The effects of aerosols on water cloud microphysics and   macrophysics based on satellite-retrieved data over East Asia and the   North Pacific

Michibata, Takuro; Kawamoto, Kazuhiko

doi:10.5194/acp-14-11935-2014

Cited by 25 publications

(31 citation statements)

References 41 publications

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“…The data products, 2B-TAU (Polonsky, 2008), 2B-GEOPROF , and ECMWF-AUX (Partain, 2007) were used for the period June 2006 to April 2011, i.e., a total of 5 full years. This facilitated the construction of stable statistics with a horizontal resolution (2.5 • grid boxes in this study) close to the GCM output.…”

Section: Cloudsat and Modismentioning

confidence: 99%

“…Although it could be a part of the reason for discrepancies between the model and observations, this would mostly be canceled when susceptibilities of cloud and precipitation to aerosol loading are evaluated by a logarithmic form. This study applies the uncertainty thresholds of < 5 and < 1 µm for τ c and r e from the 2B-TAU product, respectively, which contributes to the reduction of the retrieval uncertainty of N c described above as much as possible (Michibata et al, 2014).…”

Section: Cloudsat and Modismentioning

confidence: 99%

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The source of discrepancies in aerosol–cloud–precipitation interactions between GCM and A-Train retrievals

et al. 2016

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Abstract. Aerosol-cloud interactions are one of the most uncertain processes in climate models due to their nonlinear complexity. A key complexity arises from the possibility that clouds can respond to perturbed aerosols in two opposite ways, as characterized by the traditional "cloud lifetime" hypothesis and more recent "buffered system" hypothesis. Their importance in climate simulations remains poorly understood. Here we investigate the response of the liquid water path (LWP) to aerosol perturbations for warm clouds from the perspective of general circulation model (GCM) and ATrain remote sensing, through process-oriented model evaluations. A systematic difference is found in the LWP response between the model results and observations. The model results indicate a near-global uniform increase of LWP with increasing aerosol loading, while the sign of the response of the LWP from the A-Train varies from region to region. The satellite-observed response of the LWP is closely related to meteorological and/or macrophysical factors, in addition to the microphysics. The model does not reproduce this variability of cloud susceptibility (i.e., sensitivity of LWP to perturbed aerosols) because the parameterization of the autoconversion process assumes only suppression of rain formation in response to increased cloud droplet number, and does not consider macrophysical aspects that serve as a mechanism for the negative responses of the LWP via enhancements of evaporation and precipitation. Model biases are also found in the precipitation microphysics, which suggests that the model generates rainwater readily even when little cloud water is present. This essentially causes projections of unrealistically frequent and light rain, with high cloud susceptibilities to aerosol perturbations.

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Section: Cloudsat and Modismentioning

confidence: 99%

Section: Cloudsat and Modismentioning

confidence: 99%

The source of discrepancies in aerosol–cloud–precipitation interactions between GCM and A-Train retrievals

et al. 2016

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“…To reduce a possible over-estimation of AOD, cases with AOD greater than 1.5 were excluded from further analysis. In this paper, we focused on warm clouds with CTP larger than 700 hPa and CWP lower than 200 g m −2 , as most aerosols exist in the lower troposphere (Michibata et al, 2014). In addition, only cases with CPI = 1 (liquid-water cloud) were included.…”

Section: Data Processingmentioning

confidence: 99%

Analysis of aerosol effects on warm clouds over the Yangtze River Delta from multi-sensor satellite observations

