National Aeronautics and Space Administration

Living With A Star

Targeted Research and Technology

An Empirical Solar Wind Forecast Model From The Chromosphere

ROSES ID: NNH06ZDA001N      Selection Year: 2007      

Program Element: Independent Investigation

Principal Investigator: Robert Leamon

Affiliation(s): Adnet Systems Inc.

Project Member(s):
McIntosh, Scott William Co-I National Center for Atmospheric Research


The distinction between the chromosphere, transition region and corona

is entirely artificial; the same magnetic field permeates the whole

solar atmosphere and heliosphere and as such forms one complex physical

system. However, we propose that it is exactly the magnetic field, or,

more precisely, the balance of open and closed magnetic structures on

local (supergranular, ~20Mm) and global (coronal, >~100Mm) in the

photosphere and chromosphere that defines the thermodynamic properties

of coronal holes, providing a realistic basis to explore the support and

sustenance of the kinetic solar wind. The chromosphere has been largely

overlooked as a driving source of the solar wind despite its richness in

emission and structure, largely due to the aforementioned complexity.

Recently, we [McIntosh and Leamon ApJL, 624, 117, 2005] correlated the

inferred topography of the solar chromospheric plasma with in situ solar

wind velocity and composition data measured at 1 AU. Specifically, the

measured separation in height of the TRACE 1600 Ö and 1700 Ö UV band pass

filters correlate very strongly with solar wind velocity and inversely

with the ratio of ionic oxygen (O7+/O6+) densities. These correlations

suggest that the structure of the solar wind is rooted deeper in the

solar atmosphere than has been previously considered and form the basis

of an empirical solar wind model.

The proposed model provides a near continuous range of solar wind speeds

and composition quantities from the structure of the chromosphere and is

more precise than the old "fast/ coronal hole or slow/streamer belt"

estimate. By means of a coherent, planned and extended observation

campaign of the solar chromosphere at disk center, we propose to extend

our current results to better understand the nature of the solar wind,

its sources and composition. One specific end goal for this three- year

pro ject is to develop a (near) real-time solar wind propagation model,

with chromospheric topography as input. This useful tool for predictive

space weather will have great impact in 2008 when we can replace the

intermittent TRACE data with the full-disk, full-time chromospheric

topography measurements of the first LWS mission, the Solar Dynamics


This proposal addresses Strategic Sub-goal 3B: "Understand the Sun and

its effects on Earth and the solar system," specifically NASA Science

Outcomes 3B1 and 3B3. However, our improved physical understanding will

yield a better observationally driven, physically based ability, to

predict space weather on its own and as part of a community based

collaborative model within the LWS program.


Performance YearReferenceInvestigation TypeActions
1Leamon, R. J.; McIntosh, S. W.; (2007), Empirical Sola...
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1Leamon, Robert J.; McIntosh, Scott W.; (2008), Could We...
not set

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