scholarly journals Study of Moisture Budget of Meteorological Droughts over Indian Region

2018 ◽  
Vol 12 (9) ◽  
pp. 221
Author(s):  
P. Suneetha ◽  
Zedek, M. D. ◽  
Ramalingeswara Rao, S. ◽  
Naga Lakshmi, K. ◽  
Latha. P. ◽  
...  
Keyword(s):  
Summer Monsoon ◽  
Heat Budget ◽  
Indian Subcontinent ◽  
Meteorological Drought ◽  
Rainfall Anomaly ◽  
Equatorial Region ◽  
Moisture Budget ◽  
Rainfall Forecasting ◽  
Drought Conditions ◽  
Meteorological Droughts

The study mainly focuses on heat and moisture budget components and its variations during meteorological drought conditions over India for the period 1951-2013. IITM sub-divisional summer monsoon standardized rainfall anomaly is considered to identify the meteorological drought where the standardized summer monsoon rainfall anomaly is less than one. From the analysis, there are thirteen meteorological droughts are identified, and the rainfall decreased on spatial and temporal scales with significant changes in the frequency, duration and total amount of rainfall. Mainly, anticyclonic circulation is observed along 60⁰-70⁰E with weak westerlies at lower levels. At the upper level, the intensity of easterly jet stream is decreased and shifted southward during drought years.Anomalous variations in relative humidity and vertical velocity induce the maximum reduction in the moisture amount (15%) at lower and upper levels leads to weakening of the strength of local Hadley circulation. Next, the heat budget components are decreased over Bay of Bengal and coastal regions with a magnitude of 40 to 200 W/m2 in drought years. It is observed that more moisture is transported to the equatorial region producing below average rainfall over the Indian subcontinent during weak monsoon periods. Hence, this study will help to identify the quantitative and qualitative estimation of drought conditions for long-range prediction of rainfall forecasting. 

scholarly journals Different Drought Legacies of Rain-Fed and Irrigated Croplands in a Typical Russian Agricultural Region

2020 ◽  
Vol 12 (11) ◽  
pp. 1700
Author(s):  
Yuanhuizi He ◽  
Fang Chen ◽  
Huicong Jia ◽  
Lei Wang ◽  
Valery G. Bondur
Keyword(s):  
Surface Temperature ◽  
Drought Index ◽  
Growth Period ◽  
Meteorological Drought ◽  
Agricultural Drought ◽  
Drought Monitoring ◽  
Growth Stages ◽  
Drought Conditions ◽  
Irrigated Lands ◽  
Meteorological Droughts

Droughts are one of the primary natural disasters that affect agricultural economies, as well as the fire hazards of territories. Monitoring and researching droughts is of great importance for agricultural disaster prevention and reduction. The research significance of investigating the hysteresis of agricultural to meteorological droughts is to provide an important reference for agricultural drought monitoring and early warnings. Remote sensing drought monitoring indices can be employed for rapid and accurate drought monitoring at regional scales. In this paper, the Moderate Resolution Imaging Spectroradiometer (MODIS) vegetation indices and the surface temperature product are used as the data sources. Calculating the temperature vegetation drought index (TVDI) and constructing a comprehensive drought disaster index (CDDI) based on the crop growth period allowed drought conditions and spatiotemporal evolution patterns in the Volgograd region in 2010 and 2012 to be effectively monitored. The causes of the drought were then analyzed based on the sensitivity of a drought to meteorological factors in rain-fed and irrigated lands. Finally, the lag time of agricultural to meteorological droughts and the hysteresis in different growth periods were analyzed using statistical analyses. The research shows that (1) the main drought patterns in 2010 were spring droughts from April to May and summer droughts from June to August, and the primary drought patterns in 2012 were spring droughts from April to June, with an affected area that reached 3.33% during the growth period; (2) local drought conditions are dominated by the average surface temperature factor. Rain-fed lands are sensitive to the temperature and are therefore prone to summer droughts. Irrigated lands are more sensitive to water shortages in the spring and less sensitive to extremely high temperature conditions; (3) there is a certain lag between meteorological and agricultural droughts during the different growth stages. The strongest lag relationship was found in the planting stage and the weakest one was found in the dormancy stage. Therefore, the meteorological drought index in the growth period has a better predictive ability for agricultural droughts during the appropriately selected growth stages.

scholarly journals A daytime climatological distribution of high opaque ice cloud classes over the Indian summer monsoon region observed from 25-year AVHRR data

