Indian monsoon inter-annual variability and climate change

2018 ◽  
Vol 07 ◽  
Author(s):  
Madhav Khandekar
Keyword(s):  
Climate Change ◽  
Indian Monsoon ◽  
Annual Variability

scholarly journals Intra-annual variability of the Western Mediterranean Oscillation (WeMO) and occurrence of extreme torrential rainfall in Catalonia (NE Iberia)

2019 ◽  
Author(s):  
Joan Albert Lopez-Bustins ◽  
Laia Arbiol-Roca ◽  
Javier Martin-Vide ◽  
Antoni Barrera-Escoda ◽  
Marc Prohom
Keyword(s):  
Climate Change ◽  
Mediterranean Region ◽  
Western Mediterranean ◽  
Sensitive Area ◽  
Weather Extremes ◽  
Late Autumn ◽  
Annual Variability ◽  
Torrential Rainfall ◽  
Mediterranean Oscillation

Abstract. In previous studies the Western Mediterranean Oscillation index (WeMOi) at daily resolution has proven to constitute an effective tool for analysing the occurrence of episodes of torrential rainfall over eastern Spain. The Western Mediterranean region is therefore a very sensitive area, since climate change can enhance these weather extremes. In the present study we selected the extreme torrential episodes (≥ 200 mm in 24 hours) that took place in Catalonia (NE Iberia) during the 1951–2016 study period (66 years). We computed daily WeMOi values and constructed WeMOi calendars. Our principal results reveal the occurrence of 50 episodes (0.8 cases per year), mainly concentrated in the autumn months. We inferred a threshold of WeMOi ≤ −2 to define an extreme negative WeMO phase at daily resolution. Most of the 50 episodes (60 %) in the study area occurred on days presenting an extreme negative WeMOi value. Specifically, the most negative WeMOi values are detected in autumn, during the second 10-day period of October (11th–20th), coinciding with the highest frequency of extreme torrential events. On comparing the subperiods, we observed a statistically significant decrease in WeMOi values in all months, particularly in late October, and in November and December. No changes in the frequency of these extreme torrential episodes were observed between both subperiods; in contrast, a displacement of the episodes is detected from early to late autumn.

scholarly journals Complex Principal Component Analysis of Mass Balance Change on Qinghai-Tibet Plateau

2016 ◽  
Author(s):  
Jingang Zhan ◽  
Hongling Shi ◽  
Yong Wang ◽  
Yixin Yao
Keyword(s):  
Climate Change ◽  
Mass Balance ◽  
El Niño ◽  
Indian Monsoon ◽  
El Nino ◽  
Principal Component ◽  
Mass Gain ◽  
Tibet Plateau ◽  
Major Influence ◽  
Qinghai Tibet Plateau

Abstract. Abstract. This paper analyzes the spatial characteristics of mass balance change on the Qinghai-Tibet Plateau and surrounding areas, using 153 monthly solutions of temporal gravity data from the Gravity Recovery and Climate Experiment(in this case GRACE) satellite. Spatial mode characteristics and phase information of mass balance change are analyzed using complex principal component analysis (in this case CPCA). Information on time-frequency change of major components is analyzed using the wavelet amplitude-period spectrum. The results show that the mass balance change on the plateau is influenced by various atmospheric circulations and there are obvious systemic differences, namely, glacial fluctuation of the Himalayas area was mainly influenced by the weakening Indian monsoon, El Niño and East Asian monsoon. There were drastic changes of glacier mass gain and loss balance. Apart from the Indian monsoon and El Niño affected on mass balance in inland areas of the plateau, the northern parts of the plateau was also affected by the westerlies and there was a positive mass balance, with mass gain exceeding loss. The Pamirs and the Karakoram Range areas are influenced not only by the Indian monsoon and westerlies but also by the climate change of El Niño and La Niña, and mass change shows a weak mass balanced. The major influence on the change of mass balance on the Qinghai-Tibet Plateau was the weakening Indian monsoon, which was responsible for 54.0 % of that change. Because El Niño is strengthening, it has recently become the second major factor affecting the change of mass balance, responsible for 16.3 % of that change. The third major influence was the westerlies and of La Niña-related climate change, accounting for 5.6 % of the mass balance change.

scholarly journals Anthropogenic climate change versus internal climate variability: Impacts on Alpine snow cover

2020 ◽  
Author(s):  
Fabian Willibald ◽  
Sven Kotlarski ◽  
Adrienne Grêt-Regamey ◽  
Ralf Ludwig
Keyword(s):  
Climate Change ◽  
Climate Variability ◽  
Snow Cover ◽  
Climate Model ◽  
Regional Climate ◽  
Anthropogenic Climate Change ◽  
Swiss Alps ◽  
Internal Climate Variability ◽  
Annual Variability ◽  
The Future

Abstract. Snow is a sensitive component of the climate system. In many parts of the world, water, stored as snow, is a vital resource for agriculture, tourism and the energy sector. As uncertainties in climate change assessments are still relatively large, it is important to investigate the interdependencies between internal climate variability and anthropogenic climate change and their impacts on snow cover. We use regional climate model data from a new single model large ensemble with 50 members (ClimEX LE) as driver for the physically based snow model SNOWPACK at eight locations across the Swiss Alps. We estimate the contribution of internal climate variability to uncertainties in future snow trends by applying a Mann-Kendall test for consecutive future periods of different lengths (between 30 and 100 years) until the end of the 21st century. Under RCP8.5, we find probabilities between 15 % and 50 % that there will be no significantly negative trend in future mean snow depths over a period of 50 years. While it is important to understand the contribution of internal climate variability to uncertainties in future snow trends, it is likely that the variability of snow depth itself changes with anthropogenic forcing. We find that relative to the mean, inter-annual variability of snow increases in the future. A decrease of future mean snow depths, superimposed by increases in inter-annual variability will exacerbate the already existing uncertainties that snow-dependent economies will have to face in the future.

