scholarly journals ANALYSIS AND MAPPING OF SPATIO-TEMPORAL CLIMATE VARIABILITY IN PUNJAB USING CLASSICAL STATISTICS AND GEOSTATISTICS

MAUSAM ◽  
2021 ◽  
Vol 69 (1) ◽  
pp. 147-155
Author(s):  
P. K. KINGRA ◽  
RAJ SETIA ◽  
SATINDER KAUR ◽  
JATINDER KAUR ◽  
SIMRANJEET SINGH ◽  
...  
Keyword(s):  
Climate Variability ◽  
Classical Statistics ◽  
Spatio Temporal

scholarly journals Spatio-Temporal Analysis of Vegetation Dynamics as a Response to Climate Variability and Drought Patterns in the Semiarid Region, Eritrea

2019 ◽  
Vol 11 (6) ◽  
pp. 724 ◽  
Author(s):  
Simon Measho ◽  
Baozhang Chen ◽  
Yongyut Trisurat ◽  
Petri Pellikka ◽  
Lifeng Guo ◽  
...  
Keyword(s):  
Climate Variability ◽  
Vegetation Dynamics ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Negative Impact ◽  
Pearson Correlation ◽  
Temporal Analysis ◽  
Semiarid Region ◽  
Ecological Zones ◽  
Spatio Temporal

There is a growing concern over change in vegetation dynamics and drought patterns with the increasing climate variability and warming trends in Africa, particularly in the semiarid regions of East Africa. Here, several geospatial techniques and datasets were used to analyze the spatio-temporal vegetation dynamics in response to climate (precipitation and temperature) and drought in Eritrea from 2000 to 2017. A pixel-based trend analysis was performed, and a Pearson correlation coefficient was computed between vegetation indices and climate variables. In addition, vegetation condition index (VCI) and standard precipitation index (SPI) classifications were used to assess drought patterns in the country. The results demonstrated that there was a decreasing NDVI (Normalized Difference Vegetation Index) slope at both annual and seasonal time scales. In the study area, 57.1% of the pixels showed a decreasing annual NDVI trend, while the significance was higher in South-Western Eritrea. In most of the agro-ecological zones, the shrublands and croplands showed decreasing NDVI trends. About 87.16% of the study area had a positive correlation between growing season NDVI and precipitation (39.34%, p < 0.05). The Gash Barka region of the country showed the strongest and most significant correlations between NDVI and precipitation values. The specific drought assessments based on VCI and SPI summarized that Eritrea had been exposed to recurrent droughts of moderate to extreme conditions during the last 18 years. Based on the correlation analysis and drought patterns, this study confirms that low precipitation was mainly attributed to the slowly declining vegetation trends and increased drought conditions in the semi-arid region. Therefore, immediate action is needed to minimize the negative impact of climate variability and increasing aridity in vegetation and ecosystem services.

scholarly journals Evolving climate network perspectives on global surface air temperature effects of ENSO and strong volcanic eruptions

2021 ◽  
Author(s):  
Tim Kittel ◽  
Catrin Ciemer ◽  
Nastaran Lotfi ◽  
Thomas Peron ◽  
Francisco Rodrigues ◽  
...  
Keyword(s):  
Climate Variability ◽  
Large Scale ◽  
Southern Oscillation ◽  
Global Climate ◽  
Surface Air Temperature ◽  
Volcanic Eruptions ◽  
Internal Variability ◽  
Hierarchical Organization ◽  
Spatio Temporal ◽  
Global Surface

AbstractEpisodically occurring internal (climatic) and external (non-climatic) disruptions of normal climate variability are known to both affect spatio-temporal patterns of global surface air temperatures (SAT) at time-scales between multiple weeks and several years. The magnitude and spatial manifestation of the corresponding effects depend strongly on the specific type of perturbation and may range from weak spatially coherent yet regionally confined trends to a global reorganization of co-variability due to the excitation or inhibition of certain large-scale teleconnectivity patterns. Here, we employ functional climate network analysis to distinguish qualitatively the global climate responses to different phases of the El Niño–Southern Oscillation (ENSO) from those to the three largest volcanic eruptions since the mid-20th century as the two most prominent types of recurrent climate disruptions. Our results confirm that strong ENSO episodes can cause a temporary breakdown of the normal hierarchical organization of the global SAT field, which is characterized by the simultaneous emergence of consistent regional temperature trends and strong teleconnections. By contrast, the most recent strong volcanic eruptions exhibited primarily regional effects rather than triggering additional long-range teleconnections that would not have been present otherwise. By relying on several complementary network characteristics, our results contribute to a better understanding of climate network properties by differentiating between climate variability reorganization mechanisms associated with internal variability versus such triggered by non-climatic abrupt and localized perturbations.

