New evidence of warm early-Holocene summers in subarctic Finland based on an enhanced regional chironomid-based temperature calibration model

2014 ◽  
Vol 81 (1) ◽  
pp. 50-62 ◽  
Author(s):  
Tomi P. Luoto ◽  
Marjut Kaukolehto ◽  
Jan Weckström ◽  
Atte Korhola ◽  
Minna Väliranta
Keyword(s):  
Temperature Reconstruction ◽  
Early Holocene ◽  
Calibration Model ◽  
Finnish Lapland ◽  
Temperature Trends ◽  
Holocene Paleoclimate ◽  
Combined Models ◽  
Performance Statistics ◽  
Improved Performance ◽  
Improved Accuracy

AbstractPaleoclimate reconstructions based on biological proxies present methodological challenges, especially during non-analog conditions, such as the early Holocene. Here, two chironomid-based training sets from Finland were amalgamated to create a more accurate transfer function of summer air temperature. The aim was to reconstruct Holocene paleoclimate in northernmost Lapland, in an area that has been either too warm or too cold for reliable reconstructions using the original calibration models. The results showed that the combined calibration model had improved performance statistics. The temperature trends inferred from the downcore chironomid record using the original and combined models were very similar. However, there were major changes in their absolute values with the combined model showing greatly improved accuracy. The chironomid-based temperature reconstruction showed significant correlation with the previous pollen-based reconstructions from northwestern Finnish Lapland. However, differences were observed in the temperature trends of the early Holocene, when the chironomid-inferred temperatures rapidly increased, but the pollen-based reconstructions lagged behind suggesting that a cool climate continued for much longer. However, similar to the chironomid record, new plant macrofossil evidence from northwestern Finland also showed warmer-than-present early Holocene temperatures. Therefore, we conclude that the early Holocene was probably warm in northern Lapland.

scholarly journals Improved Performance of Trash Detection and Human Target Detection Systems using Robot Operating System (ROS)

2021 ◽  
Vol 17 (2) ◽  
Author(s):  
Kisron Kisron ◽  
Bima Sena Bayu Dewantara ◽  
Hary Oktavianto
Keyword(s):  
Operating System ◽  
Computer System ◽  
Target Detection ◽  
Detection System ◽  
Computation Time ◽  
Cascade Algorithm ◽  
Histogram Of Oriented Gradient ◽  
Detection Systems ◽  
Improved Performance ◽  
Improved Accuracy

In a visual-based real detection system using computer vision, the most important thing that must be considered is the computation time. In general, a detection system has a heavy algorithm that puts a strain on the performance of a computer system, especially if the computer has to handle two or more different detection processes. This paper presents an effort to improve the performance of the trash detection system and the target partner detection system of a trash bin robot with social interaction capabilities. The trash detection system uses a combination of the Haar Cascade algorithm, Histogram of Oriented Gradient (HOG) and Gray-Level Coocurrence Matrix (GLCM). Meanwhile, the target partner detection system uses a combination of Depth and Histogram of Oriented Gradient (HOG) algorithms. Robotic Operating System (ROS) is used to make each system in separate modules which aim to utilize all available computer system resources while reducing computation time. As a result, the performance obtained by using the ROS platform is a trash detection system capable of running at a speed of 7.003 fps. Meanwhile, the human target detection system is capable of running at a speed of 8,515 fps. In line with the increase in fps, the accuracy also increases to 77%, precision increases to 87,80%, recall increases to 82,75%, and F1-score increases to 85,20% in trash detection, and the human target detection system has also improved accuracy to 81%, %, precision increases to 91,46%, recall increases to 86,20%, and F1-score increases to 88,42%.

scholarly journals EMONET: A Cross Database Progressive Deep Network for Facial Expression Recognition

2020 ◽  
Vol 13 (6) ◽  
pp. 31-41
Author(s):  
Michael Thiruthuvanathan ◽  
◽  
Balachandran Krishnan ◽  
Keyword(s):  
Facial Expression ◽  
Facial Expression Recognition ◽  
Image Data ◽  
Filter Method ◽  
Expression Recognition ◽  
Deep Convolutional Neural Networks ◽  
Improved Performance ◽  
Improved Learning ◽  
Improved Accuracy ◽  
Progressive Learning