2009 ◽  
Vol 9 (12) ◽  
pp. 4185-4196 ◽  
Author(s):  
A. Devasthale ◽  
H. Grassl
Keyword(s):  
Summer Monsoon ◽  
Indian Subcontinent ◽  
Deep Convection ◽  
Temporal Distribution ◽  
Radiative Balance ◽  
Ice Cloud ◽  
Brightness Temperatures ◽  
Spatio Temporal ◽  
Very High ◽  
Summer Monsoon Region

Abstract. A daytime climatological spatio-temporal distribution of high opaque ice cloud (HOIC) classes over the Indian subcontinent (0–40° N, 60° E–100° E) is presented using 25-year data from the Advanced Very High Resolution Radiometers (AVHRRs) for the summer monsoon months. The HOICs are important for regional radiative balance, precipitation and troposphere-stratosphere exchange. In this study, HOICs are sub-divided into three classes based on their cloud top brightness temperatures (BT). Class I represents very deep convection (BT<220 K). Class II represents deep convection (220 K

scholarly journals Dynamics and composition of the Asian summer monsoon anticyclone

2017 ◽  
Author(s):  
Klaus-Dirk Gottschaldt ◽  
Hans Schlager ◽  
Robert Baumann ◽  
Duy S. Cai ◽  
Veronika Eyring ◽  
...  
Keyword(s):  
Summer Monsoon ◽  
Atmospheric Chemistry ◽  
Asian Summer Monsoon ◽  
Monsoon Season ◽  
Lower Troposphere ◽  
Equatorial Region ◽  
Ozone Production ◽  
Trace Gas ◽  
Asian Summer ◽  
Southern Fringe

Abstract. This study places HALO research aircraft observations in the upper-tropospheric Asian summer monsoon anticyclone (ASMA) obtained during the Earth System Model Validation (ESMVal) campaign in September 2012 into the context of regional, intra-annual variability by hindcasts with the ECHAM/MESSy Atmospheric Chemistry (EMAC) model. The simulations demonstrate that tropospheric trace gas profiles in the monsoon season are distinct from the rest of the year. Air uplifted from the lower troposphere to the tropopause layer dominates the eastern part of the ASMA’s interior, while the western part is characterised by subsidence down to the mid-troposphere. Soluble compounds are being washed out when uplifted by convection in the eastern part, where lightning simultaneously replenishes reactive nitrogen in the upper troposphere. Net photochemical ozone production is significantly enhanced in the ASMA, contrasted by an ozone depleting regime in the mid-troposphere and more neutral conditions in autumn and winter. An analysis of multiple monsoon seasons in the simulation shows that stratospherically influenced tropopause layer air is regularly entrained at the eastern ASMA flank, and then transported in the southern fringe around the interior region. Observed and simulated tracer-tracer relations reflect photochemical O3 production, as well as in-mixing from the lower troposphere and the tropopause layer. The simulation additionally shows entrainment of clean air from the equatorial region by northerly winds at the western ASMA flank. Although the in situ measurements were performed towards the end of summer, the main ingredients needed for their interpretation are present throughout the monsoon season. A transition between two dynamical modes of the ASMA took place during the HALO ESMVal campaign. Transport barriers of the original anticyclone are overcome effectively when it splits up. Air from the fringe is stirred into the interiors of the new anticyclones and vice versa. Instabilities of this and other types occur quite frequently. Our study emphasises their paramountcy for the trace gas composition of the ASMA and its outflow into regions around the world.

scholarly journals Impact of climate change on hydro-meteorological drought over the Be River Basin, Viet Nam

2021 ◽  
Author(s):  
Dao Nguyen Khoi ◽  
Truong Thao Sam ◽  
Pham Thi Loi ◽  
Bui Viet Hung ◽  
Van Thinh Nguyen
Keyword(s):  
Climate Change ◽  
River Basin ◽  
General Circulation ◽  
Southern Oscillation ◽  
Meteorological Drought ◽  
Climate Projections ◽  
Research Station ◽  
Climate Change Scenarios ◽  
Study Region ◽  
Meteorological Droughts

Abstract In this paper, the responses of hydro-meteorological drought to changing climate in the Be River Basin located in Southern Vietnam are investigated. Climate change scenarios for the study area were statistically downscaled using the Long Ashton Research Station Weather Generator tool, which incorporates climate projections from Coupled Model Intercomparison Project 5 (CMIP5) based on an ensemble of five general circulation models (Can-ESM2, CNRM-CM5, HadGEM2-AO, IPSL-CM5A-LR, and MPI-ESM-MR) under two Representative Concentration Pathway (RCP) scenarios (RCP4.5 and RCP8.5). The Soil and Water Assessment Tool model was employed to simulate streamflow for the baseline time period and three consecutive future 20 year periods of 2030s (2021–2040), 2050s (2041–2060), and 2070s (2061–2080). Based on the simulation results, the Standardized Precipitation Index and Standardized Discharge Index were estimated to evaluate the features of hydro-meteorological droughts. The hydrological drought has 1-month lag time from the meteorological drought and the hydro-meteorological droughts have negative correlations with the El Niño Southern Oscillation and Pacific Decadal Oscillation. Under the climate changing impacts, the trends of drought severity will decrease in the future; while the trends of drought frequency will increase in the near future period (2030s), but decrease in the following future periods (2050 and 2070s). The findings of this study can provide useful information to the policy and decisionmakers for a better future planning and management of water resources in the study region.

