R. Kumar, G S Gopikrishnan and J. Kuttippurath
Cold nights and days have decreased by 4-fold from 1980 to 2020 in India.
Warm nights and warm days would rise nearly 7-fold in the far-future (2080–2100).
Warm nights and warm days would increase 10–13 days/dec from 2015 to 2100.
The number of cold nights (days) would reduce by 6 (4) times by end of the century.
B.R. Sharma, J. Kuttippurath and G S Gopikrishnan
Positive trend in tropospheric ozone up to 0.35 DU yr−1 in the west and north Third Pole.
Highest tropospheric ozone trends up to 0.2–0.35 DU yr−1 in summer in the Third Pole.
Tropospheric ozone contributes to a radiative forcing up to 0.3 Wm-2 in the Third Pole.
Ozone-induced temperature rise is about 0.4 °C in the Third Pole during 2005–2020.
G.S. Gopikrishnan, D.M. Westervelt and J. Kuttippurath
Higher aerosol uptake enhances radical sinks, increasing surface ozone levels by 40–60% in 2018.
North America, Europe and East-Asia remain under an aerosol-inhibited photochemical regime (AIR) in future scenarios.
However, total AIR extent reduces in both near and distant future simulations.
G.S. Gopikrishnan, T.S. Ardra and J. Kuttippurath
Annual ozone varies between 20 and 30 μg/m3, but in pre-monsoon it often exceeds 70 μg/m3
Populated areas have high ozone exposure, above 70 μg/m3, about 10–15 days in 2022.
Mortality due to ozone exposure in India exceeds 50000 in the year 2022 alone.
It costs an economic burden of US $16.83 Bn in 2022; 1.5 times the health budget of India
G.S. Gopikrishnan and J. Kuttippurath
Higher PM levels in cities of Indo-Gangetic Plain and Central India (80–120 μg/m3)
17 out of 28 cities show 15–60 % decline in PM10 concentration from 2018 to 2022.
PM2.5, NO2 and O3 are the key precursors of PM10, suggested by Random Forest model.
The NCAP target attained cities still have 62,219 people in excess mortalities.
P. Sangeetha, G.S. Gopikrishnan, J. Kuttippurath and P. K. Thapliyal
This study validates TCO measurements from the Indian geostationary satellites INSAT-3D (2017–2019) and INSAT-3DR (2021–2023) by comparing them with Atmospheric Infrared Sounder (AIRS) satellite measurements and the Copernicus Atmosphere Monitoring Service (CAMS) reanalysis data.
INSAT-3D data have a homogenised distribution, with values generally between 265 and 270 DU, which peaks to 275 DU in the northern India. Seasonal analysis indicates the highest TCO during pre-monsoon around 280 DU and the lowest during monsoon, around 220 DU.
INSAT-3DR data show consistent TCO of around 240 DU over the southern peninsula, which increases to about 270–280 DU in the northernmost India.
In general, the INSAT measurements are accurate within ± 15–20 DU or 5–10% when compared to AIRS and CAMS data, and are comparable to that of other satellite and ground-based instruments.
G.S. Gopikrishnan, J. Kuttippurath and P. K. Thapliyal
The Indian National Satellite (INSAT)-3D (January 2014–May 2017) and INSAT-3DR (January 2017–December 2021) are the geostationary weather monitoring space systems of India
We use the collocated humidity measurements from INSAT-3D/3DR with radiosonde and the satellite-based AIRS to assess bias and Root Mean Square Difference (RMSD) in these INSAT data.
The bias of RH measurements in INSAT is within 10–20% for most regions when compared to the radiosonde measurements, and 10–15% with respect to the AIRS observations.
In general, the accuracy of RH is within 10–20% throughout the troposphere for both INSAT-3D and INSAT-3DR measurements and thus, they are suitable for scientific analysis.
Tropospheric ozone (TPO) is significantly rising in the global tropics (0.2–0.4 DU/yr).
TPO shows regional insignificant negative trends in the southern hemisphere (0.1–0.2 DU/yr).
Multi-Linear Regression can explain 95% variability of tropical tropospheric ozone.
Ozone induced radiative forcing (RF) in the tropics is within the range ±0.5 W/m2.
Ozone-driven RF makes a temperature rise of 0.2–0.3 °C from 2006 to 2020
S. Amritha, H. Varikoden, V. Patel, J. Kuttippurath, G.S. Gopikrishnan
Significant positive trends are found in NO₂ globally, except in the USA and Europe
Most cities in the USA and Europe show a decline in NO₂, at about -0.1 × 1015 molec./cm2/yr
NO₂ pollution is rising in the cities of developing country cities; a threat to their sustainability
Strict vehicular emission norms led to the reduction of NO₂ in the USA and Europe
J. Kuttippurath, G.S. Gopikrishnan, R. Muller, S. Godin-Beekmann, J. Brioude
Stratospheric ozone is an important constituent of the atmosphere. Significant changes in its concentrations have great consequences for the environment in general and for ecosystems in particular
The amount of column ozone in the tropics is relatively small (250–270 DU) compared to high and mid-latitudes
In addition, the tropical total ozone trend is very small , as estimated for the period 1998–2022.
