scholarly journals Temperature Profiles and Lapse Rate Climatology in Altostratus and Nimbostratus Clouds Derived from GPS RO Data

2013 ◽  
Vol 26 (16) ◽  
pp. 6000-6014 ◽  
Author(s):  
S. Yang ◽  
X. Zou
Keyword(s):  
Water Content ◽  
Liquid Water Content ◽  
Lapse Rate ◽  
Cloud Base ◽  
Retrieval Algorithm ◽  
Cosmic Radio ◽  
Temperature Profiles ◽  
Ice Water Content ◽  
Lapse Rates ◽  
Ice Water

Abstract Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC) radio occultation (RO) refractivity profiles in altostratus and nimbostratus clouds from 2007 to 2010 are first identified based on collocated CloudSat data. Vertical temperature profiles in these clouds are then retrieved from cloudy refractivity profiles. Contributions of cloud liquid water content and ice water content are also included in the retrieval algorithm. The temperature profiles and their lapse rates are compared with those from a standard GPS RO wet retrieval without including cloud effects. On average, the temperatures from cloudy retrieval are about 0.5–1.0 K warmer than the GPS RO wet retrieval, except for the altitudes near the nimbostratus base. The differences of temperature between the two methods are largest in summer and smallest in winter. The lapse rate in altostratus clouds is around 6.5°–7.5°C km−1 and does not vary greatly with height. On the contrary, the lapse rate increases significantly with height in nimbostratus clouds, from about 2.5°–3.5°C km−1 near the cloud base to about 5.0°–6.0°C km−1 at cloud center and 6.5°–7.5°C km−1 below the cloud top. Seasonal variability of lapse rate derived from the cloudy retrieval is larger than that derived from the wet retrieval. The lapse rate within clouds is smaller in summer and larger in winter. The mean lapse rate decreases with temperature in all seasons.

scholarly journals Properties of Arctic liquid and mixed phase clouds from ship-borne Cloudnet observations during ACSE 2014

2020 ◽  
Author(s):  
Peggy Achtert ◽  
Ewan J. O'Connor ◽  
Ian M. Brooks ◽  
Georgia Sotiropoulou ◽  
Matthew D. Shupe ◽  
...  
Keyword(s):  
Water Content ◽  
Liquid Water ◽  
Liquid Water Content ◽  
Mixed Phase ◽  
Cloud Base ◽  
Ice Clouds ◽  
Ice Water Content ◽  
Mixed Phase Clouds ◽  
Ice Water ◽  
Cloud Top Temperature

Abstract. This study presents Cloudnet retrievals of Arctic clouds from measurements conducted during a three-month research expedition along the Siberian shelf during summer and autumn 2014. During autumn, we find a strong reduction in the occurrence of liquid clouds and an increase for both mixed-phase and ice clouds at low levels compared to summer. About 80 % of all liquid clouds observed during the research cruise show a liquid water path below the infra-red black body limit of approximately 50 g m−2. The majority of mixed-phase and ice clouds had an ice water path below 20 g m−2. Cloud properties are analysed with respect to cloud-top temperature and boundary layer structure. Changes in these parameters have little effect on the geometric thickness of liquid clouds while mixed-phase clouds during warm-air advection events are generally thinner than when such events were absent. Cloud-top temperatures are very similar for all mixed-phase clouds. However, more cases of lower cloud-top temperature were observed in the absence of warm-air advection. Profiles of liquid and ice water content are normalised with respect to cloud base and height. For liquid water clouds, the liquid water content profile reveals a strong increase with height with a maximum within the upper quarter of the clouds followed by a sharp decrease towards cloud top. Liquid water content is lowest for clouds observed below an inversion during warm-air advection events. Most mixed-phase clouds show a liquid water content profile with a very similar shape to that of liquid clouds but with lower maximum values during warm-air advection. The normalised ice water content profiles in mixed-phase clouds look different from that of liquid water content. They show a wider range in maximum values with lowest ice water content for clouds below an inversion and highest values for clouds above or extending through an inversion. The ice water content profile generally peaks at a height below the peak in the liquid water content profile – usually in the centre of the cloud, sometimes closer to cloud base, likely due to particle sublimation as the crystals fall through the cloud.

