scholarly journals Evaluation of cloud properties from reanalyses over East Asia with a radiance-based approach

2020 ◽  
Vol 13 (3) ◽  
pp. 1033-1049 ◽  
Author(s):  
Bin Yao ◽  
Chao Liu ◽  
Yan Yin ◽  
Zhiquan Liu ◽  
Chunxiang Shi ◽  
...  
Keyword(s):  
East Asia ◽  
Deep Convection ◽  
China Meteorological Administration ◽  
Ice Clouds ◽  
Brightness Temperatures ◽  
Evaluation Approach ◽  
Cloud Properties ◽  
Fifth Generation ◽  
East Asia Region ◽  
Modern Era

Abstract. Extensive observational and numerical investigations have been performed to better characterize cloud properties. However, due to the large variations in cloud spatiotemporal distributions and physical properties, quantitative depictions of clouds in different atmospheric reanalysis datasets are still highly uncertain. A radiance-based evaluation approach is introduced and performed to evaluate the quality of cloud properties from reanalysis datasets. The China Meteorological Administration reanalysis (CRA); the ECMWF fifth-generation reanalysis (ERA5); and the Modern-Era Retrospective analysis for Applications, Version 2 (MERRA-2), i.e., those reanalyses providing sufficient cloud information, are considered. To avoid the influence of assumptions and uncertainties on satellite retrieval algorithms, forward radiative transfer simulations are used as a bridge to translate the reanalyses to corresponding radiances that are expected to be observed by satellites. The simulated reflectances and brightness temperatures (BTs) are directly compared with observations from the Advanced Himawari Imager onboard the Himawari-8 satellite in the East Asia region. We find that the simulated reflectances and BTs based on CRA and ERA5 are close to each other. CRA represents the total and midlayer cloud cover better than the other two datasets, and ERA5 depicts deep-convection structures more closely than CRA does. Comparisons of the simulated and observed BT differences suggest that water clouds are generally overestimated in ERA5 and MERRA-2, and MERRA-2 also overestimates the ice clouds over cyclone centers. Overall, clouds from CRA, ERA5, and MERRA-2 show their own advantages in different aspects. The ERA5 reanalysis has the best capability to represent the cloudy atmospheres over East Asia, and the CRA representations are close to those in ERA5.

scholarly journals Assessment of cloud properties from the reanalysis with satellite observations over East Asia

2019 ◽  
Author(s):  
Bin Yao ◽  
Chao Liu ◽  
Yan Yin ◽  
Zhiquan Liu ◽  
Chunxiang Shi ◽  
...  
Keyword(s):  
Radiative Transfer ◽  
East Asia ◽  
Deep Convection ◽  
Satellite Observation ◽  
Reanalysis Data ◽  
Satellite Observations ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
China Meteorological Administration ◽  
Cloud Properties

Abstract. Extensive observational and numerical investigations have been performed to better characterize cloud properties. However, due to the large variations of cloud spatiotemporal distributions and physical properties, quantitative depictions of clouds in different atmospheric reanalysis datasets are still highly uncertain, and cloud parameters in the models to produce those datasets remain largely unconstrained. A radiance-based evaluation approach is introduced and performed to assess the quality of cloud properties by directly comparing reanalysis-driven forward radiative transfer results with radiances from satellite observation. The newly developed China Meteorological Administration Reanalysis data (CRA), the ECMWF’s Fifth-generation Reanalysis (ERA5), and the Modern-Era Retrospective Analysis for Applications, Version 2 (MERRA-2) are considered in the present study. To avoid the unrealistic assumptions and uncertainties on satellite retrieval algorithms and products, the radiative transfer model (RTM) is used as a bridge to “translate” the reanalysis to corresponding satellite observations. The simulated reflectance and brightness temperatures (BTs) are directly compared with observations from the Advanced Himawari Imager (AHI) onboard the Himawari-8 satellite in the region from 80° E to 160° W between 60° N and 60° S, especially for results over East Asia. Comparisons of the reflectance in the solar and BTs in the infrared (IR) window channels reveal that CRA reanalysis better represents the total cloud cover than the other two reanalysis datasets. The simulated BTs for CRA and ERA5 are close to each other in many pixels, whereas the vertical distributions of cloud properties are significantly different, and ERA5 depicts a better deep convection structure than CRA reanalysis. Comparisons of the BT differences (BTDs) between the simulations and observations suggest that the water clouds are generally overestimated in ERA5 and MERRA-2, whereas the ice cloud is responsible for the overestimation over the center of cyclones in ERA5. Overall, the cloud from CRA, ERA5, and MERRA-2 show their own advantages in different aspects. The ERA5 reanalysis is found the most capability in representing the cloudy atmosphere over East Asia, and the results in CRA are close to those in ERA5.

