Wednesday, September 24, 2008

Hunting for Sprites

Here are the two incidents of sprites that I captured last Friday (Sept. 19).





I had never thought I could observe sprites at home in front of a computer! The Danish National space Institute installed two camera observing systems at two locations – one on Pic Du Midi in Pyrenees and one on Monte Corona in Corsica. The camera systems can be operated remotely as long as there is a computer and internet connection, and they are controlled via the Danish National Space Institute. The Institute hosts a site where people can view real time images and maps of thunderstorm locations from a satellite. I signed up to be part of a group of interested scientists who would like to participate in the 2008 EuroSprite Observational campaign.

My first observation period started on Monday September 15 through Sunday September 22. In the first two days of my observations, there were not many lightning activities. On the 3rd day (Wednesday), there was a huge thunderstorm system. I spent a few hours on my laptop, following the lightning activity and pointing the cameras to where positive lightning occurred. On Thursday, I accidentally looked at a page in the EuroSprite manual and noticed that I forgot to key in an important command that would be needed to trigger images. I felt like a goof. It is like sitting behind the wheel stepping on gas and thought I was driving while the engine was not even turned on. Thursday was not good for hunting because the cameras on Pic Du Midi were not cooperating and the cameras on Monte Corona were too far away from the thunderstorm. Friday was the only good day for sprite hunting. It was exhilarating to see the sprites that I captured though I was exhausted after hours in front of my laptop. So during the whole week, I only captured two incidents of sprites with the cameras on Monte Corona.

Though the pictures were not close-up shots (I’m a new user so I still have lots to learn how to get a better shot), I’m pleased to have at least captured something. It was fun and interesting. This could be a great project for my students!


Wednesday, September 10, 2008

LITEs

Below is an extract from the article “On the Lightning Induced Transient Emissions in the OH Airglow Layer Observed by ISUAL Instrument Onboard FORMOSAT-II Satellite” by Tai-Yin Huang1, C. Y. Chiang2, C. L. Kuo3, A. B. Chen2, H. T. Su2, and R. R. Hsu2. Click here http://www.lv.psu.edu/tuh4/LITEs. for the full article. For article citation, please use http://taiyin.blogspot.com/2008/09/LITEs

1. Department of Physics, The Pennsylvania State University Lehigh Valley, Fogelsville, PA 18051, USA
2. Physics Department, Cheng Kung University, Tainan, Taiwan
3. Institute of Space Science, National Central University, Chung-Li, Taiwan

Abstract

Observations by The Imager of Sprites and Upper Atmospheric Lightning (ISUAL) broadband filter onboard the FORMOSAT-II satellite have sometimes shown a transient brightness in or below the OH airglow layer accompanied by lightning activity. The ISUAL team conducted a nine-day campaign in January 2007 with some of the observations devoted exclusively to capturing lightning-induced transient emissions (LITEs) with a narrowband filter for such investigations. The observations of lightning-induced intensity enhancements in the OH airglow layer with a narrowband filter presented here are the first and only narrowband observations currently in existence. Our analysis of the narrow-band observations shows that there is a significant intensity increase (87.5%) in the OH airglow layer when there is lightning activity and a residual intensity increase (25%) in post lightning activity. Three mechanisms are proposed to explain the airglow enhancements.

This image shows an intensity enhancement in the OH airglow induced by lightning captured by a broadband filter (623-750 nm).




This image shows an intensity enhancement in OH airglow induced by lightning captured by a narrowband filter centered at 630 nm.


We propose three mechanisms to explain the lightning-induced transient emissions (LITEs) in the OH airglow.



ISUAL’s broadband filter has also captured LITEs below the OH airglow layer like the one below.


Monday, September 1, 2008

Memorable Encounters

I have attended quite a few meetings over the years. Most of the meetings were uneventful except two memorable encounters that stood out in my mind. Below are the two interesting encounters.

The first one occurred during the time I went for a job interview for a postdoctoral position after I finished my job in Canada and was a visiting scientist at University of Cincinnati. As part of the interview, I gave a presentation about some of the work I did. It was about the mesospheric temperature inversion layer at around 85-90 km altitude. The phenomenon of the observed mesospheric temperature inversion layer is that temperature increased 30 to 40 K in a few hours in that altitude range. We proposed that the formation of the inversion layer observed during the ALOHA-93 campaign was due to the gravity wave-critical layer interaction modulated by the descending tidal motion. The mechanism was considered new, and some people had a hard time accepting what we proposed at that time. People who opposed our mechanism preferred tides over gravity waves.