Recognizing facial features to detect emotions has always been an interesting topic for research in the field of Computer vision and cognitive emotional analysis. In this research a model to detect and classify emotions is explored, using Deep Convolutional Neural Networks (DCNN). This model intends to classify the primary emotions (Anger, Disgust, Fear, Happy, Sad, Surprise and Neutral) using progressive learning model for a Facial Expression Recognition (FER) System. The proposed model (EmoNet) is developed based on a linear growing-shrinking filter method that shows prominent extraction of robust features for learning and interprets emotional classification for an improved accuracy. EmoNet incorporates Progressive- Resizing (PR) of images to accommodate improved learning traits from emotional datasets by adding more image data for training and Validation which helped in improving the model’s accuracy by 5%. Cross validations were carried out on the model, this enabled the model to be ready for testing on new data. EmoNet results signifies improved performance with respect to accuracy, precision and recall due to the incorporation of progressive learning Framework, Tuning Hyper parameters of the network, Image Augmentation and moderating generalization and Bias on the images. These parameters are compared with the existing models of Emotional analysis with the various datasets that are prominently available for research. The Methods, Image Data and the Fine-tuned model combinedly contributed in achieving 83.6%, 78.4%, 98.1% and 99.5% on FER2013, IMFDB, CK+ and JAFFE respectively. EmoNet has worked on four different datasets and achieved an overall accuracy of 90%.

Improved Methods for PCA-Based Reconstructions: Case Study Using the Steig et al. (2009) Antarctic Temperature Reconstruction

2011 ◽  
Vol 24 (8) ◽  
pp. 2099-2115 ◽  
Author(s):  
Ryan O’Donnell ◽  
Nicholas Lewis ◽  
Steve McIntyre ◽  
Jeff Condon
Keyword(s):  
Satellite Data ◽  
Expectation Maximization Algorithm ◽  
Principal Component ◽  
Temperature Reconstruction ◽  
Previous Method ◽  
West Antarctica ◽  
Temperature Trends ◽  
Temporal Relationships ◽  
Improved Methods

Abstract A detailed analysis is presented of a recently published Antarctic temperature reconstruction that combines satellite and ground information using a regularized expectation–maximization algorithm. Though the general reconstruction concept has merit, it is susceptible to spurious results for both temperature trends and patterns. The deficiencies include the following: (i) improper calibration of satellite data; (ii) improper determination of spatial structure during infilling; and (iii) suboptimal determination of regularization parameters, particularly with respect to satellite principal component retention. This study proposes two methods to resolve these issues. One utilizes temporal relationships between the satellite and ground data; the other combines ground data with only the spatial component of the satellite data. Both improved methods yield similar results that disagree with the previous method in several aspects. Rather than finding warming concentrated in West Antarctica, the authors find warming over the period of 1957–2006 to be concentrated in the peninsula (≈0.35°C decade−1). This study also shows average trends for the continent, East Antarctica, and West Antarctica that are half or less than that found using the unimproved method. Notably, though the authors find warming in West Antarctica to be smaller in magnitude and find that statistically significant warming extends at least as far as Marie Byrd Land. This study also finds differences in the seasonal patterns of temperature change, with winter and fall showing the largest differences and spring and summer showing negligible differences outside of the peninsula.

A millennium-length temperature reconstruction for the eastern Mediterranean

2020 ◽  
Author(s):  
Jan Esper ◽  
Lara Klippel ◽  
Paul J. Krusic ◽  
Oliver Konter ◽  
Christoph Raible ◽  
...  
Keyword(s):  
Central Europe ◽  
Climate Model ◽  
Eastern Mediterranean ◽  
Temperature Reconstruction ◽  
Ice Age ◽  
Temperature Trends ◽  
Latewood Density ◽  
Scale Temperature ◽  
The Mediterranean ◽  
Millennial Scale