Retrieval of Hydrometeor Profiles in Tropical Cyclones and Convection from Combined Radar and Radiometer Observations

2006 ◽  
Vol 45 (8) ◽  
pp. 1096-1115 ◽  
Author(s):  
Haiyan Jiang ◽  
Edward J. Zipser
Keyword(s):  
Water Content ◽  
Tropical Cyclones ◽  
Liquid Water ◽  
Liquid Water Content ◽  
Retrieval Algorithm ◽  
Large Variability ◽  
Ice Water Content ◽  
Ice Water ◽  
Combined Algorithm

Abstract A retrieval algorithm is described to estimate vertical profiles of precipitation ice water content and liquid water content in tropical cyclones and convection over ocean from combined spaceborne radar and radiometer measurements. In the algorithm, the intercept parameter N0s in the exponential particle size distribution for rain, snow, and graupel are adjusted iteratively to minimize the difference between observed brightness temperatures and simulated ones by using a simulated annealing optimization method. Sensitivity tests are performed to understand the effects of the input parameters. The retrieval technique is investigated using the Earth Resources (ER)-2 aircraft Doppler radar and Advanced Microwave Precipitation Radiometer data in tropical cyclones and convection. An indirect validation is performed by comparing the measured and retrieved 50-GHz (independent channel) brightness temperature. The global agreement shows not only the quality of the inversion procedure, but also the consistency of the retrieved parameters with observations. The direct validation of the ice water content retrieval by using the aircraft in situ microphysical measurements indicates that the algorithm can provide reliable ice water content estimates, especially in stratiform regions. In convective regions, the large variability of the microphysical characteristics causes a large uncertainty in the retrieval, although the mean difference between the retrieved ice water content and aircraft-derived ice water content is very small. The ice water content estimated by a radar-only empirical relationship is higher than those retrieved by the combined algorithm and derived by the aircraft in situ observations. The new combined algorithm contains information that should improve ice water content estimates from either radar-only or passive microwave–only measurements. An important caveat for this study is that it concerns precipitation estimates. In this paper, ice and liquid water content should be interpreted as precipitation ice and liquid water content.

scholarly journals Properties of Arctic liquid and mixed-phase clouds from shipborne Cloudnet observations during ACSE 2014

2020 ◽  
Vol 20 (23) ◽  
pp. 14983-15002
Author(s):  
Peggy Achtert ◽  
Ewan J. O'Connor ◽  
Ian M. Brooks ◽  
Georgia Sotiropoulou ◽  
Matthew D. Shupe ◽  
...  
Keyword(s):  
Water Content ◽  
Liquid Water ◽  
Liquid Water Content ◽  
Mixed Phase ◽  
Cloud Base ◽  
Ice Clouds ◽  
Ice Water Content ◽  
Mixed Phase Clouds ◽  
Ice Water ◽  
Cloud Top Temperature

Abstract. This study presents Cloudnet retrievals of Arctic clouds from measurements conducted during a 3-month research expedition along the Siberian shelf during summer and autumn 2014. During autumn, we find a strong reduction in the occurrence of liquid clouds and an increase for both mixed-phase and ice clouds at low levels compared to summer. About 80 % of all liquid clouds observed during the research cruise show a liquid water path below the infrared black body limit of approximately 50 g m−2. The majority of mixed-phase and ice clouds had an ice water path below 20 g m−2. Cloud properties are analysed with respect to cloud-top temperature and boundary layer structure. Changes in these parameters have little effect on the geometric thickness of liquid clouds while mixed-phase clouds during warm-air advection events are generally thinner than when such events were absent. Cloud-top temperatures are very similar for all mixed-phase clouds. However, more cases of lower cloud-top temperature were observed in the absence of warm-air advection. Profiles of liquid and ice water content are normalized with respect to cloud base and height. For liquid water clouds, the liquid water content profile reveals a strong increase with height with a maximum within the upper quarter of the clouds followed by a sharp decrease towards cloud top. Liquid water content is lowest for clouds observed below an inversion during warm-air advection events. Most mixed-phase clouds show a liquid water content profile with a very similar shape to that of liquid clouds but with lower maximum values during events with warm air above the planetary boundary layer. The normalized ice water content profiles in mixed-phase clouds look different from those of liquid water content. They show a wider range in maximum values with the lowest ice water content for clouds below an inversion and the highest values for clouds above or extending through an inversion. The ice water content profile generally peaks at a height below the peak in the liquid water content profile – usually in the centre of the cloud, sometimes closer to cloud base, likely due to particle sublimation as the crystals fall through the cloud.

