Aneesh Sundaresan

Pusan National University | PNU · IBS Center for Climate Physics

Side effects of solar radiation management geoengineering are unavoidable because the forcing involved is different in nature from the anthropogenic greenhouse forcing. Yet, the side effects should scale with the magnitude of the geonegineering forcing. Even then it is crucial to have detailed information about them. We use a response theory based...

There is a palpable shift in mainstream attitude towards geoengineering, seen now as a potential part of a climate policy mix. Still, no-one wants to get on a slippery slope, compounding the risks, and, therefore, we should ask ourselves what is the minimal geoengineering that we can get away with. Such questions lead mathematically to inverse prob...

“Decadal influence” on the El Niño–Southern Oscillation‐Indian summer monsoon teleconnection has been much studied but with plurality and ambiguity about the concept of influence. Here (a) we provide formal definitions of the apparent influence of a specific factor on the teleconnection, as correlation coefficients, which enable us to test them as...

Concerning the robustness of the forced response of the ENSO - Indian monsoon teleconnection, three periods can be distinguished. (1) In the late 20 th century, the change is insignificant in most models, which does not permit a statement on robustness in this period. This is in stark contrast with earlier claims of a weakening teleconnection alleg...

The deep convection and associated moist processes have a major role in regulating the circulation and precipitation characteristics of the Indian summer monsoon. This aspect is examined by conducting sensitivity experiments with the Weather Research and Forecast model. Three active monsoon cases during the periods 16–25 June 2015, 20–29 July 2010...

“Decadal influence” on the El Nino–Southern Oscillation-Indian summer monsoon (ENSO-ISM) teleconnection has been much studied but with plurality and ambiguity about the concept of influence. Here we provide formal definitions of the apparent influence of a specific factor which enable us to test them as null-hypotheses. Using the recently released...

“Decadal influence” on the El Nin ̃o–Southern Oscillation-Indian summer monsoon (ENSO-ISM) teleconnection has been much studied but with plurality and ambiguity about the concept of influence. Here we provide formal definitions of the apparent influence of a specific factor on the teleconnection, as correlation coefficients, which enable us to test...

“Decadal influence” on the El Nin ̃o–Southern Oscillation-Indian summer monsoon (ENSO-ISM) teleconnection has been much studied but with plurality and ambiguity about the concept of influence. Here (I) we provide formal definitions of the apparent influence of a specific factor on the teleconnec- tion, as correlation coefficients, which enable us t...

Plain Language Summary The variability of far separated regions can be correlated, teleconnected, which can give rise to seasonal predictability. Teleconnections can also undergo forced changes under external influence. These changes are not perfectly reflected in observed time series because of systematic errors, biases, of the estimates of correl...

In the context of increasing probability of advancement in onset date of Indian Summer Monsoon during recent years, precipitation and circulation features of early monsoon onset events are investigated in detail using reanalysis data and model simulations. During the onset pentad (± 2 days from the onset day), an anomalous increase in precipitation...

Seasonal variation of raindrop size distribution (DSD) is examined using long-term (2007–2015) observations made with Joss-Waldvogel disdrometer at Thumba (8.53°N, 76.87°E), a tropical coastal station. Data sets were classified based on the rain rate and studied the DSD variations for pre-monsoon (PRE) season, post-monsoon (POST) season and summer...

In view of the large uncertainties in the methane (CH4) emission estimates and the large spatial gaps in its measurements, studies on near-surface CH4 on regional basis become highly relevant. This paper presents the first time observational results of a study on the impacts of mesoscale meteorology on the temporal variations of near-surface CH4 at...

The interannual variability of Indian Summer Monsoon (ISM) rainfall is strongly associated with the El Niño-Southern Oscillation (ENSO), experiencing below and above normal rainfall during El Niño and La Niña years respectively. However, during recent La Niña years, particularly after 1980, the above normal ISM rainfall events are decreased compare...

Aerosol distribution over the Arabian Sea and the Indian subcontinent during the northern hemispheric summer is dominated by mineral dust transport from the West Asian desert regions. The radiative impact of these dust plumes is expected to have a prominent role in regulating the Asian Summer Monsoon circulation. While satellite observations have p...

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 (10–16 km) ozone by 20–50 ppbv, which has extended down to the middle (6–10 km) and lower troposphere ( < 6 km). The descent rate of enhanced ozone layer durin...

June–September mean wind at 850 hPa from ERA-Interim, MERRA and NCEP2 reanalyses shows an increasing trend in the south Asian monsoon Low Level Jet (LLJ) during 1980–2014. In the sub-seasonal scale, the LLJ during July and September exhibits increasing trend, while August shows a decreasing trend. Lesser changes in surface pressure over heat low re...

The present study examines the role of tropical cyclones in the enhancement of tropospheric ozone. The most significant and new observation is the increase in the upper tropospheric (10–16 km) ozone by 20–50 ppbv, which has extended down to the middle (6–10 km) and lower troposphere (< 6 km). The descending rate of enhanced ozone layer is found to...