One of the people in the audience preferred tidal explanations. He was a well respected senior scientist in the field of Aeronomy. When I got into the mechanism, he stopped me and asked questions. So I answered the questions with supporting materials that I had prepared. He was not satisfied and asked more questions. I showed more supporting materials and answered that there were data that could not be explained by tides along. Gravity waves had to play an important role in triggering the formation of the temperature inversion layer. We went back and forth with questions and answers. We were like locking horns with each other in the tug-of-war. He insisted that his views were right, while I did not back down and insisted that mine were right as well. The whole debate lasted for quite some time. Finally, the host came to our rescue. He stood up and asked us to discuss it after the presentation. During the whole time while I was defending my views, I cringed inside. The presentation was part of the job interview. It is common sense that people should put on their best behavior and leave a good impression at a time like this. I could have pretended to agree with him just to be amiable, but I couldn’t. I felt that the tidal explanation could not explain the observations with satisfaction and that the gravity wave explanation could do it better.

I flew back to Cincinnati after the interview. When I went to see my thesis advisor, he asked me how the interview went. I relayed the whole thing to him. He smiled (probably because he knew me well, and knew that I would go into debate with people if I thought my views were right) and said the scientist called him the other day to tell him that I did not listen to him (the scientist). Luckily, the host hired me anyway. Our mechanism was getting acceptance. Years later, the scientist wrote a review paper on temperature inversion layers. He very graciously included my work and discussed it in his paper.

Another memorable encounter is not as professional as the previous one. It occurred about two years ago. I attended a meeting and presented a poster on my recent research in the field of lightning. I was new to that field. I got interested in lightning after I attended a NATO-sponsored workshop on lightning and transient luminous events (sprites, elves, etc) in 2004. I wanted to know if lightning could have any effect on the chemical reactions in the mesosphere and lower thermosphere. I utilized my background in Aeronomy and did research in Lightning. I did some simulations of OH nightglow emissions in the event of sprites.

During the poster session, I stood in front of my poster. A junior scientist came to look at my poster and then he asked me a few questions. A senior scientist walked toward our direction and stopped at where we were. He didn’t look friendly. I did not know that person. Like I said, I was new to this field, so I don’t think many people in the field of lightning knew about my research background. The senior scientist looked at the junior scientist and asked him questions. At first I thought the senior was asking the junior a question because his face was toward the junior one. But after I heard the question, I thought to myself “He was asking a question about my work! Why didn’t he ask me? Why did he ask a person who was like him, just a viewer of my poster???” The junior one apparently thought the same. He apologetically looked at me and asked me if I could answer the question. So I explained nicely about my work and answered his question. However, the senior rarely looked at me when I was explaining things to him. During my explanation to him, he just looked at the junior without the courteous look toward my direction, and he appeared to be not approving what I said. After I finished, he said something to show that my answer was not reaching his ears. He then said a few more things to the junior that my work was wrong. He seemed to be quite upset about my work or me. I don’t know. Like I said, I did not even know him, and I don’t think he knew me. I don’t know why he should get upset about me or about my work. Come to think of it, here is an interesting observation: People in the field of Aeronomy generally said nice things to me about this work, while people in Lightning tended to trash it.

Anyway, the whole scenario prolonged for some time. It was actually a very funny situation. The three of us stood there forming an equal lateral triangle. The senior looked and talked only to the junior. The junior looked rather uncomfortable in his position, and shifted his gaze between me and the senior. I was feeling upset inside but tried to maintain civil. I have never encountered people this rude and this unprofessional at professional gatherings. If he has any questions about my work, he should just ask me directly. But no, instead, he treated me as if I was not there. I don’t know why he acted that way, but that kind of behavior was really uncalled for, nor was it justified. No one should take this kind of attitude from anybody even if he is someone like Einstein, and to be honest he is nowhere near Einstein. The only reason that I did not give him a piece of my mind at that time was out of the respect for his seniority in his age. Come to think of it, I really should stop him and tell him that we need to discuss his attitude before we discuss my work. Further, even if my work was wrong, which it is not, he could have discussed it with me with a more civil, professional attitude. To be honest, his action is simply beyond my comprehension. At the next meeting, he walked past by a few times, but he did not stop by my poster. I guess during our previous encounter I was sending out the message that I am not someone who can be easily intimidated or harassed. It is wise of him to stay away from me. The whole thing was really hilarious and absurd. I hope that person can realize that too.

Here is another interesting observation. Most scientists tend to think their views are right. If someone holds a different view from theirs, that person must be in the wrong because they feel and think that they are always right therefore that person must be wrong. It seems that the more senior you are the more adamant you become in believing you cannot be no wrong. I admit, I am one of them. Well, at least, I’ve recognized my flaw and will always remind myself to be critical and yet open-minded. One thing is for sure, I certainly won’t treat people bad simply because we hold different views!