posted 02-23-2003 09:28 PM            

It was you that provided the link to the NASA site that provides a modeling capability for the prediction of persistent contrails...partially developed by "The Esteemed" Dr. Patrick Minnis.

This site even maintains an archive of past atmospheric conditions so it is possible to assess historical conditions.

Using this site I was unable to provide input parameters that would account for the dramatic differences observed in the sky of the San Francisco Bay Area between Friday, February 21st and Saturday February 22nd.

It was my opinion that you presented this site as a vehicle to determine whether atmospheric conditions were favorable to contrail persistence.

When asked to provide an example, you backed off and basically said that it is worthless.

As I've said before, you can't have it both ways.

Given that air traffic over major metropolitan areas is a relative constant, the specific atmospheric conditions that produce persistent contrails one day, should do so again when comparable conditions ARE MEASURED.

This is science.

If this is not reproducible, it is reasonable to question why.

And it is for this reason that those who have studied and examined this issue feel that what we are seeing in SOME persistent contrails is not simply exhaust ice crystals.

posted 02-23-2003 11:23 PM            

I believe the point I was making when I gave you the link was the part about how the RUC model has a dry bias (you posted MAPS sounding data which is derived from the RUC and I did not want you to think that a model derived sounding is gospel) and that the output on the website may not be totally accurate. That does not make the site useless however. One must use numerical models as tools and not answers.

Here is a quote from that site, BTW:

"The relative humidity data from the RUC 40km model are suspect since 18 April, 2002. Therefore, all contrail forecasts since April 18, 2002 are suspect."

continuing on:
"To obtain a better estimate of potential contrail formation, examine the 'Individual level (mb)' results. Select a pressure value between 200 and 250 mb for the best estimate. Relative humidity values above 80% are good indicators of contrails in the new RUC data. You can use any pressure level , but the large values may be too warm for contrail formation."

Based on the(MAPS) sounding you posted, I thought it looked like a weak/marginal atmosphere for persistent contrails on the 21st. However, I went back on looked at the printed upper air maps we keep at my office and the dewpoint depressions at 250mb were about 8C over OAK at 1200 GMT and this is probaly within the error of the humidity sensor that measured it. From what I've seen of "real" data, I'd say, so far, it was not the most "classic" environment for persistent contrails. Unfortunately, ne of the problems I have is that our database time purges and if I am not here soon after I hear about a case, I don't get to look at all the info I'd like. When you have another day like the 21st, please email me (Not everyone. Just ST please) and I will look at it and give you my take on it. As I have told Lulu, I don't have an agenda but I want to be fair about this thing. If there is something fishy, I will be the first one to admit it. AND if it conclude that there is nothing fishy, I will tell you that too.

>>As I've said before, you can't have it both ways.<<

I agree and I am not asking for it.

>>Given that air traffic over major metropolitan areas is a relative constant, the specific atmospheric conditions that produce persistent contrails one day, should do so again when comparable conditions ARE MEASURED.

This is science.

If this is not reproducible, it is reasonable to question why.<<

Absolutely true. I agree 100%

>>DO you GET IT ?<<

I don't think I ever missed, but yes.

posted 02-24-2003 09:22 PM            

Let's consider our points of agreement:

You state, "Based on the(MAPS) sounding you posted, I thought it looked like a weak/marginal atmosphere for persistent contrails on the 21st."

Exactly what I thought, yet there they were, horizon-to-horizon contrails that persisted for hours and were the most dramatic for months!

You say, "From what I've seen of "real" data, I'd say, so far, it was not the most "classic" environment for persistent contrails. ".

Quite an understatement, but once again, we are in agreement.

You post a link to the NASA Contrail Formation Forecast, developed by "The ESteemed" Dr. Patrick Minnis theoretically as an aid to understanding why contrails would form that day.

I check out the site, make entries, and cannot get anything to come up that would indicate that persistent contrails should have formed that day in the SAn Francisco Bay Area.

When I ask you to provide input parameters that would justify such formation, you feed me back the site disclaimer, " The relative humidity data from the RUC 40km model are suspect since 18 April, 2002. Therefore, all contrail forecasts since April 18, 2002 are suspect."

Well, isn't that special. What we have here is a NASA Contrail Formation Forecast web site for which all output is suspect and unreliable.

Kinda puts this in the ranks of the $500 plastic toilet seat doesn't it? You have to wonder how much taxpayer money was invested into this project? ... and the return on that investment?

Or am I missing something?

Also, I hope you have noticed, that NO OTHER , what shall we politely call them, hummm, ChemTrails skeptics, have bothered to address the NOAA and NASA data presented on this thread.

Too hot to handle?

