Darin W Toohey

University of Colorado Boulder | CUB · Department of Atmospheric and Oceanic Sciences (ATOC)

Supercooled liquid clouds are ubiquitous over the Southern Ocean (SO), even to temperatures below -20 °C, and comprise a large fraction of the marine boundary layer (MBL) clouds. Earth system models and reanalysis products have struggled to reproduce the observed cloud phase distribution and occurrence of cloud ice in the region. Recent simulations...

Southern Ocean (SO) low‐level mixed phase clouds have been a long‐standing challenge for Earth system models to accurately represent. While improvements to the Community Earth System Model version 2 (CESM2) resulted in increased supercooled liquid in SO clouds and improved model radiative biases, simulated SO clouds in CESM2 now contain too little...

The interaction between biomass burning aerosols and clouds remains challenging to accurately determine in part because of difficulties in using direct observations to account for influences of scavenging and dilution separately from sources. The prevalence of mixing versus precipitation processes in biomass burning aerosol (BBA) laden air over the...

Coincident radar data with Doppler radar measurements at X, Ku, Ka, and W bands on the NASA ER-2 aircraft overflying the NASA P-3 aircraft acquiring in situ microphysical measurements are used to characterize the relationship between radar measurements and ice microphysical properties. The data were obtained from the Investigation of Microphysics a...

Light absorbing organic carbon, or brown carbon (BrC), can be a significant contributor to the visible light absorption budget. However, the sources of BrC and the contributions of BrC to light absorption are not well understood. Biomass burning is thought to be a major source of BrC. Therefore, as part of the WE-CAN (Western Wildfire Experiment fo...

Light absorbing organic carbon, or brown carbon (BrC), can be a significant contributor to the visible light absorption budget. However, the sources of BrC and the contributions of BrC to light absorption are not well understood. Biomass burning is thought to be a major source of BrC. Therefore, as part of the WE-CAN (Western Wildfire Experiment fo...

The exhalation of aerosols during musical performances or rehearsals posed a risk of airborne virus transmission in the COVID‐19 pandemic. Previous research studied aerosol plumes by only focusing on one risk factor, either the source strength or convective transport capability. Furthermore, the source strength was characterized by the aerosol conc...

This paper presents aircraft in situ measurements of water concentration and heavy water isotope ratios D/H and 18O/16O during the NASA ObseRvations of Aerosols above CLouds and their intEractionS (ORACLES) project. The aircraft measurement system is also presented. The dataset is unique in that (1) it contains both total water and cloud condensed...

Wildfires are an important atmospheric source of primary organic aerosol (POA) and precursors for secondary organic aerosol (SOA) at regional and global scales. However, there are large uncertainties surrounding the...

This paper presents the water vapor heavy isotope ratio measurement system developed for aircraft in-situ measurements and used in the NASA ObseRvations of Aerosols above CLouds and their intEractionS (ORACLES) project. The resultant dataset collected, which includes measurements of specific humidity and the heavy isotope ratios D / H and 18O / 16O...

No PDF available ABSTRACT Outbreaks from choirs showed that singing brings potential risk of COVID-19 infection. There is less known about the risks of airborne infection from other musical performance, such as playing wind instruments or performing theatre. In addition, it is important to understand methods to reduce infection risk. In this study,...

Outbreaks from choir performances, such as the Skagit Valley Choir, showed that singing brings potential risk of COVID-19 infection. There is less known about the risks of airborne infection from other musical performances, such as playing wind instruments or performing theater. In addition, it is important to understand methods that can be used to...

Small cumulus clouds over the western United States were measured via airborne instruments during the wildfire season in summer of 2018. Statistics of the sampled clouds are presented and compared to smoke aerosol properties. Cloud droplet concentrations were enhanced in regions impacted by biomass burning smoke, at times exceeding 3,000 cm⁻³. Imag...

Controls on pristine aerosol over the Southern Ocean (SO) are critical for constraining the strength of global aerosol indirect forcing. Observations of summertime SO clouds and aerosols in synoptically varied conditions during the 2018 SOCRATES aircraft campaign reveal novel mechanisms influencing pristine aerosol-cloud interactions. The SO free t...

Abstract Stratocumulus clouds over the Southern Ocean have fewer droplets and are more likely to exist in the predominately supercooled phase than clouds at similar temperatures over northern oceans. One likely reason is that this region has few continental and anthropogenic sources of cloud‐nucleating particles that can form droplets and ice. In t...

