Parameters ◽  
Amplitude Response ◽  
Wave Measurements ◽  
Long Term Changes ◽  
The Mean ◽  
Mesosphere And Lower Thermosphere

Abstract. We report on long-term observations of atmospheric parameters in the mesosphere and lower thermosphere (MLT) made over the last 2 decades. Within this study, we show, based on meteor wind measurement, the long-term variability of winds, tides, and kinetic energy of planetary and gravity waves. These measurements were done between the years 2002 and 2018 for the high-latitude location of Andenes (69.3∘ N, 16∘ E) and the mid-latitude locations of Juliusruh (54.6∘ N, 13.4∘ E) and Tavistock (43.3∘ N, 80.8∘ W). While the climatologies for each location show a similar pattern, the locations differ strongly with respect to the altitude and season of several parameters. Our results show annual wind tendencies for Andenes which are toward the south and to the west, with changes of up to 3 m s−1 per decade, while the mid-latitude locations show smaller opposite tendencies to negligible changes. The diurnal tides show nearly no significant long-term changes, while changes for the semidiurnal tides differ regarding altitude. Andenes shows only during winter a tidal weakening above 90 km, while for the Canadian Meteor Orbit Radar (CMOR) an enhancement of the semidiurnal tides during the winter and a weakening during fall occur. Furthermore, the kinetic energy for planetary waves showed strong peak values during winters which also featured the occurrence of sudden stratospheric warming. The influence of the 11-year solar cycle on the winds and tides is presented. The amplitudes of the mean winds exhibit a significant amplitude response for the zonal component below 82 km during summer and from November to December between 84 and 95 km at Andenes and CMOR. The semidiurnal tides (SDTs) show a clear 11-year response at all locations, from October to November.

Are mean size data adequate to monitor freshwater eel fisheries?

1999 ◽  
Vol 50 (4) ◽  
pp. 355 ◽  
Author(s):  
R. I. C. Chris Francis ◽  
Don J. Jellyman
Keyword(s):  
Sampling Error ◽  
Fish Population ◽  
Fishing Pressure ◽  
Freshwater Eel ◽  
Long Term Changes ◽  
Mean Size ◽  
The Mean ◽  
Natural Variations ◽  
Size Data

As the biomass of a fish population is reduced by fishing, the mean size (length or weight) of individuals in the population can be expected to decrease. Thus, it should be possible, in principle, to detect changes in fishing pressure by monitoring mean size. A simulation experiment was carried out to see whether this might work in practice with New Zealand freshwater eel fisheries. Information on the dynamics of eel populations was used to construct a simulation model of a fishery with a range of exploitation scenarios. It was found that size data, by themselves, could be useful for detecting large long-term changes in stock status, but are not likely to be good indicators for use in year-to-year management. Natural variations in eel recruitment cause substantial year-to-year variations in the mean size of eels, even when fishing pressure is constant. This makes it difficult to detect changes in size caused by long-term changes in fishing pressure. Even without sampling error, biomass would need to drop by more than 40% (or more, if the drop is gradual) before this change could be reliably detected. The presence of typical levels of sampling error makes this detection even harder.

scholarly journals Long-term changes in regional vegetation cover along the west coast of southern Norway: The importance of human impact

2018 ◽  
Vol 29 (3) ◽  
pp. 404-415 ◽  
Author(s):  
Kari Loe Hjelle ◽  
Lene S. Halvorsen ◽  
Lisbeth Prøsch-Danielsen ◽  
Shinya Sugita ◽  
Aage Paus ◽  
...  
Keyword(s):  
Human Impact ◽  
West Coast ◽  
Vegetation Cover ◽  
The West ◽  
Long Term Changes ◽  
Southern Norway

scholarly journals Long-Term Glacier Mass-Balance Investigations in Svalbard, 1950–88

1990 ◽  
Vol 14 ◽  
pp. 102-106 ◽  
Author(s):  
Jon Ove Hagen ◽  
Olav Liestøl
Keyword(s):  
Mass Balance ◽  
Winter Precipitation ◽  
Summer Temperature ◽  
Glacier Mass Balance ◽  
Climatic Warming ◽  
Equilibrium Line Altitude ◽  
Stable Conditions ◽  
The Mean ◽  
One Year