<p>The Mediterranean has been identified as particularly vulnerable to climate change, yet a high-resolution temperature reconstruction extending back into the Medieval Warm Period is still lacking. Here we present such a record from a high-elevation site on Mt. Smolikas in northern Greece, where some of Europe’s oldest trees provide evidence of warm season temperature variability back to 730 CE. The reconstruction is derived from 192 annually resolved, latewood density series from ancient living and relict Pinus heldreichii trees calibrating at r<sub>1911-2015</sub> = 0.73 against regional July-September (JAS) temperatures. Although the recent 1985-2014 period was the warmest 30-year interval (JAS T<sub>wrt.1961-90</sub> = +0.71°C) since the 11<sup>th</sup> century, temperatures during the 9-10<sup>th</sup> centuries were even warmer, including the warmest reconstructed 30-year period from 876-905 (+0.78°C). These differences between warm periods are statistically insignificant though. Several distinct cold episodes punctuate the Little Ice Age, albeit the coldest 30-year period is centered during high medieval times from 997-1026 (-1.63°C). Comparison with reconstructions from the Alps and Scandinavia shows that a similar cold episode occurred in central Europe but was absent at northern latitudes. The reconstructions also reveal different millennial-scale temperature trends (NEur = -0.73°C/1000 years, CEur = -0.13 °C, SEur = +0.23°C) potentially triggered by latitudinal changes in summer insolation due to orbital forcing. These features, the opposing millennial-scale temperature trends and the medieval multi-decadal cooling recorded in Central Europe and the Mediterranean, are not well captured in state-of-the-art climate model simulations.</p>

scholarly journals Soil micromorphogenesis and Early Holocene paleoclimate at the desert margin of Southern Arabia .

2014 ◽  
Vol 3 ◽  
Author(s):  
Peter Kühn ◽  
Dana Pietsch
Keyword(s):  
Organic Matter ◽  
Soil Formation ◽  
Early Holocene ◽  
Geochemical Data ◽  
Buried Soils ◽  
Climate Conditions ◽  
Climate Fluctuations ◽  
Holocene Paleoclimate ◽  
Single Grain ◽  
Southern Arabia

The Ramlat as-Sab’atayn desert margin near Ma’rib, Yemen, displays well-preserved Early Holocene paleosols that are documented by micromorphological and pedological data. The buried soils, which are represented by Ahb horizons, indicate soil formation mostly before 8.3 cal ka BP. In contrast, sandy cover sediments without signs of pedogenesis appeared between 8.3 and 6.6 cal ka BP due to increasing aridity. Characteristic micromorphological features of the cover sediments are a single grain microstructure, crystallitic b-fabric, predominant occurrence of fresh sideromelane, and remnants of microlayers. Micromorphological pedogenic features in the buried Ah horizons include a subangular blocky microstructure, undifferentiated b-fabric as a result of enrichment of organic matter and decalcification, and the predominant occurrence of completely altered sideromelane. Most of these horizons appeared to be nearly completely decalcified so that in parts a stipple speckled b-fabric and neoformed clay coatings could be detected as a result of stronger weathering and soil formation. Pedogenic data provide important information about Holocene climate fluctuations, including the amount of precipitation, which was calculated on the basis of geochemical data from buried A, AB and B horizons. The buried paleosols represent moist climate conditions with precipitation ranging from 400 to 600 mm a<sup>-1</sup>.

The relationship between water and air temperature in chironomid-based paleoclimate reconstructions: Records from boreal and subarctic Finland

The Holocene ◽  
2014 ◽  
Vol 24 (11) ◽  
pp. 1584-1590 ◽  
Author(s):  
Tomi P Luoto ◽  
Marjut Kaukolehto ◽  
Liisa Nevalainen
Keyword(s):  
Water Temperature ◽  
Air Temperature ◽  
Sediment Cores ◽  
Regional Scale ◽  
Calibration Model ◽  
Related Factors ◽  
Temperature Reconstructions ◽  
Close Relationship ◽  
Performance Statistics ◽  
Temperature Optima

Fossil remains of larval chironomids are one of the most useful paleolimnological proxies to reconstruct Holocene paleoclimate. We investigate the within-lake distribution of chironomids in relation to water temperature and test the usability of intralake calibration in chironomid-based temperature reconstructions. We compare our findings against the traditional multilake calibration technique in Holocene sediment cores from Finland. The results show that intralake water temperature optima of common taxa correspond closely with mean July air temperature optima in a regional multilake dataset, with exception of a few vegetation-associated taxa. A calibration model based on intralake water temperatures shows performance statistics that correspond to the general performance statistics level of multilake calibration models. However, the intralake model has somewhat increased prediction error. Despite the fact that the intralake model is sensitive to poor modern analogues, it shows correlation with the results using the multilake calibration approach in the Holocene reconstructions. Our results confirm that the within-lake distribution of chironomids along a water depth gradient is closely linked with water temperature gradient. This provides evidence for the close relationship between chironomids and temperature in general and suggests that, in addition to the regional scale, water temperature is a key variable in determining chironomid distribution at the site-specific scale. However, long-term changes in intralake gradients in other depth-related factors, such as hypolimnetic oxygen conditions, extent of photic zone and habitat distribution, may hamper the quantitative accuracy of chironomid-based temperature reconstructions, though the results also suggest that these changes are likely to have little general impact on the trends of chironomid-based air temperature reconstructions.

