Meteorological data to help in understanding Gimbal (January 20 and 21, 2015)

dimebag2

Active Member
Hi all,

Lately there has been discussions about the weather conditions during Gimbal, especially the wind, clouds, that are clues to help us better locating where Gimbal happened, and to recreate the event. I'd like to contribute with this because I'm familiar with this kind of data.

First, here is information we get from the video :

- the wind was westerly (i.e. blowing from the west to the east) -> one of the pilot says "the wind is 120 Knots to the West"
- Gimbal was going towards the wind -> one of the pilot says ("it's going towards the wind")
- there were clouds in the background (or foreground), as seen in the video
- the F-18 was flying at 25000 ft (~7650 m)
- this happened off Jacksonville, Florida, on January 20 or 21st 2015 (sources mentioned in other threads)

Now, the weather data

There is some really good weather data publicly available nowadays, and fairly easy to visualize even for non-meteorologists. I downloaded the January 20-21 2015 weather data from the ERA5 reanalysis, this comes from the UK met office. A reanalysis is state-of-the-art weather data assimilating the most possible available weather observations throughout the entire atmosphere, and filling the blank using a weather atmospheric model. ERA5 has been made available recently, and what makes it awesome is that it has a high spatial (0.25°, ~25km) and temporal (1 hour) resolution.

I downloaded the following variables at pressure levels 925hPa to 300 hPa (~750m to 9000m) : temperature, wind, geopotential (or altitude of the corresponding isobar) and relative humidity (correlated to cloud cover).

There are very interesting things in the data, I am going to try to give a quick summary and my interpretation here, but for those who are interested, the weather data file can be downloaded here :

Source: https://drive.google.com/file/d/1nyWJTvE5mvQzAH_9m1P6F8Z97wDX5GRl/view?usp=sharing

The data format is Grib, to visualize it you simply need to install this .grib viewer : https://opengribs.org/en/downloads

Then you have to open the .grib file in the software (File->Open), then you can select the altitude in the "Altitude Tab". The 400 millibar pressure level is the closest to the F-18 altitude.

In the "Weather Map" tab, you can select the meteorological variable you wish to plot.

- Wind : if you select Wind, you can point to any location and on the left you'll see the corresponding wind speed (in Knots), and direction.

- Clouds : for clouds, looks at the relative humidity. Definition : expressed as a percentage, it indicates a present state of absolute humidity relative to a maximum humidity given the same temperature. When it's 100%, the air is fully saturated in water vapor, i.e. there is condensation, or clouds. So the areas in dark blue are where the clouds are present. Even better, we can see relative humidity at each available altitude ! At one given location, on the left you'll see the vertical profile of relative humidity, i.e. the vertical profile of clouds. This is a strong indication of the type of clouds, and of the altitude of their top. It can be super helpful to estimate where and at what time Gimbal was shot, and at what height the background clouds were (which given the horizontal angle of the ATFLIR, can also tell us about their distance I guess).

I'll spend more time analyzing this data, but here is a quick take on what I see so far.

The wind

The only time when there is strong wind off the coast of Jacksonville is on January 21st. It does not reach the 120 Knots the pilots mention, but it gets as high as 90 Knots. Note that at 300 hPa it is around 120 Knots, so there are stronger winds aloft. On January 20, the winds never get higher than 60 Knots at 400 mb in this area. Based on this, I think the encounter may have happened around the marked area on this wind map. Here this is for 13:00 UTC.

ERA5 Wind.jpg


The clouds

ERA5 RH.jpg

Again, the clouds are where the humidity is 100% and above (dark blue). If the position of the F-18 is in the band of high winds I point out above, the F-!8 had to go tailwind, from west to east, because the clouds were on its left in the video. There were no clouds on the south, only on the north (or left of the plane). What's interesting about them but is not visible on this map is their vertical profile. Relative humidity is >100% at 400 hPa, or around 7300 m, but not above. That would make for a cloud layer with a top at ~ 7300 m, a little below the altitude of the fighter. This is an important requirement for the clouds to be in the FOV of the ATFLIR. Given the low vertical line of sight (-2°), low clouds could not be seen in the ATFLIR. In the configuration above the clouds would then be ~100 Nautical miles from the F18, which is an important parameter for the reconstructions that have been made so far. But that's only one potential option here.

