Suresh Dhaniyala

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Large particles containing nitric acid (HNO3) were observed in the 1999/2000 Arctic winter stratosphere. These in situ observations were made over a large altitude range (16 to 21 kilometers) and horizontal extent (1800 kilometers) on several airborne sampling flights during a period of several weeks. With diameters of 10 to 20 micrometers, these(More)
[1] We present a hypothesis that the known formation of nitric acid hydrates in lee-wave ice clouds produces a ‘‘standing crop’’ of nitric acid trihydrate (NAT) particles, and that growth and sedimentation of these particles efficiently denitrifies the polar stratosphere. Simulations using a simple two-dimensional model illustrate that the large NAT number(More)
Ice nucleating particles (INPs) are vital for ice initiation in, and precipitation from, mixed-phase clouds. A source of INPs from oceans within sea spray aerosol (SSA) emissions has been suggested in previous studies but remained unconfirmed. Here, we show that INPs are emitted using real wave breaking in a laboratory flume to produce SSA. The number(More)
To effectively use a passive sampler for monitoring trace contaminants in the gas-phase, its sampling characteristics as a function of ambient wind conditions must be known. In this study two commonly used passive samplers were evaluated using computational fluid dynamics. Contaminant uptake by the polyurethane foam (PUF) was modeled using a species(More)
[1] Large (>2 mm diameter) HNO3-containing polar stratospheric cloud (PSC) particles were measured in situ by the NOAA NOy instrument on board the NASA ER-2 aircraft during seven flights in the 1999/2000 Arctic winter vortex. Here we discuss the detection of these large PSC particles, their spatial distribution, the ambient conditions under which they were(More)
A sensitive laser spectrometer, named IRIS (water isotope ratio infrared spectrometer), was developed for the in situ detection of the isotopic composition of water vapour in the upper troposphere and the lower stratosphere. Isotope ratio measurements can be used to quantify troposphere-stratosphere exchange, and to study the water chemistry in the(More)
Aircraft-based aerosol sampling in clouds is complicated by the generation of shatter artifact particles from aerodynamic or im-paction breakup of cloud droplets and ice particles in and around the aerosol inlet. Aerodynamic breakup occurs when the Weber number of a droplet, which primarily depends on the droplet size and the magnitude of the relative(More)
[1] Large (5 to >20 mm diameter) nitric-acid-containing polar stratospheric cloud (PSC) particles were observed in the Arctic stratosphere during the winter of 1999–2000. We use a particle growth and sedimentation model to investigate the environment in which these particles grew and the likely phase of the largest particles. Particle trajectory(More)
Objectives. Current efforts to study fugitive dust (FD) are hampered by the lack of an effective, real-time instrument to measure the broad range of particle sizes that make up FD. To meet this need the overall objective of this project was to develop and evaluate a novel instrument capable of measuring, in real-time, ambient concentrations of particles(More)
Design and analysis of a new low-noise, fast-response, high-sensitivity, compact electrometer are described. This electrometer are battery operated and capable of measuring currents down to the femtoampere level. The portable, high performance nature of the electrometer renders it applicable for deployment in compact instruments for applications such as(More)