scholarly journals Limnological changes and chironomid-inferred summer air temperature from the Late Pleniglacial to the Early Holocene in the East Carpathians

2021 ◽  
pp. 1-15
Author(s):  
Mónika Tóth ◽  
Oliver Heiri ◽  
Ildikó Vincze ◽  
Mihály Braun ◽  
Zoltán Szabó ◽  
...  
Keyword(s):  
Air Temperature ◽  
Temperature Reconstruction ◽  
Late Glacial ◽  
Early Holocene ◽  
Nutrient Level ◽  
Temperature Changes ◽  
Heinrich Event ◽  
Eastern Carpathians ◽  
Decreasing Ph ◽  
East Carpathians

Abstract Here we provide the first chironomid record and associated summer air-temperature (TVII) reconstruction between ca. 16,800–9100 cal yr BP from Lake Saint Anne (SZA), situated in the Eastern Carpathians. SZA was formed by the youngest volcanic eruption of Ciomadul volcano at ca. 29,600 cal yr BP. Our main goals in this study are to test whether warming after Heinrich event 1 (H1; ca. 16,200 cal yr BP) had similar amplitude to the late glacial warming, while Younger Dryas (YD) summers remained relatively warm in this region of Europe. We found the most remarkable chironomid assemblage change with a TVII increase of ~3.5–3.8°C at ca. 16,350 cal yr BP at SZA, followed by another slight TVII increase of ~0.8–1.0°C at ca. 14,450 cal yr BP. Only very minor temperature variations were recorded between 14,450 cal yr BP and 11,700 cal yr BP, with an unexpected TVII decrease in the Early Holocene. Variations in water depth together with increasing analogue problems and paludification from ca. 14,200 cal yr BP onwards may have influenced the reliability of our paleotemperature record obtained from SZA. In addition, Sphagnum-indicated decreasing pH, and hence decreasing nutrient level, likely overrode the effect of summer air-temperature changes during the Early Holocene, and this may explain the bias in the chironomid-inferred summer air-temperature reconstruction in the Early Holocene section.

A chironomid-based reconstruction of late glacial summer temperatures in the Pareng Mountains (Romania)

2021 ◽  
Author(s):  
Zoltán Szabó ◽  
Oliver Heiri ◽  
Gabriella Darabos ◽  
Ivett Pálfi ◽  
Mihály Molnár ◽  
...  
Keyword(s):  
Air Temperature ◽  
Temperature Increase ◽  
Ice Core ◽  
Temperature Reconstruction ◽  
Late Glacial ◽  
Early Holocene ◽  
Cold Event ◽  
Air Temperatures ◽  
Important Addition ◽  
Summer Temperatures

&lt;p&gt;Late Glacial and Early Holocene summer temperatures were reconstructed based on fossil chironomid assemblages at Lake Latorica (Lacul Iezerul Latoritei; Pareng Mountains, 1530 m a.s.l.) with a joint Norwegian &amp;#8211; Swiss transfer function, providing an important addition to the late glacial quantitative climate reconstructions from eastern-central Europe. The reconstructed pattern of the Late Glacial faunal and chironomid-inferred temperature changes in Lake Latorica shows some differences from the NGRIP &amp;#948;&lt;sup&gt;18&lt;/sup&gt;O record and other European chironomid-based reconstructions; however, it is consistent with the chironomid results of Lake Brazi from the neighbouring Retyezat Mountains (1740 m a.s.l.). Our reconstruction shows that the summer air temperature at Lake Latorica increased by ~ 3&amp;#176;C at the Oldest Dryas/B&amp;#248;lling transition (GS-2/GI-1) and reached 8.1-10.8&amp;#176;C during the Late Glacial interstadial. The Younger Dryas (GS-1) climate reversal in the chironomid-based temperature reconstruction is shown by only a weak decrease (~1&amp;#176;C), while slow temperature increase (9.7&amp;#8211;11&amp;#176;C) is observed in the second half of the period. At the Holocene transition temperature increase of nearly 2&amp;#176;C was observed in the reconstruction. Before the Preboreal Oscillation (PO) the mean summer air temperature in the Early Holocene was 12.5&amp;#176;C. During PO the temperature reconstruction shows a decrease of 1.8&amp;#176;C. This cold event coincides with cooling in the Greenland ice core records and other European temperature reconstructions. After the Preboral oscillation the summer air temperatures increase to ~12.8&amp;#176;C in the Early Holocene.&lt;/p&gt;