I only show an example here, I encourage you to download the data and software, and look at the data yourself. This is very easy to install and use. Hopefully this will serve as a reference for discussions of Gimbal that involve weather conditions. If only we could have the location and time of the event, we coud retrieve more precisely the distance of the clouds, and greatly refine the geometrical reconstructions. But at least we have some strong indications to guide us here.
 

dimebag2

Active Member
An animation for the wind at 400 mb (every hour from January 20, 00:00 UTC, to January 21, 23:00 UTC)

Wind_animation.gif
 

Leonardo Cuellar

Active Member
Hello!
Among the various hypotheses to be taken into consideration there are also the following:
1) the pilot's statement can also refer to the fact that the object seemed to fly against the wind because it was stationary, or with zero horizontal velocity. This claim has been reported in some testimonies.
2) the call of the wind could be referred to the position of the object. In commercial flights it is possible to know the wind situation at various flight levels by interrogating the FMS. It is likely that a similar device also exists aboard military aircraft.
 
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dimebag2

Active Member
1) the pilot's statement can also refer to the fact that the object seemed to fly against the wind because it was stationary, or with zero horizontal velocity. This claim has been reported in some testimonies.

Yes and that's in fact what Ryan Graves describes in this interview : https://thedebrief.org/devices-of-unknown-origin-part-ii-interlopers-over-the-atlantic-ryan-graves/

“It was going like 120 knots, basically stationary. None of our jets are just going to be sitting there stationary at 120 knots. I forget the altitude, maybe like 20,000 feet, but that’s really slow. Maybe in a full dogfight, if you’re a good pilot, you could get down to maybe 80 knots without stalling the aircraft, but you’re probably borderline stall, and you’re going to be pure vertical, or at least close to 70 degrees nose up,” said Graves.

Also, something very interesting he mentions is that it happened ~ 300 miles off the coast.

“On that particular day, the day the Gimbal was filmed, we were involved in a large air-to-air mission. You’ve got anywhere from 10 to 12 jets in the air wing going off to an area to do a mission. Then you’ve got a group of aircraft overhead the boat acting as the aerial refuelers. When my buddy took that video, he was heading back to the ship, and then here goes this thing like 40 miles away from the boat. It’s not in the data link. All the radars are reporting it, but it’s nothing popping up identifying what type of aircraft it is or whether it’s friend or foe. Then you’ve also got the five or six other objects in the wedge formation. We were like 300 miles out off the coast. It’s hard for me to imagine it was just another jet in the system.”
 

jplaza

Member
Yes and that's in fact what Ryan Graves describes in this interview : https://thedebrief.org/devices-of-unknown-origin-part-ii-interlopers-over-the-atlantic-ryan-graves/

“It was going like 120 knots, basically stationary. None of our jets are just going to be sitting there stationary at 120 knots. I forget the altitude, maybe like 20,000 feet, but that’s really slow. Maybe in a full dogfight, if you’re a good pilot, you could get down to maybe 80 knots without stalling the aircraft, but you’re probably borderline stall, and you’re going to be pure vertical, or at least close to 70 degrees nose up,” said Graves.
But that is different from what can be heard in the video, ("the wind is 120 knots"). What Graves says here is that the object was travelling at 120kt... am I misunderstanding something?
 

dimebag2

Active Member
But that is different from what can be heard in the video, ("the wind is 120 knots"). What Graves says here is that the object was travelling at 120kt... am I misunderstanding something?

I think it may be what Leonardo says above, that it was going 120 Knots against the wind (of 120 Knots), so it was stationary.
 

Rory

Senior Member.
Sorry if this has already been answered (there are a lot of posts on the subject and I haven't read them all) but I'm curious as to what the confirmation is that it was either January 20th or 21st? Is there any chance it could have been an earlier date in January?
 

jarlrmai

Senior Member
Ryan Graves just tweeted.

Source: https://twitter.com/uncertainvector/status/1503478901636358144


As I had expected, the observation took place at night. Obviously now it is time to understand exactly where a 120 knot wind was found between 20 and 21 January 2015 off Jacksonville!
The major problem with that Graves description are it indicates ATFLIR in SLAVE but video shows its not in SLAVE.

There are 2 screens in the F18 what was on the other one at this time? I assume the SA? As they talk about it. So which is this radar screen they switched from to show ATFLIR?

Ryan Graves should know his stuff but whenever he speaks it never seems to quite correlate with the videos.

Maybe a separate thread for Graves' words vs the videos?
 

Tim Printy

Member
Ryan Graves just tweeted.

