scholarly journals Climate extremes in multi-model simulations of stratospheric aerosol and marine cloud brightening climate engineering

2015 ◽  
Vol 15 (16) ◽  
pp. 9593-9610 ◽  
Author(s):  
V. N. Aswathy ◽  
O. Boucher ◽  
M. Quaas ◽  
U. Niemeier ◽  
H. Muri ◽  
...  
Keyword(s):  
Extreme Precipitation ◽  
Extreme Temperature ◽  
The Arctic ◽  
Large Temperature ◽  
Frequency Of Occurrence ◽  
Climate Engineering ◽  
Temperature Changes ◽  
Dry Spell ◽  
Low Latitudes ◽  
The Mean

Abstract. Simulations from a multi-model ensemble for the RCP4.5 climate change scenario for the 21st century, and for two solar radiation management (SRM) schemes (stratospheric sulfate injection (G3), SULF and marine cloud brightening by sea salt emission SALT) have been analysed in terms of changes in the mean and extremes of surface air temperature and precipitation. The climate engineering and termination periods are investigated. During the climate engineering period, both schemes, as intended, offset temperature increases by about 60 % globally, but are more effective in the low latitudes and exhibit some residual warming in the Arctic (especially in the case of SALT which is only applied in the low latitudes). In both climate engineering scenarios, extreme temperature changes are similar to the mean temperature changes over much of the globe. The exceptions are the mid- and high latitudes in the Northern Hemisphere, where high temperatures (90th percentile of the distribution) of the climate engineering period compared to RCP4.5 control period rise less than the mean, and cold temperatures (10th percentile), much more than the mean. This aspect of the SRM schemes is also reflected in simulated reduction in the frost day frequency of occurrence for both schemes. However, summer day frequency of occurrence increases less in the SALT experiment than the SULF experiment, especially over the tropics. Precipitation extremes in the two SRM scenarios act differently – the SULF experiment more effectively mitigates extreme precipitation increases over land compared to the SALT experiment. A reduction in dry spell occurrence over land is observed in the SALT experiment. The SULF experiment has a slight increase in the length of dry spells. A strong termination effect is found for the two climate engineering schemes, with large temperature increases especially in the Arctic. Globally, SULF is more effective in reducing extreme temperature increases over land than SALT. Extreme precipitation increases over land is also more reduced in SULF than the SALT experiment. However, globally SALT decreases the frequency of dry spell length and reduces the occurrence of hot days compared to SULF.

scholarly journals Climate extremes in multi-model simulations of stratospheric aerosol and marine cloud brightening climate engineering

2014 ◽  
Vol 14 (23) ◽  
pp. 32393-32425
Author(s):  
V. N. Aswathy ◽  
O. Boucher ◽  
M. Quaas ◽  
U. Niemeier ◽  
H. Muri ◽  
...  
Keyword(s):  
The Arctic ◽  
Large Temperature ◽  
Solar Radiation Management ◽  
Change Scenario ◽  
Climate Engineering ◽  
Cold Temperatures ◽  
Dry Spell ◽  
Low Latitudes ◽  
The Mean ◽  
The Tropics

Abstract. Simulations from a multi-model ensemble for the RCP4.5 climate change scenario for the 21st century, and for two solar radiation management schemes (stratospheric sulfate injection, G3, and marine cloud brightening, G3SSCE) have been analyzed in terms of changes in the mean and extremes for surface air temperature and precipitation. The climate engineered (SRM 2060s – RCP4.5 2010s) and termination (2080s – 2060s) periods are investigated. During the climate engineering period, both schemes, as intended, offset temperature increases by about 60% globally, but are more effective in the low latitudes and exhibit some residual warming in the Arctic (especially in the case of marine cloud brightening that is only applied in the low latitudes). In both climate engineering scenarios, extreme temperatures changes are similar to the mean temperature changes over much of the globe. The exception is in Northern Hemisphere high latitudes, where high temperatures (90th percentile of the distribution) of climate engineering relative to RCP4.5 rise less than the mean and cold temperatures (10th percentile) much more than the mean. When defining temperature extremes by fixed thresholds, namely number of frost days and summer days, it is found that both climate engineering experiments are not completely alleviating the changes relative to RCP 4.5. The reduction in 2060s dry spell occurrence over land region in G3-SSCE is is more pronounced than over oceans. Experiment G3 exhibits same pattern as G3-SSCE albeit, stronger in magnitude. A strong termination effect is found for the two climate engineering schemes, with large temperature increases especially in the Arctic. Mean temperatures rise faster than the extremes, especially over oceans, with the exception of the Tropics. Conversely precipitation extremes rise much more than the mean, even more so over the ocean, and especially in the Tropics.

