Question
Hi Gary,
 Thank you for your previous respond and suggestion. I'm afraid you may have gotten the wrong idea. As part of our research, we are required to ask experts and professors about our topic in order to get feedbacks, suggestions and ideas on how to improve our project.
 We have core samples not only from the Czech Republic but also around the state of Connecticut. This will allow us to compare the 2 places because there is a good amount of distant between the US and the Czech Republic.
 You also mentioned, "Just because there was also higher sunspot activity does not mean the sunspots were the cause." We did a lot of research on sunspots and we've out that they greatly affect our climate. For much of the 17th and 18th century during the Maunder Minimum, the number of sunspots were less than 5 per year, which caused a global "mini ice age" There were proven facts that this happened, unfortunately, our core samples only go back 100 years. In the last century, the number of sunspots increased and we are experiencing a warmer period comparing to the past.
  From 1988-1992, the amount of sunspots activity averaged out to be about 120 per year, which is a lot of sunspots during the 5 year period. Then, we looked at our core samples from 1998 and 2002 and noticed that there is a relationship between the two. Near the bark of the tree (not next to the bark but about 3 cm away), there were about 10-12 rings that are very narrowly packed with one another but then as the rings get closer to the bark, the rings became wider. This corespond to the sunspots data. Our question to you is that how can we scientificly prove the 5 year period when the rings were narrowly packed together, that it was from 1988-1992 if we already know the age of the tree and when it was planted and when the core was taken.
  Once again, we appreciate you taking your time to answer our questions and we applogize for any misunderstand. We hope that our extending explanation of our project help you in answering our questions.
  Thank you,
  Bieu
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Followup To
Question -
My partner and I are 11th graders and we are workin together on a science fair project on "How does sunspots affect local climate?" by looking at tree rings. A professor from NH University provided us with about 80 core samples of Norway Sprunes from the Czech Republic that were collected in 1998 and 2002. The tree cores from 1998 were above 50 years old and the samples from 2002 were younger than 50 years old. We determined the age of each tree by using a simple equation we found online.
1.After measuring the DBH and obtaining a core sample Divide the DBH by 2 to find the radius of the tree.
2.Measure the length of the core sample (cm).
3.Divide the length by the number of rings to determine the annual growth rate of the tree.
4.Divide the radius (cm) by the annual growth rate to calculate the age of the tree.

I was wondering if you know how we can determine a specific period of time by looking at the tree rings. For example, sunspots activity were above 90 per year ten years ago, and supposedly we can tell that by looking at the rings. When the rings are narrowly packed together, they tend to tell us that in those years, the conditions were dry and hot because sunspots appear more regularly, which affected the climate by increasing the temperature therefore the trees didn't get the amount of water needed. The tree rings that were a bit wider showed us that the sunspots didn't appear as often during those years, which allow the trees to receive enough water needed resulting in wider rings.

Therefore, we would appreciate it if you can show us how to determine a specific period of time on the tree and if you have any additional information that we could use, please include.

         Thank you very much
         Bieu
Answer -
Bieu,

First , I do not do homework for students.

Now that I have said that let me offer an opinion.  I do not believe you can make the statement that the environment becomes hot and dry during periods of higher sunspot activity.  If this were the case we would experience world-wide dry and hot conditions and this is just not the case.  

You are right concerning the width of tree rings do correspond to the local environment where that tree grew.  Just because there was also higher sunspot activity does not mean the sunspots were the cause.  

I am afraid you can not prove the relationship between sunspot activity and width of tree rings.

Good luck

Gary

Answer
I do not think you can prove your hypothesis.  The Earth is 4+ billion years old and has been exposed to sunspot activity for this period.  We have only been keeping records for 100+ years.  You are trying to link sunspot activity with environmental data for a 5 year period, out of 4+ billion years, without regard to any natural cycle that may be in play.  What if we are in a 10,000 year cycle?

You may suggest there is a link but you can in no way prove it no matter what the 5 year data says.

Good luck