Using Synthetic Brightness Temperatures to Address Uncertainties in Cloud-Top-Height Verification

2017 ◽  
Vol 56 (2) ◽  
pp. 283-296
Author(s):  
Jason E. Nachamkin ◽  
Yi Jin ◽  
Lewis D. Grasso ◽  
Kim Richardson
Keyword(s):  
North Atlantic ◽  
North Atlantic Ocean ◽  
Deep Convection ◽  
Vertical Position ◽  
Sargasso Sea ◽  
Ice Clouds ◽  
Brightness Temperatures ◽  
The North ◽  
Common Problems ◽  
Cloud Tops

AbstractCloud-top verification is inherently difficult because of large uncertainties in the estimates of observed cloud-top height. Misplacement of cloud top associated with transmittance through optically thin cirrus is one of the most common problems. Forward radiative models permit a direct comparison of predicted and observed radiance, but uncertainties in the vertical position of clouds remain. In this work, synthetic brightness temperatures are compared with forecast cloud-top heights so as to investigate potential errors and develop filters to remove optically thin ice clouds. Results from a statistical analysis reveal that up to 50% of the clouds with brightness temperatures as high as 280 K are actually optically thin cirrus. The filters successfully removed most of the thin ice clouds, allowing for the diagnosis of very specific errors. The results indicate a strong negative bias in midtropospheric cloud cover in the model, as well as a lack of land-based convective cumuliform clouds. The model also predicted an area of persistent stratus over the North Atlantic Ocean that was not apparent in the observations. In contrast, high cloud tops associated with deep convection were well simulated, as were mesoscale areas of enhanced trade cumulus coverage in the Sargasso Sea.

An Initialization Scheme for Tropical Cyclone Numerical Prediction by Enhancing Humidity in Deep-Convection Region

2013 ◽  
Vol 52 (10) ◽  
pp. 2260-2277 ◽  
Author(s):  
Jianyong Liu ◽  
Shunan Yang ◽  
Leiming Ma ◽  
Xuwei Bao ◽  
Dongliang Wang ◽  
...  
Keyword(s):  
Tropical Cyclone ◽  
Inner Core ◽  
Deep Convection ◽  
Background Field ◽  
Weather Research And Forecasting ◽  
China Meteorological Administration ◽  
Brightness Temperatures ◽  
Simulated Distribution ◽  
Initialization Scheme ◽  
Spiral Rainbands

AbstractA nudging scheme for humidity fields is implemented in the Advanced Hurricane Weather Research and Forecasting model (WRF) for tropical cyclone (TC) initialization. The scheme improves TC simulation by enhancing the TC humidity profile in deep-convection regions, where it uses satellite Fengyun 2 cloud-top brightness temperatures as a judging criterion. The impacts of the nudging on predicting TC intensity and structure are evaluated through the simulation of TC Khanun (2005) during its movement toward landfall at the coast of Zhejiang Province, China. During the nudging, the humidity distributions at the TC's inner core and along its outer spiral rainbands, where deep convections occur, are both enhanced. As a result, the intensity of the vortex is enhanced, being more consistent to the best-track data from the China Meteorological Administration. Specifically, the nudging modifies the simulated distribution of humidity according to convective activities captured by the satellite and therefore adjusts the development of deep convection in the model, which then influences the intensity and size of TC vortex through diabatic heating. During WRF simulation, the TC vortex initialized from the humidity nudging is dynamically and thermodynamically balanced with the background field, favoring a steady development of the vortex's intensity and structure. Because of the better simulation of TC inner core and outer spiral rainbands, the WRF simulation skills of TC intensity and track are improved.

