Submitting a manuscript dependent on another one also submitted I have a manuscript A, ready for submission, that describes a method for characterizing topographic features (computer sciences). I also have another manuscript B, ready for submission, that uses the method from the manuscript A where I extract the features I want  and do some statistical analyses to explain the topographic variations (geosciences). A and B cannot be merged, and I consider to publish them in different journals since they treat different topics.

Should I submit A and B at the same time, but mention in B that I use a method from A? If yes, what should put as in-text citation?
Is there a compelling reason to submit both simultaneously? In case (I hope this doesn't happen!) there is an oversight in A, and the reviewer asks for modifications to the method, the results in B may no longer be valid. So it would be better to wait for acceptance of A. 

If you must submit both soon because of deadlines etc, you can cite A as "journal xyz- submitted" (i.e. 'submitted' in place of volume number etc). This does happen now and then, but in my field (materials science), most journals discourage it.