NASA-PAIR SITE VISITMay 2002

Modeling the Sun’s Energy Output

Ana Cristina Cadavid Stephen Walton

Department of Physics and AstronomyCalifornia State University, Northridge

Goals

Goal 1: to expose students to a research experience using a large data set

Goal 2: to guide students to re-discover the discrepancy between the models and the satellite measurements of solar irradiance for Cycle 23

Objectives• Students will learn basics about the

Sun • Students will learn about solar

variability, measurements and models• Students will learn MATLAB and

Excel• Students will learn how to obtain solar

data through the Internet• Students will learn how to model data

via linear regression analysis• Students will learn how to conduct a

research project working in groups• Students will prepare a scientific

report and presentation

Course Structure

• After the first meeting, students are organized in groups of 3-5 members

• A field trip to the San Fernando Observatory and three guest speakers during Weeks 1 and 2

• Weeks 1 and 2

The course is structured as a

mixture of lecture and computational

laboratory experiences

• Week 3

Major project

Weeks 1 and 2

Lectures

• Solar Spectral Analysis

• Radiative Transfer

• Solar magnetism and dynamo

theory

• Features: sunspots, faculae

• Total Solar Irradiance (TSI)

• Observations: satellite and

ground based

• Models for TSI

Weeks 1 and 2

Laboratory Experiences

• Learning MATLAB: Image handling, graphics

• Learning Excel: linear regression capabilities

• Internet access to solar databases

• Friday of 2nd week: Mock experience of big project

Weeks 1 and 2Assignments

Both in class and overnight

• Numerical:

Basics of MATLAB and Excel

Download data

Analysis of magnetograms (mask)

Preparation of irradiance data

Linear fit

• Analytical:

Radiative transfer

Dynamo

Week 3

Major Project

• TSI Modeling: One mandatory and several optional components

• Students worked in groups of 3—5

• Groups discovered discrepancy in models when comparing cycle 22 (1986—1996) with cycle 23 (1996—present)

• Presentations made on last day of week

• Written report on last day

• The TSI is modeled as the sum of a basal level, a sunspot contribution, and a facular contribution

• The balance between them determines short (weeks) and long (decade) variability

• Models for cycle 22 (1986—1996) match data extremely well (R=0.9 or more)

• The same models do not match cycle 23 (1996 to present)

• Total Solar Irradiance measured from different satellites

• Data put on the same scale by cross-calibration: the 'composite' record

• Daily digital images in continuum showing sunspots in the photosphere

• Ca II line core images showing faculae in the chromosphere

• An optional third UV component

Evaluation Questionaire

1. Which of the topics in the class did you find most interesting?

• Solar structure, dynamo (5)•  Magnetic fields, sunspots, faculae

(4)•  Solar irradiance (4) • MATLAB, Excel linear regression,

computer applications (4)• Data analysis, image processing model fitting (4)• Project (3)• Solar atmosphere and radiative

transfer• Linear regression and linear algebra• Field Trip

2. Which of the topics in the class did you find least interesting?

 

• Solar atmospheres and radiative transfer. Related first assignment (6)

• MATLAB exercises

• Phenomenology of sunspots

• Data discussion

• Dynamo

 

3. Which topic(s) would you like to have spent more time on?

• Final project (4)• Radiative transfer (to make it

clear) (4)• Dynamo (3)• Basic solar physics, Coronal

Mass Ejections (3)• Solar irradiance (2)• Working with MATLAB (2)• Practice analyzing data • Linear regression • Fractal patterns on the Sun

4. Which topic(s) would you like to have spent less time on?

• Introduction to solar atmosphere and radiative transfer (5)

• Exercises with software, MATLAB problems (4)

• Sunspot and faculae phenomenology

• Dynamo

5. What was your opinion of the final project?

• Interesting (7)• Teaches how to work with real

data (7)• Puts concepts together (6)• Excellent, the best part (5)• Very educational. Learned a lot

(3) • Enjoyed presenting the final

project results (2)• Enjoyed working in groups • Fun• All• Still vague even at the end• More stressful than it should be

6. What advice would you give a future student taking this class?

• Ask lots of questions, take notes, pay attention in class, record the course (6)

• Be patient. In the beginning there is confusion but things come together (5)

• Work hard (4)• Enjoy it (4)• Read about the Sun ahead of time (4)• Have previous knowledge of statistics• Have previous knowledge of MATLAB

and Excel• Use your group. Explain to each other • Did not learn as much as the effort

invested

The Evaluation Forms used at California State University Northridge were used to get thestudent evaluation of faculty. The scores rangefrom not at all descriptive (1), to verydescriptive (5), and a non-applicable option(N/A). There were 24 responses. W=Walton C=Cadavid1. The professor demonstrated knowledge of the

field well. 4.9 0.3 (W) 4.9 0.3 (C)  2. The professor organized the course well.

4.9 0.2 (W) 4.9 0.3 (C)

3. The professor prepared well for class sessions. 5 (W) 4.9 0.3 (C)4. The professor communicated the knowledge

effectively. 4.6 0.7 (W) 4.8 0.4 (C) 

5. The professor encouraged questions and discussion by students. 4.9 0.2 (W) 5 (C)

6. Exams and other requirements are adequate for fair evaluation

of student achievement 4.5 0.8 (W) 4.7 0.5 (C)7. The professor was helpful in case

difficulties were encountered in he course

4.9 0.2 (W) 4.9 0.2 (C)8. The professor was punctual in

meeting and conducting classes. 5 (W) 5 (C)

9. The professor was available to me during office hours. 5 (W) 5 (C)

10. The overall performance of the professor in the course was excellent 4.9 0.2 (W) 5 (C)

Follow up: Spring 2001

• Students received tutorial on Fourier and Wavelet analysis of time series:

Theory and numerical analysis using MATLAB

(Cadavid, Shubin, Walton)

• Speaker series on topics in Astronomy

Feb 13 Matt Penn (CSUN) Solar Coronal Magnetic Fields

Feb 20 Mike Jura (UCLA) Infrared Observations of pre-supernova starsMar 6 Phil Goode (BBSO/NJIT)

Solar Physics at Big Bear Solar ObservatoryMar 13 Kim Griest (UCSD) Dark Matter in the UniverseMar 20 James Colbert (UCLA)

Searching the High Redshift UniverseMar 27 Angelle Tanner (UCLA)

Journey to the Center of the GalaxyApr 3 David B. Cline (UCLA)

Supernova Type II Dynamics and the Neutrino Mass

Apr 17 Shoko SakaiMeasuring the Expansion Rate of the Universe using the Hubble Space Telescope

Apr 24 Peter Gallagher (BBSO/OVSA) Solar Radio Astronomy

May 8 Albert Lazzarini (LIGO) Gravitational Waves

Lessons Learned

• Present a global overview the first day

• Simplify the radiative transfer presentation

• Tie the radiative transfer more closely to the TSI problem

• Different backgrounds of students a challenge: perhaps ‘student leaders’ the first week?

• Additional project options