scholarly journals Taklimakan dust aerosol radiative heating derived from CALIPSO observations using the Fu-Liou radiation model with CERES constraints

2009 ◽  
Vol 9 (12) ◽  
pp. 4011-4021 ◽  
Author(s):  
J. Huang ◽  
Q. Fu ◽  
J. Su ◽  
Q. Tang ◽  
P. Minnis ◽  
...  
Keyword(s):  
Energy Budget ◽  
Satellite Observations ◽  
Dust Aerosol ◽  
Radiative Heating ◽  
Radiative Energy ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Taklimakan Desert ◽  
Dust Aerosols ◽  
Aerosol Radiative

Abstract. The dust aerosol radiative forcing and heating rate over the Taklimakan Desert in Northwestern China in July 2006 are estimated using the Fu-Liou radiative transfer model along with satellite observations. The vertical distributions of the dust aerosol extinction coefficient are derived from the CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) lidar measurements. The CERES (Cloud and the Earth's Energy Budget Scanner) measurements of reflected solar radiation are used to constrain the dust aerosol type in the radiative transfer model, which determines the dust aerosol single-scattering albedo and asymmetry factor as well as the aerosol optical properties' spectral dependencies. We find that the dust aerosols have a significant impact on the radiative energy budget over the Taklimakan desert. In the atmospheres containing light, moderate and heavy dust layers, the dust aerosols heat the atmosphere (daily mean) by up to 1, 2, and 3 K day−1, respectively. The maximum daily mean radiative heating rate reaches 5.5 K day−1 at 5 km on 29 July. The averaged daily mean net radiative effect of the dust are 44.4, −41.9, and 86.3 W m−2, respectively, at the top of the atmosphere (TOA), surface, and in the atmosphere. Among these effects about two thirds of the warming effect at the TOA is related to the longwave radiation, while about 90% of the atmospheric warming is contributed by the solar radiation. At the surface, about one third of the dust solar radiative cooling effect is compensated by its longwave warming effect. The large modifications of radiative energy budget by the dust aerosols over Taklimakan Desert should have important implications for the atmospheric circulation and regional climate, topics for future investigations.

scholarly journals Taklimakan dust aerosol radiative heating derived from CALIPSO observations using the Fu-Liou radiation model with CERES constraints

2009 ◽  
Vol 9 (2) ◽  
pp. 5967-6001 ◽  
Author(s):  
J. Huang ◽  
Q. Fu ◽  
J. Su ◽  
Q. Tang ◽  
P. Minnis ◽  
...  
Keyword(s):  
Solar Radiation ◽  
Radiative Transfer ◽  
Energy Budget ◽  
Satellite Observations ◽  
Dust Aerosol ◽  
Radiative Heating ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Taklimakan Desert ◽  
Aerosol Radiative

Abstract. The dust aerosol radiative forcing and heating rate over the Taklimakan Desert in northwestern China in July 2006 are estimated using the Fu-Liou radiative transfer model along with satellite observations. The vertical distributions of the dust aerosol extinction coefficient are derived from the CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) lidar measurements. The CERES (Cloud and the Earth's Energy Budget Scanner) measurements of reflected solar radiation are used to constrain the dust aerosol type in the radiative transfer model, which determines the dust aerosol single-scattering albedo and asymmetry factor as well as the aerosol optical properties spectral dependencies. We find that the dust aerosol radiative heating and effect have a significant impact on the energy budget over the Taklimakan desert. In the atmospheres containing light, moderate and heavy dust layers, the dust aerosols heat the atmosphere by up to 1, 2, and 3 K day−1, respectively. The maximum daily mean radiative heating rate reaches 5.5 K day−1 at 5 km on 29 July. The averaged daily mean net radiative effect of the dust are 44.4, −41.9, and 86.3 W m−2, respectively, at the top of the atmosphere (TOA), surface, and in the atmosphere. Among these effects about two thirds of the warming effect at the TOA is related to the longwave radiation, while about 90% of the atmospheric warming is contributed by the solar radiation. At the surface, about one third of the dust solar radiative cooling effect is compensated by its longwave warming effect. The large modifications of radiative energy budget by the dust aerosols over Taklimakan Desert should have important implications for the atmospheric circulation and regional climate, topics for future investigations.

scholarly journals Estimating radiative forcing efficiency of dust aerosol based on direct satellite observations: case studies over the Sahara and Taklimakan Desert

