Roronoa Zoro's sense of climate/aura/motion and other observation capabilities

Question

It's not a luck or co-incidence, of all people Zoro sensed first that their Ship isn't moving (when they entered Calm belt for the first time)

In episode 385 he sensed (along with Nami) change in climate before Serpent Currents emerged.

There are several incidences he has sensed changes in Climate and motion before all (or along with Nami, who's a navigator) in the series

Is it zoro's Kenbunshoku Haki, which was active all time? or does he have any special ability? Isn't it noteworthy? I don't see any sources highlighting this ability of his (even in Wiki)!

Answer 1

As per One Piece wiki

Kenbunshoku Haki, also known as Mantra on Skypiea, is a form of Haki that allows the user to sense the presence of others, even if they are concealed from view or too far to see naturally.

This is the aura which is seen through Kenbunshoku Haki.

The user can also use this Haki to predict an opponent's moves shortly before they make them, thereby making the attack much easier to evade with enough skill. This prediction appears to the user as an image or brief "premonition" of what the opponent will do in the user's mind's eye, and the damage the user will take if the attack actually "hits". It appears that the more killing intent the enemy has, the easier they are to predict. Although, more skilled users can predict future moves whether there are ambient murderous intents or not.

Hence, Zoro detecting the change in climate can't be a consequence of his Kenbunshoku Haki, because it's inanimate and has nothing to do with a living thing. It's not possible to detect the "aura" of climate either.

Though the power allows the user to predict most attacks, it can be circumvented by various means. It cannot predict inherently random attacks; for example, Luffy managed to bypass Enel's Mantra by bouncing his fists off a nearby wall, to prevent himself and thus Enel from knowing where they would land.

As for Zoro sensing the halt of the ship in the Calm Belt, it's highly unlikely that it was his Kenbunshoku Haki as well because the Straw Hats had merely begun their journey then, and noone was aware of their Haki, or even unconsciously used it. Not to mention, the halting of their ship was not intentional (a result of the action of another living thing).

I think it's more of Zoro keeping an eye out for changes in the surroundings than it being his Haki.

Answer 2

I think it's a case of Zoro always being cautious and alert much like a Samurai as opposed to him subconsciously using haki.

We see evidence of this in Whiskey Peak where Zoro doesn't put his guard down against the villagers and ensures limits his drinking when the crew were partying which pays off when we find out they were bounty hunters.

Answer 3

I do agree with Ashish Gupta's answer. Also would like to add some more points to it:

Evidently Zoro is given a duty of Monitoring the surroundings, generally sits(or sleeps) on top of the ship.
This Duty, however was never announced. And shown to be shared by other strawhat members too. So not sure if he chose it himself or his team members acknowledged his ability. But the SHP team does depend on his observation skills.

As Ashish noted, it's definitely not an "Observation Haki" but could merely be a presence of mind and cautiousness, perhaps a sign of a true swordsman..