A5052404448- Atmospheric aerosols and clouds
- Atmospheric chemistry and aerosols
- Climate variability and models
- Meteorological Phenomena and Simulations
- Atmospheric and Environmental Gas Dynamics
- Atmospheric Ozone and Climate
- Fiscal Policy and Economic Growth
- Aeolian processes and effects
- Oceanographic and Atmospheric Processes
- Ionosphere and magnetosphere dynamics
- Geophysics and Gravity Measurements
- Tropical and Extratropical Cyclones Research
- Marine and coastal ecosystems
- Solar Radiation and Photovoltaics
- Particle Dynamics in Fluid Flows
- Delphi Technique in Research
- Earthquake Detection and Analysis
- Cryospheric studies and observations
- Global Energy and Sustainability Research
- Advanced Aircraft Design and Technologies
- Phase Equilibria and Thermodynamics
- Ocean Acidification Effects and Responses
- Engineering and Test Systems
- FinTech, Crowdfunding, Digital Finance
- demographic modeling and climate adaptation
University of Wyoming
2020-2025
University of California, San Diego
2024
Wyoming Department of Education
2020-2024
Northern Illinois University
2021-2022
National Centre for Atmospheric Science
2018-2020
University of Leeds
2017-2020
Seattle University
2014-2017
University of Washington
2014-2017
New Mexico Institute of Mining and Technology
2008
Abstract Equilibrium climate sensitivity, the global surface temperature response to CO doubling, has been persistently uncertain. Recent consensus places it likely within 1.5–4.5 K. Global models (GCMs), which attempt represent all relevant physical processes, provide most direct means of estimating sensitivity via quadrupling experiments. Here we show that closely related effective increased substantially in Coupled Model Intercomparison Project phase 6 (CMIP6), with values spanning...
Atmospheric aerosols, suspended solid and liquid particles, act as nucleation sites for cloud drop formation, affecting clouds properties-ultimately influencing the dynamics, lifetime, water path, areal extent that determine reflectivity (albedo) of clouds. The concentration N d droplets in influences planetary albedo is sensitive to availability aerosol particles on which form. Natural concentrations affect not only properties themselves but also modulate sensitivity changes anthropogenic...
Abstract Aerosol processes and, in particular, aerosol‐cloud interactions cut across the traditional physical‐Earth system boundary of coupled Earth models and remain one key uncertainties estimating anthropogenic radiative forcing climate. Here we calculate historical aerosol effective (ERF) HadGEM3‐GA7 climate model order to assess suitability this for inclusion UK model, UKESM1. The ERF, calculated year 2000 relative 1850, is large negative standard GA7 leading an unrealistic total over...
Abstract In this study, it is shown that CMIP5 global climate models (GCMs) convert supercooled water to ice at relatively warm temperatures tend have a greater mean‐state cloud fraction and more negative feedback in the middle high latitude Southern Hemisphere. We investigate possible reasons for these relationships by analyzing mixed‐phase parameterizations 26 GCMs. The atmospheric temperature where liquid are equally prevalent (T5050) used characterize parameterization each GCM. Liquid...
Significance Enhancement of aerosol that can nucleate cloud droplets increases the droplet number concentration and albedo clouds. This amount sunlight reflected to space. Uncertainty in how aerosol−cloud interactions over industrial period have increased planetary by this mechanism leads significant uncertainty climate projections. Our work presents a method for observationally constraining change due anthropogenic emissions: hemispheric difference remotely sensed between pristine Southern...
Aerosol-cloud interactions (ACIs) are considered to be the most uncertain driver of present-day radiative forcing due human activities. The nonlinearity cloud-state changes aerosol perturbations make it challenging attribute causality in observed relationships forcing. Using correlations infer can when meteorological variability also drives both and cloud independently. Natural anthropogenic from well-defined sources provide "opportunistic experiments" (also known as natural experiments)...
Marine cloud brightening (MCB) is the deliberate injection of aerosol particles into shallow marine clouds to increase their reflection solar radiation and reduce amount energy absorbed by climate system. From physical science perspective, consensus a broad international group scientists that viability MCB will ultimately depend on whether observations models can robustly assess scale-up local-to-global in today's identify strategies ensure an equitable geographical distribution benefits...
Abstract Increasing optical depth poleward of 45° is a robust response to warming in global climate models. Much this cloud increase has been hypothesized be due transitions from ice‐dominated liquid‐dominated mixed‐phase cloud. In study, the importance liquid‐ice partitioning for feedback quantified 19 Coupled Model Intercomparison Project Phase 5 All models show monotonic ice and liquid as function temperature, but temperature at which are equally mixed (the glaciation temperature) varies...
Abstract Aerosol‐cloud interactions (ACI) represent a significant source of forcing uncertainty in global climate models (GCMs). Estimates radiative due to ACI Fifth Assessment Report range from −0.5 −2.5 W m −2 . A portion this is related the first indirect, or Twomey, effect whereby aerosols act as nuclei for cloud droplets condense upon. At constant liquid water content increases number (Nd) and thus albedo. In study we use remote‐sensing estimates Nd within stratocumulus regions...
Abstract Decreases in subtropical low cloud cover (LCC) occur climate model simulations of global warming. In this study 8-day-averaged observations from the Moderate Resolution Imaging Spectroradiometer (MODIS) and Atmospheric Infrared Sounder (AIRS) spanning 2002–14 are combined with European Centre for Medium-Range Weather Forecasts (ECMWF) interim reanalysis to compute dependence observed variability LCC on various predictor variables. Large-scale thermodynamic dynamic predictors...