scholarly journals Measuring ice- and liquid-water properties in mixed-phase cloud layers at the Leipzig Cloudnet station

2016 ◽  
Vol 16 (16) ◽  
pp. 10609-10620 ◽  
Author(s):  
Johannes Bühl ◽  
Patric Seifert ◽  
Alexander Myagkov ◽  
Albert Ansmann
Keyword(s):  
Water Content ◽  
Liquid Water ◽  
Mass Flux ◽  
Mixed Phase ◽  
Cloud Base ◽  
Doppler Velocity ◽  
Special Focus ◽  
Data Set ◽  
Ice Water Content ◽  
Ice Water

Abstract. An analysis of the Cloudnet data set collected at Leipzig, Germany, with special focus on mixed-phase layered clouds is presented. We derive liquid- and ice-water content together with vertical motions of ice particles falling through cloud base. The ice mass flux is calculated by combining measurements of ice-water content and particle Doppler velocity. The efficiency of heterogeneous ice formation and its impact on cloud lifetime is estimated for different cloud-top temperatures by relating the ice mass flux and the liquid-water content at cloud top. Cloud radar measurements of polarization and Doppler velocity indicate that ice crystals formed in mixed-phase cloud layers with a geometrical thickness of less than 350 m are mostly pristine when they fall out of the cloud.

scholarly journals Physical Properties of High-Level Cloud over Land and Ocean from CloudSat–CALIPSO Data

2014 ◽  
Vol 27 (23) ◽  
pp. 8966-8978 ◽  
Author(s):  
Juan Huo ◽  
Daren Lu
Keyword(s):  
Linear Relationship ◽  
Water Content ◽  
Northern China ◽  
Occurrence Frequency ◽  
Radiative Energy ◽  
Cloud Base ◽  
The Pacific ◽  
Ice Water Content ◽  
High Level ◽  
Ice Water

Abstract Unlike other cloud types, high-level clouds play an important role, often imposing a warming effect, in the earth–atmosphere radiative energy budget. In this paper, macro- and microphysical characteristics of cirrus clouds, such as their occurrence frequency, geometric scale, water content, and particle size, over northern China (land area, herein called the L area) and the Pacific Ocean (ocean area, herein the O area) are analyzed and compared based on CloudSat and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) products from 1 January 2007 to 31 December 2010. Over both areas, statistical analysis shows that cirrus occurrence approached 33% in summer whereas it was only ~10% in winter, >50% of cirrus cloud thicknesses were in the range of ~(0.25–1.5) km, there were >98% ice particles in high-level clouds, and temperature had a closer linear relationship with ice effective radius (IER) than height. Also, the seasonal difference of this linear relationship is minor over both land and ocean. Comparisons reveal that the mean occurrence frequency, mean cloud thickness, range of cloud-base and cloud-top height, IER, and ice water content of cirrus in summer were generally greater in winter, and greater over the O area than over the L area. However, the relationship between IER and temperature over land is close to that over ocean.

Evaluation of Microphysics Schemes in Tropical Cyclones using Polarimetric Radar Observations: Convective Precipitation in an Outer Rainband

2021 ◽  
Author(s):  
Dan Wu ◽  
Fuqing Zhang ◽  
Xiaomin Chen ◽  
Alexander Ryzhkov ◽  
Kun Zhao ◽  
...  
Keyword(s):  
Water Content ◽  
Liquid Water ◽  
Liquid Water Content ◽  
Cloud Microphysics ◽  
Convective Precipitation ◽  
Polarimetric Radar ◽  
Error Source ◽  
Ice Water Content ◽  
Ice Water ◽  
Ice Phase

AbstractCloud microphysics significantly impact tropical cyclone precipitation. A prior polarimetric radar observational study by Wu et al. (2018) revealed the ice-phase microphysical processes as the dominant microphysics mechanisms responsible for the heavy precipitation in the outer rainband of Typhoon Nida (2016). To assess the model performance regarding microphysics, three double-moment microphysics schemes (i.e., Thompson, Morrison, and WDM6) are evaluated by performing a set of simulations of the same case. While these simulations capture the outer rainband’s general structure, microphysics in the outer rainbands are strikingly different from the observations. This discrepancy is primarily attributed to different microphysics parameterizations in these schemes, rather than the differences in large-scale environments due to cloud-environment interactions. An interesting finding in this study is that the surface rain rate or liquid water content is inversely proportional to the simulated mean raindrop sizes. The mass-weighted raindrop diameters are overestimated in the Morrison and Thompson schemes and underestimated in the WDM6 scheme, while the former two schemes produce lower liquid water content than WDM6. Compared with the observed ice water content based on a new polarimetric radar retrieval method, the ice water content above the environmental 0 °C level in all simulations is highly underestimated, especially at heights above 12 km MSL where large concentrations of small ice particles are typically prevalent. This finding suggests that the improper treatment of ice-phase processes is potentially an important error source in these microphysics schemes. Another error source identified in the WDM6 scheme is overactive warm-rain processes that produce excessive concentrations of smaller raindrops.