scholarly journals Adaptation to climate change: historical evidence from the Indian monsoon

2017 ◽  
Vol 22 (5) ◽  
pp. 517-545 ◽  
Author(s):  
Vis Taraz
Keyword(s):  
Climate Change ◽  
Panel Data ◽  
Spatial Variation ◽  
Fixed Effects ◽  
Indian Monsoon ◽  
Historical Evidence ◽  
Adaptation To Climate Change ◽  
Rainfall Variation ◽  
Average Rainfall ◽  
Impacts Of Climate Change

AbstractEstimating the potential impacts of climate change requires understanding the ability of agents to adapt to changes in their climate. This paper uses panel data from India spanning from 1956 to 1999 to investigate the ability of farmers to adapt. To identify adaptation, the author exploits persistent, multidecadal monsoon regimes during which droughts or floods are more common. These regimes generate medium-run variation in average rainfall, and there is spatial variation in the timing of the regimes. Using a fixed-effects strategy, she tests whether farmers have adapted to the medium-run rainfall variation induced by the monsoon regimes. The author finds evidence that farmers adjust their irrigation investments and their crop portfolios in response to the medium-run rainfall variation. However, adaptation only recovers a small fraction of the profits farmers have lost due to adverse climate variation.

scholarly journals High-resolution analysis of observed thermal growing season variability over northern Europe

2021 ◽  
Author(s):  
Juha Aalto ◽  
Pentti Pirinen ◽  
Pekka E. Kauppi ◽  
Mika Rantanen ◽  
Cristian Lussana ◽  
...  
Keyword(s):  
Climate Change ◽  
High Resolution ◽  
Spatial Variation ◽  
Forest Cover ◽  
Temporal Trends ◽  
Growing Season ◽  
Urban Land Use ◽  
Environmental Data ◽  
Northern Europe ◽  
Annual Variability

AbstractStrong historical and predicted future warming over high-latitudes prompt significant effects on agricultural and forest ecosystems. Thus, there is an urgent need for spatially-detailed information of current thermal growing season (GS) conditions and their past changes. Here, we deployed a large network of weather stations, high-resolution geospatial environmental data and semi-parametric regression to model the spatial variation in multiple GS variables (i.e. beginning, end, length, degree day sum [GDDS, base temperature + 5 °C]) and their intra-annual variability and temporal trends in respect to geographical location, topography, water and forest cover, and urban land use variables over northern Europe. Our analyses revealed substantial spatial variability in average GS conditions (1990–2019) and consistent temporal trends (1950–2019). We showed that there have been significant changes in thermal GS towards earlier beginnings (on average 15 days over the study period), increased length (23 days) and GDDS (287 °C days). By using a spatial interpolation of weather station data to a regular grid we predicted current GS conditions at high resolution (100 m × 100 m) and with high accuracy (correlation ≥ 0.92 between observed and predicted mean GS values), whereas spatial variation in temporal trends and interannual variability were more demanding to predict. The spatial variation in GS variables was mostly driven by latitudinal and elevational gradients, albeit they were constrained by local scale variables. The proximity of sea and lakes, and high forest cover suppressed temporal trends and inter-annual variability potentially indicating local climate buffering. The produced high-resolution datasets showcased the diversity in thermal GS conditions and impacts of climate change over northern Europe. They are valuable in various forest management and ecosystem applications, and in adaptation to climate change.

scholarly journals Thunderstorm and stratocumulus: how does their contrasting morphology affect their interactions with aerosols?

2010 ◽  
Vol 10 (2) ◽  
pp. 4305-4343
Author(s):  
S. S. Lee ◽  
L. J. Donner ◽  
J. E. Penner
Keyword(s):  
Climate Change ◽  
Climate Model ◽  
Indian Monsoon ◽  
Hydrological Cycle ◽  
Model Studies ◽  
Convective Clouds ◽  
Stratiform Clouds ◽  
Stratocumulus Clouds ◽  
Aerosol Cloud Interactions ◽  
Gust Front

Abstract. It is well-known that aerosols affect clouds and that the effect of aerosols on clouds is critical for understanding human-induced climate change. Most climate model studies have focused on the effect of aerosols on warm stratiform clouds (e.g., stratocumulus clouds) for the prediction of climate change. However, systems like the Asian and Indian Monsoon, storm tracks, and the intertropical convergence zone, play important roles in the global hydrological cycle and in the circulation of energy and are driven by thunderstorm-type convective clouds. Here, we show that the different morphologies of these two cloud types lead to different aerosol-cloud interactions. Increasing aerosols are known to suppress the conversion of droplets to rain (i.e., so-called autoconversion). This increases droplets as a source of evaporative cooling, leading to an increased intensity of downdrafts. The acceleration of the intensity of downdrafts is larger in convective clouds due to their larger cloud depths (providing longer paths for downdrafts to follow to the surface) than in stratiform clouds. More accelerated downdrafts intensify the gust front, leading to significantly increased updrafts, condensation and thus the collection of cloud liquid by precipitation, which offsets the suppressed autoconversion. This leads to an enhancement of precipitation with increased aerosols in convective clouds. However, the downdrafts are less accelerated in stratiform clouds due to their smaller cloud depths, and they are not able to induce changes in updrafts as large as those in convective clouds. Thus, the offset is not as effective, and this allows the suppression of precipitation with increased aerosols. Thus aerosols affect these cloud systems differently. The dependence of the effect of aerosols on clouds on the morphology of clouds should be taken into account for a more complete assessment of climate change.

Sign in / Sign up

Export Citation Format

Share Document