2021 ◽  
Vol 21 (15) ◽  
pp. 11669-11687
Author(s):  
Lin Tian ◽  
Lin Chen ◽  
Peng Zhang ◽  
Lei Bi
Keyword(s):  
Radiative Forcing ◽  
Complex Refractive Index ◽  
Satellite Observations ◽  
Dust Aerosol ◽  
Taklimakan Desert ◽  
Dust Source ◽  
Dust Aerosols ◽  
Microphysical Properties ◽  
Source Regions ◽  
The Taklimakan Desert

Abstract. The direct radiative forcing efficiency of dust aerosol (DRFEdust) is an important indicator to measure the climate effect of dust. The DRFEdust is determined by the microphysical properties of dust, which vary with dust source regions. However, there are only sparse in situ measurements of them, such as the distribution of the dust aerosol particle size and the complex refractive index in the main dust source regions. Furthermore, recent studies have shown that the non-spherical effect of the dust particle is not negligible. The DRFEdust is often evaluated by estimating given microphysical properties of the dust aerosols in the radiative transfer model (RTM). However, considerable uncertainties exist due to the complex and variable dust properties, including the complex refractive index and the shape of the dust. The DRFEdust over the Taklimakan Desert and Sahara is derived from the satellite observations in this paper. The advantage of the proposed satellite-based method is that there is no need to consider the microphysical properties of the dust aerosols in estimating the DRFEdust. For comparison, the observed DRFEdust is compared with that simulated by the RTM. The differences in the dust microphysical properties in these two regions and their impacts on DRFEdust are analyzed. The DRFEdust derived from the satellite observation is -39.6±10.0 W m-2τ-1 in March 2019 over Tamanrasset in the Sahara and -48.6±13.7 W m-2τ-1 in April 2019 over Kashi in the Taklimakan Desert. According to the analyses of their microphysical properties and optical properties, the dust aerosols from the Taklimakan Desert (Kashi) scatter strongly. The RTM-simulated results (−41.5 to −47.4 W m-2τ-1 over Kashi and −32.2 to −44.3 W m-2τ-1 over Tamanrasset) are in good agreement with the results estimated by satellite observations. According to previous studies, the results in this paper are proven to be reasonable and reliable. The results also show that the microphysical properties of the dust can significantly influence the DRFEdust. The satellite-derived results can represent the influence of the dust microphysical properties on the DRFEdust, which can also validate the direct radiative effect of the dust aerosol and the DRFEdust derived from the numerical model more directly.

Sudden Stratospheric Warmings - The Role of Radiation Revealed Through an Energy Budget Analysis

2020 ◽  
Author(s):  
Kevin Bloxam
Keyword(s):  
Energy Budget ◽  
Temperature Anomaly ◽  
Negative Temperature ◽  
Radiative Heating ◽  
Radiative Transfer Model ◽  
Radiative Cooling ◽  
Transfer Model ◽  
Heating Rates ◽  
Budget Analysis

<p>Sudden stratospheric warmings (SSWs) are impressive events that occur in the winter hemisphere's polar stratosphere and are capable of producing temperature anomalies upwards of +50 degrees within a matter of days. While much work has been dedicated towards determining how SSWs occur and their ability to interact with the underlying troposphere, one under-explored aspect of SSWs is the role of radiation. Using a radiative transfer model and an energy budget analysis for distinct layers of the stratosphere, this work accounts for the radiative contribution to the removal of the anomalous energy associated with SSWs. In total, 19 events are investigated over the 1979-2016 period. This work reveals that in the absence of dynamical heating following major SSWs, longwave radiative cooling dominates and often results in a strong negative temperature anomaly. The stratospheric temperature change driven by the radiative cooling is characterized by an exponential decay of the temperature anomaly with an increasing e-folding time of 6.3 ± 2.6 to 21.6 ± 8.3 days from the upper to lower stratosphere. This work also demonstrates a negligible impact that water vapour and ozone have on the longwave and shortwave radiative heating rates during SSWs when the concentrations of these gases are perturbed from their climatological state.</p>

scholarly journals Estimating Radiative Forcing Efficiency of Dust Aerosol Based on Direct Satellite Observations: Case Studies over the Sahara Desert and Taklimakan Desert

