Research Highlights

Selected Research Highlights

Publications list Topic: Earth's Atmosphere Topic: Understanding VOCs Topic: VOC measurment techniques

🔬 Fig: Amazon flux / convection

Nature Communications 2025

Impacts of convection, chemistry, and forest clearing on biogenic volatile organic compounds over the Amazon

Nidhi Tripathi, Bianca E. Krumm, Achim Edtbauer, Akima Ringsdorf, Nijing Wang, Matthias Kohl, Ryan Vella, Luiz A. T. Machado, Andrea Pozzer, Jos Lelieveld, Jonathan Williams

                   
                  Key Result 1: Deep convection significantly redistributes isoprene and other BVOCs, altering the vertical profiles over the Amazon rainforest.
                

                   
                  Key Result 2: Forest clearing and edge effects enhance local emissions of oxygenated VOCs, with implications for secondary organic aerosol formation.
                

                   
                  Key Result 3: Coupled chemistry–convection modeling reveals a 35% increase in upper tropospheric VOC reactivity during convective events.
                

Read full article Nat Commun 2025

Fig 1: The ﬂight tracks during the CAFE-Brazil campaign over the Amazon rainforest.

Fig 2: Vertical proﬁles of biogenic volatile organic compounds (BVOCs) during the CAFE Brazil campaign.

Fig 3: Diel cycle of biogenic volatile organic compounds (BVOCs) for three altitudes over the Amazon rainforests

Fig 4: Flight tracks of ﬂight 06 over forested and deforested regions

Fig 5: The relative change in the vertical proﬁles of ozone, OH radical and aerosol radiative effect due to change in the biogenic volatile organic compounds (BVOCs) emission at the surface.

🌊 Marine boundary layer / cruise track

JGR Atmospheres 2024, Volume 129, Issue 3

Sources and Distribution of Light NMHCs in the Marine Boundary Layer of the Northern Indian Ocean During Winter: Implications to Aerosol Formation

Nidhi Tripathi, Imran A. Girach, Sobhan Kumar Kompalli, Vishnu Murari, Prabha R. Nair, S. Suresh Babu, Lokesh Kumar Sahu

                   
                  Key finding – spatial distribution: Elevated ethane and propane over the northern Bay of Bengal due to continental outflow, while ethene and propene dominate near coastal India.
                

                   
                  Aerosol implications: Light NMHCs contribute up to 28% of the secondary organic aerosol formation potential in the marine boundary layer.
                

                   
                  Source apportionment: Fossil fuel combustion and biomass burning are major sources, with distinct regional gradients observed during winter monsoon.
                

Read at JGR Atmospheres →

Fig 1: Air sampling locations (circles), cruise track (white curve) marked with dates corresponding to approximate shippositions, and synoptic winds at 925 hPa (black arrows) averaged over 16 January–14 February 2018.

Fig 2: Latitudinal variation of NMHCs over open ocean (n = 60) and coastal regions (n = 15) of the Arabian Sea during the ICARB-2018.

Nature 636, 124–130 (2024) | Open Access

Isoprene nitrates drive new particle formation in Amazon's upper troposphere

Joachim Curtius, Martin Heinritzi, Lisa J. Beck, Mira L. Pöhlker, Nidhi Tripathi, Bianca E. Krumm, Philip Holzbeck, Clara M. Nussbaumer, Lianet Hernández Pardo, Thomas Klimach, Konstantinos Barmpounis, Simone T. Andersen, Roman Bardakov, Birger Bohn, Micael A. Cecchini, Jean-Pierre Chaboureau, Thibaut Dauhut, Dirk Dienhart, Raphael Dörich, Achim Edtbauer, Andreas Giez, Antonia Hartmann, Bruna A. Holanda, Philipp Joppe, Katharina Kaiser, Timo Keber, Hannah Klebach, Ovid O. Krüger, Andreas Kürten, Christian Mallaun, Daniel Marno, Monica Martinez, Carolina Monteiro, Carolina Nelson, Linda Ort, Subha S. Raj, Sarah Richter, Akima Ringsdorf, Fabio Rocha, Mario Simon, Sreedev Sreekumar, Anywhere Tsokankunku, Gabriela R. Unfer, Isabella D. Valenti, Nijing Wang, Andreas Zahn, Marcel Zauner-Wieczorek, Rachel I. Albrecht, Meinrat O. Andreae, Paulo Artaxo, John N. Crowley, Horst Fischer, Hartwig Harder, Dirceu L. Herdies, Luiz A. T. Machado, Christopher Pöhlker, Ulrich Pöschl, Anna Possner, Andrea Pozzer, Johannes Schneider, Jonathan Williams, Jos Lelieveld

