[MITgcm-support] Values about adjoint ADJ* results

[Matthew Mazloff]

ps> Though its an average the costfunction will accumulate. So I think it should be divided by secs per day and number of boxes in the average, making 10^-7 sounds about right!




> On May 3, 2017, at 9:37 AM, Matthew Mazloff <mmazloff at ucsd.EDU> wrote:
> 
> Hello
> 
> Essentially yes, though weighted by your cost function design. So ADJtheta will have volume and timestep weigthing in it.
> 
> Its linear so your average is essentially the sum of grid cell costfunctions. Try letting your costfunction be SST for one grid cell and one time step and figuring out the weighting from that.
> 
> Matt
> 
> 
>> On May 3, 2017, at 9:29 AM, Peng Zhan <peng.zhan at kaust.edu.sa <mailto:peng.zhan at kaust.edu.sa>> wrote:
>> 
>> Dear all,
>> 
>> I am doing the adjoint sensitivity analysis, but get confused about the values' physical meaning in the ADJ* results.
>> 
>> For instance, the cost function J is defined using daily average SST over a box, the ADJ* results are about 10^-7 to 10^-6 in magnitude.
>> 
>> 1. Is the surface ADJtheta the sensitivity to SST it self?
>> 2. If yes, the sum of ADJtheta over the box right before the target day should be close to 1?
>> 
>> 
>> Thanks in advance, Peng
>> 
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