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Blot R.,University of Hawaii at Manoa | Clarke A.D.,University of Hawaii at Manoa | Freitag S.,University of Hawaii at Manoa | Kapustin V.,University of Hawaii at Manoa | And 6 more authors.
Atmospheric Chemistry and Physics | Year: 2013

Accurate measurements of natural aerosol emissions over the ocean are needed to estimate the anthropogenic impact on the environment. In this study, we measured sea spray aerosol (SSA) concentrations with diameters larger than 0.040 μ produced by open-ocean breaking waves over the SEP (southeastern Pacific). Robust statistics were established through repeated airborne flights over 1000 km along 20 S from the coastline of Chile to 85 W during VOCALS-REx (VAMOS Ocean-Cloud-Atmosphere-Land-Study Regional Experiment). Non-volatile SSA number concentrations were inferred using a thermally resolved technique constrained for clean conditions with an Ångström exponent below 0.5, black carbon mass concentration at values lower than 15 ng m-3 and organic aerosol concentration less than 0.02 μg m-3. We found that number concentrations of SSAs active as cloud condensation nuclei (CCN) for a supersaturation of 0.25% varied between 17 and 36 cm-3, but these did not increase with the increasing mean wind speed typically observed further offshore along 20 S. Concurrent increases in mean offshore precipitation rate in excess of about 1 mm d-1 indicate that scavenging of SSAs by precipitation exceeds increases in production at wind speeds above about 8 m s-1. This demonstrates the critical role of precipitation as a major sink of SSA over the remote ocean. Finally, we found that under clean conditions and for estimated stratus supersaturations between 0.20 and 0.43%, SSA represented about 20% of the total potential CCN along 20 S. © 2013 Author(s). Source


Serke D.,NCAR RAL | Hubbert J.,NCAR EOL | Reehorst A.,NASA | Politovich M.,NCAR RAL | And 6 more authors.
SAE Technical Papers | Year: 2011

From November 2010 until May of 2011, NASA's Icing Remote Sensing System was positioned at Platteville, Colorado between the National Science Foundation's S-Pol radar and Colorado State University's CHILL radar (collectively known as FRONT, or 'Front Range Observational Network Testbed'). This location was also underneath the flight-path of aircraft arriving and departing from Denver's International Airport, which allowed for comparison to pilot reports of in-flight icing. This work outlines how the NASA Icing Remote Sensing System's derived liquid water content and in-flight icing hazard profiles can be used to provide in-flight icing verification and validation during icing and non-icing scenarios with the purpose of comparing these times to profiles of polarized moment data from the two nearby research radars. In this work, the authors present case studies to show how NASA's Icing Remote Sensing System can support the effort to develop a polarized S-band radar 'Icing Hazard Level' algorithm. With high temporal resolution range versus height scans from both radars over the NASA system location, detailed synoptic and micro-scale weather timelines for each case are analyzed. The new radar product, when combined with NIRSS, would provide crucial real-time hazard detection capabilities to improve aviation safety in the near-airport environment. Copyright © 2011 SAE International. Source


Rabier F.,Meteo - France | Cohn S.,NCAR EOL | Cocquerez P.,French National Center for Space Studies | Hertzog A.,Laboratoire Of Meteorologie Dynamique | And 31 more authors.
Bulletin of the American Meteorological Society | Year: 2013

Concordiasi was a multidisciplinary effort jointly operated by France and the US to study the lower stratosphere and troposphere above Antarctica and the land surface of the Antarctic continent. Concordiasi field experiments were conducted in austral springs 2008, 2009, and 2010, including surface measurements and radiosoundings at the Concordia Antarctica station at Dome C and radio-soundings at the Dumont d'Urville and Rothera sites on Antarctica. An innovative constellation of balloons provided a unique set of measurements covering both volume and time in 2010. The balloon flotilla formed a regional observatory of the atmosphere, which provided in situ measurements inside the winter stratospheric polar vortex and allowed the performance of several soundings of the troposphere. The in situ measurements included position, temperature, pressure, ozone, and aerosol particles, along with profiles below the balloon-borne gondolas. Source

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