Evaluation of MODIS and Himawari-8 Low Clouds Retrievals over the Southern Ocean with In Situ Measurements from the SOCRATES Campaign

Kang, Litai; Marchand, Roger; Smith, William L.

doi:10.1002/essoar.10504069.1

Cited by 3 publications

(3 citation statements)

References 37 publications

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“…Cloud observations occur in more altitude bins to the south, either a manifestation of the more frequent occurrence of multi‐layered clouds in the southern SO or the more frequent sampling in that region during SOCRATES. Most N d samples range between 60 and 100 or more mg −1 (similar in cm −3 , Figure ) which is consistent with satellite derived N d climatologically (Bodas‐Salcedo et al., 2019; Grosvenor et al., 2018; I. L. McCoy et al., 2020) and instantaneously (Kang et al., 2021) sampled in this region and season.…”

Section: Resultssupporting

confidence: 83%

Influences of Recent Particle Formation on Southern Ocean Aerosol Variability and Low Cloud Properties

et al. 2021

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The Southern Ocean (SO) is our closest present-day (PD) analog to the pre-industrial (PI) state due to its pristine aerosol (Hamilton et al., 2014). It is also frequently cloudy, providing ample opportunity for aerosol-cloud interactions (ACI) to take place. Understanding the climate response to changes in anthropogenic aerosol (i.e., PI to PD states) will help to reduce the uncertainty in global climate model climate sensitivity and improve climate predictions (Andreae et al., 2005;Forster, 2016). Aerosol-cloud interactions are the main contributor to uncertainty in total radiative forcing (Bellouin et al., 2020). Poor understanding of PI aerosol state is a leading driver of this uncertainty (Carslaw et al., 2013), making observations in pristine

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Section: Resultssupporting

confidence: 83%

Influences of Recent Particle Formation on Southern Ocean Aerosol Variability and Low Cloud Properties

et al. 2021

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“…Bias is also quite low, where observed N d is 101 cm −3 while predicted N eq is 106 cm −3 . This level of performance with a low bias and a correlation coefficient ∼0.7 is comparable to the performance of satellite retrievals for N d (Kang et al., 2021). This confirms that the budget model, which has been previously applied over the sub‐tropics (W12; Mohrmann et al., 2018; Zheng et al., 2018), can be used with confidence in the mid‐latitudes once the wind speed parameterization in the surface term is appropriately adjusted.…”

Section: Resultssupporting

confidence: 74%

“…Specifically, we calculated N eq based on the mean rain rate for the below‐cloud legs and other supporting observations from surrounding legs (see Figure S1 in Supporting Information for schematic), as described below, and obtained an associated estimate for observed N d from cloud droplet probe measurements taken in the adjacent in‐cloud ramps. The observed cloud are close to adiabatic with little systematic variation in the observed N d with height (Kang et al., 2021).…”

Section: Methodsmentioning

confidence: 89%

Coalescence Scavenging Drives Droplet Number Concentration in Southern Ocean Low Clouds

Kang

Marchand

Wood

et al. 2022

Geophysical Research Letters

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Cloud droplet number concentration (Nd) is a key microphysical property that is largely controlled by the balance between sources and sinks of aerosols that serve as cloud condensation nuclei (CCN). Despite being a key sink of CCN, the impact of coalescence scavenging on Southern Ocean (SO) cloud is poorly known. We apply a simple source‐and‐sink budget model based on parameterizations to austral summer aircraft observations to test model behavior and examine the relative influence of processes that determine Nd in SO stratocumulus clouds. The model predicts Nd with little bias and a correlation coefficient of ∼0.7 compared with observations. Coalescence scavenging is found to be an important sink of CCN in both liquid and mixed‐phase precipitating stratocumulus and reduces the predicted Nd by as much as 90% depending on the precipitation rate. The free tropospheric aerosol source controls Nd more strongly than the surface aerosol source during austral summer.

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Evaluation of satellite retrievals of liquid clouds from the GOES-13 imager and MODIS over the midlatitude North Atlantic during the NAAMES campaign

et al. 2021

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Abstract. Satellite retrievals of cloud droplet effective radius (re) and optical depth (τ) from the Thirteenth Geostationary Operational Environmental Satellite (GOES-13) and the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard Aqua and Terra, based on the Clouds and the Earth's Radiant Energy System (CERES) project algorithms, are evaluated with airborne data collected over the midlatitude boundary layer during the North Atlantic Aerosols and Marine Ecosystems Study (NAAMES). The airborne dataset comprises in situ re from the Cloud Droplet Probe (CDP) and remotely sensed re and τ from the airborne Research Scanning Polarimeter (RSP). GOES-13 and MODIS (Aqua and Terra) re values are systematically greater than those from the CDP and RSP by at least 4.8 (GOES-13) and 1.7 µm (MODIS) despite relatively high linear correlation coefficients (r=0.52–0.68). In contrast, the satellite τ underestimates its RSP counterpart by −3.0, with r=0.76–0.77. Overall, MODIS yields better agreement with airborne data than GOES-13, with biases consistent with those reported for subtropical stratocumulus clouds. While the negative bias in satellite τ is mostly due to the retrievals having been collected in highly heterogeneous cloud scenes, the causes for the positive bias in satellite re, especially for GOES-13, are more complex. Although the high viewing zenith angle (∼65∘) and coarser pixel resolution for GOES-13 could explain a re bias of at least 0.7 µm, the higher GOES-13 re bias relative to that from MODIS is likely rooted in other factors. In this regard, a near-monotonic increase was also observed in GOES-13 re up to 1.0 µm with the satellite scattering angle (Θ) over the angular range 116–165∘; that is, re increases toward the backscattering direction. Understanding the variations of re with Θ will require the combined use of theoretical computations along with intercomparisons of satellite retrievals derived from sensors with dissimilar viewing geometry.

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Evaluation of MODIS and Himawari-8 Low Clouds Retrievals over the Southern Ocean with In Situ Measurements from the SOCRATES Campaign

Cited by 3 publications

References 37 publications

Influences of Recent Particle Formation on Southern Ocean Aerosol Variability and Low Cloud Properties

Influences of Recent Particle Formation on Southern Ocean Aerosol Variability and Low Cloud Properties

Coalescence Scavenging Drives Droplet Number Concentration in Southern Ocean Low Clouds

Evaluation of satellite retrievals of liquid clouds from the GOES-13 imager and MODIS over the midlatitude North Atlantic during the NAAMES campaign

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