Articles | Volume 36, issue 1
https://doi.org/10.5194/angeo-36-149-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/angeo-36-149-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Long-term trends in stratospheric ozone, temperature, and water vapor over the Indian region
Sivan Thankamani Akhil Raj
National Atmospheric Research Laboratory, Department of Space, Gadanki
517112, India
SRM University, SRM Nagar, Potheri, Kattankulathur, Kancheepuram-603203, Chennai, India
Madineni Venkat Ratnam
CORRESPONDING AUTHOR
National Atmospheric Research Laboratory, Department of Space, Gadanki
517112, India
Daggumati Narayana Rao
SRM University, SRM Nagar, Potheri, Kattankulathur, Kancheepuram-603203, Chennai, India
Boddam Venkata Krishna Murthy
CEEBROS, 47/20, III Main Road, Gandhi Nagar, Adayar, Chennai, India
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This study investigates the formation mechanism of a tropopause cirrus cloud layer observed at extremely cold temperatures over Hyderabad in India during the 2017 Asian summer monsoon using balloon-borne sensors. Ice crystals smaller than 50 microns were found in this optically thin cirrus cloud layer. Combined analysis of back-trajectories, satellite, and model data revealed that the formation of this layer was influenced by gravity waves and stratospheric hydration induced by typhoon Hato.
Hazel Vernier, Neeraj Rastogi, Hongyu Liu, Amit Kumar Pandit, Kris Bedka, Anil Patel, Madineni Venkat Ratnam, Buduru Suneel Kumar, Bo Zhang, Harish Gadhavi, Frank Wienhold, Gwenael Berthet, and Jean-Paul Vernier
Atmos. Chem. Phys., 22, 12675–12694, https://doi.org/10.5194/acp-22-12675-2022, https://doi.org/10.5194/acp-22-12675-2022, 2022
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The chemical composition of the stratospheric aerosols collected aboard high-altitude balloons above the summer Asian monsoon reveals the presence of nitrate/nitrite. Using numerical simulations and satellite observations, we found that pollution as well as lightning could explain some of our observations.
Varaha Ravi Kiran, Madineni Venkat Ratnam, Masatomo Fujiwara, Herman Russchenberg, Frank G. Wienhold, Bomidi Lakshmi Madhavan, Mekalathur Roja Raman, Renju Nandan, Sivan Thankamani Akhil Raj, Alladi Hemanth Kumar, and Saginela Ravindra Babu
Atmos. Meas. Tech., 15, 4709–4734, https://doi.org/10.5194/amt-15-4709-2022, https://doi.org/10.5194/amt-15-4709-2022, 2022
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We proposed and conducted the multi-instrumental BACIS (Balloon-borne Aerosol–Cloud Interaction Studies) field campaigns using balloon-borne in situ measurements and ground-based and space-borne remote sensing instruments. Aerosol-cloud interaction is quantified for liquid clouds by segregating aerosol and cloud information in a balloon profile. Overall, the observational approach proposed here demonstrated its capability for understanding the aerosol–cloud interaction process.
Rohit Chakraborty, Arindam Chakraborty, Ghouse Basha, and Madineni Venkat Ratnam
Atmos. Chem. Phys., 21, 11161–11177, https://doi.org/10.5194/acp-21-11161-2021, https://doi.org/10.5194/acp-21-11161-2021, 2021
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In this study, urbanization-induced surface warming has been found to trigger prominent changes in upper-troposphere–lower-stratosphere regions leading to stronger and more frequent lightning extremes over India. Consequently, the implementation of this hypothesis in global climate models reveals that lightning frequency and intensity values across India will rise by ~10–25 % and 15–50 %, respectively, by 2100 at the current urbanization rate, which should be alarming for present policymakers.
Saginela Ravindra Babu, Madineni Venkat Ratnam, Ghouse Basha, Shantanu Kumar Pani, and Neng-Huei Lin
Atmos. Chem. Phys., 21, 5533–5547, https://doi.org/10.5194/acp-21-5533-2021, https://doi.org/10.5194/acp-21-5533-2021, 2021
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The present study explores the detailed structure, dynamics, and trace gas variability in the Asian summer monsoon anticyclone (ASMA) in the extreme El Niño of 2015/16. The results find the structure of the ASMA shows strong spatial variability between July and August. A West Pacific mode of the anticyclone is noticed in August. A significant lowering of tropospheric tracers and strong increase in stratospheric tracers are found. The tropopause temperatures also exhibit a warming in the ASMA.
