Scientific Merit

There is a demonstrated need for a marine atmospheric observatory at Bermuda. The importance of and necessity for wider spatial and temporal observation of the marine atmosphere has recently been highlighted by a number of authors in Liss and Johnson (2014). Moreover, the potential of activities based in Bermuda to play a larger role in such research has been specifically emphasized: Schulz et al. (2012) proposed that Bermuda, in addition to other locations, be used as one of the locations for coordinated atmospheric and marine measurements to better understand geochemical processes such as the latitudinal distribution of dust and nutrient deposition to the oceans, and von Glasow and Saltzman (2013) reported on the recommendation that Bermuda be used as a location for studying halogen chemistry in the marine atmosphere.

In the context of anticipated future changes in the Earth’s climate and environment (IPCC, 2007), there is a need for an improved understanding of atmospheric composition, atmospheric transport and atmosphere-ocean exchange, in order to predict and mitigate the impacts of such changes. This requires an improved observational and experimental capability, which has been formally recognized in research initiatives such as SOLAS, IGAC, GEOTRACES and OOI, and within the wider scientific community (Shulz et al., 2012; Law et al., 2013; Liss and Johnson, 2014). With regard to the observational and experimental research conducted under these initiatives, there is a clear need for a permanent sampling/observing platform in the MBL of the western subtropical North Atlantic Ocean. For this reason, it is proposed to continue to maintain and operate the atmospheric sampling facility at Tudor Hill, Bermuda, with the rationale that research contributions from this facility will significantly advance understanding of the Earth system, and the ability to monitor, predict and mitigate future environmental change.

As a research platform for time-series observations of the marine troposphere, the Tudor Hill facility will complement ongoing ocean time-series programs in the Bermuda region. In the same way that Hydrostation S, the Bermuda Atlantic Time-series Study (BATS) program, and the Oceanic Flux Program have provided data and samples used in a wide range of oceanographic studies, the project proposed here will provide observational facilities, meteorological data and atmospheric samples that will support and augment a wide range of future atmospheric and oceanic studies, thereby improving understanding of ocean-atmosphere processes in the North Atlantic region. Indeed, as the only such permanent mid-ocean sampling/observing site in the western North Atlantic, continued operation of the Tudor Hill facility is essential to the success of future atmospheric and oceanographic studies in this region. Together with the other ongoing time-series research programs in the Bermuda region mentioned above, the Tudor Hill atmospheric sampling facility must be considered as a key component of a research framework that will greatly advance understanding of the ocean-atmosphere system.

In the past decade, significant NSF-sponsored research conducted at the facility includes providing support for the ATM-funded project Collaborative Research: The Processing and Radiative Properties of Aerosols over the Western North Atlantic Ocean at Bermuda (PI’s Keene, Voss, Galloway and Moody). This project ran from 2006-2009, entailing daily sampling of size-fractionated aerosols and rainwater achieved by the installation of two MOUDI aerosol samplers, a second rain collector, a nephelometer, a pyranometer and pyrgeometer, a sun photometer, and a micropulse lidar system at the facility (Moody et al., 2014).

Another major NSF-sponsored project at the facility commenced in 2011. PIs Hastings (Brown University), Sigman (Princeton University) and Peters (BIOS) were granted an AGS award Collaborative Research: Isotopic and compositional investigation of the sources and interactions of reactive N in the marine atmosphere at Bermuda. This project was designed to characterize the sources, composition, and interrelationships among N species in rainwater and aerosols deposited in the North Atlantic Ocean. The grant included funding for a post-doctoral fellow, Dr. Katye Altieri (Princeton and Brown Universities) who was responsible for a significant part of the work. Funding was also included for a dedicated research technician to undertake routine, rain event-based and intensive atmospheric sampling at the site over an 18 month period in 2011-12. This project resulted in four peer-reviewed publications.