Wildfires in the western United States are large sources of particulate matter, and the area burned by wildfires is predicted to increase in the future. Some particles released from wildfires can affect cloud formation by serving as ice‐nucleating particles (INPs). INPs have numerous impacts on cloud radiative properties and precipitation developme...

Very few measurements exist of the composition and contribution to cloud condensation nuclei (CCN) of organic mass (OM) at different sizes for particles over the Southern Ocean. Airborne and shipboard measurements of organic composition, aerosol number and mass size distributions, and CCN spectra during the Southern Ocean Clouds, Radiation, Aerosol...

The bulk microphysical properties and number distribution functions (N(D)) of supercooled liquid water (SLW) and ice inside and between ubiquitous generating cells (GCs) observed over the Southern Ocean (SO) during the Southern Ocean Clouds Radiation Aerosol Transport Experimental Study (SOCRATES) measured by in situ cloud probes onboard the NCAR/N...

Modeling the shortwave radiation balance over the Southern Ocean region remains a challenge for Earth system models. To investigate whether this is related to the representation of aerosol-cloud interactions, we compared measurements of the total number concentration of sea spray generated particles within the Southern Ocean region to model predict...

In this study, airborne in situ measurements of ice concentrations in mixed-phase clouds over the tropical ocean sampled during the Ice in Clouds Experiment (ICE-T) project are analyzed. High concentrations of ice larger than 250 μm in diameter (0.05–10 L⁻¹) were observed in three shallow stratiform clouds whose top temperatures were warmer than −8...

With the space industry’s rapid growth, rocket exhaust will increasingly accumulate in the atmosphere. How this accumulation might affect the planet is unknown—because we’re not taking it seriously.

The Southern Ocean plays a critical role in the global climate system by mediating atmosphere–ocean partitioning of heat and carbon dioxide. However, Earth system models are demonstrably deficient in the Southern Ocean, leading to large uncertainties in future air–sea CO2 flux projections under climate warming and incomplete interpretations of natu...

The objectives of this study were to measure levels of particulate matter (PM) in mechanically ventilated buildings and to improve understanding of filtration requirements to reduce exposure. With the use of an Ultra High Sensitivity Aerosol Spectrometer and an Aerodyne Mass Spectrometer, ultrafine (0.055–0.1 µm) and fine (0.1–0.7 µm) indoor and ou...

Some types of biological particles are known to nucleate ice at warmer temperatures than mineral dust, with the potential to influence cloud microphysical properties and climate. However, the prevalence of these particle types above the atmospheric boundary layer is not well known. Many types of biological particles fluoresce when exposed to ultrav...

The United States Embassy in Beijing, China publicly released a record of mass concentrations of particulate matter 2.5 µm and smaller in aerodynamic diameter (PM2.5), from April 2008 to the present, measured with a beta attenuation monitor (BAM). We compare these measurements with observations of particulate matter recorded at the Beijing Institut...

Some types of biological particles are known to nucleate ice at warmer temperatures than mineral dust, with the potential to influence cloud microphysical properties and climate. However, the prevalence of these particle types above the atmospheric boundary layer is not well known. Many types of biological particles fluoresce when exposed to ultrav...

This study examines the occurrence and morphology of frozen-drop aggregates in thunderstorm anvils from the United States Midwest and describes the environmental conditions where they are found. In situ airborne data collected in anvils using several particle imaging and sizing probes and bulk total water instrumentation during the 2012 Deep Convec...

The second-generation University of Colorado closed-path tunable-diode laser hygrometer (CLH-2) is an instrument for the airborne in situ measurement of total water content - the sum of vapor-, liquid- and ice-phase water - in clouds. This compact instrument has been flown on the NSF/NCAR Gulfstream-V aircraft in an underwing canister. It operates...

For 12 months in 2011–2012, I had the honor of serving as a Jefferson Science Fellow (JSF) in the U.S. Department of State. In a partnership with U.S. universities, 78 senior scientists, engineers, and professionals have now served as JSFs in the State Department and U.S. Agency for International Development (USAID); 13 new fellows arrived in Washi...

Halogen-containing compounds from Earth's surface that reach the stratosphere release their constituent atoms by exposure to ultraviolet light and oxidation. The halogen atoms, mainly chlorine and bromine, undergo a series of photochemical reactions that catalytically destroy ozone. Consequently, very small abundances of halogens produce dramatic l...

