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1. Introduction There are 10 basic cloud types, grouped into three primary categories: high clouds, mid clouds, and low clouds ( http://www.srh.noaa.gov/srh/jetstream/clouds/cloudwise/types.html ). The focus of this study is to characterize the macrophysical and microphysical properties of the high clouds: cirrus. The motivation for this chapter comes from workshops conducted on “Data Analysis and Presentation of Cloud Microphysical Measurements” in Seaside, Oregon, in 2010, at the Swiss
1. Introduction There are 10 basic cloud types, grouped into three primary categories: high clouds, mid clouds, and low clouds ( http://www.srh.noaa.gov/srh/jetstream/clouds/cloudwise/types.html ). The focus of this study is to characterize the macrophysical and microphysical properties of the high clouds: cirrus. The motivation for this chapter comes from workshops conducted on “Data Analysis and Presentation of Cloud Microphysical Measurements” in Seaside, Oregon, in 2010, at the Swiss
) and International Satellite Cloud Climatology Project (ISCCP) satellite data. They find definite biases in longwave cloud forcing for tropical and midlatitude cirrus that suggest the models are producing high clouds that are generally too thick (i.e., have too strong of a longwave cloud forcing) relative to measurements. This high bias in longwave cloud forcing suggests that the model climates are using cirrus to offset other significant problems in the simulated hydrological cycle that must have
) and International Satellite Cloud Climatology Project (ISCCP) satellite data. They find definite biases in longwave cloud forcing for tropical and midlatitude cirrus that suggest the models are producing high clouds that are generally too thick (i.e., have too strong of a longwave cloud forcing) relative to measurements. This high bias in longwave cloud forcing suggests that the model climates are using cirrus to offset other significant problems in the simulated hydrological cycle that must have
1. Introduction Numerous studies have demonstrated that thin cirrus clouds are frequently present near the tropical tropopause ( Winker and Trepte 1998 ; McFarquhar et al. 2000 ; Massie et al. 2002 ; Pfister et al. 2001 ; Dessler et al. 2006 ). These clouds have been identified as one of the sources of uncertainty in the study of the earth’s radiation budget and climate ( Liou 1986 ; Lynch et al. 2002 ). Pfister et al. (2001) classified cirrus clouds into two types in terms of their
1. Introduction Numerous studies have demonstrated that thin cirrus clouds are frequently present near the tropical tropopause ( Winker and Trepte 1998 ; McFarquhar et al. 2000 ; Massie et al. 2002 ; Pfister et al. 2001 ; Dessler et al. 2006 ). These clouds have been identified as one of the sources of uncertainty in the study of the earth’s radiation budget and climate ( Liou 1986 ; Lynch et al. 2002 ). Pfister et al. (2001) classified cirrus clouds into two types in terms of their
1. Introduction Cirrus clouds are composed of varying densities of ice crystals of a variety of shapes and sizes. As light passes through the suspended layers of ice crystals, some is scattered over a range of directions and some is absorbed. The fraction of the original light exiting the cloud is of interest in determining levels of incoming solar radiation, or the light levels from stars in nighttime observations of the galaxy. Another application for determining the transmissive properties
1. Introduction Cirrus clouds are composed of varying densities of ice crystals of a variety of shapes and sizes. As light passes through the suspended layers of ice crystals, some is scattered over a range of directions and some is absorbed. The fraction of the original light exiting the cloud is of interest in determining levels of incoming solar radiation, or the light levels from stars in nighttime observations of the galaxy. Another application for determining the transmissive properties
1. Introduction Ice clouds of the upper troposphere, hereinafter referred to as cirrus, are known to play a key role in the radiative balance of Earth ( Stephens et al. 1990 ; Ackerman et al.1988 ) because the infrared greenhouse and solar albedo effects depend on both microphysical (condensed water mass and effective particle size) and macroscopic properties (cloud cover and vertical location). These properties are poorly represented in numerical models, and many outstanding issues regarding
1. Introduction Ice clouds of the upper troposphere, hereinafter referred to as cirrus, are known to play a key role in the radiative balance of Earth ( Stephens et al. 1990 ; Ackerman et al.1988 ) because the infrared greenhouse and solar albedo effects depend on both microphysical (condensed water mass and effective particle size) and macroscopic properties (cloud cover and vertical location). These properties are poorly represented in numerical models, and many outstanding issues regarding