et al. 2017

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Abstract. Aerosol effects on low warm clouds over the Yangtze River Delta (YRD, eastern China) are examined using co-located MODIS, CALIOP and CloudSat observations. By taking the vertical locations of aerosol and cloud layers into account, we use simultaneously observed aerosol and cloud data to investigate relationships between cloud properties and the amount of aerosol particles (using aerosol optical depth, AOD, as a proxy). Also, we investigate the impact of aerosol types on the variation of cloud properties with AOD. Finally, we explore how meteorological conditions affect these relationships using ERA-Interim reanalysis data. This study shows that the relation between cloud properties and AOD depends on the aerosol abundance, with a different behaviour for low and high AOD (i.e. AOD < 0.35 and AOD > 0.35). This applies to cloud droplet effective radius (CDR) and cloud fraction (CF), but not to cloud optical thickness (COT) and cloud top pressure (CTP). COT is found to decrease when AOD increases, which may be due to radiative effects and retrieval artefacts caused by absorbing aerosol. Conversely, CTP tends to increase with elevated AOD, indicating that the aerosol is not always prone to expand the vertical extension. It also shows that the COT-CDR and CWP (cloud liquid water path)-CDR relationships are not unique, but affected by atmospheric aerosol loading. Furthermore, separation of cases with either polluted dust or smoke aerosol shows that aerosol-cloud interaction (ACI) is stronger for clouds mixed with smoke aerosol than for clouds mixed with dust, which is ascribed to the higher absorption efficiency of smoke than dust. The variation of cloud properties with AOD is analysed for various relative humidity and boundary layer thermodynamic and dynamic conditions, showing that high relative humidity favours larger cloud droplet particles and increases cloud formation, irrespective of vertical or horizontal level. Stable atmospheric conditions enhance cloud cover horizontally. However, unstable atmospheric conditions favour thicker and higher clouds. Dynamically, upward motion of air parcels can also facilitate the formation of thicker and higher clouds. Overall, the present study provides an understanding of the impact of aerosols on cloud properties over the YRD. In addition to the amount of aerosol particles (or AOD), evidence is provided that aerosol types and ambient environmental conditions need to be considered to understand the observed relationships between cloud properties and AOD.

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“…Conversely, for LWP > 200 g m -2 , there are no obvious changes with growing LWPs because of limited data. This can be contrasted to an increasing tendency that has been observed in the Amazon because of different meteorological and biosphere conditions (Yu et al, 2007;Michibata et al, 2014). In this study, we use AOD/LWP to reflect the proportion of aerosol and water content.…”

Section: Cloud Droplet Radius (Cdr)mentioning

confidence: 93%

“…The discrepancy between the ROI-A and ROI-D is possibly due to different dominant aerosol types, leading to different conversion rates (from cloud water to rainwater) (Sorooshian et al, 2013). The amount of precipitation increases slowly at low CDR of 10-15 µm but rapidly at higher values of 15-25 µm (Michibata et al, 2014). Since there are few CDRs of high values in the study, the low frequency of large rain events becomes explanatory.…”

Section: Cloud Droplet Radius (Cdr)mentioning

confidence: 96%

Effects of Wintertime Polluted Aerosol on Clouds over the Yangtze River Delta: Case Study

Duan

Wang

et al. 2018

Aerosol Air Qual. Res.

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The effects of aerosol on clouds are examined over the Yangtze River Delta (YRD) using 3 months of satellite data from the polluted wintertime from December 2013 to February 2014. The relationships between aerosol properties, and cloud micro-and macro-physical parameters are analyzed in detail to clarify the differences in cloud development under various aerosol and meteorological conditions. Complex relationships between the aerosol optical depth (AOD), and the cloud droplet radius (CDR), liquid water path (LWP) and cloud optical thickness (COT) exist in four regions of interest (ROIs). High aerosol loading does not obviously affect LWPs and COTs; in fact, aerosols inhibit development of low-and medium-low clouds over coastal areas-an effect that is more pronounced in low clouds (< 5 km) than high ones. Low aerosol loading plays a positive role in promoting the COT of high-and low-clouds over areas dominated by maritime aerosol. Aerosol loading exerts a significant influence on COTs, LWPs and CDRs in valley and coal industry districts except during high-cloud conditions. The ranges of COTs, LWPs and CDRs in dry-polluted areas are lower than in other places, which suggests that dust aerosol has little effect on cloud properties. Synoptic conditions also strongly impact cloud distribution, in particular, an unstable synoptic condition leads to cloud development on a larger horizontal and vertical scale. Ground pollution enhances the amount of low-level cloud cover even under stable conditions. Aerosol plays an important role in wintertime cloud evolution in the low layers of the troposphere (< 5 km) when the atmosphere is stable.

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The effects of aerosols on water cloud microphysics and macrophysics based on satellite-retrieved data over East Asia and the North Pacific

Cited by 25 publications

References 41 publications

The source of discrepancies in aerosol–cloud–precipitation interactions between GCM and A-Train retrievals

The source of discrepancies in aerosol–cloud–precipitation interactions between GCM and A-Train retrievals

Analysis of aerosol effects on warm clouds over the Yangtze River Delta from multi-sensor satellite observations

Effects of Wintertime Polluted Aerosol on Clouds over the Yangtze River Delta: Case Study

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