scholarly journals Comparison of Long-Term Changes in Non-Linear Aggregated Drought Index Calibrated by MERRA–2 and NDII Soil Moisture Proxies

Water ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 26
Author(s):  
Fhumulani Mathivha ◽  
Nkanyiso Mbatha
Keyword(s):  
Soil Moisture ◽  
Drought Index ◽  
Water Cycle ◽  
Critical Role ◽  
Phase Relationship ◽  
Positive Trend ◽  
Long Term Changes ◽  
Non Linear ◽  
Seasonal Correlation

This study aimed at evaluating Modern-Era Retrospective Analysis for Research and Applications, Version 2 (MERRA–2) and Normalized Difference Infrared Index (NDII) soil moisture proxies in calibrating a comprehensive Non-linear Aggregated Drought Index (NADI). Soil moisture plays a critical role in temperature variability and controlling the partitioning of water into evaporative fluxes as well as ensuring effective plant growth. Long-term variability and change in climatic variables such as precipitation, temperatures, and the possible acceleration of the water cycle increase the uncertainty in soil moisture variability. Streamflow, temperature, rainfall, reservoir storage, MERRA–2, and NDII soil moisture proxies’ data from 1986 to 2016 were used to formulate the NADI. The trend analysis was performed using the Mann Kendall, SQ-MK was used to determine the point of trend direction change while Theil-Sen trend estimator method was used to determine the magnitude of the detected trend. The seasonal correlation between the NADI-NDII and NADI-MERRA–2 was higher in spring and autumn with an R2 of 0.9 and 0.86, respectively. A positive trend was observed over the 30 years period of study, NADI-NDII trend magnitude was found to be 2.94 units per year while that of NADI-MERRA–2 was 1.21 units. Wavelet analysis showed an in-phase relationship with negligible lagging between the NDII and MERRA–2 calibrated NADI. Although a robust comparison is recommended between soil moisture proxies and observed soil moisture, the soil moisture proxies in this study were found to be useful in monitoring long-term changes in soil moisture.

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.

TGF-β1-Induced Long-Term Changes in Neuronal Excitability in Aplysia Sensory Neurons Depend on MAPK

2006 ◽  
Vol 95 (5) ◽  
pp. 3286-3290 ◽  
Author(s):  
Jeannie Chin ◽  
Rong-Yu Liu ◽  
Leonard J. Cleary ◽  
Arnold Eskin ◽  
John H. Byrne
Keyword(s):  
Sensory Neuron ◽  
Transforming Growth Factor Beta ◽  
Neuronal Excitability ◽  
Transforming Growth Factor ◽  
Critical Role ◽  
Camp Response Element Binding ◽  
Long Term Changes ◽  
Tgf Β1

Transforming growth factor beta-1 (TGF-β1) plays important roles in the early development of the nervous system and has been implicated in neuronal plasticity in adult organisms. It induces long-term increases in sensory neuron excitability in Aplysia as well as a long-term enhancement of synaptic efficacy at sensorimotor synapses. In addition, TGF-β1 acutely regulates synapsin phosphorylation and reduces synaptic depression induced by low-frequency stimuli. Because of the critical role of MAPK in other forms of long-term plasticity in Aplysia, we examined the role of MAPK in TGF-β1-induced long-term changes in neuronal excitability. Prolonged (6 h) exposure to TGF-β1 induced long-term increases in excitability. We confirmed this finding and now report that exposure to TGF-β1 was sufficient to activate MAPK and increase nuclear levels of active MAPK. Moreover, TGF-β1 enhanced phosphorylation of the Aplysia transcriptional activator cAMP response element binding protein (CREB)1, a homologue to vertebrate CREB. Both the TGF-β1-induced long-term changes in neuronal excitability and the phosphorylation of CREB1 were blocked in the presence of an inhibitor of the MAPK cascade, confirming a role for MAPK in long-term modulation of sensory neuron function.

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.

Long-term changes in soil moisture conditions and their relation to atmospheric circulation in the Poyang Lake basin, China

2017 ◽  
Vol 440 ◽  
pp. 23-29 ◽  
Author(s):  
Mingjin Zhan ◽  
Yanjun Wang ◽  
Guojie Wang ◽  
Heike Hartmann ◽  
Lige Cao ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Atmospheric Circulation ◽  
Poyang Lake ◽  
Lake Basin ◽  
Poyang Lake Basin ◽  
Long Term Changes ◽  
Moisture Conditions

scholarly journals Supergiant Variables: Recent Observational Results

1993 ◽  
Vol 134 ◽  
pp. 123-136
Author(s):  
J. R. Percy
Keyword(s):  
Mass Loss ◽  
Variable Stars ◽  
Long Term Changes ◽  
Non Linear ◽  
Red Supergiants ◽  
Continuous Mass ◽  
R Coronae Borealis Stars

