Current and Potential Anthropogenic Moisture Effects on the New York City Planetary Boundary Layer

Abstract

Fuel usage data for New York City during 1965 were used to compute annual anthropogenic heat and moisture emission rates. These data were used to simulate spatial distributions of urban surface heat island intensity and mixing depth at 0700 EST on the cold winter morning of 9 March 1966. Calculations were carried out using a steady state well mixed urban advective model. Results showed a maximum surface heat island of 8 K and a maximum mixing depth of 373 m, values consistent with observations over New York City.

Anthropogenic moisture production, as well as spatial distribution of average urban mixed layer absolute humidity excess, were computed for two cases, i.e., actual 1965 fuel usage distribution and a point and area source hypothetical conversion (on equal heat basis) to hydrogen gas fuel. Results for the 1965 emission pattern showed a peak grid-area anthropogenic moisture flux of 1.95 × 10¹² g per year. The peak urban absolute humidity excess was 0.13 g m⁻³, about 17% of the observed average mixed layer value.

Results for the hypothetical conversion case show similar distributions of anthropogenic moisture production and absolute humidity excess. However, maximum values were increased by a factor of four for the first parameter and a factor of three for the other.