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Goal 1, Priority 1: Exploring Atmospheric, Earth System, and Solar Processes, Variability and Change

Exploring Atmospheric, Earth System, and Solar Processes, Variability and Change

Developing a better understanding of atmospheric, Earth system, and solar processes, as well as the variability and change associated with these processes, is critical to achieving NCAR's first strategic goal. Exploration of these “Priority 1” areas focuses on three key activities: simulating the Earth system’s natural variability, investigating the Sun’s magnetic-flux eruptions, and understanding effects of gravity waves, including related interactions between the upper troposphere and lower stratosphere.

FY2007 Accomplishments

Click to enlarge. MHD Turbulence structures The scientific leadership of NCAR recognized early on that to understand the dynamics of the atmosphere and oceans, the Sun, and solar-terrestrial interactions, it is essential to investigate relevant turbulent processes at a fundamental level. The Institute for Mathematics Applied to Geosciences (IMAGe), part of CISL, shoulders this task, bringing mathematical models and tools to bear on understanding fundamental problems in the geosciences.

IMAGe’s Turbulence Numerics Team, in collaboration with faculty from universities around the world, has pursued a broad range of research topics. An FY2007 highlight was the creation of a large magnetohydrodynamic (MHD) simulation at a resolution of 15363. This is the largest numerical experiment completed of this type, and it illustrates for the first time the self-similar growth of current and vorticity maxima by the formation, rolling, and stretching of current and vorticity sheets. This study has important applications to solar physics, astrophysics, and fusion studies. Other results stemming from this research include:

  • Mathematical modeling of small scales in turbulent flows
  • Adaptive Mesh Refinement for two-dimensional incompressible turbulent flows with pressure
  • Scaling laws in turbulent flows, and a possible origin of self-similar behavior
  • The origin of magnetic fields: extension to spherical geometry
  • Generalization of an inviscid model of dissipative flows

Click to enlarge. Annual air temperature simulated by the NCAR Community Climate System Model (CCSM3) for four different past time periods: a warm period approximately 250 Mya – the Permian-Triassic, a period of abrupt warming approximately 55 Mya – the Paleocene-Eocene Thermal Maximum, a glacial period approximately 21 kya - the Last Glacial Maximum, and a cold period approximately 500 years ago - the Little Ice Age. This image illustrates the large range of climates under natural forcings. A comparison of the CCSM3 simulations with geologic data confirms that this model captures the magnitudes of change about right justifying its use of future climate projections. Modeling efforts are also fundamental for achieving NCAR’s mission to support the wider community and to enhance understanding of atmospheric, Earth system, and solar processes. NCAR climate, weather, and solar process models are used to study past, present and future natural variability of the Earth system. Among these modeling efforts, ESSL scientists are exploring changes over many time periods–including the distant geologic past, when continental configurations, surface temperature, latitudinal gradients, and levels of atmospheric carbon dioxide, methane, and other greenhouse gases were significantly different. Simulations have covered a range of applications, including the last millennium, the Holocene El Niño-Southern Oscillation (ENSO), and the Last Glacial Maximum, among other periods.

These simulations highlight the importance of considering atmosphere, ocean, land surface, and sea ice feedbacks to compare the magnitude of past climate change to changes in past forcings. These runs also provide a benchmark for the Community Climate System Model (CCSM), and allow testing of various hypotheses of mechanisms to explain proxy records of past climate change. The ESSL Laboratory Annual Report (LAR) provides exciting details on the paleoclimate modeling efforts.

Click to enlarge. MOZART-4 has been used to calculate the impact of emissions from a specific region on the regional O3 concentrations. When it comes to developing chemical weather forecasting, ESSL’s Atmospheric Chemistry Division (ACD) has expertise in all of the required research areas–satellite remote sensing, field campaign measurements, global and regional modeling, and data assimilation. In FY2007, ACD’s work in this area centered on refining assimilation of carbon monoxide measurements from MOPITT–a remote sensing instrument flying on NASA's Terra spacecraft–into MOZART-3 (Model for Ozone and Related chemical Tracers) and the Community Atmosphere Model (CAM-Chem), two global chemistry transport models. Recent modeling experiments under the direction of the U.N. Task Force on Hemispheric Transport of Air Pollution also allowed CAM-Chem to be evaluated against other chemistry transport models, and contributed to an international assessment of the importance of intercontinental transport to air quality.