AbstractRecent observations of several types of supergiant variable stars are reviewed: massive blue, yellow and red supergiants; classical and population II Cepheids; RV Tauri stars; yellow semi-regular (SRd) variables, including UU Herculis stars; and R Coronae Borealis stars. The emphasis is on non-linear aspects such as: amplitude and shape of the light and velocity curves; multiperiodicity, irregularity and chaos; long-term changes in period and amplitude; episodic and continuous mass loss.

scholarly journals Long-term total water storage change from a Satellite Water Cycle reconstruction over large southern Asian basins

2020 ◽  
Vol 24 (6) ◽  
pp. 3033-3055
Author(s):  
Victor Pellet ◽  
Filipe Aires ◽  
Fabrice Papa ◽  
Simon Munier ◽  
Bertrand Decharme
Keyword(s):  
Climate Variability ◽  
Water Cycle ◽  
Critical Role ◽  
Water Storage ◽  
Anthropogenic Pressure ◽  
Total Water ◽  
Storage Change ◽  
Discharge Measurements

Abstract. The total water storage change (TWSC) over land is a major component of the global water cycle, with a large influence on the climate variability, sea level budget and water resource availability for human life. Its first estimates at a large scale were made available with GRACE (Gravity Recovery and Climate Experiment) observations for the 2002–2016 period, followed since 2018 by the launch of the GRACE-FO (Follow-On) mission. In this paper, using an approach based on the water mass conservation rule, we propose to merge satellite-based observations of precipitation and evapotranspiration with in situ river discharge measurements to estimate TWSC over longer time periods (typically from 1980 to 2016), compatible with climate studies. We performed this task over five major Asian basins, subject to both large climate variability and strong anthropogenic pressure for water resources and for which long-term records of in situ discharge measurements are available. Our Satellite Water Cycle (SAWC) reconstruction provides TWSC estimates very coherent in terms of seasonal and interannual variations with independent sources of information such as (1) TWSC GRACE-derived observations (over the 2002–2015 period), (2) ISBA-CTRIP (Interactions between Soil, Biosphere and Atmosphere CNRM – Centre National de Recherches Météorologiques – Total Runoff Integrating Pathways) model simulations (1980–2015) and (3) the multi-satellite inundation extent (1993–2007). This analysis shows the advantages of the use of multiple satellite-derived datasets along with in situ data to perform a hydrologically coherent reconstruction of a missing water component estimate. It provides a new critical source of information for the long-term monitoring of TWSC and to better understand its critical role in the global and terrestrial water cycle.

scholarly journals From isolated labels and nudges to sustained tinkering: assessing long-term changes in sustainable eating at a lunch restaurant

2020 ◽  
Vol 122 (11) ◽  
pp. 3313-3329 ◽  
Author(s):  
Minna Kaljonen ◽  
Marja Salo ◽  
Jari Lyytimäki ◽  
Eeva Furman
Keyword(s):  
Critical Role ◽  
Climate Impacts ◽  
Community Research ◽  
Eating Behaviours ◽  
Research Strategies ◽  
Sustainable Food ◽  
Content Type ◽  
Long Term Changes ◽  
Long Term Experiment

PurposeThe critical role of diet in climate change mitigation has raised behavioural approaches to the top of the agenda. In this paper, the authors take a critical look at these behavioural approaches and call for a more dynamic, practice-oriented understanding of long-term changes in sustainable food consumption and supply.Design/methodology/approachThis approach is based on the experiences from a long-term experiment promoting sustainable eating in a workplace lunch restaurant using a series of informational and nudging techniques. In the experiment, the authors found that focussing solely on eating behaviours did not help to capture the multi-level change processes mobilised. The authors therefore propose a more dynamic, practice-oriented methodology for examining long-term changes in sustainable eating. The emprical data of the experiment are based on qualitative and quantitative data, consisting of customer survey, customer and kitchen personnel focus group discussions and monitoring data on the use of food items in the restaurant and their climate impacts.FindingsThe results draw attention to a series of practical challenges restaurants face when promoting sustainable eating. Directing analytical attention to tinkering helped to reveal the tensions brought about by labelling and nudging in menu planning and recipe development. The results show how tinkering required attentiveness to customers' wishes in both cases. Nudging offered more freedom for the restaurant to develop menus and recipes. In the case scrutinised, however, nudging customers towards tastier and more satiating vegetarian dishes included the use of dairy. This partly watered down the climate benefits gained from reduced meat consumption.Originality/valueRather than looking separately at changes in consumer behaviour and in the supply of food, the authors show how we need analytical concepts that enable the evaluation of their mutual evolution. Tinkering can assist us in this endeavour. Its adaptive, adjustive character, however, calls for caution. The development of praxis in food services and catering requires critical companions from the transdisciplinary research community. Research can provide systematic knowledge on the impacts of labels and nudges on kitchen praxis. However, research itself also needs to tinker and learn from experiments. This necessitates long-term speculative research strategies.

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