Clouds, aerosols, and precipitation in the marine boundary layer: an ARM Mobile Facility Deployment

The Clouds, Aerosol, and Precipitation in the Marine Boundary Layer (CAP-MBL) deployment at Graciosa Island in the Azores generated a 21-month (April 2009–December 2010) comprehensive dataset documenting clouds, aerosols, and precipitation using the Atmospheric Radiation Measurement Program (ARM) Mobile Facility (AMF). The scientific aim of the deployment is to gain improved understanding of the interactions of clouds, aerosols, and precipitation in the marine boundary layer. Graciosa Island straddles the boundary between the subtropics and midlatitudes in the northeast Atlantic Ocean and consequently experiences a great diversity of meteorological and cloudiness conditions. Low clouds are the dominant cloud type, with stratocumulus and cumulus occurring regularly. Approximately half of all clouds contained precipitation detectable as radar echoes below the cloud base. Radar and satellite observations show that clouds with tops from 1 to 11 km contribute more or less equally to surface-measured precipitation at Graciosa. A wide range of aerosol conditions was sampled during the deployment consistent with the diversity of sources as indicated by back-trajectory analysis. Preliminary findings suggest important two-way interactions between aerosols and clouds at Graciosa, with aerosols affecting light precipitation and cloud radiative properties while being controlled in part by precipitation scavenging. The data from Graciosa are being compared with short-range forecasts made with a variety of models. A pilot analysis with two climate and two weather forecast models shows that they reproduce the observed time-varying vertical structure of lower-tropospheric cloud fairly well but the cloud-nucleating aerosol concentrations less well. The Graciosa site has been chosen to be a permanent fixed ARM site that became operational in October 2013.

OzFACE: the Australian savanna free air CO2 enrichment facility and its relevance to carbon-cycling issues in a tropical savanna

A free air CO2 enrichment (FACE) facility has recently been constructed in a tropical savanna in north-eastern Queensland, Australia. The system has a novel and cost-effective design and uses an industrial source of pure CO2 piped directly to the site. We describe the design details of this facility and assess the likely contribution it will make towards advancing our understanding of the direct impacts of rising atmospheric CO2 on savannas. These include addressing uncertainties about future shifts in the tree–grass balance and associated changes in carbon stocks, responses of C4 grasses in dry tropical environments, potential sequestration of soil carbon, and the modifications of CO2 responses by moisture and nutrient interactions. Tropical regions have been poorly represented in climate change research, and the work at the OzFACE facility will complement existing and ongoing FACE studies at temperate latitudes.

The kommuna impulse: collective mechanisms and commune-ists in the early Soviet State

This study examines the creation of the urban kommuna (commune) and the ideals that stimulated this social phenomenon – the kommuna impulse of the nascent Soviet state. Collective idealism affected Soviet housing, architecture and even urban planning, but little is known of social experiments in commune‐ism. As a result, these collective cells have been dismissed as utopian anomalies or the product of a housing shortage. Here it is argued that these discursive assessments are unsatisfactory and isolated from the historical narrative. While utopian ideals and domestic necessity were central to the formation of collective living, the kommuna was also involved in an active discourse with collectivism and socialist ideology. The kommuna cell was a dynamic entity that required considerable formative planning. The activists who forged these cells – the self‐identified ‘communards’ – turned their everyday domestic life into a socialist battleground, in which they struggled with the key debates of the early Soviet state. This article examines the communard as a social activist in order to better understand this phenomenon. It clarifies the coexistence of ideological and idealist trends among Soviet youth with practical contingencies for socialism. Furthermore, it reveals the process by which the kommuna impulse and these contingencies developed throughout the 1920s and early 1930s.