scholarly journals Deciphering the spatio-temporal complexity of climate change of the last deglaciation: a model analysis

2011 ◽  
Vol 7 (2) ◽  
pp. 591-602 ◽  
Author(s):  
D. M. Roche ◽  
H. Renssen ◽  
D. Paillard ◽  
G. Levavasseur
Keyword(s):  
Climate Variability ◽  
Large Scale ◽  
Last Deglaciation ◽  
Regional Variability ◽  
Internal Climate Variability ◽  
The North ◽  
Sequence Of Events ◽  
Transient Simulations ◽  
The Last Deglaciation ◽  
Spatio Temporal

Abstract. Understanding the sequence of events occuring during the last major glacial to interglacial transition (21 ka BP to 9 ka BP) is a challenging task that has the potential to unveil the mechanisms behind large scale climate changes. Though many studies have focused on the understanding of the complex sequence of rapid climatic change that accompanied or interrupted the deglaciation, few have analysed it in a more theoretical framework with simple forcings. In the following, we address when and where the first significant temperature anomalies appeared when using slow varying forcing of the last deglaciation. We used here coupled transient simulations of the last deglaciation, including ocean, atmosphere and vegetation components to analyse the spatial timing of the deglaciation. To keep the analysis in a simple framework, we did not include freshwater forcings that potentially cause rapid climate shifts during that time period. We aimed to disentangle the direct and subsequent response of the climate system to slow forcing and moreover, the location where those changes are more clearly expressed. In a data – modelling comparison perspective, this could help understand the physically plausible phasing between known forcings and recorded climatic changes. Our analysis of climate variability could also help to distinguish deglacial warming signals from internal climate variability. We thus are able to better pinpoint the onset of local deglaciation, as defined by the first significant local warming and further show that there is a large regional variability associated with it, even with the set of slow forcings used here. In our model, the first significant hemispheric warming occurred simultaneously in the North and in the South and is a direct response to the obliquity forcing.

scholarly journals Seesaw terrestrial wetting and drying between eastern and western Australia

2020 ◽  
Author(s):  
Ajiao Chen ◽  
Huade Guan ◽  
Okke Batelaan
Keyword(s):  
Climate Variability ◽  
Western Australia ◽  
La Niña ◽  
Wetting And Drying ◽  
La Nina ◽  
Eastern Australia ◽  
Terrestrial Water ◽  
Grace Satellite ◽  
Spatio Temporal

Australia, the driest inhabited continent, is prone to natural disasters, such as droughts, floods, bushfires and heatwaves. Strong climate variability causes regular threats to water supply, agriculture and the environment. Improving our insight into changes in hydroclimatic patterns is required to provide useful information for society. Previous studies mainly focused on the causes of extreme wet or dry events in specific periods and their impacts on agriculture and ecosystems. An understanding of long-term spatio-temporal patterns of wetting and drying in Australia is still lacking. Here we show, based on analyses of GRACE satellite derived terrestrial water storage (TWS) and extended datasets, that there are four continuous periods of seesaw wetting and drying between eastern and western Australia in the past five decades. The seesaw phenomenon is characterized by eastern Australia gaining water, while western Australia is losing water, and vice versa. Strong La Niña induced continent-wide wetting, resets this pattern, leaving each seesaw to last for 11±5 years. We provide one possible mechanism related to vegetation response to climate variability and its feedback on hydrological processes to explain the seesaw resetting pattern. The identified reoccurring seesaw pattern indicates that society would need to become more adaptive in managing forest, water, and disaster risks in the wake of a next strong La Niña induced continent-wide wetting in Australia.