scholarly journals Effects of Urbanization on Regional Extreme-Temperature Changes in China, 1960–2016

2020 ◽  
Vol 12 (16) ◽  
pp. 6560 ◽  
Author(s):  
Junliang Qiu ◽  
Xiankun Yang ◽  
Bowen Cao ◽  
Zhilong Chen ◽  
Yuxuan Li
Keyword(s):  
Northeast China ◽  
Urban Climate ◽  
Extreme Temperature ◽  
Maximum Temperature ◽  
Temperature Changes ◽  
Low Latitudes ◽  
Different Seasons ◽  
Extreme Minimum Temperature ◽  
Temperature Indices ◽  
Urbanization In China

Urbanization in China has been expanding dramatically since 1978, significantly affecting the extreme temperature changes in cities, which is a vital indicator of urban climate change. To assess urban-related effect on regional extreme-temperature changes in China, this study employed high-resolution land use data to divide meteorological stations into rural stations, suburban stations, and urban stations, and evaluated the annual and seasonal changes in extreme minimum temperature (TNN), mean temperature (Tavg) and extreme maximum temperature (TXX) at each meteorological station. The result revealed that extreme temperature indices (TNN, TXX) and Tavg increased significantly from 1960 to 2016 with varied degrees in different seasons and different regions. Extreme temperature indices in high latitudes increased more rapidly than in low latitudes; while the trends in summer are slower than in other seasons. Urbanization effects on the trends of TNN, Tavg and TXX were all statistically significant, but urbanization effects on TNN and Tavg were more significant than TXX. The urbanization effects were more significant in low altitudes, especially in North, South, Northwest and Northeast China. In North, Northwest and Northeast China, the urban-related effects on temperature increase were mainly observed in spring and winter, but in South China, the urban-related effects were more evident in summer. This study is valuable for sustainable urban planning in China.

scholarly journals Spatial Heterogeneity and Complexity of the Impact of Extreme Climate on Vegetation in China

2021 ◽  
Vol 13 (10) ◽  
pp. 5748
Author(s):  
Shuang Li ◽  
Feili Wei ◽  
Zheng Wang ◽  
Jiashu Shen ◽  
Ze Liang ◽  
...  
Keyword(s):  
Extreme Precipitation ◽  
Vegetation Index ◽  
Precipitation Amount ◽  
Extreme Temperature ◽  
Climate Indices ◽  
Natural Ecosystems ◽  
Extreme Climate ◽  
Dry Spell ◽  
Compound Type ◽  
The Impact

The impact of extreme climate on natural ecosystems and socioeconomic systems is more serious than that of the climate’s mean state. Based on the data of 1698 meteorological stations in China from 2001 to 2018, this study calculated the 27 extreme climate indices of the Expert Team on Climate Change Detection and Indices (ETCCDI). Through correlation analysis and collinearity diagnostics, we selected two representative extreme temperature indices and three extreme precipitation indices. The spatial scale of the impact of extreme climate on Normalized Difference Vegetation Index (NDVI) in China during the growing season from 2001 to 2018 was quantitatively analyzed, and the complexity of the dominant factors in different regions was discussed via clustering analysis. The research results show that extreme climate indices have a scale effect on vegetation. There are spatial heterogeneities in the impacts of different extreme climate indices on vegetation, and these impacts varied between the local, regional and national scales. The relationship between the maximum length of a dry spell (CDD) and NDVI was the most spatially nonstationary, and mostly occurred on the local scale, while the effect of annual total precipitation when the daily precipitation amount was more than the 95th percentile (R95pTOT) showed the greatest spatial stability, and mainly manifested at the national scale. Under the current extreme climate conditions, extreme precipitation promotes vegetation growth, while the influence of extreme temperature is more complicated. As regards intensity and range, the impact of extreme climate on NDVI in China over the past 18 years can be categorized into five types: the humidity-promoting type, the cold-promoting and drought-inhibiting compound type, the drought-inhibiting type, the heat-promoting and drought-inhibiting compound type, and the heat-promoting and humidity-promoting compound type. Drought is the greatest threat to vegetation associated with extreme climate in China.

