Simultaneous Occurrence of Different Cloud Types

Warren, Stephen G.; Hahn, Carole J.; London, Julius

doi:10.1175/1520-0450(1985)024<0658:soodct>2.0.co;2

Cited by 121 publications

(80 citation statements)

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“…4a and b. results in Fig. 4b are in good agreement with surface observations (Warren et al, 1985) that provide an estimate of the percentage of low level clouds without any cloud above to be about 40%. Winker et al (1998) show about the same CPDF as that retrieved from the Local Method.…”

Section: Lidar-derived Cloud Top Heightsupporting

confidence: 85%

Comparison of cloud statistics from spaceborne lidar systems

et al. 2008

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Abstract. The distribution of clouds in a vertical column is assessed on the global scale through analysis of lidar measurements obtained from three spaceborne lidar systems: LITE (Lidar In-space Technology Experiment, NASA), GLAS (Geoscience Laser Altimeter System, NASA), and CALIOP (Cloud-Aerosol LIdar with Orthogonal Polarization). Cloud top height (CTH) is obtained from the LITE profiles based on a simple algorithm that accounts for multilayer cloud structures. The resulting CTH results are compared to those obtained by the operational algorithms of the GLAS and CALIOP instruments. Based on our method, spaceborne lidar data are analyzed to establish statistics on the cloud top height. The resulting columnar results are used to investigate the inter-annual variability in the lidar cloud top heights. Statistical analyses are performed for a range of CTH (high, middle, low) and latitudes (polar, middle latitude and tropical). Probability density functions of CTH are developed. Comparisons of CTH developed from LITE, for 2 weeks of data in 1994, with ISCCP (International Satellite Cloud Climatology Project) cloud products show that the cloud fraction observed from spaceborne lidar is much higher than that from ISCCP. Another key result is that ISCCP products tend to underestimate the CTH of optically thin cirrus clouds. Significant differences are observed between LITE-derived cirrus CTH and both GLAS and CALIOP-derived cirrus CTH. Such a difference is due primarily to the lidar signal-to-noise ratio that is approximately a factor of 3 larger for the LITE system than for the other lidars. A statistical analysis for a full year of data highlights the influence of both the InterTropical Convergence Zone and polar stratospheric clouds.

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Section: Lidar-derived Cloud Top Heightsupporting

confidence: 85%

Comparison of cloud statistics from spaceborne lidar systems

et al. 2008

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“…For very thin low clouds (with an optical thickness of ∼ 2), the difference between retrieved cloud heights from CAL and from CRB increased to as much as 1.6 km. Nevertheless, as stated above, when two cloud layers co-exist in the same atmospheric column, usually the low-level cloud is optically thicker than the mid-level cloud (Warren et al, 1985;Wang et al, 1999).…”

Section: Error Characterisationmentioning

confidence: 98%

“…With a view to obtaining estimates of the uncertainties of ROCINN to such double-layer conditions, we have simulated the radiances for a double-cloud-layer model consisting of a mid-level cloud deck (altocumulus/altostratus) on top of the low-level cloud. The upper layer has a top height of 6 km, geometrical thickness of 2 km, and an optical thickness of 10 (Warren et al, 1985).…”

Section: Error Characterisationmentioning

confidence: 99%

“…The large cloud top height values were retrieved for an optically thin lower cloud. However, in reality, with atmospheric scenes with two-layered clouds, it is common that the lower cloud is thicker than the upper one (Warren et al, 1985;Wang et al, 1999). In such cases (lower cloud optical thickness > 20), the cloud top height retrieved with ROCINN_CAL is below 4 km.…”

Section: Error Characterisationmentioning

confidence: 99%

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The operational cloud retrieval algorithms from TROPOMI on board Sentinel-5 Precursor

et al. 2018

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Abstract. This paper presents the operational cloud retrieval algorithms for the TROPOspheric Monitoring Instrument (TROPOMI) on board the European Space Agency Sentinel-5 Precursor (S5P) mission scheduled for launch in 2017.Two algorithms working in tandem are used for retrieving cloud properties: OCRA (Optical Cloud Recognition Algorithm) and ROCINN (Retrieval of Cloud Information using Neural Networks). OCRA retrieves the cloud fraction using TROPOMI measurements in the ultraviolet (UV) and visible (VIS) spectral regions, and ROCINN retrieves the cloud top height (pressure) and optical thickness (albedo) using TROPOMI measurements in and around the oxygen A-band in the near infrared (NIR).Cloud parameters from TROPOMI/S5P will be used not only for enhancing the accuracy of trace gas retrievals but also for extending the satellite data record of cloud information derived from oxygen A-band measurements, a record initiated with the Global Ozone Monitoring Experiment (GOME) on board the second European Remote-Sensing Satellite (ERS-2) over 20 years ago.The OCRA and ROCINN algorithms are integrated in the S5P operational processor UPAS (Universal Processor for UV/VIS/NIR Atmospheric Spectrometers), and we present here UPAS cloud results using the Ozone Monitoring Instrument (OMI) and GOME-2 measurements. In addition, we examine anticipated challenges for the TROPOMI/S5P cloud retrieval algorithms, and we discuss the future validation needs for OCRA and ROCINN.

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“…They collaborated on studies of global cloudiness from 1985 to 2001 (Warren et al, 1985). Around the same time, I worked on the rapid change in Arctic cloudiness in spring using DMSP optical images and PhD student Jeff Key and I analyzed Arctic cloudiness using AVHRR data (Key and Barry, 1989).…”

Section: Cryosphere-climate Initiatives In Ciresmentioning

confidence: 99%

The shaping of climate science: half a century in personal perspective

Barry¹

2015

Hist. Geo Space. Sci.

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Abstract. The paper traces my career as a climatologist from the 1950s and that of most of my graduate students from the late 1960s. These decades were the formative ones in the evolution of climate science. Following a brief account of the history of climatology, a summary of my early training, my initial teaching and research in the UK is discussed. This is followed by new directions at the University of Colorado, Boulder from October 1968. The history of the World Data Center for Glaciology/National Snow and Ice Data Center in Boulder from 1977 is described and climate-cryosphere initiatives at the Cooperative Institute for Research in Environmental Sciences (CIRES). International activities and links are then reported, followed by a section on national and international committees. I then describe my activities during sabbaticals and research leaves. The paper concludes with discussion of my "retirement" activities and an epilogue.

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Simultaneous Occurrence of Different Cloud Types

Cited by 121 publications

References 0 publications

Comparison of cloud statistics from spaceborne lidar systems

Comparison of cloud statistics from spaceborne lidar systems

The operational cloud retrieval algorithms from TROPOMI on board Sentinel-5 Precursor

The shaping of climate science: half a century in personal perspective

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