Characterizing relative humidity with respect to ice in midlatitude cirrus clouds as a function of atmospheric state

Dzambo, Andrew M.; Turner, David D.

doi:10.1002/2015jd024643

Cited by 6 publications

(5 citation statements)

References 48 publications

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“…Sakai et al (2014) measured cirrus clouds with an instrumented balloon and ground-based lidar and also detected their highest supersaturations near the cloud tops. Dzambo and Turner (2016) also came to the same conclusions by using a combination of radiosonde and millimeter-wavelength cloud radar data from the SGP, as did Korolev and Isaac (2006) by using in situ measurements.…”

Section: Conclusion and Discussionmentioning

confidence: 54%

“…Groß et al (2014) analyzed water vapor measurements by WALES taken over Germany during November 2010 and found an RHi mode of 98 % and an ice supersaturation frequency of 30 %, which is in accordance with our findings, but contrary to our findings they reported only 2 % of data points over RHi 120 %. Differences may arise due to the seasonal variability of RHi and the fact that they performed measurements only in one atmospheric system (Kahn et al, 2008;Dzambo and Turner, 2016). Other studies also found supersaturations of around 30 % in midlatitude cirrus clouds; namely, Comstock et al (2004) analyzed Raman lidar measurements taken over the Southern Great Plains (SGP) and Ovarlez et al (2002) in situ measurements over Scotland, during the INter hemispheric difference in Cirrus properties from Anthropogenic emissions (INCA) campaign (Ström et al, 2003).…”

Section: Conclusion and Discussionmentioning

confidence: 99%

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Characteristics of supersaturation in midlatitude cirrus clouds and their adjacent cloud-free air

et al. 2023

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Abstract. Water vapor measurements of midlatitude cirrus clouds, obtained by the WAter vapour Lidar Experiment in Space (WALES) lidar system during the Mid-Latitude Cirrus (ML-CIRRUS) airborne campaign, which took place in the spring of 2014 over central Europe and the NE Atlantic Ocean, are combined with model temperatures from the European Centre for Medium-Range Weather Forecasts (ECMWF) and analyzed. Our main focus is to derive the distribution and temporal evolution of humidity with respect to ice within cirrus clouds and in their adjacent cloud-free air. We find that 34.1 % of in-cloud data points are supersaturated with respect to ice. Supersaturation is also detected in 6.8 % of the cloud-free data points. When the probability density of the relative humidity over ice (RHi) is calculated with respect to temperature for the in-cloud data points from the ML-CIRRUS dataset, there are two peaks: one around 225 K and close to saturation, RHi = 100 %, and a second one at colder temperatures around 218 K in subsaturation, RHi = 79 %. These two regions seem to represent two cirrus cloud categories: in situ formed and liquid origin. Regarding their vertical structure, most clouds have higher supersaturations close to the cloud top and become subsaturated near the cloud bottom. Finally, we find that the vertical structure of RHi within the clouds is also indicative of their life stage. RHi skewness tends to go from positive to negative values as the cloud ages. RHi modes are close to saturation in young clouds, supersaturated in mature clouds and subsaturated in dissipating clouds.

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Section: Conclusion and Discussionmentioning

confidence: 54%

Section: Conclusion and Discussionmentioning

confidence: 99%

Characteristics of supersaturation in midlatitude cirrus clouds and their adjacent cloud-free air

et al. 2023

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“…Using lidar measurements of cirrus clouds over the mid-latitudes and following the abovementioned methods, we found that the distribution of RHi in mid-latitude cirrus clouds has a 96 % mode value, which is close to the ice saturation threshold, (2014) analysed water vapor measurements by WALES taken over Germany, during November 2010 and found an RHi mode of 98 %, and an ice supersaturation frequency of 30 %, which is in accordance with our findings, but contrary to our findings they reported only 2 % of data points over RHi 120 %. Differences may arise due to the seasonal variability of RHi, and the fact that they performed measurements only in one atmospheric system (Kahn et al, 2008;Dzambo and Turner, 2016). Other studies also found supersaturations around 30 % in mid-latitude cirrus clouds.…”

Section: Conclusion and Discussionmentioning

confidence: 97%

Characteristics of supersaturation in mid-latitude cirrus clouds and their adjacent cloud-free air

