The part of a sentence "an upsurge in the number of" is correct and usable in written English.
You can use it to describe an increase in the quantity of something. For example, "There has been an upsurge in the number of new businesses opening in the area."
The emergency measures follow an upsurge in the number of migrants reaching Italy in recent days.
Meanwhile, the register of births has noted an upsurge in the number of babies named Rio, Sol and Emile.
This led to an upsurge in the number of studies investigating the potential of Arctic maritime routes.
Recent days have seen an upsurge in the number of attempted crossings – and evidence of a change in tactics by the organisers.
But the immediate impact has been an upsurge in the number of companies offering American-style stock-option plans for their most prized employees.
Then there was an upsurge in the number of first-time buyers as the baby-boomers born in the late 1950s and early 1960s scrambled into the market.
It coincided with an upsurge in the numbers of people reaching Italy by sea.
On Monday the UN high commissioner for human rights said there has been an "alarming upsurge" in the number of killings and arrests in Burundi since the president was sworn in for his third term.
Late last month, United Nations High Commissioner for Human Rights Zeid Ra'ad al-Hussein said that there had been an "alarming upsurge" in the number of killings and arrests in Burundi after the president was sworn in for his third term.
Shortly after, there was a massive upsurge in the number of cases as a result of the rapid spread of SARS through a residential block.
An increasing interest in this approach is indicated by a steady upsurge in the number of articles on targeting dual/multi proteins published in the last 5 years.