Maybe "The Esteemed" Dr. Patrick Minnis' "acquaintance" at NASA, CANEX could clear up this situation.

posted 02-24-2003 11:28 PM            

Yep. However:

>>The relative humidity data from the RUC 40km model are suspect since 18 April, 2002. Therefore, all contrail forecasts since April 18, 2002 are suspect."<<

The RUC has a dry bias and the MAPS soundings are based on the RUC so I don't give the MAPS data much credit for contrail prediction unless a "true" expert can give me cause.

>>You say, "From what I've seen of "real" data, I'd say, so far, it was not the most "classic" environment for persistent contrails. ".<<

This is still my opinion but like I said, the RH values looked close or inside the error range of the humidity sensor. What I've been reading of Dr Minnis's work, there are a lot of factors to consider besides RH. The NASA site even talks about engine efficiency as a factor, but who the heck knows what the efficience of all those different engines are. Not this guy.

I will say this. If I see a case where the atmosphere is bone dry. Ie, no clouds and dewpoint depressions of 15+ deg C through the entire sounding (based on measured data. Not models) and there are still persistent contrails, I will personally write Dr. Minnis to see if he will look at it because I will be stumped (not too uncommon for a weather forecaster ).

>>Well, isn't that special. What we have here is a NASA Contrail Formation Forecast web site for which all output is suspect and unreliable.

Kinda puts this in the ranks of the $500 plastic toilet seat doesn't it? You have to wonder how much taxpayer money was invested into this project? ... and the return on that investment?

Or am I missing something?<<

I understand what you are saying: The NASA site is not totally useless though. You must realize that this model, like all models have limitations. They are tools, not answers although some of the forecasters I've been around treat them that way.

Later,

posted 02-26-2003 12:32 AM            

FK, claims to be "operations meteorologist" who makes his living forecasting weather.

As far as our atmospheric conditions go, especially with respect to "persistent contrails" FK assures us that, "If there is something fishy, I will be the first one to admit it."

Apparently this professional meteoroligist hasn't witnessed ANYTHING yet that appears to him to be "fishy".

He does admit that conditions in the SF Bay Area were "a weak/marginal atmosphere for persistent contrails".

Nevertheless, this doesn't rise to his professional criteria for "fishy".

What he now says is this, "If I see a case where the atmosphere is bone dry. Ie, no clouds and dewpoint depressions of 15+ deg C through the entire sounding (based on measured data. Not models) and there are still persistent contrails, I will personally write Dr. Minnis to see if he will look at it because I will be stumped."

The point is this, for FK it has to be absolutely "bone dry" for a persistent contrail to be considered "unusual". Otherwise, presumably, due to such things as the "dry bias" of humidity measurements, persistent contrails are perfectly normal. In fact he would EXPECT them to be present.

Well guess what Jack? There are plenty of days...plenty, where conditions are much more favorable for persistent trails than on the 21st of Feb...

and you know what? There aren't any. Nada.

So we've already agreed that air traffic is a relative constant...

...and that science is reproducible.

So given the dry bias of humidity measurements, and the fact that it is always cold at altitude, how do the skeptics say that persistent trails are perfectly normal on a day of marginal conditions, and yet DON'T exist on days with much more favorable conditions?

The planes didn't stop flying.

We didn't just have the "high efficiency" engines overhead.

Nope, THEY don't have an answer for this one.

And that's why FK was abandon by his fellow skeptics on this particular thread.

He was left out to hang himself with his own words.

But take comfort folks...becuase if and when FK ever does consider something "fishy", you know what this professional meteorologist is going to do?

Well he's just going to pick up his pen and write to "The Esteemed" Dr. Patrck Minnis and ask for help.

posted 02-26-2003 10:39 PM            

enjoy

posted 02-26-2003 11:04 PM            

Gotta get my rest, Ill do some more research when I have time tommorow.

posted 02-26-2003 11:27 PM            

Kinda like tag team wrestling.

NASA to the rescue.

His NOAA buddy FK was pretty hard on the mat, whining about being twisted when the fact was he was being quoted directly.

We of course notice CANEX's reference to "Frisco".

Ohhh, ouch ! (not a pretty reflection on CANEX, but then again, envy is hard to control).

So are you now saying, despite the disclaimers to the contrary, that the Contrail Forecasting model actually IS reliable...that there in fact SHOULD HAVE BEEN persistent trails in the sky on February 21st?

Well OK! Now we're getting somewhere.

So here's what I did CANEX. I returned to the Contrail Forecast site,
http://enso.larc.nasa.gov/sass/contrail_forecast/contrail_prediction.html#REALTIME

and I entered the following parameters,

Archive Data: check

Year 2003
Month Feb
Time 1600
0.3 efficiency at 250 mb

Sorry... no circles over San Francisco.

None even close.

I suppose it's just a matter of what you consider a wazoo... but then again you did say "Frisco".

Maybe "The Esteemed" Dr. Patrick Minnis can help YOU use his modeling program.

posted 02-27-2003 01:55 PM            

F.K.