scholarly journals Deglaciation of the Caucasus Mountains, Russia/Georgia, in the 21st century observed with ASTER satellite imagery and aerial photography

2014 ◽  
Vol 8 (6) ◽  
pp. 2367-2379 ◽  
Author(s):  
M. Shahgedanova ◽  
G. Nosenko ◽  
S. Kutuzov ◽  
O. Rototaeva ◽  
T. Khromova
Keyword(s):  
Aerial Photography ◽  
Landsat Imagery ◽  
Positive Trend ◽  
Positive Temperature ◽  
Southern Slope ◽  
Rate Of Increase ◽  
Recession Rates ◽  
Summer Temperatures ◽  
Precipitation Anomalies ◽  
Caucasus Mountains

Abstract. Changes in the map area of 498 glaciers located on the Main Caucasus ridge (MCR) and on Mt. Elbrus in the Greater Caucasus Mountains (Russia and Georgia) were assessed using multispectral ASTER and panchromatic Landsat imagery with 15 m spatial resolution in 1999/2001 and 2010/2012. Changes in recession rates of glacier snouts between 1987–2001 and 2001–2010 were investigated using aerial photography and ASTER imagery for a sub-sample of 44 glaciers. In total, glacier area decreased by 4.7 ± 2.1% or 19.2 ± 8.7 km2 from 407.3 ± 5.4 km2 to 388.1 ± 5.2 km2. Glaciers located in the central and western MCR lost 13.4 ± 7.3 km2 (4.7 ± 2.5%) in total or 8.5 km2 (5.0 ± 2.4%) and 4.9 km2 (4.1 ± 2.7%) respectively. Glaciers on Mt. Elbrus, although located at higher elevations, lost 5.8 ± 1.4 km2 (4.9 ± 1.2%) of their total area. The recession rates of valley glacier termini increased between 1987–2000/01 and 2000/01–2010 (2000 for the western MCR and 2001 for the central MCR and Mt.~Elbrus) from 3.8 ± 0.8, 3.2 ± 0.9 and 8.3 ± 0.8 m yr−1 to 11.9 ± 1.1, 8.7 ± 1.1 and 14.1 ± 1.1 m yr−1 in the central and western MCR and on Mt. Elbrus respectively. The highest rate of increase in glacier termini retreat was registered on the southern slope of the central MCR where it has tripled. A positive trend in summer temperatures forced glacier recession, and strong positive temperature anomalies in 1998, 2006, and 2010 contributed to the enhanced loss of ice. An increase in accumulation season precipitation observed in the northern MCR since the mid-1980s has not compensated for the effects of summer warming while the negative precipitation anomalies, observed on the southern slope of the central MCR in the 1990s, resulted in stronger glacier wastage.

scholarly journals Deglaciation of the Caucasus Mountains, Russia/Georgia, in the 21st century observed with ASTER satellite imagery and aerial photography

2014 ◽  
Vol 8 (4) ◽  
pp. 4159-4194
Author(s):  
M. Shahgedanova ◽  
G. Nosenko ◽  
S. Kutuzov ◽  
O. Rototaeva ◽  
T. Khromova
Keyword(s):  
Aerial Photography ◽  
Landsat Imagery ◽  
Positive Trend ◽  
Positive Temperature ◽  
Southern Slope ◽  
Rate Of Increase ◽  
Recession Rates ◽  
Summer Temperatures ◽  
Precipitation Anomalies ◽  
Caucasus Mountains