Kizhathur Narasimhan Uma, Siddarth Shankar Das, Madineni Venkat Ratnam, and Kuniyil Viswanathan Suneeth
Atmos. Chem. Phys., 21, 2083–2103, https://doi.org/10.5194/acp-21-2083-2021, https://doi.org/10.5194/acp-21-2083-2021, 2021
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Reanalysis data of vertical wind (w) are widely used by the atmospheric community to determine various calculations of atmospheric circulations, diabatic heating, convection, etc. There are no studies that assess the available reanalysis data with respect to observations. The present study assesses for the first time all the reanalysis w by comparing it with 20 years of radar data from Gadanki and Kototabang and shows that downdrafts and peaks in the updrafts are not produced in the reanalyses.
Ghouse Basha, M. Venkat Ratnam, and Pangaluru Kishore
Atmos. Chem. Phys., 20, 6789–6801, https://doi.org/10.5194/acp-20-6789-2020, https://doi.org/10.5194/acp-20-6789-2020, 2020
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This study explores the variability of the Asian summer monsoon anticyclone (ASMA) spatial variability and trends using long-term observational and reanalysis data sets. The decadal variability of the anticyclone is very large at the edges compared with the core region. We propose that the transport process over the Tibetan Plateau and the Indian region is significant in active monsoon, strong monsoon and strong La Niña years. Thus, different phases of the monsoon are important in UTLS analyses.
Ghouse Basha, M. Venkat Ratnam, Pangaluru Kishore, S. Ravindrababu, and Isabella Velicogna
Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2019-743, https://doi.org/10.5194/acp-2019-743, 2019
Preprint withdrawn
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The Asian Summer Monsoon Anticyclone (ASMA) plays an important role in confining the trace gases and aerosols for a longer period. This study explores the variability of tropopause parameters, trace gases and aerosols and its relation with ENSO and QBO in ASMA. Further, the influence of the Indian summer monsoon activity on the ASMA trace gases and aerosols is studied with respect to active and break spells of monsoon, strong and weak monsoon years and strong La Niña, El Niño years.
Rohit Chakraborty, Bijay Kumar Guha, Shamitaksha Talukdar, Madineni Venkat Ratnam, and Animesh Maitra
Atmos. Chem. Phys., 19, 12325–12341, https://doi.org/10.5194/acp-19-12325-2019, https://doi.org/10.5194/acp-19-12325-2019, 2019
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The present study investigates the plausible aspects which influence the probability of drought occurrences over three Indian regions during the southwest Asian mid-monsoon period. The investigation reveals that an increasing tendency of dry day frequency (DDF) over urbanized regions in the last few decades has significant association with the abundance of anthropogenic aerosols. Additionally, future projections of DDF indicate a five-fold rise which can be a crucial concern for policy makers.
Rohit Chakraborty, Madineni Venkat Ratnam, and Shaik Ghouse Basha
Atmos. Chem. Phys., 19, 3687–3705, https://doi.org/10.5194/acp-19-3687-2019, https://doi.org/10.5194/acp-19-3687-2019, 2019
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Intense convective phenomena are a common climatic feature in the Indian tropical region which occur during the pre-monsoon to post-monsoon seasons (April–October) and are generally accompanied by intense thunderstorms, lightning, and wind gusts with heavy rainfall. Here we show long-term trends of the parameters related to convection and instability obtained from 27 radiosonde stations across six subdivisions over the Indian region during the period 1980–2016.
Nelli Narendra Reddy, Madineni Venkat Ratnam, Ghouse Basha, and Varaha Ravikiran
Atmos. Chem. Phys., 18, 11709–11727, https://doi.org/10.5194/acp-18-11709-2018, https://doi.org/10.5194/acp-18-11709-2018, 2018
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Cloud vertical structure affects large-scale atmosphere circulation by altering gradients in total diabatic heating and cooling and latent heat release. Detailed cloud vertical structure in all seasons, including diurnal variation over the Indian region, is made for the first time. The detected cloud layers are verified with independent observations using cloud particle sensor sonde. Heating and cooling in the troposphere and lower stratosphere due to these cloud layers are also investigated.