Source: https://twitter.com/uncertainvector/status/1503478901636358144


As I had expected, the observation took place at night. Obviously now it is time to understand exactly where a 120 knot wind was found between 20 and 21 January 2015 off Jacksonville!
Looking at radiosonde data for Jacksonville, there were 120 knot winds above 30,000 feet at 12Z on 21 January. On the radiosonde at 0000Z on 21 January, they were closer to 110 knots. At 0000Z on 22 January, they were just under 120 knots above 40,000 feet. Prior to 0000Z on 21 January wind speeds did not approach 100 knots. This indicates that the region was seeing high winds at high altitudes at the date in question. It would be hard to pinpoint the exact location of the incident. See:

https://weather.uwyo.edu/cgi-bin/sounding?region=naconf&TYPE=TEXT:LIST&YEAR=2015&MONTH=01&FROM=2000&TO=2200&STNM=72206
 
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Leonardo Cuellar

Active Member
Looking at radiosonde data for Jacksonville, there were 120 knot winds above 30,000 feet at 12Z on 21 January. On the radiosonde at 0000Z on 21 January, they were closer to 110 knots. At 0000Z on 22 January, they were just under 120 knots above 40,000 feet. Prior to 0000Z on 21 January wind speeds did not approach 100 knots. This indicates that the region was seeing high winds at high altitudes at the date in question. It would be hard to pinpoint the exact location of the incident. See:

https://weather.uwyo.edu/cgi-bin/sounding?region=naconf&TYPE=TEXT:LIST&YEAR=2015&MONTH=01&FROM=2000&TO=2200&STNM=72206
Exact. So why did the pilots report wind of a higher flight level than them?
 

Leonardo Cuellar

Active Member
What are the error bars in that "120" figure?
The WMO makes two types of data available. GRIB and BUFR. These are processed through information from radio soundings, pilots and mathematical models. They are updated every 6 hours and can extend to 7 days in the forecast. The advantage of reading archive data therefore is that they have been obtained from information very close to the date we are analyzing. In fact you can compare the analysis of the weather forecast provided through the Xygrib tool, as suggested in the Thread of our friend @dimebag2, and the observations of the sounding balloons produced on Jacksonville and provided in the post by @Tim Printy.

The error is acceptable at 1-2% . We have hourly data, geographically arranged on a grid of about 5NM at different geopotential altitudes. During the night between 20 and 21 January 2015, the maximum wind recorded at the geopotential altitude of 400mb was 95 knots. If we take a wind reading of 120 knots for good, we are talking about an inaccuracy of 21%, which should have been corrected by subsequent observations anyway. Also consider that during space operations in Cape Canaveral, the soundings have increased considerably and that in any case we are talking about a layer of the atmosphere at high altitude where a stability persists in which flows travel in the absence of turbulent motions.
 

FatPhil

Senior Member.
The WMO makes two types of data available. GRIB and BUFR. These are processed through information from radio soundings, pilots and mathematical models. They are updated every 6 hours and can extend to 7 days in the forecast. The advantage of reading archive data therefore is that they have been obtained from information very close to the date we are analyzing. In fact you can compare the analysis of the weather forecast provided through the Xygrib tool, as suggested in the Thread of our friend @dimebag2, and the observations of the sounding balloons produced on Jacksonville and provided in the post by @Tim Printy.

The error is acceptable at 1-2% . We have hourly data, geographically arranged on a grid of about 5NM at different geopotential altitudes. During the night between 20 and 21 January 2015, the maximum wind recorded at the geopotential altitude of 400mb was 95 knots. If we take a wind reading of 120 knots for good, we are talking about an inaccuracy of 21%, which should have been corrected by subsequent observations anyway. Also consider that during space operations in Cape Canaveral, the soundings have increased considerably and that in any case we are talking about a layer of the atmosphere at high altitude where a stability persists in which flows travel in the absence of turbulent motions.

You're addressing the wrong "120". When comparing 2 numbers, both of them have error bars.
 

jplaza

Member
I haven't understood. What do you mean by wrong "120"?
How accurate is the 120 knots figure mentioned by the pilot/WSO in the gimbal video? Where do they get the value from? Is there any instrument on the plane that gives that value for the moment and position of the plane? Is it given by controllers in the ship/(somewhere else) taking care of meteorology?
 

Leonardo Cuellar

Active Member
How accurate is the 120 knots figure mentioned by the pilot/WSO in the gimbal video? Where do they get the value from? Is there any instrument on the plane that gives that value for the moment and position of the plane? Is it given by controllers in the ship/(somewhere else) taking care of meteorology?
This is the problem. If the wind is the one referred to the position of the super hornet, then the WSO is most likely using a function available in nav mode to obtain the instant wind through the FMS data and the GPS position. And therefore we would have a discrepancy of over 20% with the grib data, and these should still be updated in subsequent predictions. If instead the WSO gets the data from a distant source through the link16, or it was getting through the FMS the wind in the position of the aircraft itself or the object, then those are the grib data in our possession!
 
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