Understanding the spatio-temporal influence of climate variability on Australian heatwaves

2016 ◽  
Vol 37 (10) ◽  
pp. 3963-3975 ◽  
Author(s):  
Tammas F. Loughran ◽  
Sarah E. Perkins-Kirkpatrick ◽  
Lisa V. Alexander
Keyword(s):  
Climate Variability ◽  
Temporal Influence ◽  
Spatio Temporal

scholarly journals Deciphering the spatio-temporal complexity of climate change of the last deglaciation: a model analysis

2010 ◽  
Vol 6 (6) ◽  
pp. 2593-2623 ◽  
Author(s):  
D. M. Roche ◽  
H. Renssen ◽  
D. Paillard
Keyword(s):  
Climate Variability ◽  
Large Scale ◽  
Last Deglaciation ◽  
Regional Variability ◽  
Temporal Complexity ◽  
Internal Climate Variability ◽  
Sequence Of Events ◽  
Transient Simulations ◽  
The Last Deglaciation ◽  
Spatio Temporal

Abstract. Understanding the sequence of events occuring during the last major glacial to interglacial transition (21 ka BP to 9 ka BP) is a challenging task that has the potential to unveil the mechanisms behind large scale climate changes. Though many studies have focused at a complex understanding of the sequence of rapid climatic change that accompanied or interrupted the deglaciation, few have analysed it in a more theoretical framework with simple forcings. In the following, we address when and where the first significant temperature anomalies appear when using slow varying forcing of the last deglaciation. We use here coupled transient simulations of the last deglaciation, including ocean, atmosphere and vegetation components to analyse the spatial timing of the deglaciation. To keep the analysis in a simple framework, we do not include rapid freshwater forcings that have led to rapid climate shifts during that time period. We aim to disentangle the direct and subsequent response of the climate system to slow forcing and moreover the location where those changes are more clearly expressed. In a data-modelling comparison perspective this could help understanding the physically plausible phasing between known forcings and recorded climatic changes. Our analysis of climate variability could also help to distinguish deglacial warming signals from internal climate variability. We thus are able to better pinpoint the onset of local deglaciation, as defined by the first significant local warming, and further show that there is a large regional variability associated with it, even with the set of slow forcings used here.

Spatio-temporal temperature and precipitation patterns in the southern Peruvian Andes - insights from the Climandes project

2020 ◽  
Author(s):  
Christoph Spirig ◽  
Gubler Stefanie ◽  
Avalos Grinia ◽  
Huerta Adrian ◽  
Imfeld Noemi ◽  
...  
Keyword(s):  
Climate Variability ◽  
Maximum Temperature ◽  
Strong Increase ◽  
Small Scale ◽  
Drought Risk ◽  
Seasonal Forecasts ◽  
Austral Spring ◽  
Peruvian Andes ◽  
Temperature And Precipitation ◽  
Spatio Temporal

&lt;p&gt;In the southern Peruvian Andes, climatic threats such as water scarcity or frost pose major challenges for agriculture. Such events may result in severe yield losses threatening the livelihood of smallholder farmers due to missing adaptive and coping strategies. Knowledge on climate variability and change, on the current state of the climate, as well as short- to midrange predictions potentially improve the farmers&amp;#8217; risk management. However, such knowledge is only partly available and often does not reach rural communities. Climandes, a pilot project of the Global Framework for Climate Services, tackled these shortcomings through the enhancement of climatological observations, the production of gridded datasets using satellite and station observations, the verification of seasonal forecasts to determine their usefulness for small-scale applications, and through the establishment of communication channels and user engagement. This contribution highlights some of the insights from the Climandes project: climatological analyses of spatio-temporal patterns in the southern Peruvian Andes, past trends, as well as the performance of seasonal forecasts in the region. The work focuses on temperature and precipitation using the newly developed gridded datasets, quality controlled observational data, and seasonal forecasts of ECMWF SEAS5.&lt;/p&gt;&lt;p&gt;The results of the climatological analysis let us draw the conclusion that precipitation and minimum temperature patterns are likely related through increased / reduced cloud cover and increased / reduced incoming longwave radiation. Both variables show similar spatial patterns for example in austral spring (SON), namely a pronounced northeast / southwest gradient. Trends, which were derived from the enhanced climatological observation data available since 1964, show a strong increase in maximum temperature of around 0.2&amp;#176;C / decade, while minimum temperatures show only very moderate trends. In addition to the slight decrease of total precipitation in austral spring, i.e., the time of sowing, the strong increase of maximum temperatures further decreases soil water availability and enhances drought risk. With regard to seasonal predictions, we found that especially the performance of precipitation forecasts is only very limited in the southern Peruvian Andes, and mostly does not exceed information from climatology. We conclude that seasonal predictions are not applicable for small-scale applications in the region, whereas they may serve as a beneficial basis to assess climate variability and discuss decision-making based thereon.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;

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