Abstract. Changes in map area of 498 glaciers located in the Main Caucasus Ridge (MCR) and on Mt. Elbrus in the Greater Caucasus Mountains (Russia and Georgia) were assessed using multispectral ASTER and panchromatic Landsat imagery with 15 m spatial resolution from 1999–2001 and 2010–2012. Changes in recession rates of glacier snouts between 1987–2001 and 2001–2010 were investigated using aerial photography and ASTER imagery for a sub-sample of glaciers. In total, glacier area declined by 4.7 ± 1.6% or 19.24 km2. Glaciers located in the central and western MCR lost 13.4 km2 (4.6 ± 1.8%) in total or 8.56 km2 (5.0 ± 1.8%) and 4.87 km2 (4.1 ± 1.9%) respectively. Glaciers on Mt. Elbrus, although located at higher elevations, lost 5.8 km2 (4.9 ± 0.7%) of their total area. The recession rates of valley glacier termini increased between 1987–2000/01 and 2010 from 3.8 ± 0.8 m a−1, 3.2 ± 0.9 m a−1 and 8.3 ± 0.8 m a−1 to 11.9 ± 1.1 m a−1, 8.7 ± 1.1 m a−1 and 14.1 ± 1.1 m a−1 in the central and western MCR and on Mt. Elbrus respectively. The highest rate of increase in glacier termini retreat was registered on the southern slope of the central MCR where it has tripled. A positive trend in summer temperatures forced glacier recession and strong positive temperature anomalies of 1998, 2006, and 2010 contributed to the enhanced loss of ice. An increase in accumulation season precipitation observed in the northern MCR since the mid-1980s has not compensated for the effects of summer warming while the negative precipitation anomalies, observed on the southern slope of the central MCR in the 1990s, resulted in stronger glacier wastage.

scholarly journals How to correctly apply Gaussian statistics in a non-stationary climate?

2021 ◽  
Author(s):  
Reinhold Steinacker
Keyword(s):  
Time Series ◽  
Actual Data ◽  
Temperature Record ◽  
Positive Trend ◽  
Positive Temperature ◽  
Climatic Trend ◽  
Filter Methods ◽  
Periodic Time Series ◽  
Past Data

AbstractTime series with a significant trend, as is now being the case for the temperature in the course of climate change, need a careful approach for statistical evaluations. Climatological means and moments are usually taken from past data which means that the statistics does not fit to actual data anymore. Therefore, we need to determine the long-term trend before comparing actual data with the actual climate. This is not an easy task, because the determination of the signal—a climatic trend—is influenced by the random scatter of observed data. Different filter methods are tested upon their quality to obtain realistic smoothed trends of observed time series. A new method is proposed, which is based on a variational principle. It outperforms other conventional methods of smoothing, especially if periodic time series are processed. This new methodology is used to test, how extreme the temperature of 2018 in Vienna actually was. It is shown that the new annual temperature record of 2018 is not too extreme, if we consider the positive trend of the last decades. Also, the daily mean temperatures of 2018 are not found to be really extreme according to the present climate. The real extreme of the temperature record of Vienna—and many other places around the world—is the strongly increased positive temperature trend over the last years.

Future Changes to El Niño Teleconnections over the North Pacific and North America

2021 ◽  
pp. 1-43
Author(s):  
Jonathan D. Beverley ◽  
Matthew Collins ◽  
F. Hugo Lambert ◽  
Robin Chadwick
Keyword(s):  
North America ◽  
El Niño ◽  
North Pacific ◽  
El Nino ◽  
Positive Temperature ◽  
Central Pacific ◽  
Wave Source ◽  
The North ◽  
Precipitation Anomalies ◽  
The North Pacific

AbstractThe El Niño-Southern Oscillation (ENSO) is the leading mode of interannual climate variability and it exerts a strong influence on many remote regions of the world, for example in northern North America. Here, we examine future changes to the positive-phase ENSO teleconnection to the North Pacific/North America sector and investigate the mechanisms involved. We find that the positive temperature anomalies over Alaska and northern North America that are associated with an El Niño event in the present day are much weaker, or of the opposite sign, in the CMIP6 abrupt 4×CO2 experiments for almost all models (22 out of 26, of which 15 are statistically significant differences). This is largely related to changes to the anomalous circulation over the North Pacific, rather than differences in the equator-to-pole temperature gradient. Using a barotropic model, run with different background circulation basic states and Rossby wave source forcing patterns from the individual CMIP6 models, we find that changes to the forcing from the equatorial central Pacific precipitation anomalies are more important than changes in the global basic state background circulation. By further decomposing this forcing change into changes associated with the longitude and magnitude of ENSO precipitation anomalies, we demonstrate that the projected overall eastward shift of ENSO precipitation is the main driver of the temperature teleconnection change, rather than the increase in magnitude of El Niño precipitation anomalies which are, nevertheless, seen in the majority of models.