The current understanding and observational evidence do not provide any support for the possibility of an ozone hole occurring outside Antarctica today with respect to the present-day stratospheric halogen levels.
B.R. Sharma, J. Kuttippurath, V.K. Patel, G.S. Gopikrishnan
High amounts of atmospheric NH₃ are observed in the south TP, near IGP.
There is a significant positive trend in CO in the inner regions of TP.
Measurements and emission inventory reveal high anthropogenic activities in TP.
Policies are needed in high mountain regions to control the air pollution there.
G.S. Gopikrishnan and J. Kuttippurath
Frequency of 8 h ozone exposure exceeding 100 ppb/year reduced after NCAP implementation.
Most stations show negative trends in surface ozone (0–0.03 ppb month−1) from 2018 to 2022.
Most cities, except in winter, shows an NOx-limited regime, where O3 production is limited by NOx.
Some cities show positive ozone trends; indicating the need for tailored mitigation strategies.
G.S. Gopikrishnan, J. Kuttippurath, P.K. Thapliyal and M.V. Shukla
This study makes use of collocated measurements of INSAT-3D and INSAT-3DR with those from 18 radiosondes, Atmospheric Infrared Sounder (AIRS), and reanalysis data within the troposphere (1,000–100 hPa) to validate INSAT temperature profiles
Daytime temperature retrievals from INSAT‐3DR have been improved by 0.5–1 K
Nighttime observations have a similar bias (1–2 K) and RMSD for both INSAT‐3D and 3DR
R. Kumar, J. Kuttippurath, G.S. Gopikrishnan, P. Kumar and H. Varikoden
We investigate the long-term trends of surface temperature in India using surface, satellite and reanalysis data for the period of 1980–2020
The highest mean surface temperatures are observed in the southern India and the lowest in Himalaya
Analyses with the Coupled Model Intercomparison Project 6 (CMIP6) results show that temperature can increase up to 1.1–5.1 °C by year 2100 under the Shared Socioeconomic Pathways (SSP5)–8.5 scenario.
A. Rathore, G.S. Gopikrishnan and J. Kuttippurath
High concentrations of tropospheric ozone are found in the Indo-Gangetic Plain.
All regions show increasing ozone with the highest trends in the Peninsular India.
Highest seasonal trends are found during monsoon in all regions (0.3–0.5 DU/year).
Tropospheric ozone alone contributes to a radiative forcing of 0.2–0.5 W/m2.
J. Kuttippurath, V.K. Patel, G.S. Gopikrishnan and H. Varikoden
This study helps to understand the connection between energy demand, air quality and meteorology.
This comprehensive assessment on the reduction in air pollution and its impact on regional weather can assist policymakers in drafting regulations based on the experiences gained from lockdown
B.R. Sharma, J. Kuttippurath, G.S. Gopikrishnan and M.Pathak
The Third Pole, encompassing Hindu Kush Himalaya (HKH) and Tien Shan mountains, has been closely monitored for the past few decades because of its deteriorating environmental conditions.
This study reveals that the inner TP, one of the most pristine regions on Earth, is getting polluted because of high anthropogenic activities within and nearby areas/cities, indicating the impact of regional development activities and socioeconomic changes in recent years.
J. Kuttippurath, B.R. Sharma and G.S. Gopikrishnan
High temporal variability is found at the lower latitudes in seasonal to interannual scales than those at the higher latitudes; showcasing the influence of atmospheric circulation in TCO distribution.
Change in the temperature in the high latitude glacier TP region is a concern for the water security of south Asia.
It is inevitable to continuously monitor and analyze TCO in the region, as performed here, for the assessment of public health and climate change in the region
G.S. Gopikrishnan, J. Kuttippurath, S. Raj, A. Singh and K. Abbhishek
• Most cities show a reduction up to 15% of NO2 during the lockdown
• The unlock periods show again an increase of about 40–50% in NO2
• An increase in tropospheric O3 is observed together with the decrease in NO2
J. Kuttippurath, K. Abbhishek, G.S. Gopikrishnan and M. Pathak
Detailed analysis of HCHO over Indian region for the past two decades.
High concentrations of HCHO in the Indo-Gangetic Plain and eastern India.
Ports, cities and mining regions show increasing trends in HCHO.
Analysis for the COVID-19 lockdown period shows significant biogenic sources.
J. Kuttippurath, W. Feng, R. Muller, P. Kumar, S.Raj, G.S. Gopikrishnan and R. Roy
Severe vortex-wide ozone loss in the Arctic would expose both ecosystems and several millions of people to unhealthy ultraviolet radiation
Sporadic occurrences of low ozone with less than 220 DU at different regions of the vortex for almost 3 weeks were found for the first time in the observed history in the Arctic
The polar processing situation led to the first-ever appearance of loss saturation in the Arctic.
G.S. Gopikrishnan and J. Kuttippurath
• First detailed analysis of HCHO over Indian Ocean.
• Significant increase in HCHO pollution over the shipping routes.
• Indian Ocean sea route emissions are equal to that of the World Oceans.
• A concern for public health in marine, island and coastal regions.