2021 ◽  
Author(s):  
Lin Tian ◽  
Lin Chen ◽  
Peng Zhang ◽  
Lei Bi
Keyword(s):  
Radiative Forcing ◽  
Complex Refractive Index ◽  
Satellite Observations ◽  
Dust Aerosol ◽  
Taklimakan Desert ◽  
Sahara Desert ◽  
Dust Aerosols ◽  
Microphysical Properties ◽  
Source Regions ◽  
The Taklimakan Desert

Abstract. The direct radiative forcing efficiency of the dust aerosol (DRFEdust) is an important indicator to measure the climate effect of the dust. The DRFEdust is determined by the microphysical properties of the dust, which vary with the dust source regions. However, there are only sparse in-situ measurements of them, such as the distribution of the dust aerosol particle size and the complex refractive index in the main dust source regions. Furthermore, recent studies have shown that the non-spherical effect of the dust particle is not negligible. The DRFEdust is often evaluated by estimating given microphysical properties of the dust aerosols in the radiative transfer model (RTM). However, considerable uncertainties exist due to the complex and variable dust properties, including the complex refractive index and the shape of the dust. The DRFEdust over the Taklimakan Desert and the Sahara Desert is derived from the satellite observations in this paper. The advantage of the proposed satellite-based method is that there is no need to consider the microphysical properties of the dust aerosols in estimating the DRFEdust. For comparison, the observed DRFEdust is compared with that simulated by the RTM. The differences in the dust microphysical properties in these two regions and their impacts on DRFEdust are analyzed. The DRFEdust derived from the satellite observation is −39.6 ± 10.0 W m−2 τ−1 in March 2019 over Tamanrasset and −48.6 ± 13.7 W m−2 τ−1 in April 2019 over Kashi. According to the analyses of their microphysical properties and optical properties, the dust aerosols from the Taklimakan desert (Kashi) scatter strongly. The RTM simulated results (−41.5 to −47.4 W m−2 τ−1 in the Taklimakan Desert and −32.2 to −44.3 W m−2 τ−1 in the Sahara Desert) are in good agreement with the results estimated by satellite observations. According to previous studies, the results in this paper are proved to be reasonable and reliable. The results also show that the microphysical properties of the dust can significantly influence the DRFEdust. The satellite-derived results can represent the influence of the dust microphysical properties on the DRFEdust, which can also validate the direct radiative effect of the dust aerosol and the DRFEdust derived from the numerical model more directly.

scholarly journals Analysis of the decrease in the tropical mean outgoing shortwave radiation at the top of atmosphere for the period 1984-2000

2005 ◽  
Vol 5 (6) ◽  
pp. 1721-1730 ◽  
Author(s):  
A. Fotiadi ◽  
N. Hatzianastassiou ◽  
C. Matsoukas ◽  
K. G. Pavlakis ◽  
E. Drakakis ◽  
...  
Keyword(s):  
Cloud Cover ◽  
Climate Models ◽  
Climate Model ◽  
Shortwave Radiation ◽  
Radiative Energy ◽  
Radiative Transfer Model ◽  
Physical Parameters ◽  
Transfer Model ◽  
Monthly Basis ◽  
Decadal Scale

Abstract. A decadal-scale trend in the tropical radiative energy budget has been observed recently by satellites, which however is not reproduced by climate models. In the present study, we have computed the outgoing shortwave radiation (OSR) at the top of atmosphere (TOA) at 2.5° longitude-latitude resolution and on a mean monthly basis for the 17-year period 1984-2000, by using a deterministic solar radiative transfer model and cloud climatological data from the International Satellite Cloud Climatology Project (ISCCP) D2 database. Anomaly time series for the mean monthly pixel-level OSR fluxes, as well as for the key physical parameters, were constructed. A significant decreasing trend in OSR anomalies, starting mainly from the late 1980s, was found in tropical and subtropical regions (30° S-30° N), indicating a decadal increase in solar planetary heating equal to 1.9±0.3Wm-2/decade, reproducing well the features recorded by satellite observations, in contrast to climate model results. This increase in solar planetary heating, however, is accompanied by a similar increase in planetary cooling, due to increased outgoing longwave radiation, so that there is no change in net radiation. The model computed OSR trend is in good agreement with the corresponding linear decadal decrease of 2.5±0.4Wm-2/decade in tropical mean OSR anomalies derived from ERBE S-10N non-scanner data (edition 2). An attempt was made to identify the physical processes responsible for the decreasing trend in tropical mean OSR. A detailed correlation analysis using pixel-level anomalies of model computed OSR flux and ISCCP cloud cover over the entire tropical and subtropical region (30° S-30° N), gave a correlation coefficient of 0.79, indicating that decreasing cloud cover is the main reason for the tropical OSR trend. According to the ISCCP-D2 data derived from the combined visible/infrared (VIS/IR) analysis, the tropical cloud cover has decreased by 6.6±0.2% per decade, in relative terms. A detailed analysis of the inter-annual and long-term variability of the various parameters determining the OSR at TOA, has shown that the most important contribution to the observed OSR trend comes from a decrease in low-level cloud cover over the period 1984-2000, followed by decreases in middle and high-level cloud cover. Note, however, that there still remain some uncertainties associated with the existence and magnitude of trends in ISCCP-D2 cloud amounts. Opposite but small trends are introduced by increases in cloud scattering optical depth of low and middle clouds.

