A5060659878- Climate variability and models
- Atmospheric and Environmental Gas Dynamics
- Meteorological Phenomena and Simulations
- Atmospheric chemistry and aerosols
- Atmospheric Ozone and Climate
- Arctic and Antarctic ice dynamics
- Atmospheric aerosols and clouds
- Marine and coastal ecosystems
- Computational Physics and Python Applications
- Cryospheric studies and observations
- Oceanographic and Atmospheric Processes
- Methane Hydrates and Related Phenomena
- Climate Change and Geoengineering
- Climate change and permafrost
- Calibration and Measurement Techniques
- Climate Change Policy and Economics
- Advanced NMR Techniques and Applications
- Energy Load and Power Forecasting
- Ocean Acidification Effects and Responses
- Radioactive Decay and Measurement Techniques
- Enzyme Structure and Function
- Air Quality Monitoring and Forecasting
- Gas Dynamics and Kinetic Theory
- Wind and Air Flow Studies
- Freezing and Crystallization Processes
Oregon State University
2007-2020
NSF National Center for Atmospheric Research
2008
Scripps Institution of Oceanography
2003-2007
University of California, San Diego
2003-2007
Abstract The extent to which the climate will change due an external forcing depends largely on radiative feedbacks, act amplify or damp surface temperature response. There are a variety of issues that complicate analysis feedbacks in global models, resulting some confusion regarding their strengths and distributions. In this paper, authors present method for quantifying based “radiative kernels” describe differential response top-of-atmosphere fluxes incremental changes feedback variables....
Abstract Climate models differ in their responses to imposed forcings, such as increased greenhouse gas concentrations, due different climate feedback strengths. Feedbacks NCAR’s Community Atmospheric Model (CAM) are separated into two components: the change components response an forcing and “radiative kernel,” effect that changes have on top-of-the-atmosphere (TOA) radiative budget. This technique’s usefulness depends linearity of processes. For case CO2 doubling, sum effects water vapor,...
Equilibrium climate sensitivity of the Community Climate System Model, version 4 (CCSM4) is 3.20°C for 1° horizontal resolution in each component. This about a half degree Celsius higher than previous (CCSM3). The transient CCSM4 at 1.72°C, which 0.2°C CCSM3. These sensitivities cannot be explained by change to preindustrial baseline climate. study uses radiative kernel technique show that, from CCSM3 CCSM4, global mean lapse-rate feedback declines magnitude and shortwave cloud increases....
The major evolution of the National Center for Atmospheric Research Community Atmosphere Model (CAM) is used to diagnose climate feedbacks, understand how feedbacks change with different physical parameterizations, and identify processes regions that determine sensitivity. In CAM from version 4 5, water vapor, temperature, surface albedo, lapse rate are remarkably stable across changes parameterization suite. However, sensitivity increases 3.2 K in CAM4 4.0 CAM5. difference mostly due (i)...
Abstract An approach to climate change feedback analysis is described in which tropospheric relative humidity replaces specific as the state variable that, along with temperature structure, surface albedos, and clouds, controls magnitude of response global mean a radiative forcing. Despite being simply regrouping terms analysis, this alternative perspective has benefit removing most pervasive cancellation between water lapse-rate feedbacks seen models. As consequence, individual have less...
Abstract Climate feedbacks vary strongly among climate models and continue to represent a major source of uncertainty in estimates the response anthropogenic forcings. One method evaluate global is radiative kernel technique, which well suited for model intercomparison studies because its computational efficiency. However, usefulness this technique predicated on assumption linearity between top-of-atmosphere (TOA) fluxes feedback variables, limiting application simulations small...
Abstract Are equilibrium climate sensitivity and the associated radiative feedbacks a constant property of system, or do they change with forcing magnitude base climate? Using kernel technique, are evaluated in fully coupled general circulation model (GCM) for three successive doublings carbon dioxide starting from present-day concentrations. Climate increases by 23% between first third CO2 doublings. Increases positive water vapor cloud partially balanced decrease surface albedo feedback an...
The use of radiative kernels to diagnose climate feedbacks is a recent development that may be applied existing change simulations. We apply the kernel technique transient simulations from multi-thousand member perturbed physics ensemble coupled atmosphere-ocean general circulation models, comparing distributions model with those taken CMIP-3 multi GCM ensemble. Although range clear sky longwave in similar seen multi-GCM ensemble, underestimates net clear-sky (or forcing) some models...
Phytoplankton alter the absorption of solar radiation, affecting upper ocean temperature and circulation. These changes, in turn, influence atmosphere through modification sea surface (SST). To investigate effects present‐day phytoplankton concentration on atmosphere, an atmospheric general circulation model was forced by SST changes due to phytoplankton. The modified obtained from runs with space‐ time‐varying abundances Coastal Zone Color Scanner data. simulations indicate that amplify...