[1] Trace gases, submicron particle size distributions, and bulk filterable halogen content were measured on Ross Island, Antarctica, in austral spring 2007. During several surface level, partial ozone depletion events, enhanced submicron particle concentrations, and changes in filterable halogens were observed. These events were characterized by o...

Hydrocarbon species and related meteorological and chemical variables were measured within and immediately above a loblolly pine forest in North Carolina, USA during 15–18 July 2003. The degree of photochemical processing within the forest canopy of biogenic hydrocarbons emitted at the foliage level is investigated with the aid of a one-dimensional...

Black carbon (BC) is a fraction of the PM2.5 aerosol mode and a major component of the soot produced by incomplete combustion of fossil fuels, biofuels and biomass. In addition to its health impacts as a pollutant, BC can absorb UV and visible radiation directly, therefore affecting the Earth’s climate balance. The most recent estimates suggest tha...

This study examines the occurrence and morphology of frozen drop aggregates in thunderstorm anvils from the US Midwest and describes the environmental conditions where they are found. In situ airborne data collected in anvils using several particle imaging and sizing probes and bulk total water instrumentation during the 2012 Deep Convective Clouds...

subtropical convective boundary layer (CBL) plays a critical role in climate by regulating the vertical exchange of moisture, energy, trace gases, and pollutants between the ocean surface and free troposphere. Yet bulk features of this exchange are poorly constrained in climate models. To improve our understanding of moisture transport between the...

The second-generation University of Colorado closed-path tunable-diode laser hygrometer (CLH-2) is an instrument for the airborne in situ measurement of total water content – the sum of vapor-, liquid- and ice-phase water – in clouds. This compact instrument has been flown on the NSF/NCAR Gulfstream-V aircraft in an underwing canister. It operates...

Organic aerosols (OA) in Pasadena are characterized using multiple measurements from the CalNex campaign. Five OA components are identified using positive matrix factorization including hydrocarbon-like OA (HOA), and two types of oxygenated OA (OOA). The Pasadena OA elemental composition when plotted as H:C versus O:C follows a line less steep than...

The southeast Pacific Ocean is covered by the world's largest stratocumulus cloud layer, which has a strong impact on ocean temperatures and climate in the region. The effect of anthropogenic sources of aerosol particles on the stratocumulus deck was investigated during the VOCALS field experiment. Aerosol measurements below and above cloud were ma...

The Southeast Pacific Ocean is covered by the world's largest stratocumulus cloud layer, which has a strong impact on ocean temperatures and climate in the region. The effect of anthropogenic sources of aerosol particles such as power plants, urban pollution and smelters on the stratocumulus deck was investigated during the VOCALS field experiment....

The role of ice in the formation of chemically active halogens in the environment requires a full understanding because of its role in atmospheric chemistry, including controlling the regional atmospheric oxidizing capacity in specific situations. In particular, ice and snow are important for facilitating multiphase oxidative chemistry and as media...

The role of ice in the formation of chemically active halogens in the environment requires a full understanding because of its role in atmospheric chemistry, including controlling the oxidizing capacity of the atmosphere. In particular, ice and snow are important for facilitating multiphase oxidative chemistry and as media upon which marine algae l...

Owen Brian Toon was awarded the 2011 Roger Revelle Medal at the AGU Fall Meeting Honors Ceremony, held on 7 December 2011 in San Francisco, Calif. The medal is for “outstanding contributions in atmospheric sciences, atmosphere-ocean coupling, atmosphere-land coupling, biogeochemical cycles, climate, or related aspects of the Earth system.”

Tropical maritime cumulus clouds represent an important component of the global water cycle, but the relative roles of primary and secondary ice production in these clouds are poorly understood. Heterogeneous ice nuclei (IN) are responsible for ice initiation in towering tropical cumulus clouds, so information regarding their abundance, distributio...

A particularly difficult, long-standing problem has been to explain observations in extra-tropical and tropical maritime clouds, made as early as the mid-1960's but also in later field studies, that exhibited far greater ice crystal number concentrations than expected from past ice nuclei measurements, especially when cloud top temperatures were gr...

Atmospheric aerosols impact climate and health, but their sources and composition are poorly understood. To address this knowledge gap, a high-resolution aerosol mass spectrometer (AMS) and complementary instrumentation were deployed during the 2010 CalNex campaign to characterize aerosol composition in the Los Angeles (LA) area. Total mass concent...

