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L. Cucurull, R. Atlas, R. Li, M. J. Mueller, and R. N. Hoffman

1. Introduction Observing system simulation experiments (OSSEs) provide a unique framework to evaluate the impact of current and proposed or future observing systems ( Atlas 1997 ; Atlas et al. 1985 ). While observing system experiments (OSEs) can be used to assess the value of existing observations, OSSEs enable a quantitative evaluation of proposed observing technologies. Different from the real-world scenario, the “truth” is known in the OSSE system, providing an effective technique to

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Tanya R. Peevey, Jason M. English, Lidia Cucurull, Hongli Wang, and Andrew C. Kren

the DA system. Both Atlas et al. (2015) and Ma et al. (2015) evaluated the impact of simulated wind lidar observations on forecast skill and found an improvement in the wind and mass fields, both in the extratropics and tropics. Moreover, Atlas et al. (2015) found that the short-term forecasts over the tropics were significantly reduced. OSSE studies have also evaluated the impact of rawinsondes globally for wind and temperature fields ( Privé et al. 2014a ) and dropsondes for tropical

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Maike Ahlgrimm and Richard Forbes

) are calculated from the 30-s Cloudnet retrieval of the two-channel microwave radiometer observations. Hourly samples with inferior quality observations of either surface radiation or hydrometeor profile are excluded from the evaluation. The target classification is only performed when both lidar and radar are available, and surface radiation measurements must be available for at least 50 out of 60 min within an hourly period. b. Model Data from the operational global ECMWF IFS model at the grid

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Aaron J. Hill, Christopher C. Weiss, and Brian C. Ancell

1. Introduction Since the 1940s, targeted observing has been employed to improve numerical weather prediction (NWP) forecasts, particularly for weather phenomena that NWP models struggle to forecast accurately and for which errors may grow quickly. Over the last few decades, sophisticated algorithms have been developed and tested that objectively target new observations, such as adjoint sensitivity (e.g., Errico 1997 ; Bergot 1999 ) and singular vectors (e.g., Palmer et al. 1998 ; Buizza

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Maike Ahlgrimm and Richard Forbes

occurrence and cloud-top height using spaceborne lidar observations . Mon. Wea. Rev. , 137 , 4225 – 4237 . Bechtold , P. , M. Köhler , T. Jung , F. Doblas-Reyes , M. Leutbecher , M. Rodwell , F. Vitart , and G. Balsamo , 2008 : Advances in simulating atmospheric variability with the ECMWF model: From synoptic to decadal time-scales . Quart. J. Roy. Meteor. Soc. , 134 ( 634 ), 1337 – 1351 . Berg , L. , and E. Kassianov , 2008 : Temporal variability of fair

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Jon M. Schrage and Andreas H. Fink

sunrise. The perpendicular backscatter coefficient at 532 nm from the Cloud Aerosol Lidar with Orthogonal Polarization (CALIOP) lidar on board the Cloud–Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite has been used to illustrate examples of stratiform clouds. CALIPSO is part of the A-train satellite constellation ( Stephens et al. 2002 ) and passes over the region between approximately 0115 and 0130 LT. The CALIOP lidar is a nonscanning instrument with a very

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Anthony W. Lyza, Todd A. Murphy, Barrett T. Goudeau, Preston T. Pangle, Kevin R. Knupp, and Ryan A. Wade

pixel. (Copyright American Meteorological Society. Used with permission.) LK18 detailed evidence that surface winds tend to be stronger and more backed atop Sand Mountain than in the adjacent Tennessee Valley, and that a maximum in surface wind magnitude has been observed along the northwestern edge of Sand Mountain. Long-term surface observations from both atop Sand Mountain and within the Tennessee Valley presented in LK18 suggest that cloud-base heights relative to ground level tend to differ

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C. E. Dorman, D. P. Rogers, W. Nuss, and W. T. Thompson

pattern that extended from 30 m to above 800 m elevation were flown in both alongcoast and cross-coast legs. A nominally 30-m level flight leg will be referred to as a 10-m track when pressure and air temperature are systematically adjusted to 10 m as explained in section 4 . Vertical section profiles were constructed from the various levels flown along a leg and the sawtooth soundings. In addition to standard flight-level observations, the C-130 also carried a Scanning Aerosol Backscatter Lidar

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Scot T. Heckman and William R. Cotton

) show evidence of ashort-wave trough passing over Green Bay, Wisconsin,between 1500 and 2100 UTC. This disturbance wascharacterized by a wind shift and a temperature changebetween 5 and 10 km. The timing of these changeswere such that they coincided with the passage of awell-defined clearing of upper-level clouds, as seen inGOES imagery. Lidar observations from Wausaushowed the clouds clearing in the 5-10-km layer butsome cirrus r~maining at 10.5 km. This evidence suggests that a short

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Bart Geerts, Binod Pokharel, and David A. R. Kristovich

and orographic precipitation . J. Atmos. Sci. , 60 , 1543 – 1559 , doi: 10.1175/2995.1 . Korolev , A. V. , J. W. Strapp , and G. A. Isaac , 1998 : Evaluation of the accuracy of PMS optical array probes . J. Atmos. Oceanic Technol. , 15 , 708 – 720 , doi: 10.1175/1520-0426(1998)015<0708:EOTAOP>2.0.CO;2 . Kristovich , D. A. R. , B. Geerts , Q. Miao , L. Stoecker , and J. M. Ritzman , 2012 : Airborne cloud radar and lidar observations of blowing snow during the ASCII

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