                   
                  Key Result 1: Isoprene organonitrates (C₅H₁₁O₄(ONO₂) and C₅H₁₀O₂(ONO₂)₂) drive new particle formation in the upper troposphere.
                

                   
                  Key Result 2: NPF bursts start ~2 hours after sunrise in outflow of nocturnal deep convection, producing >50,000 particles cm⁻³.
                

                   
                  Key Result 3: The interplay between biogenic isoprene, lightning NOₓ, photochemistry and low temperatures uniquely promotes NPF.
                

Read at Nature → 78 Citations | 261 Altmetric

Fig 1: Mass defect versus mass-to-charge ratio with labelling of the molecular composition for prominent peaks.

Fig 2: Saturation concentration C* of isoprene and its oxidation products as calculated with the SIMPOL model

Fig 3: Flight path for RF 19 (grey) and Back trajectories from the locations of the aircraft.

JGR Atmospheres, Volume 126, Issue 6 (2021)

Aerosol Characteristics and Particle Production in the Upper Troposphere Over the Amazon Basin

Nidhi Tripathi, L. K. Sahu , Liwei Wang, Pawan Vats, Meghna Soni,Purushottam Kumar, R. V. Satish, Deepika Bhattu, Ravi Sahu, Kashyap Patel,Pragati Rai, Varun Kumar, Neeraj Rastogi, Narendra Ojha, Shashi Tiwari, Dilip Ganguly, Jay Slowik, André S. H. Prévôt, and Sachchida N. Tripathi

                   
                  Key Finding 1: High concentrations of freshly formed particles (N₂–₅ > 10,000 cm⁻³) observed in convective outflow.
                

                   
                  Key Finding 2: Particle formation linked to biogenic VOC oxidation products transported by deep convection.
                

                   
                  Key Finding 3: Upper tropospheric aerosol layers can descend via subsidence, contributing to CCN in lower troposphere.
                

Read at JGR Atmospheres → 87 Citations (Google Scholar)

Fig 1: locations (red square) of IITD urban and MRIIRS suburban sites and industrial estates on the map of New Delhi and surroundingregions.

Fig 2: Scatter plots of the mixing ratios of toluene and xylene with benzene for the urban [(i) and (ii)] and suburban [(iii) and (iv)] sites

Fig 3: Scatter plots of the mixing ratios of acetone and MVK + MACR with isoprene for the urban.

Fig 3: Box-model simulated diurnal variations of ozone.

Integrated Impact & Methodological Highlights

Amazon study: combined aircraft measurements (IAGOS-CORE) + high-resolution chemical transport modeling (EMAC)
Indian Ocean: PTR-TOF-MS observations during winter cruise campaign, back-trajectory analysis and OH reactivity estimation

Both papers highlight the role of VOC chemistry in regional climate & air quality feedbacks.
Policy relevance: improving atmospheric models over tropical and marine environments.

"Our work emphasizes the need to include small-scale convective transport and deforestation edges in biogenic emission models to capture VOC budgets accurately."

"Light NMHCs in the Northern Indian Ocean are strongly influenced by continental pollution, increasing aerosol burden over remote marine regions."

More research outcomes on atmospheric VOC chemistry, aerosol-cloud interactions and climate modeling will be added soon.