Convective clouds play a significant role in the moisture and heat balance of the tropics. The dynamics of organized and isolated convection are a function of the background thermodynamic profile and wind shear, buoyancy sources near the surface and the latent heating inside convective updrafts. The stable oxygen and hydrogen isotope ratios in wate...

Distributions of water vapor and cloud have the potential to effect significant feedbacks on changes in climate. This motivates a greater understanding of the hydrological processes that regulate atmospheric humidity and cloudiness, as well as key cloud parameters like albedo and lifetime. In this work, the signatures of large-scale condensation an...

Water vapor in the subtropical troposphere plays an important role in the radiative balance, the distribution of precipitation, and the chemistry of the Earth's atmosphere. Measurements of the water vapor mixing ratio paired with stable isotope ratios provide unique information on transport processes and moisture sources that is not available with...

We report airborne measurements of emission factors (EF) for trace gases and PM 2.5 made in southern Mexico in March of 2006 on 6 crop residue fires, 3 tropical dry forest fires, 8 savanna fires, 1 garbage fire, and 7 mountain pine-oak forest fires. The savanna fire EF were measured early in the local dry season and when compared to 5 EF measured l...

We report airborne measurements of emission factors (EF) for trace gases and PM_2.5 made in southern Mexico in March of 2006 on 6 crop residue fires, 3 tropical dry forest fires, 8 savanna fires, 1 garbage fire, and 7 mountain pine-oak forest fires. The savanna fire EF were measured early in the local dry season and when compared to EF me...

The oxidation of secondary organic aerosol (SOA) is studied with mass spectra analysis of SOA formed in a Potential Aerosol Mass (PAM) chamber, a small flow-through photo-oxidation chamber with extremely high OH and ozone levels. Oxidation for a few minutes in the PAM chamber is equivalent to days to weeks in the atmosphere. The mass spectra were m...

The southeast Pacific Ocean is covered by the world's largest stratocumulus cloud layer, which has a strong impact on ocean temperatures and climate in the region. The effect of anthropogenic sources of aerosol particles such as power plants, urban pollution and smelters from Chile and Peru on the stratocumulus deck was investigated during the VOCA...

Submicron atmospheric aerosols impact climate and human health, but their sources and composition are poorly understood. To address this knowledge gap, high-resolution time-of-flight aerosol mass spectrometry (AMS) [DeCarlo et al. Anal. Chem. 2006] and other advanced instrumentation were deployed during the CalNex field campaign in May and June 201...

A new type of hydrocarbon rocket engine is expected to power a fleet of suborbital rockets for commercial and scientific purposes in coming decades. A global climate model predicts that emissions from a fleet of 1000 launches per year of suborbital rockets would create a persistent layer of black carbon particles in the northern stratosphere that c...

Very often, changes in atmospheric constituents are strongly influenced by atmospheric transport and mixing processes, and it is difficult to separate out changes due to chemistry. Changes in particle number, size, and composition due to in situ nucleation and growth or evaporation may be difficult to differentiate from changes due strictly to adve...

A new type of hydrocarbon rocket engine with a larger soot emission index than current kerosene rockets is expected to power a fleet of suborbital rockets for commercial and scientific purposes in coming decades. At projected launch rates, emissions from these rockets will create a persistent soot layer in the northern middle stratosphere that woul...

Rockets are the sole source of human produced nonvolatile particulate directly injected into the atmosphere above 20 km altitude. The main components of rocket particulate are submicron black carbon soot (BC) from hydrocarbon (HC) fueled engines and Al2O3 (alumina) from solid rocket motors. Since the emission index and atmospheric lifetime of BC em...

Smoking methamphetamine (MA) creates a potential risk of environmental (second-hand) exposure to others. Despite the public health concerns, essentially no data are available on the health effects of smoked MA. Using a unique rodent inhalation exposure system, our laboratory has previously published that acute inhalation of relevant doses of MA vap...

The oxidation of secondary organic aerosol (SOA) is studied with mass spectra analysis of SOA formed in a Potential Aerosol Mass (PAM) chamber, a small flow-through photo-oxidation chamber with extremely high OH and ozone levels. Oxidation for a few minutes in the PAM chamber is equivalent to days to weeks in the atmosphere. The mass spectra were m...

Aircraft emissions impact the atmosphere in a variety of ways, including enhancing greenhouse gases, especially water vapor and carbon dioxide, in the upper troposphere and lower stratosphere, forming persistent contrails, and altering the distributions of reactive chemical species, which change the oxidative capacity of the atmosphere. This paper...