A5067975129- Atmospheric Ozone and Climate
- Atmospheric chemistry and aerosols
- Atmospheric aerosols and clouds
- Atmospheric and Environmental Gas Dynamics
- Ionosphere and magnetosphere dynamics
- Microtubule and mitosis dynamics
- Cancer-related Molecular Pathways
- Landslides and related hazards
- Climate variability and models
- Solar and Space Plasma Dynamics
- Spectroscopy and Laser Applications
- Cancer, Hypoxia, and Metabolism
- Meteorological Phenomena and Simulations
- Spaceflight effects on biology
- Laser Design and Applications
- Astro and Planetary Science
- Isotope Analysis in Ecology
- Retinoids in leukemia and cellular processes
- Cancer Mechanisms and Therapy
- Solar Radiation and Photovoltaics
- Cryospheric studies and observations
- Seismology and Earthquake Studies
- Soil erosion and sediment transport
- Geophysics and Gravity Measurements
- Spacecraft and Cryogenic Technologies
Harvard University Press
2003-2025
Harvard University
2013-2024
Colorado School of Mines
2024
University of Liverpool
2022-2024
Liverpool John Moores University
2022-2024
Vanderbilt University
2024
University of Tasmania
2023
Children's National
2022-2023
UC Irvine Health
2023
Indiana University
2023
Dusty Origins The formation of cirrus clouds begins with the production ice nuclei, on which water vapor then condenses. Cziczo et al. (p. 1320 , published online 9 May) determined kinds particles crystals form by sublimating samples collected research aircraft and analyzing chemical physical properties residual seeds. Most seed were either mineral dust or metallic.
Abstract. The microphysical and radiative properties of cirrus clouds continue to be beyond understanding thus still represent one the largest uncertainties in prediction Earth's climate (IPCC, 2013). Our study aims provide a guide microphysics, which is compiled from an extensive set model simulations, covering broad range atmospheric conditions for formation evolution. results are portrayed same parameter space as field measurements, i.e., Ice Water Content-Temperature (IWC-T) space. We...
The observed presence of water vapor convectively injected deep into the stratosphere over United States can fundamentally change catalytic chlorine/bromine free-radical chemistry lower by shifting total available inorganic chlorine catalytically active form, ClO. This chemical shift markedly affects ozone loss rates and makes system extraordinarily sensitive to convective injection mid-latitude in summer. Were intensity frequency increase as a result climate forcing continued addition CO(2)...
In situ observations of H 2 O and HDO in the midlatitude stratosphere are used to evaluate role convection determining stratospheric water budget. The show that vapor overworld (potential temperature > 380 K) is isotopically heavier than expected. Measurements an airmass with anomalously high concentrations isotopic signatures characteristic evaporated ice lofted from troposphere during convective storms. Observed plume enhanced background suggest extratropical can account for a...
Abstract. The AquaVIT-1 intercomparison of atmospheric water vapor measurement techniques was conducted at the aerosol and cloud simulation chamber AIDA (Aerosol Interaction Dynamics in Atmosphere) Karlsruhe Institute Technology, Germany, October 2007. overall objective to intercompare state-of-the-art prototype hygrometers with each other independent humidity standards under controlled conditions. This activity as a blind coordination by selected referees. effort motivated persistent...
Abstract On 27 August 2013, during the Studies of Emissions and Atmospheric Composition, Clouds Climate Coupling by Regional Surveys field mission, NASA's ER‐2 research aircraft encountered a region enhanced water vapor, extending over depth approximately 2 km minimum areal extent 20,000 in stratosphere (375 K to 415 potential temperature), south Great Lakes (42°N, 90°W). Water vapor mixing ratios this plume, measured Harvard Vapor instrument, constitute highest values recorded situ at these...
The explosive eruption of the Hunga Tonga-Hunga Ha'apai (HTHH) volcano on 15 January 2022 injected more water vapor into stratosphere and to higher altitudes than ever observed in satellite era. Here, evolution stratospherically is examined as a function latitude, altitude, time year following (February December 2022), perturbations stratospheric chemical composition resulting from increased sulfate aerosols are identified analyzed. average calculated mass distribution elevated between...
Abstract. Recent in situ measurements at tropical tropopause temperatures as low 187 K indicate supersaturations with respect to ice exceeding 100% little or no present. In contrast, models used simulate cloud formation near the assume a supersaturation threshold for nucleation of about 65% based on laboratory aqueous aerosol freezing. The high reported here, along simulations assuming plausible range temperature histories sampled air mass, that vast majority aerosols this flight must have...
We present observations defining (
Abstract In situ and remote sensing observations of water vapor are analyzed to assess the evidence for direct convective hydration lower stratosphere. We have examined several hundred balloon‐borne airborne in measurements stratospheric humidity tropics northern midlatitudes. find that tropical H 2 O enhancements above background occur quite infrequently, height is within about 1 km cold‐point tropopause. Following Schwartz et al. (2013, https://doi.org/10.1002/grl.50421 ), we examine...
The redistribution of HNO 3 via uptake and sedimentation by cirrus cloud particles is considered an important term in the upper tropospheric budget reactive nitrogen. Numerous encounters NASA WB‐57F high‐altitude research aircraft during Cirrus Regional Study Tropical Anvils Layers‐Florida Area Experiment (CRYSTAL‐FACE) were accompanied observation condensed‐phase with NOAA chemical ionization mass spectrometer. instrument measures two independent channels detection connected to separate...
Abstract. Recent high-altitude aircraft measurements with in situ imaging instruments indicated the presence of relatively large (≃100 μm length), thin (aspect ratios ≃6:1 or larger) hexagonal plate ice crystals near tropical tropopause very low concentrations (<0.01 L−1). These were not produced by deep convection aggregation. We use simple growth-sedimentation calculations as well detailed cloud simulations to evaluate conditions required grow crystals. Uncertainties crystal aspect...