THE "INTERPRETER EFFECT" IN MAPPING TERRAIN IN NORTHERN BRITISH COLUMBIA USING COLOR AERIAL PHOTOGRAPHY AND LANDSAT IMAGERY

1978 ◽  
Vol 58 (3) ◽  
pp. 357-368
Author(s):  
K. W. G. VALENTINE
Keyword(s):  
British Columbia ◽  
Standard Deviation ◽  
University Students ◽  
Aerial Photography ◽  
Landsat Imagery ◽  
Landsat Image ◽  
Percentage Agreement

Thirteen professional soil surveyors and sixteen university students produced a terrain map of a 2,000-km2 area just east of Telegraph Creek in northern British Columbia. The mapping was done on three adjacent color photographs (scale 1:120,000) and a LANDSAT image (enlarged to 1:250,000). Results were compared to a previous biophysical survey and expressed as percentage agreement with the previous map. These results were analyzed for three types of consistency; between all interpreters on one image; between images for each interpreter; and between valleys and mountains. The professionals’ and students’ results were analyzed separately. There was nearly 60% agreement with the previous map using photographs and about 50% using the LANDSAT image. The professionals obtained slightly higher agreement than the students. Mapping variability between interpreters was satisfactorily low: the standard deviation was 6.0% or less in 8 out of 12 image comparisons. Interpreter consistence from image to image was less than satisfactory; r values between images were positive and high in only 3 out of 12 comparisons. More interpreters mapped a greater proportion of the mountains than the valleys in agreement with the previous map. The thick vegetation in the valleys may mask the terrain more. Groups of interpreters could be consistent on one image but there appears to be a significant amount of interpreter bias from image to image and area to area.

Twentieth-century variations in temperature and precipitation in the Nordic Arctic

Polar Record ◽  
2002 ◽  
Vol 38 (206) ◽  
pp. 203-210 ◽  
Author(s):  
E. J. Førland ◽  
I. Hanssen-Bauer ◽  
T. Jónsson ◽  
C. Kern-Hansen ◽  
P.Ø. Nordli ◽  
...  
Keyword(s):  
Twentieth Century ◽  
Temperature Trend ◽  
Annual Precipitation ◽  
Data Series ◽  
Positive Trend ◽  
Positive Temperature ◽  
Climate Data ◽  
Data Set ◽  
Temperature And Precipitation

AbstractIn a joint Nordic effort, a high-quality climate data set for the Nordic Arctic is established. The data set consists of monthly values from 20 stations in Greenland, Iceland, the Faeroes, and the Norwegian Arctic. The data set is made available on the web. Ten climate elements are included, and most of the series covers the period 1890–2000. The data series illustrate the large climatic contrasts in the Nordic Arctic, and demonstrate that parts of the region have experienced substantial climate variations during the last century. Despite increasing temperatures during recent decades, the present temperature level is still lower than in the 1930s and 1950s in large parts of the region. The pattern of long-term precipitation variations is more complicated, but in parts of the region the annual precipitation has increased substantially. At Svalbard Airport and Bjørnøya the annual precipitation has increased by more than 2.5% per decade during the twentieth century.Variations in atmospheric circulation can account for most of the long-term positive trend in precipitation in the Norwegian Arctic, and also for the positive temperature trend from the 1960s. The positive temperature trend before 1930 and the negative trend during the following decades, are, however, not accounted for by the circulation models.

scholarly journals Genetic Trends Estimation in IRRIs Rice Drought Breeding Program and Identification of High Yielding Drought-Tolerant Lines

2021 ◽  
Author(s):  
Apurva Khanna ◽  
Mahender Anumalla ◽  
Margaret Catolos ◽  
Jérôme Bartholomé ◽  
Roberto Fritsche-Neto ◽  
...  
Keyword(s):  
Grain Yield ◽  
Genetic Gain ◽  
Recurrent Selection ◽  
Historical Data ◽  
Breeding Program ◽  
Positive Trend ◽  
Breeding Values ◽  
Genetic Gains ◽  
Rate Of Increase ◽  
Genetic Trends

