Observations of CO2 exchanges and micrometeorology of an ephemeral city in a desert: The Burning Man experiment

This paper presents the results from a micrometeorological study of Black Rock City, NV (BRC) during the annual Burning Man festival. Observations were made from 22 August to 2 September 2013 to include the initial construction of the city and the rapid exodus from the city at the end of the event. While it differs from most modern cities, the appearance of BRC affects the roughness of the surface as well as the size of sources and sinks of CO₂, water and heat, as with other cities. Due to the temporary nature of the city and the high degree of spatial organization, the effects of changing population density and surface cover can be captured in a very short observational period. Eddy covariance measurements of CO₂, water vapor, heat and momentum fluxes were made at 12 m and profiles of temperature, humidity, wind speed and direction were measured from 1- 30 m. A second smaller meteorological station was placed on the outskirts of the city and mobile bicycle observations were used to obtain cross sectional temperature profiles of the urban area.

In this paper, we present an overview of the experiment and preliminary results. CO₂ fluxes were negligible prior to rapid urbanization and grew steadily with population density within the flux footprint. Diurnal CO₂ flux patterns were controlled most strongly by dynamic surface layer drivers, including large swings in surface layer stability. The signal from human activities is also clear, such as vehicle migration patterns and even the effect of the culminating event gathering. Also discussed is the role of changing surface roughness on turbulence and vertical exchange processes as well as much smaller changes found in the surface energy balance, Bowen ratio and urban heat island.