Sanjay Kumar Mehta, Madineni Venkat Ratnam, Sukumarapillai V. Sunilkumar, Daggumati Narayana Rao, and Boddapaty V. Krishna Murthy
Atmos. Chem. Phys., 17, 531–549, https://doi.org/10.5194/acp-17-531-2017, https://doi.org/10.5194/acp-17-531-2017, 2017
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Study of the diurnal variation of the atmospheric boundary layer (ABL) height is important for the knowledge of pollutant dispersion, crucial for all living beings. The most difficult part in the study of the diurnal variation is in identification of the stable boundary layer which occurs ~ 50% of times only and mostly during nighttime winter. Surface temperature and clouds directly affect the diurnal pattern of the ABL. Thus, stronger (weaker) diurnal variation found during pre-monsoon (winter).
Madineni Venkat Ratnam, Alladi Hemanth Kumar, and Achuthan Jayaraman
Atmos. Meas. Tech., 9, 5735–5745, https://doi.org/10.5194/amt-9-5735-2016, https://doi.org/10.5194/amt-9-5735-2016, 2016
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Launch of INSAT-3D carrying a multi-spectral imager by the ISRO made it possible to obtain profiles of temperature and water vapour over India with higher temporal and vertical resolutions. Initial validation is made with the radiosonde, other satellites and reanalysis data sets. Good correlation between INSAT-3D and in situ measurements is noticed with a few cautions. Temperature data from INSAT-3D are of high quality and can be directly assimilated for better forecasts over India.
M. Venkat Ratnam, S. Ravindra Babu, S. S. Das, G. Basha, B. V. Krishnamurthy, and B. Venkateswararao
Atmos. Chem. Phys., 16, 8581–8591, https://doi.org/10.5194/acp-16-8581-2016, https://doi.org/10.5194/acp-16-8581-2016, 2016
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The impact of cyclones that occurred over the north Indian Ocean during 2007–2013 on the STE process is quantified using satellite observations. It is shown that cyclones have a significant impact on the tropopause structure, ozone and water vapour budget, and consequentially STE in the UTLS region. The cross-tropopause mass flux from the stratosphere to the troposphere for cyclonic storms is found to be 0.05 ± 0.29 × 10−3 kg m−2, and for very severe cyclonic storms it is 0.5 ± 1.07 × 10−3 kg m−2.
K. K. Shukla, K. Niranjan Kumar, D. V. Phanikumar, R. K. Newsom, V. R. Kotamarthi, T. B. M. J. Ouarda, and M. V. Ratnam
Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2016-162, https://doi.org/10.5194/amt-2016-162, 2016
Revised manuscript not accepted
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Estimation of Cloud base height was carried out by using various ground based instruments (Doppler Lidar and Ceilometer) and satellite datasets (MODIS) over central Himalayan region for the first time. The present study demonstrates the potential of Doppler Lidar in precise estimation of cloud base height and updraft velocities. More such deployments will be invaluable inputs for regional weather prediction models over complex Himalayan terrains.
Siddarth Shankar Das, Madineni Venkat Ratnam, Kizhathur Narasimhan Uma, Kandula Venkata Subrahmanyam, Imran Asatar Girach, Amit Kumar Patra, Sundaresan Aneesh, Kuniyil Viswanathan Suneeth, Karanam Kishore Kumar, Amit Parashuram Kesarkar, Sivarajan Sijikumar, and Geetha Ramkumar
Atmos. Chem. Phys., 16, 4837–4847, https://doi.org/10.5194/acp-16-4837-2016, https://doi.org/10.5194/acp-16-4837-2016, 2016
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The present study examines the role of tropical cyclones in the enhancement of tropospheric ozone. The most significant and new observation reported is the increase in the upper-tropospheric ozone by 20–50 ppbv, which has extended down to the middle and lower troposphere. The descent rate of enhanced ozone layer during the passage of tropical cyclone is 0.8–1 km day−1. Enhancement of surface ozone concentration by ~ 10 ppbv in the daytime and 10–15 ppbv at night-time is observed.
Sanjeev Dwivedi, M. S. Narayanan, M. Venkat Ratnam, and D. Narayana Rao
Atmos. Chem. Phys., 16, 4497–4509, https://doi.org/10.5194/acp-16-4497-2016, https://doi.org/10.5194/acp-16-4497-2016, 2016
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Monsoon inversion (MI) over the Arabian Sea is one of the important characteristics associated with the monsoon activity over Indian region. The initiation and dissipation times of MI, their percentage of occurrence, strength etc., has been examined. We suggest MI could also be included as one of the semi-permanent features of southwest monsoon.