Abstract BackgroundEstimation of genetic trends using historical data is an important parameter to check the success of the breeding programs. The estimated genetic trends can act as a guideline to target the appropriate breeding strategies and optimize the breeding program for improved genetic gains. In this study, 17 years of historical data from IRRI’s rice drought breeding program was used to estimate the genetic trends and assess the success of the breeding program. We also identified top-performing lines based on grain yield breeding values as an elite panel for implementing future population improvement-based breeding schemes.ResultsA two-stage approach of pedigree-based mixed model analysis was used to analyze the data and extract the breeding values and estimate the genetic trends for grain yield under non-stress, drought, and in combined data of non-stress and drought. Lower grain yield values were observed in all the drought trials. Heritability for grain yield estimates ranged between 0.20-0.94 under the drought trials, and 0.43-0.83 under non-stress trials. Under non-stress conditions the genetic gain of 0.44% (21.20 kg/ha/year) for genotypes and 0.17 % (7.90 kg/ha/year) for checks was observed. The genetic trend under the drought conditions exhibited a positive trend with the genetic gain of 0.11% (1.98kg/ha/year) for genotypes and 0.55% (9.52kg/ha/year) for checks. For combined analysis showed a genetic gain of 0.39% (12.13 kg/ha/year) for genotypes and 0.60% (13.69 kg/ha/year) for checks was observed. For elite panel selection, 200 promising lines were selected based on higher breeding values for grain yield and prediction accuracy of >0.40. The breeding values of the 200 genotypes formulating the core panel ranged between 2366.17 and 4622.59 (kg/ha).ConclusionsA positive genetic rate was observed under all the three conditions; however, the rate of increase was lower than the required rate of 1.5% genetic gain. We propose a recurrent selection breeding strategy within the elite population with the integration of modern tools and technologies to boost the genetic gains in IRRI’s drought breeding program. The elite breeding panel identified in this study forms an easily available and highly enriched genetic resource for future recurrent selection programs to boost the genetic gains.

Modeling the physical drivers of the decadal variability of the Southern Ocean carbon uptake

2021 ◽  
Author(s):  
Lavinia Patara ◽  
Torge Martin ◽  
Ivy Frenger ◽  
Jan Klaus Rieck ◽  
Chia-Te Chien
Keyword(s):  
Southern Ocean ◽  
Decadal Variability ◽  
Open Ocean ◽  
Global Ocean ◽  
Carbon Uptake ◽  
Positive Trend ◽  
The Past ◽  
Rate Of Increase ◽  
Ocean Biogeochemistry ◽  
Ocean Carbon

<p>Observational estimates point to pronounced changes of the Southern Ocean carbon uptake in the past decades, but the mechanisms are still not fully understood. In this study we assess physical drivers of the Southern Ocean carbon uptake variability in a suite of global ocean biogeochemistry models with 0.5º, 0.25º and 0.1º horizontal resolution as well as in a 3-member ensemble performed with an Earth System Model (ESM) sharing the same ocean biogeochemistry model. The ocean models show a positive trend of the Southern Ocean CO<sub>2</sub> uptake in the past decades, with a weakening of its rate of increase in the 1990s. The 0.1º model exhibits the strongest trend in the Southern Ocean carbon uptake. <span>Different physical drivers of the carbon up</span>take variability and of its trends (such as changes in stratification, ventilation, overturning circulation, and SST) are analyzed. A particular focus of this study is to assess the role of open-ocean polynyas in driving Southern Ocean carbon uptake. Open-ocean polynyas in the Southern Ocean have pronounced climate fingerprints, such as reduced sea-ice coverage, heat loss by the ocean and enhanced bottom water formation, but their role for the Southern Ocean carbon uptake has been as yet little studied. To this end we analyze conjunctly ESM simulations and an ocean-only sensitivity experiment where open-ocean polynyas are artificially created by perturbing the Antarctic freshwater runoff. We find that enhanced CO<sub>2</sub> outgassing takes place during the polynya opening, because old carbon-rich waters come in contact with the atmosphere. The concomitant increased uptake of anthropogenic CO<sub>2</sub> partially compensates the CO<sub>2</sub> outgassing. When the polynya closes, the ocean CO<sub>2</sub> uptake increases significantly, possibly fueled by abundant nutrients and higher alkalinity brought to the surface during the previous convective phase. Our results suggest that open-ocean polynyas could have a significant impact on the Southern Ocean CO<sub>2</sub> uptake and could thus modulate its decadal variability.</p><p> </p>

scholarly journals Climatic controls of glacier distribution and glacier changes in Austria

