Abstract
Abstract. We present recent progress on nighttime retrievals of aerosol and cloud optical properties over the PEARL (Polar Environmental Atmospheric Research Laboratory) station at Eureka (Nunavut, Canada) in the High Arctic (80° N, 86° W). In the spring of 2011 and 2012, a star photometer was employed to acquire aerosol optical depth (AOD) data, while vertical aerosol and cloud backscatter profiles were measured using the CANDAC Raman Lidar (CRL). We used a simple backscatter coefficient threshold (βthr) to distinguish aerosols from clouds and, assuming that aerosols were largely fine mode (FM)/sub-micron, to distinguish FM aerosols from coarse mode (CM)/super-micron cloud or crystal particles. Using prescribed lidar ratios, we computed FM and CM AODs that were compared with analogous AODs estimated from spectral star photometry. We found (βthr dependent) coherences between the lidar and star photometer for both FM events and CM cloud and crystal events with averaged, FM absolute differences being
Highlights
The Arctic region, often viewed as an early indicator of climate change, has been recently undergoing major alterations including alarmingly increasing temperatures, retreating seaice cover and record low-ozone concentrations in the winter (Duarte et al, 2012; Manney et al, 2011; Moritz et al, 2002; Wang and Key, 2003)
We presented recent progress related to the nighttime optical depth retrievals of aerosols and clouds using star photometry at the high Arctic PEARL station
aerosol optical depth (AOD) measurements, acquired during the polar winter are scarce compared to the ensemble of polar summer measurements but represent an important source of information for the development of aerosol optical climatologies, instrumental intercomparisons, satellite validation and tie-down points for aerosol/cloud models
Summary
The Arctic region, often viewed as an early indicator of climate change, has been recently undergoing major alterations including alarmingly increasing temperatures, retreating seaice cover and record low-ozone concentrations in the winter (Duarte et al, 2012; Manney et al, 2011; Moritz et al, 2002; Wang and Key, 2003). The synergy of ground-based sunphotometer and lidar instruments has proven to be very effective in the analysis of day-time aerosol measurements. Recent studies show the potential of moon photometry measurements using sunphotometer-type instruments (Barreto et al, 2013; Berkoff et al, 2011) Despite inherent problems such as changing lunar brightness, moon photometry can currently provide AODs near full moon (Berkoff et al, 2011). Is to show the capabilities of star photometer–lidar synergy in the Arctic as a tool for characterizing polar winter phenomena in terms of their optical properties While both instruments are discussed, the focus of the work is on star photometry with additional details on lidar analysis given elsewhere.
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