scholarly journals Signatures of Tropical Cyclone Intensification in Satellite Measurements of Ice and Liquid Water Content

2017 ◽  
Vol 145 (10) ◽  
pp. 4081-4091 ◽  
Author(s):  
Shun-Nan Wu ◽  
Brian J. Soden
Keyword(s):  
Tropical Cyclone ◽  
Water Content ◽  
Liquid Water ◽  
Vertical Profile ◽  
Liquid Water Content ◽  
Intensity Change ◽  
Latent Heating ◽  
Cloud Water Content ◽  
Ice Water Content ◽  
Ice Water

This study examines how the structure and amount of cloud water content are associated with tropical cyclone (TC) intensity change using the CloudSat Tropical Cyclone (CSTC) dataset. Theoretical and modeling studies have demonstrated the importance of both the magnitude and vertical structure of latent heating in regulating TC intensity. However, the direct observations of the latent heat release and its vertical profile are scarce. The CSTC dataset provides the opportunity to infer the vertical profile of the latent heating from CloudSat retrievals of cloud ice water content (IWC) and liquid water content (LWC). It is found that strengthening storms have ~20% higher IWC than weakening storms, especially in the midtroposphere near the eyewall. These differences in IWC exist up to 24 h prior to an intensity change and are observed for all storm categories except major TCs. A similar analysis of satellite-observed rainfall rates indicates that strengthening storms have slightly higher rainfall rates 6 h prior to intensification. However, the rainfall signal is less robust than what is observed for IWC, and disappears for lead times greater than 6 h. Such precursors of TC intensity change provide observationally based metrics that may be useful in constraining model simulations of TC genesis and intensification.

COSMIC GPS Radio Occultation Temperature Profiles in Clouds

2010 ◽  
Vol 138 (4) ◽  
pp. 1104-1118 ◽  
Author(s):  
L. Lin ◽  
X. Zou ◽  
R. Anthes ◽  
Y-H. Kuo
Keyword(s):  
Relative Humidity ◽  
Water Content ◽  
Radio Occultation ◽  
Lapse Rate ◽  
Gps Radio Occultation ◽  
Clear Sky ◽  
Ice Water Content ◽  
Temperature Retrieval ◽  
Sky Conditions ◽  
Ice Water

Abstract Thermodynamic states in clouds are closely related to physical processes such as phase changes of water and longwave and shortwave radiation. Global Positioning System (GPS) radio occultation (RO) data are not affected by clouds and have high vertical resolution, making them ideally suited to cloud profiling on a global basis. By comparing the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) RO refractivity data with those of the National Centers for Environmental Prediction–National Center for Atmospheric Research (NCEP–NCAR) reanalysis and ECMWF analysis for soundings in clouds and clear air separately, a systematic bias of opposite sign was found between large-scale global analyses and the GPS RO observations under cloudy and clear-sky conditions. As a modification to the standard GPS RO wet temperature retrieval that does not distinguish between cloudy- and clear-sky conditions, a new cloudy retrieval algorithm is proposed to incorporate the knowledge that in-cloud specific humidity (which affects the GPS refractivities) should be close to saturation. To implement this new algorithm, a linear regression model for a sounding-dependent relative humidity parameter α is first developed based on a high correlation between relative humidity and ice water content. In the absence of ice water content information, α takes an empirical value of 85%. The in-cloud temperature profile is then retrieved from GPS RO data modeled by a weighted sum of refractivities with and without the assumption of saturation. Compared to the standard wet retrieval, the cloudy temperature retrieval is consistently warmer within clouds by ∼2 K and slightly colder near the cloud top (∼1 K) and cloud base (1.5 K), leading to a more rapid increase of the lapse rate with height in the upper half of the cloud, from a nearly constant moist lapse rate below and at the cloud middle (∼6°C km−1) to a value of 7.7°C km−1, which must be closer to the dry lapse rate than the standard wet retrieval.