Temperature changes in hot flat rolling of steels at low strain rates and low reduction

1997 ◽  
Vol 211 (4) ◽  
pp. 261-284 ◽  
Author(s):  
P O Aiyedun ◽  
L G M Sparling ◽  
C M Sellars
Keyword(s):  
Temperature Gradient ◽  
Rolling Temperature ◽  
Large Temperature ◽  
Specimen Thickness ◽  
Air Cooling ◽  
Strain Rates ◽  
Low Carbon ◽  
Temperature Changes ◽  
Flat Rolling ◽  
The Mean

A finite difference (two-dimensional) model developed to describe the heat flow at low strain rates (0.08–1.5 s−1) and low reduction (∼10 per cent) for a hot flat rolled slab both during air cooling and during roll contact has been used in conjunction with experimentally measured temperatures through specimen thickness during roll contact after reheating to temperatures in the range 1000–1200°C for mild steel, low carbon SS316 and high carbon SS316 (with Nb, V and Ti). At high strain rates (∼1.5 s−1) a steep temperature gradient was produced in the specimen near the surface whereas for low strain rates (∼0.08 s−1) this temperature gradient penetrated deep into the thickness, leading to a large drop in the mean rolling temperature. Roll chilling, leading to higher values of the Zener-Holloman parameter, Z, resulted from a decrease in the mean rolling temperature and the large temperature gradient during roll contact. Temperature changes due to material composition, reheating temperature, contact time and rolling conditions led to precipitation strengthening and roll chilling effects which have accounted for the excess load and torque observed experimentally and industrially.

scholarly journals Changes in extreme climate indices in Sarajevo (Bosnia and Herzegovina)

2021 ◽  
Vol 101 (2) ◽  
pp. 1-21
Author(s):  
Slobodan Gnjato ◽  
Tatjana Popov ◽  
Marko Ivanisevic ◽  
Goran Trbic
Keyword(s):  
Bosnia And Herzegovina ◽  
Extreme Precipitation ◽  
Extreme Temperature ◽  
The Arctic ◽  
Climate Indices ◽  
East Atlantic ◽  
Extreme Climate ◽  
Extreme Precipitation Indices ◽  
Precipitation Indices ◽  
Temperature Indices

The study analyzes trends in extreme climate indices in Sarajevo (Bosnia and Herzegovina). Based on daily maximum temperatures, daily minimum temperatures and daily precipitation during the 1961-2016 periods, a set of 27 indices recommended by the CCl/CLIVAR Expert Team for Climate Change Detection and Indices (ETCCDI) was calculated in the RClimDex (1.0) software. Given the results, the extreme temperature indices displayed a warming tendency throughout the year (most prominent in summer). The positive trends in warm temperature indices were stronger than the downward trends in cold ones. The highest trend values were estimated for TXx, TNx, TX90p, TN90p, WSDI, SU25 and SU30. The extreme precipitation indices displayed trends mixed in sign (annually and seasonally), but all statistically insignificant. However, upward trends in R99p, RX1day, RX5day, SDII, R10mm and R20mm suggest an increase in the magnitude and frequency of intense precipitation events. Moreover, significant changes in distribution of majority temperature indices were determined, whereas shifts in precipitation indices were mostly insignificant. The observed changes in extreme temperature indices are related with large-scale atmospheric circulation patterns (primarily the East-Atlantic pattern) and the Atlantic Multidecadal Oscillation. The negative correlation with the North Atlantic Oscillation, the East Atlantic/West Russia pattern and the Arctic Oscillation is found for majority of extreme precipitation indices.

scholarly journals Analysis Of The Temperature Changes In The AburrÁ Valley Between 1995 And 2015 And Modeling Based On Urban, Meteorological And Energetic Parameters

2018 ◽  
Author(s):  
Enrique Posada ◽  
Andrea Cadavid
Keyword(s):  
Energy Management ◽  
Approximate Model ◽  
Mitigation Measures ◽  
Large Temperature ◽  
Urban Air ◽  
Temperature Changes ◽  
The Mean ◽  
Populated Region ◽  
Available Information ◽  
The Impact