scholarly journals Quantitative reconstruction of precipitation changes in the Iberian Peninsula during the Late Pleistocene and the Holocene

2019 ◽  
Author(s):  
Liisa Ilvonen ◽  
José Antonio López-Sáez ◽  
Lasse Holmström ◽  
Francisca Alba-Sánchez ◽  
Sebastián Pérez-Díaz ◽  
...  
Keyword(s):  
Iberian Peninsula ◽  
Late Pleistocene ◽  
Late Holocene ◽  
Calibration Model ◽  
Temperature Changes ◽  
The North ◽  
Temperature Trends ◽  
Precipitation Increase ◽  
Precipitation Changes ◽  
Reconstructed Precipitation

Abstract. Precipitation is a key climate driver of vegetation and ecosystems of the Iberian Peninsula. Here, we use a regional pollen-climate calibration model and fossil pollen data from seven sites from different parts of Spain to provide quantitative reconstructions of annual precipitation values for the last 15 000 years. Our records show that in the Late Pleistocene (~ 15 000 to 11 600 cal yr BP) precipitation changes took place markedly in tune with the temperature trends in northern Europe, with higher precipitation during the Greenland interstadial 1 (Bølling-Allerød) and lower precipitation during the Greenland stadial 1 (Younger Dryas). The early Holocene was characterized by a rapid precipitation increase after 11 600 cal yr BP, followed by a slowly declining trend until roughly 8000 cal yr BP. From 8000 to 4000 cal yr BP the reconstructed precipitation values are the highest in most records, with maximum values nearly 100 % higher that the modern reconstructed values. The results suggest a gradually declining precipitation over the last four millennia, although the late-Holocene reconstructions are biased by intensifying human impact on vegetation. In general, our results suggest that the main changes in precipitation in the Iberian Peninsula have occurred in pace with the main temperature changes in the North European-Atlantic region, with warm (cold) periods in the North corresponding with humid (dry) periods in the Iberian Peninsula.

scholarly journals High Arctic Holocene temperature record from the Agassiz ice cap and Greenland ice sheet evolution

2017 ◽  
Vol 114 (23) ◽  
pp. 5952-5957 ◽  
Author(s):  
Benoit S. Lecavalier ◽  
David A. Fisher ◽  
Glenn A. Milne ◽  
Bo M. Vinther ◽  
Lev Tarasov ◽  
...  
Keyword(s):  
Air Temperature ◽  
Ice Core ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Temperature Reconstruction ◽  
High Arctic ◽  
Early Holocene ◽  
Temperature Record ◽  
The Past ◽  
Ice Cap

We present a revised and extended high Arctic air temperature reconstruction from a single proxy that spans the past ∼12,000 y (up to 2009 CE). Our reconstruction from the Agassiz ice cap (Ellesmere Island, Canada) indicates an earlier and warmer Holocene thermal maximum with early Holocene temperatures that are 4–5 °C warmer compared with a previous reconstruction, and regularly exceed contemporary values for a period of ∼3,000 y. Our results show that air temperatures in this region are now at their warmest in the past 6,800–7,800 y, and that the recent rate of temperature change is unprecedented over the entire Holocene. The warmer early Holocene inferred from the Agassiz ice core leads to an estimated ∼1 km of ice thinning in northwest Greenland during the early Holocene using the Camp Century ice core. Ice modeling results show that this large thinning is consistent with our air temperature reconstruction. The modeling results also demonstrate the broader significance of the enhanced warming, with a retreat of the northern ice margin behind its present position in the mid Holocene and a ∼25% increase in total Greenland ice sheet mass loss (∼1.4 m sea-level equivalent) during the last deglaciation, both of which have implications for interpreting geodetic measurements of land uplift and gravity changes in northern Greenland.

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