al. (1994) proposed the independent pixel approximation (IPA) scheme, which divides the model grid box into independent pixels with separate optical/microphysical properties. Comparisons with Monte Carlo or other radiation transport simulations indicate that the IPA avoids many of the drawbacks of the PPH and is a good approximation in many cloud types, including cirrus ( Liou and Rao 1996 ; Carlin et al. 2002 ). Nonetheless, only a three-dimensional radiation transfer scheme using a realistic
al. (1994) proposed the independent pixel approximation (IPA) scheme, which divides the model grid box into independent pixels with separate optical/microphysical properties. Comparisons with Monte Carlo or other radiation transport simulations indicate that the IPA avoids many of the drawbacks of the PPH and is a good approximation in many cloud types, including cirrus ( Liou and Rao 1996 ; Carlin et al. 2002 ). Nonetheless, only a three-dimensional radiation transfer scheme using a realistic
1. Introduction The size, shape, and concentration of ice crystals in cirrus clouds have a major impact on the earth’s radiation budget. For example, Liou (1986) showed that cirrus particles play an important role in the energy balance of the earth–atmosphere system through their interactions with solar and terrestrial radiation. Stephens et al. (1990) concluded that the prediction of cirrus cloud feedback on climate is limited by our lack of understanding of the relationship between the
1. Introduction The size, shape, and concentration of ice crystals in cirrus clouds have a major impact on the earth’s radiation budget. For example, Liou (1986) showed that cirrus particles play an important role in the energy balance of the earth–atmosphere system through their interactions with solar and terrestrial radiation. Stephens et al. (1990) concluded that the prediction of cirrus cloud feedback on climate is limited by our lack of understanding of the relationship between the
GHz) cloud-profiling radar capable of measuring a broad spectrum of clouds from cumulonimbus to cirrus, with the caveat that optically thin cirrus clouds that cover 30% of the tropics are left undetected ( Haladay and Stephens 2009 ). The CALIOP, a dual-wavelength lidar aboard the CALIPSO , complements CloudSat observations owing to its high sensitivity to thin cirrus clouds at the expense of severe attenuation within modest to thick cloud layers. This work adopts the merged CloudSat and
GHz) cloud-profiling radar capable of measuring a broad spectrum of clouds from cumulonimbus to cirrus, with the caveat that optically thin cirrus clouds that cover 30% of the tropics are left undetected ( Haladay and Stephens 2009 ). The CALIOP, a dual-wavelength lidar aboard the CALIPSO , complements CloudSat observations owing to its high sensitivity to thin cirrus clouds at the expense of severe attenuation within modest to thick cloud layers. This work adopts the merged CloudSat and
1. Introduction Cirrus clouds are recognized as an important component of the earth’s climate system because of their effects on the energy and water cycles ( Ramanathan et al. 1989 ; Randall et al. 1989 ; Ackerman et al. 1988 ; Jensen et al. 2004 ). With this recognition, many projects [e.g., the Atmospheric Radiation Measurement Program (ARM; Stokes and Schwartz 1994 )] and field programs [e.g., The Cirrus Regional Study of Tropical Anvil and Cirrus Layer (CRYSTAL) Florida Area Cirrus
1. Introduction Cirrus clouds are recognized as an important component of the earth’s climate system because of their effects on the energy and water cycles ( Ramanathan et al. 1989 ; Randall et al. 1989 ; Ackerman et al. 1988 ; Jensen et al. 2004 ). With this recognition, many projects [e.g., the Atmospheric Radiation Measurement Program (ARM; Stokes and Schwartz 1994 )] and field programs [e.g., The Cirrus Regional Study of Tropical Anvil and Cirrus Layer (CRYSTAL) Florida Area Cirrus
1. Introduction Clouds consisting exclusively of ice particles, so-called cirrus clouds, account for roughly one-third of the total cloud cover (e.g., Gasparini et al. 2018 ), yet their net radiative effect is still one major source of uncertainty in the climate system. Since the albedo effect and greenhouse effect are on the same order of magnitude for those clouds, microphysical details of ice crystals (as, e.g., shape or size; see Zhang et al. 1999 ; Krämer et al. 2020 ) may
1. Introduction Clouds consisting exclusively of ice particles, so-called cirrus clouds, account for roughly one-third of the total cloud cover (e.g., Gasparini et al. 2018 ), yet their net radiative effect is still one major source of uncertainty in the climate system. Since the albedo effect and greenhouse effect are on the same order of magnitude for those clouds, microphysical details of ice crystals (as, e.g., shape or size; see Zhang et al. 1999 ; Krämer et al. 2020 ) may
