Recon question

[Scorpion]

Does anyone know why recon doesn't fly at 650 mb? I heard that 650 mb wind equals the surface wind most of the time. Wouldn't it be easier to just fly at that level instead of having to make an adjustment that can range from .75-.95?

[Aquawind]

Hmmm I have never heard higher altitude would equal the surface winds with friction and all. Where did your hear that?

[caneflyer]

There is no advantage to flying at 650 mb versus 700 mb. The farther you get from the surface, the more uncertainty there is in estimating surface winds from your flight level. Whatever level you fly at, there will be a mean relationship between the winds at that level and the surface winds, and at some level above 700 that mean adjustment would in fact be exactly 1.0. But you would still have a poorer surface estimate than if you flew lower.

Basically, the aircraft fly at the lowest safe altitude. For tropical storms, that is generally 850 mb, and for hurricanes, 700 mb.

[Aslkahuna]

Also they want to fly at a standard level so that the data can be directly input into the analyses and models at that level.

Steve

[caneflyer]

Also they want to fly at a standard level so that the data can be directly input into the analyses and models at that level.

Steve

Recon data (the flight-level data, at least) are not used in forecast models (such as the GFS, GFDL, UKMET, etc.). However, flying at constant levels certainly does facilitate the direct comparison from flight to flight subjectively by forecasters.

[x-y-no]

Also they want to fly at a standard level so that the data can be directly input into the analyses and models at that level.

Steve

Recon data (the flight-level data, at least) are not used in forecast models (such as the GFS, GFDL, UKMET, etc.). However, flying at constant levels certainly does facilitate the direct comparison from flight to flight subjectively by forecasters.

This doesn't sound right at all. Certainly dropsonde data is used in the initialzation of models whenever available. Why would flight level data not be used?

[caneflyer]

Yes, dropsonde data are used by the models, except those within the inner core (about 111 km from the center) are excluded from the GFS.

There are two reasons why the flight level data are not used in, say, the GFS model. First, that model is relatively insensitive to single level data. Second, the model doesn't have the resolution to handle the high-density flight data in the core of a tropical cyclone.

[Derek Ortt]

I am not sure. They did for 1 research flight into Dennis when it was a weak TS, but other than that, I am not sure

[x-y-no]

Yes, dropsonde data are used by the models, except those within the inner core (about 111 km from the center) are excluded from the GFS.

There are two reasons why the flight level data are not used in, say, the GFS model. First, that model is relatively insensitive to single level data. Second, the model doesn't have the resolution to handle the high-density flight data in the core of a tropical cyclone.

OK, thanks for the clarification. I wasn't aware of this.

[caneflyer]

I am not sure. They did for 1 research flight into Dennis when it was a weak TS, but other than that, I am not sure

It is unclear what it is you are not sure of.

If you are referring to the exclusion of drop data in the core, that was implemented mid-season last year (I don't recall the exact date of implementation).