Modeling the Earth’s upper atmosphere and beyond falls into the domain of scientists in ESSL's High Altitude Observatory (HAO). In FY2007, these scientists continued advancing human understanding of the 11-year solar cycle and related phenomena by investigating the hemispherical asymmetry of solar active regions. This work is important for determining which solar disturbances are most "geoeffective" –that is, disturbances that impact the Earth’s system and human activities. Click to enlarge. The top two rows of images show two MHD simulations of the eruption of a twisted flux rope in the coronal triggered by the onset of the torus instability where the erupting flux rope mainly shows an outward expansion (1st row of images), and the onset of the kink instability where the flux rope shows significant rotation as it erupts (2nd row of images). In addition, HAO researchers developed 3D MHD simulations of twisted flux tubes emerging into the corona, which have led to significant advances in understanding precursor structures and initiation mechanisms for coronal mass ejections (CMEs). ESSL’s LAR contains details on these and related modeling efforts.

HAO is also collaborating with Dartmouth College, Boston University, University of Maryland, and Rice University scientists to form a core component of the physics-based numerical modeling chain being developed at NSF's Center for Integrated Spaceweather Modeling (CISM). Version 2.0 of the Coupled Magnetosphere Ionosphere Thermosphere (CMIT) model was released to Boston University for validation in FY2007, and is being used in coupling studies to describe geomagnetic effects on the ionosphere. CMIT produces a more detailed rendition of the response to geomagnetic variations caused by space weather events, and also includes NCAR's Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIE-GCM) v.1.8.

Modeling efforts, both within the community and at NCAR require robust computing capabilities, and significant levels of computation parallelism are imperative to address the most challenging scientific problems. However, computing at such levels reduces the computing time available to other users. CISL responded to this challenge in FY2007 by continuing to provide traditional capacity computing to significant numbers of smaller scientific projects, which are also important to understanding the Earth system, while developing methods to provide capability computing resources, access, and support for large projects. A limited number of breakthrough science projects were selected from the geoscience community and awarded between 170,000 and 585,000 CPU hours on blueice, the new IBM POWER5+ cluster.

In addition to creating models and ensuring adequate capacity to run the models, observational data are critical to verifying model output. But, when it comes to modeling solar events, these data are limited, to say the least. However, the September 2006 launch of a joint Japan/US/UK Hinode solar physics mission from southern Japan will improve availability of such data. Already, spectacular views of the Sun, with unprecedented angular resolution and quantitative detail, are available. HAO and Lockheed Martin Solar and Astrophysics Laboratory collaborated to build Hinode’s enormously successful Spectro-Polarimeter–an instrument that is providing new understanding of the solar atmosphere’s magnetic fields.

Similarly, observational data from the extratropical upper troposphere/lower stratosphere (UTLS) region is limited. Led by NCAR scientists, analysis of data collected during the Stratosphere-Troposphere Analyses of Regional Transport (START) experiment began in FY2007. This experiment looked at transport processes impacting the chemical-microphysical distribution of this region. Results of this analysis suggest that, if the extratropical tropopause is treated as a transition layer, the thickness of the layer appears to have strong spatial variation.

Click to enlarge & see full caption. Time-mean salinity distributions (in psu) at a depth of 1100 m in the North Atlantic. ESSL scientists are involved in the Climate Variability and Predictability (CLIVAR) initiative, which investigates climate variability and predictability on time-scales of months to decades, and looks at effects of anthropogenic forcing on the climate system. Within ESSL’s Climate and Global Dynamics (CGD) division, major ocean model developments are proceeding under the auspices of CLIVAR’s Climate Process Teams (CPT) on both gravity current entrainment and eddy mixed layer interaction.

