Effect of wind speed on aerosol optical depth over remote oceans, based on data from the Maritime Aerosol Network

The Maritime Aerosol Network (MAN) has been collecting data over the oceans since November 2006. The MAN archive provides a valuable resource for aerosol studies in maritime environments. In the current paper we investigate correlations between ship-borne aerosol optical depth (AOD) and near-surface wind speed, either measured (onboard or from satellite) or modeled (NCEP). According to our analysis, wind speed influences columnar aerosol optical depth, although the slope of the linear regression between AOD and wind speed is not steep (~0.004–0.005), even for strong winds over 10 m s−1. The relationships show significant scatter (correlation coefficients typically in the range 0.3–0.5); the majority of this scatter can be explained by the uncertainty on the input data. The various wind speed sources considered yield similar patterns. Results are in good agreement with the majority of previously published relationships between surface wind speed and ship-based or satellite-based AOD measurements. The basic relationships are similar for all the wind speed sources considered; however, the gradient of the relationship varies by around a factor of two depending on the wind data used

Changing state of the climate system

Chapter 2 assesses observed large-scale changes in climate system drivers, key climate indicators and principal modes of variability. Chapter 3 considers model performance and detection/attribution, and Chapter 4 covers projections for a subset of these same indicators and modes of variability. Collectively, these chapters provide the basis for later chapters, which focus upon processes and regional changes. Within Chapter 2, changes are assessed from in situ and remotely sensed data and products and from indirect evidence of longer-term changes based upon a diverse range of climate proxies. The time-evolving availability of observations and proxy information dictate the periods that can be assessed. Wherever possible, recent changes are assessed for their significance in a longer-term context, including target proxy periods, both in terms of mean state and rates of change

Maritime aerosol network as a component of AERONET - First results and comparison with global aerosol models and satellite retrievals

The Maritime Aerosol Network (MAN) has been collecting data over the oceans since November 2006. Over 80 cruises were completed through early 2010 with deployments continuing. Measurement areas included various parts of the Atlantic Ocean, the Northern and Southern Pacific Ocean, the South Indian Ocean, the Southern Ocean, the Arctic Ocean and inland seas. MAN deploys Microtops hand-held sunphotometers and utilizes a calibration procedure and data processing traceable to AERONET. Data collection included areas that previously had no aerosol optical depth (AOD) coverage at all, particularly vast areas of the Southern Ocean. The MAN data archive provides a valuable resource for aerosol studies in maritime environments. In the current paper we present results of AOD measurements over the oceans, and make a comparison with satellite AOD retrievals and model simulations

Surface In situ Datasets for Marine Climatological Applications

Climatological products are required for monitoring and studying global climate change and accurately identifying secular trends over the past two centuries. These products require consistent and well-characterised observational data and metadata from the earliest ship observations and from the modern ocean observing system. Maintaining and developing long-term surface marine climatological datasets requires a different approach to data management than for operational applications. The current management of climatological datasets is discussed and specific modernization steps recommended. The status of relevant in situ observing systems is reviewed in the context of available satellite data. The extent to which requirements for maintaining sampling, redundancy, and consistency are met by existing data delivery mechanisms is considered. Recommendations include: data and metadata rescue; maintaining consistency with the historical record; modernization of data flow and climatological products; for observations with added-value through improved metadata, quality control and uncertainty characterization; and improved dataset construction methods

Observations to Quantify Air-Sea Fluxes and Their Role in Climate Variability and Predictability

Flux products quantifying exchanges between ocean and atmosphere are needed for forcing models, understanding ocean dynamics, investigating the ocean’s role in climate, and assessing coupled models. Research experiments are essential to improve flux parameterizations, and longer research deployments are required to sample rare events. Urgently needed technological improvements include longer battery life, more robust sensors and improvement of sensors for humidity, precipitation and direct gas and particle fluxes. A range of different flux products are needed, incorporating data from ships, satellites and models in different combinations and using different methods. All products must be characterized with uncertainty estimates. Dataset validation requires high quality observations from ocean flux reference sites and from ships. The continued development of flux products from satellites provides much-needed sampling. Continual intercomparisons among products and with high quality observations will lead to improved flux datasets, while improvements to the flux data management system would facilitate these intercomparisons