A Comparison of Cloud Microphysical Properties Derived From MODIS and CALIPSO With In Situ Measurements Over the Wintertime Southern Ocean

Ahn, Eunmi; Huang, Yi; Siems, Steven T.; Manton, M. J.

doi:10.1029/2018jd028535

Cited by 38 publications

(59 citation statements)

References 77 publications

(143 reference statements)

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“…The hemispheric constraint depends on the accuracy of the satellite-derived values of PD N d . As noted in the Introduction, MODIS N d has been extensively validated against aircraft measurements in the NH and parts of the SH (21,28,29). Because aircraft observations of N d are not as plentiful in the more remote regions of the SO, we use other datasets to provide additional assessment of the quality and the believability of the surprising SO MODIS N d pattern (Fig.…”

Section: Resultsmentioning

confidence: 99%

“…The N d derived from satellite retrievals has been shown to be reasonably unbiased in comparison with aircraft measurements (21,(24)(25)(26)(27)(28) and to agree well in both the remote Southern Ocean (SO) (29) and the NH (28). Biases between in situ and N d calculated based on Moderate Resolution Spectroradiometer (MODIS) data are on the order of 1 cm −3 to 20 cm −3 , depending on geographic region and boundary layer stratification, and systematic bias does not scale strongly with N d (27)(28)(29). The hemispheric contrast in N d is a difference, so this should moderate the effects of any systematic biases in N d .…”

Section: Significancementioning

confidence: 90%

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The hemispheric contrast in cloud microphysical properties constrains aerosol forcing

McCoy

Wood

et al. 2020

Proc. Natl. Acad. Sci. U.S.A.

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The change in planetary albedo due to aerosol−cloud interactions during the industrial era is the leading source of uncertainty in inferring Earth’s climate sensitivity to increased greenhouse gases from the historical record. The variable that controls aerosol−cloud interactions in warm clouds is droplet number concentration. Global climate models demonstrate that the present-day hemispheric contrast in cloud droplet number concentration between the pristine Southern Hemisphere and the polluted Northern Hemisphere oceans can be used as a proxy for anthropogenically driven change in cloud droplet number concentration. Remotely sensed estimates constrain this change in droplet number concentration to be between 8 cm−3 and 24 cm−3. By extension, the radiative forcing since 1850 from aerosol−cloud interactions is constrained to be −1.2 W⋅m−2 to −0.6 W⋅m−2. The robustness of this constraint depends upon the assumption that pristine Southern Ocean droplet number concentration is a suitable proxy for preindustrial concentrations. Droplet number concentrations calculated from satellite data over the Southern Ocean are high in austral summer. Near Antarctica, they reach values typical of Northern Hemisphere polluted outflows. These concentrations are found to agree with several in situ datasets. In contrast, climate models show systematic underpredictions of cloud droplet number concentration across the Southern Ocean. Near Antarctica, where precipitation sinks of aerosol are small, the underestimation by climate models is particularly large. This motivates the need for detailed process studies of aerosol production and aerosol−cloud interactions in pristine environments. The hemispheric difference in satellite estimated cloud droplet number concentration implies preindustrial aerosol concentrations were higher than estimated by most models.

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Section: Resultsmentioning

confidence: 99%

Section: Significancementioning

confidence: 90%

The hemispheric contrast in cloud microphysical properties constrains aerosol forcing

McCoy

Wood

et al. 2020

Proc. Natl. Acad. Sci. U.S.A.

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“…The Re biases reported in Figures g and g compare very well with the few existing in situ validation studies of MODIS Re 2.1 . For example, using data from the VAMOS Ocean‐Cloud‐Atmosphere‐Land Study Regional Experiment (VOCALS‐REx) in the Southeast Pacific during October to November 2008 (region ① in Figure g), Painemal and Zuidema () showed an ~1 to 2 μm bias in MODIS Re 2.1 ; from the Rain in Cumulus over the Ocean (RICO) field campaign from November 2004 to January 2005 (region ② in Figure g), Haney () showed MODIS Re 2.1 biases ranging from ~7 to 12μm, and aircraft observations in the southern ocean (region ③ in Figure g) from June to October in 2013 to 2015, Ahn et al () showed an overestimate in MODIS Re 2.1 of ~13 μm on average for nondrizzling clouds. All of these studies line up nicely with the regional Re 2.1 biases shown in Figures g and g.…”

Section: Resultsmentioning

confidence: 99%

“…Comparison between MODIS-retrieved Re and in situ observations shows that overestimates in MODIS Re range from about −0.22 to 13 μm, depending on cloud type, Sun-view geometry, the choice of in situ probe, and the details of the cloud microphysical properties (e.g., Ahn et al, 2018;Glienke et al, 2017;King et al, 2013;Painemal & Zuidema, 2011;Witte et al, 2018). In particular, Witte et al (2018) suggested that while satellite retrievals are commonly validated against in situ measurements, the uncertainty of the aircraft retrievals should be acknowledged.…”

Section: Introductionmentioning

confidence: 99%

Regional Biases in MODIS Marine Liquid Water Cloud Drop Effective Radius Deduced Through Fusion With MISR