Lastly, among NCAR’s FY2007 publication highlights is a landmark paper by Britt Stephens et al. published in Science that puts a new perspective on the “missing” carbon sink, greatly diminishing the apparent discrepancy between overall emissions and the rate of increase of atmospheric CO2. Another important paper, co-authored by NCAR’s Peter Thornton and included in Global Biogeochemical Cycles, shows that the response of net land carbon fluxes to changes in atmospheric CO2 concentration, temperature, and precipitation depends strongly on coupling of terrestrial carbon and nitrogen cycles.

FY2008 Plans for Strategic Priority 1

Many of NCAR’s FY2008 plans focus on modeling. To reach new levels of understanding about the Earth system, CISL will continue providing access for leading-edge scientific investigations that require large portions of supercomputing power. Support will be provided as needed and requested for:

  1. field projects that involve NCAR and/or university scientists,
  2. real-time, high-resolution weather forecasting of convective systems during periods of intense activity, and
  3. selected NCAR Capability Computing (NCC) and University Capability Computing (UCC) Earth science projects.

A few of NCAR’s model-centric efforts in FY2008 include:

  • Continued analysis of the large MHD experiments by IMAGe, with emphasis on flows occurring under more complex settings, including interactions of eddies and waves arising from the incorporation of rotation and stratification.
  • To generate observed data for solar and geospace modeling efforts, solar physicists at NCAR, the University of Hawaii, and the University of Michigan are working with HAO’s instrumentation group to design a new, large coronagraph, the Coronal Solar Magnetism Observatory (COSMO).
  • The Coupled Magnetosphere-Ionosphere-Thermosphere (CMIT) will be upgraded, and work will commence on developing the option of using a high-resolution version of the NCAR Thermosphere-Ionosphere-Mesosphere-Electrodynamics General Circulation Model (TIME-GCM) in place of the current TIE-GCM as the thermosphere-ionosphere portion of CMIT. The Global Ionosphere-Plasmasphere (GIP) model, developed for use with the TIE-GCM, will be tested to see how well it improves representation of the ionosphere. And, studies of global change in the thermosphere will be advanced by carrying out simulations with the three-dimensional TIME-GCM under different scenarios of trace-gas concentrations in the stratosphere.
  • Using a CCSM-like management structure, NCAR and our scientific partners will collaborate on developing a community Earth System Model (ESM) that will account for interactions between the physical climate system, the biogeochemical system, and the social system. Achieving this goal requires two parallel approaches–creating a roadmap for developing a next-generation “Weather Climate Model,” and crafting a model of intermediate complexity and low spatial resolution to capture increased numbers of processes, couplings and feedbacks, and accounts for relations between natural and social processes.
  • Work will begin in FY2008 on a detailed chemical weather case study using data from the MIRAGE (Megacities Impacts on Regional and Global Environments) and INTEX-B (Intercontinental Chemical Transport Experiment) spring 2006 period. A nested regional model simulation concentrating on Mexico and parts of the INTEX-B Pacific region also will be performed using the Weather Research & Forecasting (WRF)-Chem model. This will be followed by an assimilation of available satellite data sets to impose constraints on the modeled chemical fields, which can be evaluated in comparison with actual field measurements.
  • In the next year, emphasis will be placed on use of available High Resolution Dynamics Limb Sounder (HIRDLS) data for scientific studies, especially of gravity waves, and UTLS processes, notably stratosphere-troposphere exchange.
  • CGD researchers will work on adapting the Mediterranean overflow scheme to the Denmark Strait and Faroe Bank Channel Overflows–proper representations are believed to have significant climate impacts–and implement a new submesoscale parameterization on behalf of two CLIVAR CPTs.

Related Lab Annual Report Sections:
Goal 1, Priority 1