A. K. Pandit, H. S. Gadhavi, M. Venkat Ratnam, K. Raghunath, S. V. B. Rao, and A. Jayaraman
Atmos. Chem. Phys., 15, 13833–13848, https://doi.org/10.5194/acp-15-13833-2015, https://doi.org/10.5194/acp-15-13833-2015, 2015
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We present the longest (1998 to 2013) cirrus cloud climatology over a tropical station using a ground-based lidar. A statistically significant increase is found in the altitude of sub-visible cirrus clouds. Also a systematic shift from thin to sub-visible cirrus cloud type is observed. Ground-based lidar is found to detect more number of sub-visible cirrus clouds than space-based lidar. These findings have implications to global warming and stratosphere-troposphere water vapour exchange studies.
S. Ravindra Babu, M. Venkat Ratnam, G. Basha, B. V. Krishnamurthy, and B. Venkateswararao
Atmos. Chem. Phys., 15, 10239–10249, https://doi.org/10.5194/acp-15-10239-2015, https://doi.org/10.5194/acp-15-10239-2015, 2015
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The effect of tropical cyclones (TCs) that occurred over the north Indian Ocean in the last decade on the tropical tropopause parameters has been quantified for the first time. The vertical structure of temperature and tropopause parameters within the 5º radius away from the cyclone centre during TC period is also presented. The water vapour variability in the vicinity of TC is investigated.
It is demonstrated that the TCs can significantly affect the tropical tropopause and thus STE processes.
M. Pramitha, M. Venkat Ratnam, A. Taori, B. V. Krishna Murthy, D. Pallamraju, and S. Vijaya Bhaskar Rao
Atmos. Chem. Phys., 15, 2709–2721, https://doi.org/10.5194/acp-15-2709-2015, https://doi.org/10.5194/acp-15-2709-2015, 2015
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Sources and propagation characteristics of high-frequency gravity waves observed in the mesosphere using airglow emissions from Gadanki and Hyderabad, India, are investigated using reverse ray tracing. Wave amplitudes are also traced back, including both radiative and diffusive damping. Interestingly, large vertical shears in the horizontal wind are noticed near the ray terminal points (at 10-12km altitude) and are thus identified to be the source for generating the observed gravity waves.
K. Ramesh, A. P. Kesarkar, J. Bhate, M. Venkat Ratnam, and A. Jayaraman
Atmos. Meas. Tech., 8, 369–384, https://doi.org/10.5194/amt-8-369-2015, https://doi.org/10.5194/amt-8-369-2015, 2015
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The study of atmospheric convection is important for the understanding of evolution of diurnal cycles of rainfall. High-resolution observations of vertical profiles of temperature and relative humidity are very useful for understanding the behaviour of these convections. Microwave radiometers are becoming useful tools for it. In this paper, we propose a new method to retrieve these profiles based on adaptive neuro-fuzzy interface systems and find that this method has a better skill of retrieval.
M. Venkat Ratnam, N. Pravallika, S. Ravindra Babu, G. Basha, M. Pramitha, and B. V. Krishna Murthy
Atmos. Meas. Tech., 7, 1011–1025, https://doi.org/10.5194/amt-7-1011-2014, https://doi.org/10.5194/amt-7-1011-2014, 2014
P. Kishore, M. Venkat Ratnam, I. Velicogna, V. Sivakumar, H. Bencherif, B. R. Clemesha, D. M. Simonich, P. P. Batista, and G. Beig
Ann. Geophys., 32, 301–317, https://doi.org/10.5194/angeo-32-301-2014, https://doi.org/10.5194/angeo-32-301-2014, 2014
D. V. Phanikumar, K. Niranjan Kumar, K. K. Shukla, H. Joshi, M. Venkat Ratnam, M. Naja, and K. Reddy
Ann. Geophys., 32, 175–180, https://doi.org/10.5194/angeo-32-175-2014, https://doi.org/10.5194/angeo-32-175-2014, 2014
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Ozone and water vapor are two potent greenhouse gases in the atmosphere. They influence the temperature structure greatly, particularly in the upper troposphere and lower stratosphere. We have investigated the long-term trends in these trace gases over the Indian region using long-term data (1993–2015) constructed from multi-satellite observations. A decreasing trend in ozone associated with NOx chemistry in the tropical middle stratosphere and a good correlation between N2O and O3 is found.
Ozone and water vapor are two potent greenhouse gases in the atmosphere. They influence the...