Impacts of active satellite sensors' low-level cloud detection limitations on cloud radiative forcing in the Arctic

Liu, Yinghui

doi:10.5194/acp-22-8151-2022

Cited by 5 publications

(2 citation statements)

References 65 publications

(70 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Third, the lowest levels from CloudSat's vertical profiles suffer from ground clutter due to reflections at the surface called blind zone. This blind zone prevents the cloud assessment roughly below the first kilometer (Palerme et al, 2019;Lamer et al, 2020;Liu, 2022). Using ground-based radar measurements as reference, Maahn et al (2014) showed that CloudSat underestimates the total precipitation by 9 percent points (pp) over Ny-Ålesund, Svalbard.…”

Section: Introductionmentioning

confidence: 99%

“…CloudSat observations have been compared with airborne remote sensing (e.g., Gayet et al, 2009;Painemal et al, 2019) for relatively homogeneous clouds at higher altitudes to calibrate airborne instruments (Barker et al, 2008;Protat et al, 2009Protat et al, , 2011. For the first time, Liu (2022) investigates synthetic CloudSat cloud masks in the Arctic region. These data are based on radar reflectivities from QuickBeam radar forward simulations (Haynes et al, 2007) that used vertical profiles of retrieved cloud properties from ground-based radar and lidar during the SHEBA (Surface Heat Budget of the Arctic Ocean) experiment.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Assessing Arctic low-level clouds and precipitation from above – a radar perspective

Schirmacher

Kollias

Lamer

et al. 2023

Preprint

View full text Add to dashboard Cite

Abstract. Most Arctic clouds occur below 2 km altitude as revealed by CloudSat satellite observations. However, recent studies suggest that the relatively coarse spatial resolution, low sensitivity, and blind zone of the radar installed on CloudSat may not enable it to comprehensively document low-level clouds. We investigate the impact of these limitations on the Arctic low- level cloud fraction, which is the amount of cloudy points with respect to all points as a function of height, derived from CloudSat radar observations. For this purpose, we leverage highly resolved vertical profiles of low-level cloud fraction derived from downlooking Microwave Radar/radiometer for Arctic Clouds (MiRAC) radar reflectivity measurements. MiRAC has been operated during four aircraft campaigns taking place in the vicinity of Svalbard during different times of the year and covering more than 25,000 km. This allows us to study the dependence of CloudSat limitations on different synoptic and surface conditions. A forward simulator converts MiRAC measurements to synthetic CloudSat radar reflectivities. These forward simulations are compared with the original CloudSat observations for four satellite underflights to prove the suitability of our forward- simulation approach. Above CloudSat’s blind zone of 1 km and below 2.5 km, the forward simulations reveal that CloudSat would overestimate the MiRAC cloud fraction over all campaigns by about 6 percent points (pp) due to its horizontal resolution, by 12 pp due to its range resolution, and underestimate it by 10 pp due to its sensitivity. Especially during cold air outbreaks over open water, high reflectivity clouds appear below 1.5 km, which are stretched by CloudSat’s pulse length causing the forward-simulated cloud fraction to be 16 pp higher than that observed by MiRAC. The pulse length merges multilayer clouds, whereas thin low-reflectivity clouds remain undetected. Consequently, 48 % of clouds observed by MiRAC belong to multilayer clouds, which reduces by a factor of 4 for the forward-simulated CloudSat counterpart. Despite the overestimation between 1 and 2.5 km, the overall low-level cloud fraction is strongly reduced due to CloudSat’s blind zone that misses a cloud fraction of 32 % and half of the total (mainly light) precipitation amount.

show abstract

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Assessing Arctic low-level clouds and precipitation from above – a radar perspective

Schirmacher

Kollias

Lamer

et al. 2023

Preprint

View full text Add to dashboard Cite

show abstract

Decreased cloud cover partially offsets the cooling effects of surface albedo change due to deforestation

Luo,

Quaas,

Han

2024

Nat Commun

View full text Add to dashboard Cite

Characterisation of low-base and mid-base clouds and their thermodynamic phase over the Southern Ocean and Arctic marine regions

Dietel,

Sourdeval,

Hoose

2024

Atmos. Chem. Phys.

View full text Add to dashboard Cite

Abstract. The thermodynamic phase of clouds in low and middle levels over the Southern Ocean and the Arctic marine regions is poorly known, leading to uncertainties in the radiation budget in weather and climate models. To improve the knowledge of the cloud phase, we analyse 2 years of the raDAR-liDAR (DARDAR) dataset based on active satellite instruments. We classify clouds according to their base and top height and focus on low-, mid-, and mid- to low-level clouds as they are the most frequent in the mixed-phase temperature regime. Low-level single-layer clouds occur in 8 %–15 % of all profiles, but single-layer clouds spanning the mid-level also amount to approx. 15 %. Liquid clouds show mainly a smaller vertical extent but a horizontally larger extent compared to ice clouds. The results show the highest liquid fractions for low-level and mid-level clouds. Two local minima in the liquid fraction are observed around cloud top temperatures of −15 and −5 °C. Mid-level and mid- to low-level clouds over the Southern Ocean and low-level clouds in both polar regions show higher liquid fractions if they occur over sea ice compared to the open ocean. Low-level clouds and mid- to low-level clouds with high sea salt concentrations, used as a proxy for sea spray, show reduced liquid fractions. In mid-level clouds, dust shows the largest correlations with liquid fraction, with a lower liquid fraction for a higher dust aerosol concentration. Low-level clouds clearly show the largest contribution to the shortwave cloud radiative effect in both polar regions, followed by mid- to low-level clouds.

show abstract

Impacts of active satellite sensors' low-level cloud detection limitations on cloud radiative forcing in the Arctic

Cited by 5 publications

References 65 publications

Assessing Arctic low-level clouds and precipitation from above – a radar perspective

Assessing Arctic low-level clouds and precipitation from above – a radar perspective

Decreased cloud cover partially offsets the cooling effects of surface albedo change due to deforestation

Characterisation of low-base and mid-base clouds and their thermodynamic phase over the Southern Ocean and Arctic marine regions

Contact Info

Product

Resources

About