How clouds respond to anthropogenic sulfate aerosols is one of the largest sources uncertainty in radiative forcing climate over industrial era. This limits our ability predict equilibrium sensitivity (ECS)-the global warming following a doubling atmospheric CO2. Here, we use satellite observations quantify relationships between and low-level while carefully controlling for meteorology. We then combine with estimates change concentration since about 1850 constrain associated forcing....
Abstract. Cloud droplet number concentration (Nd) is of central importance to observation-based estimates aerosol indirect effects, being used quantify both the cloud sensitivity and base state cloud. However, derivation Nd from satellite data depends on a assumptions about accuracy retrievals properties which it derived, making prone systematic biases. A sampling strategies have been proposed address these biases by selecting most accurate in data. This work compares impact retrieved Nd,...
Abstract Climate models produce an increase in cloud optical depth midlatitudes associated with climate warming, but the magnitude of this and its impact on reflected solar radiation vary from model to model. Transition ice liquid midlatitude clouds is thought be one mechanism for producing increased depth. Here observations properties are used a suite remote sensing instruments estimate effect conversion warming latitude band 40° 60°S. The calculated upwelling shortwave (SW↑) found...
Abstract Exploiting the observed robust relationships between temperature and optical depth in extratropical clouds, we calculate shortwave cloud feedback from historical data, by regressing modeled property histograms onto local middle to high southern latitudes. In this region, all CMIP5 models observational data sets predict a negative feedback, mainly driven thickening. Between 45° 60°S, mean (−0.91 ± 0.82 W m −2 K −1 , relative rather than global warming) is very close multimodel RCP8.5...
Abstract. Cloud droplet number concentration (CDNC) is the key state variable that moderates relationship between aerosol and radiative forcing arising from aerosol–cloud interactions. Uncertainty related to effect of anthropogenic on cloud properties represents largest uncertainty in total forcing. Here we show regionally averaged time series Moderate-Resolution Imaging Spectroradiometer (MODIS) observed CDNC low, liquid-topped clouds well predicted by MERRA2 reanalysis near-surface sulfate...
Abstract A supervised neural network algorithm is used to categorize near‐global satellite retrievals into three mesoscale cellular convective (MCC) cloud morphology patterns. At constant amount, patterns differ in brightness associated with the amount of optically thin features. Environmentally driven transitions from closed MCC other patterns, typically accompanied by more features, are as a framework quantify contribution optical depth component shortwave feedback. marine heat wave an...
Abstract Aerosol‐cloud interactions (ACI) in warm clouds are the primary source of uncertainty effective radiative forcing (ERF) during historical period and, by extension, inferred climate sensitivity. The ERF due to ACI (ERFaci) is composed changes cloud microphysics and adjustments microphysics. Here, we examine processes that drive ERFaci using a perturbed parameter ensemble (PPE) hosted CAM6. Observational constraints on PPE result substantial response macrophysics anthropogenic...
Abstract. This paper documents the methodology and preliminary results from a perturbed parameter ensemble (PPE) technique, where multiple parameters are varied simultaneously values determined with Latin hypercube sampling. is done Community Atmosphere Model version 6 (CAM6), atmospheric component of Earth System 2 (CESM2). We apply PPE method to CESM2–CAM6 understand climate sensitivity physics parameters. The initial simulations vary 45 in microphysics, convection, turbulence aerosol...
Abstract The Bárðarbunga‐Veiðivötn fissure eruption lasted from 31 August 2014 to 28 February 2015, during which its sulfur emissions dwarfed anthropogenic Europe. This natural experiment offers an excellent opportunity investigate the aerosol indirect effect and of effusive volcanic eruptions on climate. During cloud droplet effective radius ( r e ) over region surrounding Iceland was at lowest value in 14 year Moderate Imaging Spectroradiometer data record September October 2014. change...
Abstract The sensitivity of the reflection shortwave radiation over Southern Ocean to cloud properties there is estimated using observations from a suite passive and active satellite instruments in combination with radiative transfer modeling. A composite property observational data description constructed that consistently incorporates mean liquid water content, ice particle radius information, vertical structure, overlap, spatial aggregation as measured by optical depth versus cloud-top...
Abstract. Aerosol–cloud interactions are a major source of uncertainty in inferring the climate sensitivity from observational record temperature. The adjustment clouds to aerosol is poorly constrained aspect these aerosol–cloud interactions. Here, we examine response midlatitude cyclone cloud properties change droplet number concentration (CDNC). Idealized experiments high-resolution, convection-permitting global aquaplanet simulations with constant CDNC compared 13 years remote-sensing...
Representing large-scale co-variability between variables related to aerosols, clouds and radiation is one of many aspects agreement with observations desirable for a climate model. In this study such relations are investigated in terms temporal correlations on monthly mean scale, identify points disagreement observations. Ten regions different meteorological characteristics aerosol signatures studied correlation matrices the selected offer an overview model ability represent present day...
Abstract. Aerosol–cloud interactions represent the leading uncertainty in our ability to infer climate sensitivity from observational record. The forcing changes cloud albedo driven by increases droplet number (Nd) (the first indirect effect) is confidently negative and has narrowed its probable range last decade, but sign strength of associated with macrophysics response aerosol (aerosol–cloud adjustments) remain uncertain. This reflects inability accurately quantify variability not a...