SCRIPPS OCEANOGRAPHY
  • University of California-San Diego
  • 9500 Gilman Drive
  • La Jolla CA 92093-0532 USA
  • Tel: 1-858-534-0000
  • Fax: 1-858-534-0000

EaSM Project: Aerosol-Cloud-Earth Feedbacks



People


Principal Investigator
Lynn Russell has conducted measurement and modeling experiments of aerosol indirect effects since 1994 [9, 10]. Her recent work includes using a counter-flow inlet to measure organic and elemental composition of un-activated and activated aerosol particles in cloud. The analyses have characterized many of the key microphysical features of stratocumulus clouds, showing a strong relationship between “accumulation mode” particle number and droplet number, resulting in contributions to three peer-reviewed publications [12, 13, 14]. This work set the stage for showing that these aerosol particles in the eastern Pacific were internally mixed, so that chemical composition played a much more subtle role than particle size in providing cloud condensation nuclei that activated at measured supersaturations [11]. This work led to further studies of aerosols in stratocumulus-topped boundary layers as part of VOCALS-REx [15].

UCSD Investigators
Guang Zhang has been working on convection parameterization and global climate simulation for 20 years. He developed the Zhang-McFarlane convection scheme, which has been used in all versions of the NCAR GCMs since 1995. His recent work uses the NCAR CAM3 and CCSM3 to understand how an improved convection parameterization scheme he developed impacts the simulation of tropical climate and its variability. The project has resulted in 10 peer reviewed journal publications [21-30]. The findings from the project include: 1) Modifications to the Zhang-McFarlane scheme lead to significantly enhanced MJO and improved MJO structures. The interaction between convection, moisture and convergence in the lower troposphere is found to be responsible for the MJO development over the Indian Ocean and the western Pacific in both observations and simulations. 2) The improved Zhang-McFarlane convection scheme is able to eliminate the double ITCZ in boreal summer. The analysis of CCSM3 simulations shows that the when the improved convection scheme is used, the coupled feedbacks among atmospheric convection, large-scale circulation and ocean dynamic heat transport are responsible for the reduction of SST and precipitation biases in the southern ITCZ region.

Art Miller has four recent related to decadal variability: (1) Analysis of Decadal Variability in the North Pacific: Miller and Schneider explored Pacific decadal variability in observations, theoretical models, ocean hindcasts and coupled models. (2) Dynamics of Ocean Climate Changes in the Gulf of Alaska: Miller worked with Di Lorenzo, Capotondi and Alexander on modeling the observed seasonal cycle, transient spin-up and decadal mesoscale eddy and larger-scale variations of the Gulf of Alaska. (3) Decadal coupled ocean-atmosphere interactions in the North Pacific: Miller is working with Schneider to downscale large-scale observed decadal ocean-atmosphere variability over the North Pacific using SCOAR to isolate the portion of the atmospheric response that is due to oceanic feedbacks. (4) VOCALS: Mesoscale Ocean Dynamical Analysis with Synoptic Data Assimilation and Coupled Ocean– Atmosphere Modeling: Ocean data assimilation of the VOCALS cruises is currently being executed along with regional coupled-ocean modeling experiments exploring the sensitivity of atmospheric flows to oceanic SST in the VOCALS domain.

Dan Cayan has directed the NOAA California-Nevada Regional Integrated Sciences and Assessments Center, “The California Applications Program,” from 1999 through present http:// meteora.ucsd.edu/cap/. This multi-investigator, multi-institutional center has provided research and decision support to stakeholders in the region through a wide range of peer-reviewed publications [44-50]. Thrusts of this applied research have included impacts of climate variability and climate change on water resources, wildfire, human health and agriculture. A particular emphasis that was developed involves assisting the State of California in its effort to assess its vulnerability and plan to adapt to climate change, in the midst of other stresses including population growth and land use change.

Richard Somerville has been a team member of CMMAP, the Center for Multiscale Modeling of Atmospheric Processes, an NSF Science and Technology Center, since this center was established in 2006. Somerville served as one of the lead authors for the Working Group 1 report of IPCC in 2007 [16]. Research carried out by Somerville and his graduate student Michael Pritchard with CMMAP support has been reported at many meetings and in two recent papers [17, 18]. In addition, Somerville is an editor of a multi-authored book prepared under CMMAP, The Development of Atmospheric General Circulation Models, now in press at Cambridge University Press [19]. Somerville has also authored and revised a book on the atmosphere for general audiences [20].

David Pierce has extensive experience analyzing model simulations of climate variability, particularly in the North Pacific and western U.S., on timescales associated with ENSO, decadal variability, and secular anthropogenic changes. Pierce and colleagues examined the quality of regional climate model simulations on the western U.S. and other selected locations around the globe, and how to best combine multi-model information into an ensemble simulation [51, 52]. Pierce also was part of a team that examined 50 years of snowpack, temperature, and streamflow records across the western U.S. to quantify the relative effects of anthropogenic climate change and natural climate variability over that period [52-56]. Pierce and colleagues examined various aspects of model validation and low-frequency climate variability over the North Pacific, including the role of sea surface temperatures in the interaction between ENSO and the Pacific Decadal Oscillation, the physical mechanisms of low-frequency climate variability in the North Pacific, and how anthropogenic forcing of the North Pacific might affect the biology there [8, 57-61]. Pierce wrote and operationally maintains the Scripps ENSO forecast system [62].

UCM Investigator
Tony Westerling has carried out research on the analysis and modeling of climate-vegetation- wildfire relationships on seasonal to decadal and longer time scales, including the effects of wildfire on particulate emissions and on ozone production. A particular interest has been to assess the effects of climate variability and change on emissions due to wildfires. His work on wildfire histories and climate in the western U.S. established that forest wildfire activity has increased dramatically in the western US in recent decades, driven by warming and earlier springs.

PNNL Investigators
Steve Ghan has been working on the aerosol indirect effects problem since 1990. He produced the first physically-based parameterization of aerosol activation [1] and was the first to introduce prognostic droplet number in a global model [2]. He also led the development of the modal aerosol lifecycle scheme [31] that will be released with his aerosol activation scheme [5] in CAM5 and CESM1 in June 2010. He used an earlier version of the scheme to estimate direct and indirect effects of anthropogenic aerosol in a global model [32]. He has also recently led the development of the first MMF with cloud-aerosol interactions [7].

Xiaohong Liu developed one of the first ice nucleation parameterizations for GCMs [33] which considers both the homogeneous and heterogeneous nucleation and transition between the two mechanisms. The parameterization was implemented in the NCAR CAM [34] to investigate the impacts of anthropogenic aerosol on ice clouds and climate [35] and on stratospheric water vapor [36]. This ice nucleation parameterization has been adopted in the CAM5 [37] in the NOAA GFDL AM3 [38] and in the NASA GEOS-5 model [39].

Mikhail Ovchinnikov has been engaged in developing, evaluating, and applying models to study microphysics, radiative and aerosol effects in clouds for 20 years. His work includes improvements in model’s physics [40] and numerics [41]. He applied cloud-resolving models to benchmark GCM parameterizations and conducted the first evaluation of MMF using ground- based DOE ARM observations [42]. Recently, he led the project in which a high-resolution cloud model with size-resolved microphysics was applied to study ice formation in Arctic clouds [43] and to investigate aerosol effects on deep convection [43].

NCAR Investigator
Sungsu Park was appointed as a Scientist I at NCAR on 1 January 2009. Sungsu has been working on developing and implementing moist turbulence [6], shallow convection [3] and cloud macrophysics [4] parameterizations for CAM5. He has been doing extensive test and tuning simulations using the suite of new parameterizations.

References


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