scholarly journals Sensitivity of satellite observations for freshly produced lightning NO<sub>x</sub>

2009 ◽  
Vol 9 (3) ◽  
pp. 1077-1094 ◽  
Author(s):  
S. Beirle ◽  
M. Salzmann ◽  
M. G. Lawrence ◽  
T. Wagner
Keyword(s):  
Radiative Transfer ◽  
Satellite Observations ◽  
Radiative Transfer Model ◽  
Visible Range ◽  
Transfer Model ◽  
Satellite Measurements ◽  
Vertical Column ◽  
Toga Coare ◽  
Photo Chemistry ◽  
Lightning Nox

Abstract. In this study, we analyse the sensitivity of nadir viewing satellite observations in the visible range to freshly produced lightning NOx. This is a particular challenge due to the complex and highly variable conditions of meteorology, (photo-) chemistry, and radiative transfer in and around cumulonimbus clouds. For the first time, such a study is performed accounting for photo-chemistry, dynamics, and radiative transfer in a consistent way: A one week episode in the TOGA COARE/CEPEX region (Pacific) in December 1992 is simulated with a 3-D cloud resolving chemistry model. The simulated hydrometeor mixing ratios are fed into a Monte Carlo radiative transfer model to calculate box-Air Mass Factors (box-AMFs) for NO2. From these box-AMFs, together with model NOx profiles, slant columns of NO2 (SNO2), i.e. synthetic satellite measurements, are calculated and set in relation to the actual model NOx vertical column (VNOx), yielding the "sensitivity" SNO2/VNOx. From this study, we find a mean sensitivity of 0.46. NOx below the cloud bottom is mostly present as NO2, but shielded from the satellites' view, whereas NOx at the cloud top or above is shifted to NO due to high photolysis and low temperature, and hence not detectable from space. However, a significant fraction of the lightning produced NOx in the middle part of the cloud is present as NO2 and has a good visibility from space. Due to the resulting total sensitivity being quite high, nadir viewing satellites provide a valuable additional platform to quantify NOx production by lightning; strong lightning events over "clean" regions should be clearly detectable in satellite observations. Since the observed enhancement of NO2 column densities over mesoscale convective systems are lower than expected for current estimates of NOx production per flash, satellite measurements can in particular constrain the upper bound of lightning NOx production estimates.

scholarly journals Evaluation of Cirrus Parameterizations for Radiative Flux Computations in Climate Models Using TOVS–ScaRaB Satellite Observations

2007 ◽  
Vol 20 (17) ◽  
pp. 4459-4475 ◽  
Author(s):  
C. J. Stubenrauch ◽  
F. Eddounia ◽  
J. M. Edwards ◽  
A. Macke
Keyword(s):  
Optical Properties ◽  
Radiative Transfer ◽  
Climate Models ◽  
Radiative Flux ◽  
Satellite Observations ◽  
Radiation Budget ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Ice Crystal ◽  
Infrared Observation