2011 ◽  
Vol 52 (59) ◽  
pp. 83-90 ◽  
Author(s):  
J. Abermann ◽  
M. Kuhn ◽  
A. Fischer
Keyword(s):  
Climate Change ◽  
Climatic Conditions ◽  
Climate Change Signal ◽  
Positive Temperature ◽  
Weather Forecasts ◽  
Austrian Alps ◽  
Glacier Changes ◽  
Summer Temperatures ◽  
Strong Dynamic ◽  
Different Levels

AbstractIn this study we aim to connect glacier extent in 1998 with general climatic conditions, and glacier changes between 1969 and 1998 with climate change in the Austrian Alps. The investigations are based on two complete glacier inventories, a homogenized gridded precipitation dataset and European Centre for Medium-Range Weather Forecasts re-analysis (ERA-40) data of air temperature at different levels. A relationship between median glacier elevation, minimal elevation, the general elevation of the surrounding mountains and mean climatic values was found. In the Austrian Alps, the existence of glaciers at low elevations can only be maintained with above-average accumulation or strong dynamic ice supply. For debris-free glaciers, we found a limit of ~2080ma.s.l., where mean summer temperatures (June–August) exceed 4°C. Glacier changes from 1969 to 1998 are strongly negative both in relative area and in mean thickness. There is a weak and regionally varying negative trend in precipitation over this period. A spatially consistent sequence of positive temperature anomalies in the early 1980s and after 1990 offers an explanation for the retreat. The study shows that the observed spatial variability of glacier changes is connected more strongly to the topographic differences than to a regionally different climate change signal.

scholarly journals Climate Change and Livestock Management Drove Extensive Vegetation Recovery in the Qinghai-Tibet Plateau

2021 ◽  
Vol 13 (23) ◽  
pp. 4808
Author(s):  
Enqin Liu ◽  
Xiangming Xiao ◽  
Huaiyong Shao ◽  
Xin Yang ◽  
Yali Zhang ◽  
...  
Keyword(s):  
Climate Change ◽  
Tibet Plateau ◽  
Positive Trend ◽  
Vegetation Degradation ◽  
Livestock Population ◽  
Northern Tibet ◽  
Rate Of Increase ◽  
The Impact ◽  
Qinghai Tibet Plateau ◽  
Impacts Of Climate Change

The vegetation of the Qinghai-Tibet Plateau (QTP), China, is diverse and sensitive to climate change. Because of extensive grassland degradation in the QTP, several ecological restoration projects, which affect the livestock population, have been implemented in the QTP. Although many studies have reported the impacts of climate change on vegetation in the QTP, our knowledge on the impacts of both climate change and livestock on vegetation remains very limited. Here, we investigated the impacts of climate change and livestock population on vegetation growth by using the annual maximum normalized difference vegetation index (NDVImax) and growing-season climate data from 1981 to 2019. We analyzed the relationship between NDVImax and climate and livestock population using the modified Mann-Kendall trend Test and Pearson correlation analysis. For the entire QTP, NDVImax had a two-phase trend, with a slow rise during 1981–2000 and a rapid rise during 2000–2019. Overall, NDVImax in the QTP increased and decreased in 63.7% and 6.7% of the area in 2000–2019. In areas with significant changes in NDVImax, it was strongly correlated with relative humidity and vapor pressure. The small positive trend in NDVImax during 1981–2000 was influenced by warmer and wetter climate, and the overgrazing by a large population of livestock slowed down the rate of increase in NDVImax. Livestock population for Qinghai and Tibet in recent years has been lower than in the 1980s.The warmer and wetter climate and substantial drops in the livestock population contributed to large recovery in vegetation during 2001–2019. Vegetation degradation in Qinghai during 1981–2000 and central-northern Tibet during 2000–2019 was driven mainly by drier and hotter climatic. Although 63.7% of the area in the QTP became greener, the vegetation degradation in central-northern Tibet should not be ignored and more measures should be taken to alleviate the impact of warming and drying climate. Our findings provide a better understanding of the factors that drove changes in vegetation in the QTP.

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