The soft particle spectrometer uses electrostatic deflection for simultaneous measurement of the differential energy spectra electrons and protons. range is from 10 eV to keV per unit charge with ±40% spread. Twelve stage BeCu electron multipliers are used as detectors in counting mode over a five decade dynamic range. A swept selection provides spectrum 0.5 sec high fluxes, while stepped suitable lower fluxes takes 40 sec. typical spectrogram transpolar pass included an example data...
Acquiring accurate measurements of water vapor at the low mixing ratios (< 10 ppm) encountered in upper troposphere and lower stratosphere (UT/LS) has proven to be a significant analytical challenge evidenced by persistent disagreements between high-precision hygrometers. These have caused uncertainties description physical processes controlling dehydration air tropical tropopause layer entry into hindered validation satellite retrievals. A 2011 airborne intercomparison large group situ...
Building on previously published details of the laboratory calibrations Harvard Lyman‐ α photofragment fluorescence hygrometer (HWV) NASA ER‐2 and WB‐57 aircraft, we describe here validation process for HWV, which includes intercomparisons with other water vapor instruments at mixing ratios from 0 to 10 ppmv, followed by in‐flight same hygrometers. The observed agreement exhibited in during helps corroborate accuracy HWV. In light validated present evaluate a series satellite balloon borne...
We present a climatology of O 3 , CO, and H 2 for the upper troposphere lower stratosphere (UTLS), based on large collection high‐resolution research aircraft data taken between 1995 2008. To group observations with sparse horizontal coverage, UTLS is divided into three regimes: tropics, subtropics, polar region. These regimes are defined using set simple criteria tropopause height multiple conditions. Tropopause‐referenced tracer profiles tracer‐tracer correlations show distinct...
We present the first in situ measurements of HDO across tropical tropopause, obtained by integrated cavity output spectroscopy (ICOS) and Hoxotope water isotope instruments during Costa Rica Aura Validation Experiment (CR‐AVE) Tropical Composition, Cloud Climate Coupling (TC4) aircraft campaigns out winter summer, respectively. use these data to explore role convection plays delivering tropopause layer (TTL) stratosphere. find that isotopic ratios within TTL are inconsistent with gradual...
Abstract The Atmospheric Chemistry Experiment-Fourier Transform Spectrometer (ACE-FTS) on SCISAT-1 and Microwave Limb Sounder (MLS) NASA’s Aura satellite have contributed significantly to understanding the impacts of human activities stratospheric ozone layer. two-decade-long data record from these instruments has allowed quantification depletion caused by human-released ozone-depleting substances, effects extreme natural events like major volcanic eruptions including Hunga in 2022, as well...
Far-UVC light, especially germicidal UV light at 222 nm (GUV222), has received considerable attention for its potential to deactivate airborne pathogens indoors and prevent the spread of infectious disease. However, GUV222 also generates ozone (O3), posing human health risks initiating additional photochemistry that may degrade indoor air quality. Air cleaners pose an opportunity counteract drawbacks by removing harmful byproducts; however, this never been demonstrated. Here, we conduct...
We analyzed the interaction between North American monsoon anticyclone (NAMA) and summertime cross-tropopause convective outflow by applying a trajectory analysis to climatology of overshooting tops (OTs) identified in GOES satellite images, which covers domain from 29°S 68°N 205 1.25°W for time period May through September 2013. With this we seasonally, geographically, altitude-dependent variability NAMA strength convection that control their interaction. find has strongest impact on...
Abstract Water vapor's contribution to Earth's radiative forcing is most sensitive changes in its lower stratosphere concentration. One recognized pathway for rapid increases stratospheric water vapor tropopause‐overshooting convection. Since this has been rarely sampled, the NASA Dynamics and Chemistry of Summer Stratosphere (DCOTSS) field project focused on obtaining situ observations air recently affected by convection over United States. This study reports extreme altitudes which...
Abstract. Tropopause-overshooting convection in the midlatitudes provides a rapid transport pathway for air from lower troposphere to reach upper and stratosphere (UTLS) can result formation of above-anvil cirrus plumes (AACPs) that significantly hydrate stratosphere. Such UTLS composition changes alter radiation budget impact climate. Novel situ observations NASA Dynamics Chemistry Summer Stratosphere (DCOTSS) field campaign are used this study examine impacts AACP-generating overshooting...
Abstract Hydration of the stratosphere by tropopause‐overshooting convection has received increasing interest due to extreme concentrations water vapor that can result and, ultimately, climate warming potential such hydration provides. Previous work recognized importance numerous dynamic and physical processes control stratospheric delivery convection. This study leverages recent comprehensive observations from NASA Dynamics Chemistry Summer Stratosphere (DCOTSS) field campaign determine...
The chemical composition of the lowermost stratosphere exhibits both spatial and temporal variability depending upon relative strength (1) isentropic transport from tropical tropopause layer (TTL), (2) diabatic descent midlatitude northern followed by equatorward transport, (3) ascent troposphere through convection. In situ measurements made in over Florida illustrate additional impact flow around monsoon anticyclone. This carries, along with older stratospheric air, distinct signature deep...
Aircraft‐based in situ measurements of cirrus cloud ice water content (IWC) are important for microphysical/radiative modeling and satellite validation studies, yet the have proven challenging due, part, to large dynamic range IWC values present clouds. To date, three instruments designed measurement been flown aboard NASA WB‐57F research aircraft: University Colorado closed‐path laser hygrometer, Droplet Measurement Technologies Cloud Spectrometer Impactor, Harvard Lyman‐ α total...