Girolamo

Liang

et al. 2019

JGR Atmospheres

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Satellite measurements from Terra's Moderate Resolution Imaging Spectroradiometer (MODIS) represent our longest, single‐platform, global record of the effective radius (Re) of the cloud drop size distribution. Quantifying its error characteristics has been challenging because systematic errors in retrieved Re covary with the structural characteristics of the cloud and the Sun‐view geometry. Recently, it has been shown that the bias in MODIS Re can be estimated by fusing MODIS data with data from Terra's Multi‐angle Imaging SpectroRadiometer (MISR). Here, we relate the bias to the observed underlying conditions to derive regional‐scale, bias‐corrected, monthly‐mean Re1.6, Re2.1, and Re3.7 values retrieved from the 1.6, 2.1, and 3.7 μm MODIS spectral channels. Our results reveal that monthly‐mean bias in Re2.1 exhibits large regional dependency, ranging from at least ~1 to 10 μm (15 to 60%) varying with scene heterogeneity, optical depth, and solar zenith angle. Regional bias‐corrected monthly‐mean Re2.1 ranges from 4 to 17 μm, compared to 10 to 25 μm for uncorrected Re2.1, with estimated uncertainties of 0.1 to 1.8 μm. The bias‐corrected monthly‐mean Re3.7 and Re2.1 show difference of approximately +0.6 μm in the coastal marine stratocumulus regions and down to approximately −2 μm in the cumuliform cloud regions, compared to uncorrected values of about −1 to −6 μm, respectively. Bias‐corrected Re values compare favorably to other independent data sources, including field observations, global model simulations, and satellite retrievals that do not use retrieval techniques similar to MODIS. This work changes the interpretation of global Re distributions from MODIS Re products and may further impact studies, which use the original MODIS Re products to study, for example, aerosol‐cloud interactions and cloud microphysical parameterization.

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“…Painemal and Zuidema (2011) found that the Moderate Resolution Imaging Spectroradiometer (MODIS) retrievals overestimated the cloud droplet r e by about 15–20% or 2.1 μm compared to in situ aircraft observations for marine stratocumulus over the Southeast Pacific. Ahn et al (2018) found that CALIPSO and MODIS underestimated mixed‐phase cloud occurrence, and MODIS (2.1‐μm channel) overestimated r e by about 13 μm for nondrizzling clouds and by about 10 μm for heavy drizzling cases. Using different near‐infrared bands, the satellite‐based r e could also vary significantly due to the different photon penetration depths.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Cloud Microphysical Properties Derived From MODIS and Himawari‐8 Using In Situ Aircraft Measurements Over the Southern Ocean

Zhao

Wang

et al. 2020

Earth and Space Science

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Cloud microphysical properties from aircraft measurements during the Southern Ocean Clouds, Radiation, Aerosol Transport Experimental Study are used to evaluate the cloud products from the geostationary satellite Himawari-8 (H-8) and the polar-orbiting satellite the Moderate Resolution Imaging Spectroradiometer (MODIS). Compared to the in situ aircraft observations when aircraft flew horizontally near cloud tops, the cloud droplet effective radius (r e ) and number concentration (N d ) from H-8 (MODIS) are 33% (26%-31%) and 2% (9-13%) larger. Both the H-8 and MODIS retrievals behave similarly for liquid-only and mixed-phase low-level clouds, indicating the weak sensitivity of the satellite cloud retrieval performance to cloud phase. The r e and N d of the cloud profiles from aircraft measurements were also used to compare with the satellite product. It shows that H-8 r e and N d agree better with aircraft measurements when considering only the in situ data acquired in the upper portions (highest 20%) of the clouds. Roughly, the r e overestimation by H-8 decreases from 18% to 3% when considering the upper portions of clouds compared to all cloud layer averages, except for one case with drizzles appeared. In addition, the performance of MODIS r e and N d is highly dependent on the wavelengths the retrieval method uses. The droplet r e retrievals using wavelength of 1.6 μm have much larger biases than that using the other two channels. The potential effects of the cloud vertical variation and the photon penetration depth, the cloud heterogeneity, the cloud droplet size spectra, and the drizzle on satellite retrievals have also been discussed. is a co-corresponding author with Chuanfeng Zhao Key Points:• Himawari-8 (MODIS) cloud product overestimates r e near cloud top by 33% (26-31%) over Southern Ocean • Himawari8 r e and N d agree better with aircraft measurements when considering only the in situ data acquired in the upper portions of clouds • The performance of MODIS retrievals depends on the wavelength, with larger biases at 1.6 μm than 2.1 and 3.7 μm

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A Comparison of Cloud Microphysical Properties Derived From MODIS and CALIPSO With In Situ Measurements Over the Wintertime Southern Ocean

Cited by 38 publications

References 77 publications

The hemispheric contrast in cloud microphysical properties constrains aerosol forcing

The hemispheric contrast in cloud microphysical properties constrains aerosol forcing

Regional Biases in MODIS Marine Liquid Water Cloud Drop Effective Radius Deduced Through Fusion With MISR

Evaluation of Cloud Microphysical Properties Derived From MODIS and Himawari‐8 Using In Situ Aircraft Measurements Over the Southern Ocean

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