Scripps Institution of Oceanography, University California, San Diego, Lajolla, CaliforniaNOAA/Climate Diagnostics Center, Boulder, ColoradoMeteorological Service Canada, Victoria, British Columbia, CanadaUniversity Maine, Orono, MaineOak Ridge National Laboratory, Oak Ridge, TennesseeGriffith University, Nathan, AustraliaUniversity Hawaii at Manoa, Honolulu, HawaiiDalhousie Halifax, Nova Scotia, Wisconsin—Madison, Madison, WisconsinUniversity Maryland, College Park, MarylandAdvanced Earth...
The increase in atmospheric concentrations of water vapor with global warming is a large positive feedback the climate system. Thus, even relatively small errors its magnitude can lead to uncertainties predicting response anthropogenic forcing. This study incorporates observed variability over 2002–2009 from Atmospheric Infrared Sounder instrument into radiative transfer scheme provide constraints on this feedback. We derive short‐term 2.2 ± 0.4 Wm −2 K −1 . Based relationship between...
Abstract Abrupt transitions to strongly superrotating states have been found in some idealized models of the troposphere. These are thought be caused by feedbacks between eddy momentum flux convergence low latitudes and strength equatorial flow. The behavior an axisymmetric shallow-water model with applied tropical torque is studied here determine if abrupt transition can realized without feedbacks. upper-tropospheric layer relaxed a radiative equilibrium thickness, exchanging mass thus...
Airborne mineral dust can influence the climate by altering radiative properties of atmosphere, but magnitude effect is uncertain. An idealized global model developed to study dust‐climate system. The determines longwave and shortwave direct forcing, as well resulting temperature changes, based on specified distribution, height, optical properties. Comparisons with observations general circulation results indicate that produces realistic for present‐day distribution volcanic aerosols....
Abstract The climate sensitivity uncertainty of global models (GCMs) is partly due to the spread individual feedbacks. One approach constrain long-term use relatively short observational record, assuming there exists some relationship in feedbacks between and long records. present work tests this assumption by regressing short-term feedback metrics, characterized 20-yr as well interannual intra-annual against longwave water vapor, atmospheric temperature, shortwave surface albedo calculated...
Radiative kernels have become a common tool for evaluating and comparing radiative feedbacks to climate change in different general circulation models. However, kernel feedback calculations are inaccurate simulations where the atmosphere is significantly perturbed from its base state, such as very large forcing or physics simulations. In addition, past analyses not produced relating prognostic cloud variables because of strong nonlinearities their relationship forcing. A new methodology...
An idealized global climate model is used to explore the response of a wide range dust radiative properties and layer heights. The top‐of‐the‐atmosphere (TOA) shortwave forcing becomes more negative as broadband single scattering albedo increases asymmetry parameter decreases, but sensitivity highly dependent on location with respect clouds. longwave TOA most affected by height layer. net sensitive parameter. surface atmospheric temperature responses are approximately linear forcing, opposed...
Abstract Climate sensitivity is generally studied using two types of models. Atmosphere–ocean general circulation models (AOGCMs) include interactive ocean dynamics and detailed heat uptake. Atmospheric GCMs (AGCMs) with slab (SOMs) cannot fully simulate the ocean’s response to influence on climate. However, AGCMs are computationally cheaper thus often used quantify understand climate feedbacks sensitivity. Here, physical compared between AOGCMs SOM-AGCMs from Coupled Model Intercomparison...
Abstract Energy balance models have proven useful in understanding mechanisms and feedbacks the climate system. An original global energy model is presented here. The solved numerically for equilibrium states defined by zonal average temperature as a function of latitude both surface an atmospheric layer. effects radiative, latent, sensible heating are parameterized. includes variable lapse rate parameterizations major dynamical responsible meridional heat transport: Hadley cell, midlatitude...
A three-dimensional sea ice model is presented with resolved snow thickness variations and melt ponds. The calculates heating from solar radiative transfer simulates the formation movement of brine/melt water through system. Initialization for based on observations topography made during summer seasons 2009, 2010, 2012 a location off coast Barrow, AK. Experiments are conducted to examine importance properties by comparing observed modeled pond fraction albedo. One key process simulated...
Abstract The vertical structure of radiative heating rates over the region tropical Indian Ocean associated with MJO during DYNAMO/ARM Investigation Experiment is presented. mean and variability active, suppressed, disturbed phases are determined from Pacific Northwest National Laboratory Combined Remote Sensing Retrieval (CombRet) Gan Island, Maldives (0.69°S, 73.15°E). TOA surface fluxes CombRet product compared collocated 3-hourly CERES SYN1deg Ed4A satellite retrievals. correlated in...