scholarly journals A Microphysical Analysis of Elevated Convection in the Comma Head Region of Continental Winter Cyclones

2016 ◽  
Vol 74 (1) ◽  
pp. 69-91 ◽  
Author(s):  
Amanda M. Murphy ◽  
Robert M. Rauber ◽  
Greg M. McFarquhar ◽  
Joseph A. Finlon ◽  
David M. Plummer ◽  
...  
Keyword(s):  
Water Content ◽  
Particle Concentration ◽  
Liquid Water Content ◽  
Head Region ◽  
Winter Storms ◽  
Cloud Radar ◽  
Ice Water Content ◽  
Using Data ◽  
Convective Cells ◽  
Ice Water

Abstract An analysis of the microphysical structure of elevated convection within the comma head region of two winter cyclones over the midwestern United States is presented using data from the Wyoming Cloud Radar (WCR) and microphysical probes on the NSF/NCAR C-130 aircraft during the Profiling of Winter Storms campaign. The aircraft penetrated 36 elevated convective cells at various temperatures T and distances below cloud top zd. The statistical properties of ice water content (IWC), liquid water content (LWC), ice particle concentration with diameter > 500 μm N>500, and median mass diameter Dmm, as well as particle habits within these cells were determined as functions of zd and T for active updrafts and residual stratiform regions originating from convective towers that ascended through unsaturated air. Insufficient data were available for analysis within downdrafts. For updrafts stratified by zd, distributions of IWC, N>500, and Dmm for all zd between 1000 and 4000 m proved to be statistically indistinct. These results imply that turbulence and mixing within the updrafts effectively distributed particles throughout their depths. A decrease in IWC and N>500 in the layer closest to cloud top was likely related to cloud-top entrainment. Within residual stratiform regions, decreases in IWC and N>500 and increases in Dmm were observed with depth below cloud top. These trends are consistent with particles falling and aggregating while entrainment and subsequent sublimation was occurring.

scholarly journals Ice water content vertical profiles of high-level clouds: classification and impact on radiative fluxes

2015 ◽  
Vol 15 (21) ◽  
pp. 12327-12344 ◽  
Author(s):  
A. G. Feofilov ◽  
C. J. Stubenrauch ◽  
J. Delanoë
Keyword(s):  
Water Content ◽  
Surface Fluxes ◽  
Radiative Properties ◽  
Cloud Base ◽  
Vertical Profiles ◽  
Ice Clouds ◽  
Isosceles Trapezoid ◽  
Ice Water Content ◽  
High Level ◽  
Ice Water

Abstract. In this article, we discuss the shape of ice water content (IWC) vertical profiles in high ice clouds and its effect on their radiative properties, both in short- and in long-wave bands (SW and LW). Based on the analysis of collocated satellite data, we propose a minimal set of primitive shapes (rectangular, isosceles trapezoid, lower and upper triangle), which represents the IWC profiles sufficiently well. About 75 % of all high-level ice clouds (P < 440 hPa) have an ice water path (IWP) smaller than 100 g m−2, with a 10 % smaller contribution from single layer clouds. Most IWC profiles (80 %) can be represented by a rectangular or isosceles trapezoid shape. However, with increasing IWP, the number of lower triangle profiles (IWC rises towards cloud base) increases, reaching up to 40 % for IWP values greater than 300 g m−2. The number of upper triangle profiles (IWC rises towards cloud top) is in general small and decreases with IWP, with the maximum occurrence of 15 % in cases of IWP less than 10 g m−2. We propose a statistical classification of the IWC shapes using IWP as a single parameter. We have estimated the radiative effects of clouds with the same IWP and with different IWC profile shapes for five typical atmospheric scenarios and over a broad range of IWP, cloud height, cloud vertical extent, and effective ice crystal diameter (De). We explain changes in outgoing LW fluxes at the top of the atmosphere (TOA) by the cloud thermal radiance while differences in TOA SW fluxes relate to the De vertical profile within the cloud. Absolute differences in net TOA and surface fluxes associated with these parameterized IWC profiles instead of assuming constant IWC profiles are in general of the order of 1–2 W m−2: they are negligible for clouds with IWP < 30 g m−2, but may reach 2 W m−2 for clouds with IWP > 300 W m−2.

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