There is a perception among the inhabitants of the Aburrá Valley Region, that this heavily populated region, situated in the Andean mountains of Colombia, has been suffering large temperature elevations in the last years, especially in the last decade. To give perspective about this issue, the authors have gone through the available information about temperature changes in three meteorological stations in the region and have correlated it with a set of variables of urban, climatic and energetic nature, with the intention of developing an approximate model to understand the temperature changes. Changes in the mean temperature, based on the linear correlation of the data were estimated on 0.47oC for the 20 years between 1995 and 2015; the study showed that 60% of change was found to be related to local human activities and 40% was attributed to the impact of global warming. For the local influences some practical mitigation actions are proposed, related to improve the energy management and paying more attention to the temperature changes trough improvements in the number and capability of sampling stations in the urban air and in the river, which serve as clear indicators of the changes and the effect of any mitigation measures.

scholarly journals Large Day-to-Day Changes in Extreme Temperature in Poland and Atmospheric Circulation

2020 ◽  
Author(s):  
Katarzyna Szyga-Pluta
Keyword(s):  
Atmospheric Circulation ◽  
Extreme Temperature ◽  
Cyclonic Circulation ◽  
Large Temperature ◽  
Extreme Temperatures ◽  
National Research Institute ◽  
Temperature Changes ◽  
Anticyclonic Circulation ◽  
Circulation Types

The primary purpose of the study was the determination of the spatial day-to-day variability of extreme temperatures in Poland and the dependency of large temperature changes on atmospheric circulation in accordance with the Grosswetterlagen (GWL) classification. The goal was implemented based on data from 1966 to 2015, made available by the Institute of Meteorology and Water Management – National Research Institute. Day-to-day changes in maximum and minimum temperatures were designated with a rate of ≥ 6 °C (large) and with a rate of ≥ 12 °C (very large) and their spatial distribution was presented. Finally, the analysis of the dependency of considerable temperature changes on atmospheric circulation in accordance with the Grosswetterlagen (GWL) classification was conducted. The obtained results showed that in Poland in the period 1966-2015 the number of large changes in both Tmax and Tmin slightly increased, although the fluctuations show spatial variability. Large changes in Tmax occur more frequently in spring, and in Tmin in winter. Large changes in Tmax and Tmin are mainly recorded during cyclonic circulation, however, the anticyclonic circulation types favour especially large decreases in Tmin.

scholarly journals The Climatic Analysis of Summer Monsoon Extreme Precipitation Events over West Africa in CMIP6 Simulations

2021 ◽  
Vol 5 (1) ◽  
pp. 25-41
Author(s):  
Nana Ama Browne Klutse ◽  
Kwesi Akumenyi Quagraine ◽  
Francis Nkrumah ◽  
Kwesi Twentwewa Quagraine ◽  
Rebecca Berkoh-Oforiwaa ◽  
...  
Keyword(s):  
West Africa ◽  
Extreme Precipitation ◽  
Heavy Rainfall ◽  
Extreme Rainfall ◽  
The Other ◽  
Rainfall Characteristics ◽  
Model Simulations ◽  
Dry Spell ◽  
The Mean ◽  
Spell Length

AbstractWe evaluate the capability of 21 models from the new state-of-the-art Coupled Model Intercomparison Project, Phase 6 (CMIP6) in the representation of present-day precipitation characteristics and extremes along with their statistics in simulating daily precipitation during the West African Monsoon (WAM) period (June–September). The study uses a set of standard extreme precipitation indices as defined by the Expert Team on Climate Change Detection and Indices constructed using CMIP6 models and observational datasets for comparison. Three observations; Global Precipitation Climatology Project (GPCP), Climate Hazards Group InfraRed Precipitation with Station data (CHIRPS), and Tropical Applications of Meteorology using SATellite and ground-based observation (TAMSAT) datasets are used for the validation of the model simulations. The results show that observed datasets present nearly the same spatial pattern but discrepancies in the magnitude of rainfall characteristics. The models show substantial discrepancies in comparison with the observations and among themselves. A number of the models depict the pattern of rainfall intensity as observed but some models overestimate the pattern over the coastal parts (FGOALS-f3-L and GFDL-ESM4) and western part (FGOALS-f3-L) of West Africa. All model simulations explicitly show the pattern of wet days but with large discrepancies in their frequencies. On extreme rainfall, half of the models express more intense extremes in the 95th percentiles while the other half simulate less intense extremes. All the models overestimate the mean maximum wet spell length except FGOALS-f3-L. The spatial patterns of the mean maximum dry spell length show a good general agreement across the different models, and the observations except for four models that show an overestimation in the Sahara subregion. INM-CM4-8 and INM-CM5-0 display smaller discrepancies from their long-term average rainfall characteristics, in terms of extreme rainfall estimates than the other CMIP6 datasets. For the frequency of heavy rainfall, TaiESM1 and IPSL-CMGA-LR perform better when compared with observational datasets. MIROC6 and GFDL-ESM4 displayed the largest error in representing the frequency of heavy rainfall and 95th percentile extremes, and therefore, cannot be reliable. The study has assessed how rainfall extremes are captured in both observation and the models. Though there are some discrepancies, it gives room for improvement of the models in the next version of CMIP.

