The effect of extratropical cyclones on satellite-retrieved aerosol properties over ocean
Geophysical Research Letters 38:13 (2011)
Abstract:
Extratropical cyclones may have a significant effect on column aerosol properties over ocean. European Centre for Medium Range Weather Forecasts (ECMWF) derived storm-centric composites of Moderate Resolution Imaging Spectroradiometer (MODIS) and Advanced Along-Track Scanning Radiometer (AATSR) aerosol optical depth and aerosol size parameters are produced for the North Atlantic and the South Atlantic oceans. It is found that retrieved aerosol optical depth and aerosol size both increase near the center of the composite extratropical cyclones. Using composites of ECMWF ERA-Interim reanalysis data, it is demonstrated that wind speed is a considerably more likely explanatory variable than relative humidity for the aerosol observations. A comparison of composites for both MODIS and AATSR, which uses a wind speed dependent sea-surface brightness model in the aerosol retrieval, suggests that although surface brightness effects may contribute towards some of the observations, wind speed dependent emission of sea salt also appears to make a significant contribution to the observed aerosol properties. © 2011 by the American Geophysical Union.Retrieval of macrophysical cloud parameters from MIPAS: Algorithm description
Atmospheric Measurement Techniques 4:4 (2011) 683-704
Abstract:
The Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) onboard ENVISAT has the potential to be particularly useful for studying high, thin clouds, which have been difficult to observe in the past. This paper details the development, implementation and testing of an optimal-estimation- type retrieval for three macrophysical cloud parameters (cloud top height, cloud top temperature and cloud extinction coefficient) from infrared spectra measured by MIPAS. A preliminary estimation of a parameterisation of the optical and geometrical filling of the measurement field-of-view by cloud is employed as the first step of the retrieval process to improve the choice of a priori for the macrophysical parameters themselves. Preliminary application to single-scattering simulations indicates that the retrieval error stemming from uncertainties introduced by noise and by a priori variances in the retrieval process itself is small - although it should be noted that these retrieval errors do not include the significant errors stemming from the assumption of homogeneity and the non-scattering nature of the forward model. Such errors are preliminarily and qualitatively assessed here, and are likely to be the dominant error sources. The retrieval converges for 99% of input cases, although sometimes fails to converge for vetically-thin (<1 km) clouds. The retrieval algorithm is applied to MIPAS data; the results of which are qualitatively compared with CALIPSO cloud top heights and PARASOL cloud opacities. From comparison with CALIPSO cloud products, it must be noted that the cloud detection method used in this algorithm appears to potentially misdetect stratospheric aerosol layers as cloud. This algorithm has been adopted by the European Space Agency's "MIPclouds" project. © Author(s) 2011.Cloud retrievals from satellite data using optimal estimation: Evaluation and application to ATSR
Atmospheric Measurement Techniques Discussions 4:2 (2011) 2389-2431
Global retrieval of ATSR cloud parameters and evaluation (GRAPE): dataset assessment
ATMOSPHERIC CHEMISTRY AND PHYSICS 11:8 (2011) 3913-3936
Impact of clouds on aerosol scattering as observed by lidar
(2011)