Impacts of mineral dust on ice clouds in tropical deep convection systems

2014 ◽  
Vol 143 ◽  
pp. 64-72 ◽  
Author(s):  
Q.-L. Min ◽  
R. Li ◽  
B. Lin ◽  
E. Joseph ◽  
V. Morris ◽  
...  
Keyword(s):  
Mineral Dust ◽  
Deep Convection ◽  
Ice Clouds ◽  
Tropical Deep Convection

Status and Prospects of Economic Development in East Asia

2014 ◽  
pp. 42-52
Author(s):  
M. Potapov
Keyword(s):  
Economic Growth ◽  
East Asia ◽  
Industrial Development ◽  
Free Trade Area ◽  
Chinese Economy ◽  
Domestic Investment ◽  
Trade Area ◽  
Structural Problems ◽  
East Asia Region ◽  
Post Industrial

The East Asia region had survived the global economic crisis of 2008–2009. However, the general slowdown in the region indicates many structural problems. The Chinese economy actively switches to the domestic market, giving priority to domestic investment and consumer demand in the maintenance of the economic growth. The development of integration processes in East Asia leaves open the question of the formation of a region-wide free trade area. East Asia is capable to retain the role of economic growth locomotive, moving towards the level of post-industrial development.

scholarly journals A daytime climatological distribution of high opaque ice cloud classes over the Indian summer monsoon region observed from 25-year AVHRR data

2009 ◽  
Vol 9 (12) ◽  
pp. 4185-4196 ◽  
Author(s):  
A. Devasthale ◽  
H. Grassl
Keyword(s):  
Summer Monsoon ◽  
Indian Subcontinent ◽  
Deep Convection ◽  
Temporal Distribution ◽  
Radiative Balance ◽  
Ice Cloud ◽  
Brightness Temperatures ◽  
Spatio Temporal ◽  
Very High ◽  
Summer Monsoon Region

Abstract. A daytime climatological spatio-temporal distribution of high opaque ice cloud (HOIC) classes over the Indian subcontinent (0–40° N, 60° E–100° E) is presented using 25-year data from the Advanced Very High Resolution Radiometers (AVHRRs) for the summer monsoon months. The HOICs are important for regional radiative balance, precipitation and troposphere-stratosphere exchange. In this study, HOICs are sub-divided into three classes based on their cloud top brightness temperatures (BT). Class I represents very deep convection (BT<220 K). Class II represents deep convection (220 K

scholarly journals A water vapor modulated aerosol impact on ice crystal size

2017 ◽  
Author(s):  
Bin Zhao ◽  
Kuo-Nan Liou ◽  
Yu Gu ◽  
Jonathan H. Jiang ◽  
Qinbin Li ◽  
...  
Keyword(s):  
Water Vapor ◽  
Radiative Forcing ◽  
Deep Convection ◽  
Significant Negative Correlation ◽  
Formation Mechanisms ◽  
Strong Positive Correlation ◽  
Ice Crystal ◽  
Ice Clouds ◽  
Dry Conditions ◽  
The Impact

Abstract. The interactions between aerosols and ice clouds represent one of the largest uncertainties in global radiative forcing from pre-industrial time to the present. In particular, the impact of aerosols on ice crystal effective radius (Rei), which is a key parameter determining ice clouds' net radiative effect, is highly uncertain due to limited and conflicting observational evidence. Here we investigate the effects of aerosols on Rei under different meteorological conditions using 9-year satellite observations. We find that the responses of Rei to aerosol loadings are modulated by water vapor amount in conjunction with several other meteorological parameters. While there is a significant negative correlation between Rei and aerosol loading in moist conditions, consistent with the Twomey effect for liquid clouds, a strong positive correlation between the two occurs in dry conditions. Simulations based on a cloud parcel model suggest that water vapor modulates the relative importance of different ice nucleation modes, leading to the opposite aerosol impacts between moist and dry conditions. When ice clouds are decomposed into those generated from deep convection and formed in-situ, the water vapor modulation remains in effect for both ice cloud types, although the sensitivities of Rei to aerosols differ noticeably between them due to distinct formation mechanisms. The water vapor modulation can largely explain the difference in the responses of Rei to aerosol loadings in various seasons. A proper representation of the water vapor modulation is essential for an accurate estimate of aerosol-cloud radiative forcing produced by ice clouds.

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