I'm very interesting in tracking team mood. We track ours daily (using https://moraleapp.com). Here is a graph of my team (10 devs) mood over the past six months or so:
What are you, middle manager, going to do about it?!
Just kidding, but I've had bosses in the past who would notice something like that, and attempt to correct by sending an email out suggesting that folks answer the survey with more happiness.
Well-intentioned or not on your part, I would quit my company if they required me to input my opinions into such a tool. With only 10 devs, it is instantly possible to match any downward trend to a specific individual based on keen observation, and then penalize (no raise, no promotion) or even fire/lay off that person for not "fitting the company's core values".
Because of the possibility for abuse, chances are high that some/many of the inputs are pure bullshit anyway - people saying they're happy when they're downright miserable, out of fear of being scoped out if they log negative results.
Just another management PR stunt so they can gloat about how happy their employees are, when the results may be fabricated. Perhaps this would work in a small company where downward trends in happiness result in immediate changes based on employee suggestions. For every medium and large sized company I've worked for, this would just be another manipulative game pushed onto employees by management who will never implement any real change but can show the CEO ridiculous charts about how "happy" the employees are.
tldr; Management loves to show off reports like these, but the values input are often meaningless and only serve to antagonize employees rather than help.
http://i.imgur.com/Pxla7fl.png (you might notice we had a really bad day in April, but quickly recovered)