The distribution of benthic hydrographic indicator species in Svalbard waters, 1978–1981

1984 ◽  
Vol 64 (3) ◽  
pp. 667-677 ◽  
Author(s):  
M. F. Dyer ◽  
G. J. Cranmer ◽  
P. D. Fry ◽  
W. G. Fry
Keyword(s):  
Considerable Change ◽  
Turn Of The Century ◽  
The Arctic ◽  
Past Century ◽  
Sea Temperature ◽  
Temperature Changes ◽  
The North ◽  
Arctic Regions ◽  
Temperature Ranges ◽  
The Mean

Fourteen species of benthic invertebrates, found to be indicators of hydrographic conditions by Blacker (1957), were recorded during research cruises between Finmark and north Spitsbergen during the summers of 1978, 1979, 1980 and 1981. The distributions were compared with those found during surveys carried out between 1949 and 1959.Both Atlantic and Arctic species were found to the north of Bear Island and along the west coast of Spitsbergen, and the temperature ranges at which they were found were greater than those found by Blacker (1957).IntroductionDuring the past century the annual mean temperature of the Arctic regions has undergone a considerable change. The warming of the regions began about 1885 (Willett, 1950) and peaked around 1938, when the mean air temperature of Spitsbergen was nearly 6 °C warmer than at the turn of the century (Hoel, 1953). The warming of the seas in the region seems to have started later - Jensen (1939) suggests 1917 - and sea temperature changes were detected north of Spitsbergen in 1921 (Schokalsky, 1936). This warming resulted in the reappearance of cod in great quantities on the Bear Island Bank, after the absence of any sustained quantities for about 40 years (Blacker, 1957).The marine benthos of Svalbardf was surveyed during the latter part of the last century and the first half of this century (1878–1914,1923–31) when the benthos was recorded during several cruises in the region (see Blacker (1957) for review). The benthos was again recorded between 1949 and 1955 (Blacker, 1957) and 1955 and 1959 (Blacker, 1965); see Fig. lA.

Effects of Urbanization on Regional Extreme-Temperature Change in China，1960-2016

2020 ◽  
Author(s):  
Junliang Qiu ◽  
Xiankun Yang ◽  
Bowen Cao ◽  
Zhilong Chen ◽  
Yuxuan Li
Keyword(s):  
Temperature Change ◽  
Statistical Significance ◽  
Extreme Temperature ◽  
Maximum Temperature ◽  
Seasonal Temperature ◽  
Temperature Changes ◽  
Low Latitudes ◽  
Extreme Minimum Temperature ◽  
Land Cover Map ◽  
Regional Temperature

<p>Fast urbanization is one of the aggrandizement factors to global warming, but the effects of urbanization on extreme temperature change is still not quantitatively assessed. Based on high-resolution land cover map, this study classified 613 meteorological stations in China into three classes, namely, urban station, suburban station and rural station to simulate the trends of extreme minimum temperature (TNN), mean temperature (Tavg) and extreme maximum temperature (TXX) of each meteorological station. The roles of urbanization in temperature change in the period 1960-2016 were then assessed. The results indicated that annual temperature increased significantly, but seasonal temperature increased with varied degrees. Temperature in high latitudes increased faster than that in low latitudes. Temperature in summer increased slower than that in other seasons. The effects of urbanization on TNN, Tavg and TXX were all statistically significant, but the effects on TNN and Tavg were more noticeable than TXX. The aggrandizement effects of urbanization presented by low-altitude meteorological stations are significant in South China and East China for all temperature indices, despite no statistical significance presented by high-altitude meteorological stations in Southwest China. This paper can provide a reference for understanding the regional temperature changes and the effects of urbanization on its changes in China.</p>

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