Holocene climate variability and Indian Summer Monsoon: An overview

The Holocene ◽  
2020 ◽  
Vol 30 (5) ◽  
pp. 744-773 ◽  
Author(s):  
Upasana S Banerji ◽  
P Arulbalaji ◽  
D Padmalal
Keyword(s):  
Indian Ocean ◽  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
Indian Subcontinent ◽  
Ice Age ◽  
Interglacial Period ◽  
Northern Indian Ocean ◽  
The Holocene ◽  
Indian Landmass ◽  
Holocene Period

The response of the Indian Summer Monsoon (ISM) to forcing factors and climate variables has not yet fully explored, even though the ISM plays a pivotal role in the socio-economics of the Indian subcontinent and nearby areas. The ISM progression over Indian landmass is a manifestation of the Intertropical Convergence Zone (ITCZ) migration over the northern Indian Ocean and the Indian subcontinent. The recent anomalous behaviour of ISM raises the need for a better understanding of its spatio-temporal changes during the ongoing interglacial period termed as the Holocene period. The Holocene period has been classified further based on the globally observed abrupt climatic events at 8.2 and 4.2 ka. The 8.2 ka global cooling events have been recorded from northern Indian Ocean marine archives but limited records from the continental archives of the Indian landmass has demonstrated the 8.2 ka event. At the same time, the 4.2 ka dry climate has been endorsed by both marine as well as continental records and agrees with the global studies. During the ‘Little Ice Age’ (LIA), in the India subcontinent, wet conditions prevailed in the northern, central and western regions while a dry climate existed over the greater part of peninsular India. The present review offers an account of ISM signatures and possible mechanisms associated with the monsoon variability in the Indian subcontinent and the northern Indian Ocean during the Holocene period.

scholarly journals Future Global Meteorological Drought Hot Spots: A Study Based on CORDEX Data

2020 ◽  
Vol 33 (9) ◽  
pp. 3635-3661 ◽  
Author(s):  
Jonathan Spinoni ◽  
Paulo Barbosa ◽  
Edoardo Bucchignani ◽  
John Cassano ◽  
Tereza Cavazos ◽  
...  
Keyword(s):  
Hot Spots ◽  
Regional Climate ◽  
Standardized Precipitation Index ◽  
Meteorological Drought ◽  
First Century ◽  
Horn Of Africa ◽  
Global Circulation ◽  
Global Circulation Models ◽  
The Standardized Precipitation Index ◽  
Meteorological Droughts

AbstractTwo questions motivated this study: 1) Will meteorological droughts become more frequent and severe during the twenty-first century? 2) Given the projected global temperature rise, to what extent does the inclusion of temperature (in addition to precipitation) in drought indicators play a role in future meteorological droughts? To answer, we analyzed the changes in drought frequency, severity, and historically undocumented extreme droughts over 1981–2100, using the standardized precipitation index (SPI; including precipitation only) and standardized precipitation-evapotranspiration index (SPEI; indirectly including temperature), and under two representative concentration pathways (RCP4.5 and RCP8.5). As input data, we employed 103 high-resolution (0.44°) simulations from the Coordinated Regional Climate Downscaling Experiment (CORDEX), based on a combination of 16 global circulation models (GCMs) and 20 regional circulation models (RCMs). This is the first study on global drought projections including RCMs based on such a large ensemble of RCMs. Based on precipitation only, ~15% of the global land is likely to experience more frequent and severe droughts during 2071–2100 versus 1981–2010 for both scenarios. This increase is larger (~47% under RCP4.5, ~49% under RCP8.5) when precipitation and temperature are used. Both SPI and SPEI project more frequent and severe droughts, especially under RCP8.5, over southern South America, the Mediterranean region, southern Africa, southeastern China, Japan, and southern Australia. A decrease in drought is projected for high latitudes in Northern Hemisphere and Southeast Asia. If temperature is included, drought characteristics are projected to increase over North America, Amazonia, central Europe and Asia, the Horn of Africa, India, and central Australia; if only precipitation is considered, they are found to decrease over those areas.

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