That being said, there are other obvious inter-connections between paid ads and organic search rank, due to the factors these tools work with.
Increased CTR (Click-through-rate)
The click rate is a measure of relevance and one of the most important factors in search engine algorithms. Having ads with high CTR will help increase the general click rates for your landing pages, which can marginally raise their rankings in SERP (Search Engine Results Page). If your website is fairly new and little known, struggling somewhere on the second page of the SERP, it is difficult for it to get clicks from searches. That sucks, right?
But if you are simultaneously running a paid ad campaign that gets you on the first page, and your ads are well written and relevant for the search queries, you may well get some clicks. Furthermore, if, subsequently, the users tend to spend some time on your page and, maybe, look around, this sends a message that your page is relevant. This will positively impact the rank of your page and domain.
Therefore, you can indirectly help organic results through paid ads, if you manage to get good CTRs.
Trustworthiness
When you are trying to promote your website, you are in the process of building trust, not rankings. When users do a search query and see that your website shows up in both the paid area of the SERP and the organic area, it sends the message that your presence there is not an accident and that the website is trustworthy. So, having paid advertising can also increase trust and clicks for your organic link.
Later engagement
According to this post from MOZ, there is a higher chance for users who have seen an ad at a given time to return later to the initial search and engage with an organic link:
“So if you see that many people have searched in the past, they have clicked on a paid ad, and then later in the organic results they see that same brand ranking, they might be more likely and more inclined to click it, more inclined to engage with it, more inclined actually to convert on that page, to click that Buy button generally because the brand association is stronger. If it is the first time you heard of a new brand, a new company, a new website, you are less likely to click, less likely to engage, less likely to buy, which is why some paid exposure prior to organic exposure can be good, even for the organic exposure.”
Changing the area above the fold
The content above the fold is what users see on their screens before starting to scroll. This area is different, depending on the size and resolution of the device used to browse. The above the fold is, of course, smaller on smartphones and larger on desktop screens.