Forum Index
SUBSIM Forum Search

The Web's #1 BBS for all submarine and naval simulations!
[ SUBSIM Review ] [ SUBSIM STORE ]
Current Forum | Archives 2002-2003 |

Arctic Sound Speed Profiles

 
This forum is locked: you cannot post, reply to, or edit topics.   This topic is locked: you cannot edit posts or make replies.     Forum Index -> DW Mission Designers' Forum
View previous topic :: View next topic  
Author Message
SeaQueen



Joined: 23 Jun 2005
Posts: 358
Location: Washington, DC

PostPosted: Thu Mar 02, 2006 6:42 pm    Post subject: Arctic Sound Speed Profiles Reply with quote

In my Kara Sea scenario, as I've been honing it, I've been faced with a dilema. DW lacks a truely satisfactory SSP for arctic scenarios.

Arctic waters are nearly isothermal, so at first I elected to use the "Surface Duct" SSP. I hoped the game engine would treat it as a big mixed layer, essentially. Unfortunately, that proved to be a bad idea because even in shallow water, occaisionally, a sonic layer would appear, undermining the essential characteristic of arctic waters - there is no thermocline.

So... I'm left with the "Bottom Limited" SSP, which will increase the speed of sound uniformly to the bottom. It doesn't sit well with me for other reasons, though.

Do any fellow sonar geeks out there have any thoughts about what the best compromise is?
Back to top
View user's profile Send private message
Bellman



Joined: 14 Feb 2004
Posts: 1724

PostPosted: Fri Mar 03, 2006 10:33 am    Post subject: Reply with quote

Sure getting some surprising effects near the surface. :hmm:
Back to top
View user's profile Send private message
Kapitan



Joined: 10 Mar 2005
Posts: 5385
Location: essex england also st petersburg russia

PostPosted: Fri Mar 03, 2006 7:04 pm    Post subject: Reply with quote

As a veteran of under ice missions i say this,

Try not to go near the kara sea its very shallow and the ice is unpredictable and you can easily get stuck.
if you do venture into the Kara sea stay at least 45 to 55 miles from the land (main land russia) or follow novaya zemlya.

In the kara sea the ambient noise should be higher, and the layer depths should change alot and rapidly, personaly finding a contact here is like trying to hit a basketball with a shoe horn.

Any mission i made that i had to go near the kara sea id always follow the same principles;

1) check the HF sonar ever few minuets
2) check normal sonar (dont extend TA gets broken easily)
3) never go too deep or fast.

Average water temp for Kara sea is about -3*c dropping the further you go north and down, you realy strugle to find your way through this area and it can be frustrating, i downloaded a map of the artic area and i used to double check with that and the nav screen to see if all was ok (sometimes nav map was wrong)

As for a termocline no there isnt one but there are layer depths in some parts (around iceland and greenland and the svalbard).

Best way to find contacts in this area is to use sphere sonar your hull array will be washed out and towed wont function properly because it probly be dragging on the ground even at 4 knots.

Note this is for Akula diver experiance
Back to top
View user's profile Send private message Send e-mail AIM Address Yahoo Messenger MSN Messenger
Bill Nichols



Joined: 14 Mar 2001
Posts: 2657

PostPosted: Fri Mar 03, 2006 8:28 pm    Post subject: Re: Arctic Sound Speed Profiles Reply with quote

SeaQueen wrote:
In my Kara Sea scenario, as I've been honing it, I've been faced with a dilema. DW lacks a truely satisfactory SSP for arctic scenarios.

Arctic waters are nearly isothermal, so at first I elected to use the "Surface Duct" SSP. I hoped the game engine would treat it as a big mixed layer, essentially. Unfortunately, that proved to be a bad idea because even in shallow water, occaisionally, a sonic layer would appear, undermining the essential characteristic of arctic waters - there is no thermocline.

So... I'm left with the "Bottom Limited" SSP, which will increase the speed of sound uniformly to the bottom. It doesn't sit well with me for other reasons, though.

Do any fellow sonar geeks out there have any thoughts about what the best compromise is?


In actuality, if temperature remains constant then speed will increase with depth, due to the compressibility of water at higher pressures. Granted, it's not a strong function, but in deep water it's important (it's why convergence zones exist).
Back to top
View user's profile Send private message Send e-mail Visit poster's website
SeaQueen



Joined: 23 Jun 2005
Posts: 358
Location: Washington, DC

PostPosted: Sat Mar 04, 2006 12:11 am    Post subject: Re: Arctic Sound Speed Profiles Reply with quote

Bill Nichols wrote:

In actuality, if temperature remains constant then speed will increase with depth, due to the compressibility of water at higher pressures. Granted, it's not a strong function, but in deep water it's important (it's why convergence zones exist).


Right... and that's what I'm trying to get it to do. I'm saying that DW doesn't have a good way to represent an isothermal situation. Their "Surface Duct" environment leaves you with a thermocline, hence it's not isothermal, but their "Bottom Limited" SSP (which isn't really bottom limited because in DW the sound speed increases linearly all the way to the bottom), doesn't sit well with me because I'm scared that when (if?) they fix it, I'll have to redo the scenario to make it work right, so I'm not sure what a good compromise is.
Back to top
View user's profile Send private message
Kapitan



Joined: 10 Mar 2005
Posts: 5385
Location: essex england also st petersburg russia

PostPosted: Sat Mar 04, 2006 2:14 pm    Post subject: Reply with quote

Just played the Kara sea search and posted my thoughts in the review
Back to top
View user's profile Send private message Send e-mail AIM Address Yahoo Messenger MSN Messenger
Display posts from previous:   
This forum is locked: you cannot post, reply to, or edit topics.   This topic is locked: you cannot edit posts or make replies.     Forum Index -> DW Mission Designers' Forum All times are GMT - 5 Hours
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Powered by phpBB © 2001, 2005 phpBB Group