Mass-balance investigations on glaciers in Svalbard at high latitudes (78°N) show that the ice masses have been steadily decreasing during the period 1950–88. Detailed annual observations have been carried out on Brøggerbreen since 1966 and Lovénbreen since 1967. The mean specific net balances are −0.46 and −0.37 m year−1 water equivalent respectively. Only one year had positive net balance in this period. The cumulative mass lost in the period is then more than 10% of the volume in 1967. Zero net balance would be obtained if the summer temperature was lowered about 1°C or if the winter precipitation increased about 50%. There is a strong correlation between the net mass balance and the height of the equilibrium-line altitude (ELA). Because of the high amount of superimposed ice (10–30% of winter balance) stake readings are necessary to find the ELA. There is no sign of climatic warming through increased melting. The trend analysis of the data from the last 20 years shows stable conditions with a slight increase of the winter balance. The net balance is then slightly increasing and thus less negative than 20 years ago.

scholarly journals Long-Term Monitoring of the Antibody Response to a SARS-CoV-2 Infection

Diagnostics ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1915
Author(s):  
Václav Šimánek ◽  
Ladislav Pecen ◽  
Hana Řezáčková ◽  
Ondřej Topolčan ◽  
Karel Fajfrlík ◽  
...  
Keyword(s):  
Antibody Response ◽  
The West ◽  
Blood Samples ◽  
The Third ◽  
Antibody Positivity ◽  
The Mean ◽  
Long Term Monitoring ◽  
Term Monitoring ◽  
Pcr Test

A group of 110 patients from the West Bohemian region who had been infected with COVID-19 was monitored for the purposes of this study. We focused on cases of mild or moderate COVID-19; statistically the most likely to occur. Day zero was defined as the day on which a positive PCR test was first established. The mean length of observation was 6.5 months, the maximum length 12 months. The first blood samples were taken from a smaller cohort during the 1–3 months following the first positive PCR test. We assumed that SARS-CoV-2 antibodies would be present during this period and therefore a limited number of samples were taken for the purpose of detecting antibodies. More samples were collected, starting 4 months after the first positive PCR test. A subsequent set of blood samples were drawn, mostly 6 months after the first ones. Our study confirmed the presence of total IgG SARS-CoV-2 antibodies up to 1 year after the onset of the disease. The peak of antibody production was observed in the third month after the first positive PCR test. A mathematical estimate of the median duration of antibody positivity was calculated to be 18 months from the onset of the COVID-19 infection.

scholarly journals ANTS ALTER INSECTICIDE EFFICACY ON APHIDS IN THE YARD-LONG BEAN AGROECOSYSTEM ?

2009 ◽  
Vol 9 (1) ◽  
pp. 32-38
Author(s):  
F.X. Susilo ◽  
Dewi Rosmawati ◽  
Nur Yasin
Keyword(s):  
T Test ◽  
Symbiotic Relationship ◽  
The West ◽  
Insecticide Treatment ◽  
Plant Parts ◽  
Insecticide Efficacy ◽  
The Mean ◽  
The Relationship ◽  
Made In

Ants Alter Insecticide Efficacy on Aphids in the Yard-Long Bean Agroecosystem? This study was aimed to detect the relationship between Aphis sp. and ants and to show whether ants could alter insecticide efficacy on Aphis sp. A survey was conducted in  the yard-long bean agroecosystems that have been frequently attacked by aphids and for years treated with imidacloprid insecticide (in Mulyosari Village, intensive sample) versus those barely treated in Ganjar Agung Village (non-intensive sample), both in the West Metro municipal area, Lampung. Two sampling occasions were made (in March and November 2005) where 35 plant parts (i.e. 35 flowers and 35 pods) per sample were randomly observed to record the number of Aphis sp. and ants. The efficacy of the insecticide treatment was determined by comparing the mean number of aphids or ants from intensive versus non intensive samples using a t-test at the 0.05 level. The relationships between ant and aphid numbers were determined by calculating their coefficients of correlation and testing them using a t-test at the 0.01 or 0.05 level. The study showed that the long-term application of the insecticide imidacloprid in the yard-long bean agroecosystem 1) might strengthen the relationship between Aphis sp. and ants (especially Solenopsis sp., Camponotus sp. and Paratopula sp.) and 2) was not effective to suppress  Aphis sp. number. Stronger Aphis sp. — ant symbiotic relationship might alter the insecticide efficacy on Aphis sp. in the agroecosystem.

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