Dekoutsidis

Groß

Wirth

et al. 2022

Preprint

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Abstract. Water vapor measurements of mid-latitude cirrus clouds, obtained by the WALES (WAter vapor Lidar Experiment in Space) lidar system during the Mid-Latitude Cirrus (ML-Cirrus) airborne campaign, that took place in spring of 2014 over central Europe and the NE Atlantic Ocean, are combined with model temperatures from the European Centre for Medium-Range Weather Forecasts (ECMWF) and analysed. Our main focus is to derive the distribution and temporal evolution of humidity with respect to ice within cirrus clouds and in their adjacent cloud-free air. We find that 34.1 % of in-cloud data points are supersaturated with respect to ice. Supersaturation is also detected in 6.8 % of the cloud-free data points. When the probability density of the Relative Humidity over ice (RHi) is calculated with respect to temperature for the in-cloud data points from the ML-Cirrus data-set there are two peaks. One around 225 K and close to saturation, RHi = 100 % and a second one at colder temperatures around 215 K in subsaturation, RHi = 90 %. These two regions seem to represent two cirrus cloud categories: in-situ formed and liquid-origin. Regarding their vertical structure, most clouds have higher supersaturations close to the cloud-top and become subsaturated near the cloud bottom. Finally, we find that the vertical structure of RHi within the clouds is also indicative of their life stage. RHi skewness tends to go from positive to negative values as the cloud ages. RHi modes are close to saturation in young clouds, supersaturated in mature clouds and subsaturated in dissipating clouds.

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“…Formation, extent, and lifetime of these areas are affected by convection, moisture transport, and vertical air motions on different spatial and temporal scales. Seasonal and geographical variations are linked to weather patterns and have been inferred from observations (Dzambo & Turner, 2016; Irvine et al., 2012; Lamquin et al., 2012). Magnitude and variability in RHI is observed to be large in the midlatitude storm tracks and small in the subtropics (Kahn et al., 2009).…”

Section: Introductionmentioning

confidence: 96%

Ice Supersaturation Variability in Cirrus Clouds: Role of Vertical Wind Speeds and Deposition Coefficients

Kärcher,

Jensen,

Pokrifka

et al. 2023

JGR Atmospheres

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Aircraft measurements reveal ice supersaturation statistics in cirrus (ISSs) with broad maxima around ice saturation and pronounced variance. In this study, processes shaping ISSs in midlatitude and tropical upper tropospheric conditions are systematically investigated. Water vapor deposition and sublimation of size‐resolved ice crystal populations are simulated in an air parcel framework. Mesoscale temperature fluctuations (MTFs) due to gravity waves force the temporal evolution of supersaturation. Various levels of background wave forcing and cirrus thickness are distinguished in stochastic ensemble simulations. Kinetic limitations to ice mass growth are brought about by supersaturation‐dependent deposition coefficients that represent efficient and inefficient growth modes as a function of ice crystal size. The simulations identify a wide range of deposition coefficients in cirrus, but most values stay above 0.01 such that kinetic limitations to water uptake remain moderate. Supersaturation quenching times are long, typically 0.5–2 hr. The wave forcing thus causes a remarkably large variability in ISSs and cirrus microphysical properties except in the thickest cirrus, producing ensemble‐mean ISSs in line with in‐situ measurements. ISS variance is controlled by MTFs and increases with decreasing cirrus integral radii. In comparison, the impact of ice crystal growth rates on ISSs is small. These results contribute to efforts directed at identifying and solving issues associated with ice‐supersaturated areas and non‐equilibrium cirrus physics in global models.

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Characterizing relative humidity with respect to ice in midlatitude cirrus clouds as a function of atmospheric state

Cited by 6 publications

References 48 publications

Characteristics of supersaturation in midlatitude cirrus clouds and their adjacent cloud-free air

Characteristics of supersaturation in midlatitude cirrus clouds and their adjacent cloud-free air

Characteristics of supersaturation in mid-latitude cirrus clouds and their adjacent cloud-free air

Ice Supersaturation Variability in Cirrus Clouds: Role of Vertical Wind Speeds and Deposition Coefficients

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