Abstract Combined simultaneous satellite observations are used to evaluate the performance of parameterizations of the microphysical and optical properties of cirrus clouds used for radiative flux computations in climate models. Atmospheric and cirrus properties retrieved from Television and Infrared Observation Satellite (TIROS-N) Operational Vertical Sounder (TOVS) observations are given as input to the radiative transfer model developed for the Met Office climate model to simulate radiative fluxes at the top of the atmosphere (TOA). Simulated cirrus shortwave (SW) albedos are then compared to those retrieved from collocated Scanner for Radiation Budget (ScaRaB) observations. For the retrieval, special care has been given to angular direction models. Three parameterizations of cirrus ice crystal optical properties are represented in the Met Office radiative transfer model. These parameterizations are based on different physical approximations and different hypotheses on crystal habit. One parameterization assumes pristine ice crystals and two ice crystal aggregates. By relating the cirrus ice water path (IWP) retrieved from the effective infrared emissivity to the cirrus SW albedo, differences between the parameterizations are amplified. This study shows that pristine crystals seem to be plausible only for cirrus with IWP less than 30 g m−2. For larger IWP, ice crystal aggregates lead to cirrus SW albedos in better agreement with the observations. The data also indicate that climate models should allow the cirrus effective ice crystal diameter (De) to increase with IWP, especially in the range up to 30 g m−2. For cirrus with IWP less than 20 g m−2, this would lead to SW albedos that are about 0.02 higher than the ones of a constant De of 55 μm.

scholarly journals Performance of the Line-By-Line Radiative Transfer Model (LBLRTM) for temperature, water vapor, and trace gas retrievals: recent updates evaluated with IASI case studies

2013 ◽  
Vol 13 (14) ◽  
pp. 6687-6711 ◽  
Author(s):  
M. J. Alvarado ◽  
V. H. Payne ◽  
E. J. Mlawer ◽  
G. Uymin ◽  
M. W. Shephard ◽  
...  
Keyword(s):  
Water Vapor ◽  
Radiative Transfer ◽  
Fixed Ratio ◽  
Satellite Observations ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Temperature Profiles ◽  
A Posteriori ◽  
The Impact ◽  
Temperature Water

Abstract. Modern data assimilation algorithms depend on accurate infrared spectroscopy in order to make use of the information related to temperature, water vapor (H2O), and other trace gases provided by satellite observations. Reducing the uncertainties in our knowledge of spectroscopic line parameters and continuum absorption is thus important to improve the application of satellite data to weather forecasting. Here we present the results of a rigorous validation of spectroscopic updates to an advanced radiative transfer model, the Line-By-Line Radiative Transfer Model (LBLRTM), against a global dataset of 120 near-nadir, over-ocean, nighttime spectra from the Infrared Atmospheric Sounding Interferometer (IASI). We compare calculations from the latest version of LBLRTM (v12.1) to those from a previous version (v9.4+) to determine the impact of spectroscopic updates to the model on spectral residuals as well as retrieved temperature and H2O profiles. We show that the spectroscopy in the CO2 ν2 and ν3 bands is significantly improved in LBLRTM v12.1 relative to v9.4+, and that these spectroscopic updates lead to mean changes of ~0.5 K in the retrieved vertical temperature profiles between the surface and 10 hPa, with the sign of the change and the variability among cases depending on altitude. We also find that temperature retrievals using each of these two CO2 bands are remarkably consistent in LBLRTM v12.1, potentially allowing these bands to be used to retrieve atmospheric temperature simultaneously. The updated H2O spectroscopy in LBLRTM v12.1 substantially improves the a posteriori residuals in the P-branch of the H2O ν2 band, while the improvements in the R-branch are more modest. The H2O amounts retrieved with LBLRTM v12.1 are on average 14% lower between 100 and 200 hPa, 42% higher near 562 hPa, and 31% higher near the surface compared to the amounts retrieved with v9.4+ due to a combination of the different retrieved temperature profiles and the updated H2O spectroscopy. We also find that the use of a fixed ratio of HDO to H2O in LBLRTM may be responsible for a significant fraction of the remaining bias in the P-branch relative to the R-branch of the H2O ν2 band. There were no changes to O3 spectroscopy between the two model versions, and so both versions give positive a posteriori residuals of ~ 0.3 K in the R-branch of the O3 ν3 band. While the updates to the H2O self-continuum employed by LBLRTM v12.1 have clearly improved the match with observations near the CO2 ν3 band head, we find that these updates have significantly degraded the match with observations in the fundamental band of CO. Finally, significant systematic a posteriori residuals remain in the ν4 band of CH4, but the magnitude of the positive bias in the retrieved mixing ratios is reduced in LBLRTM v12.1, suggesting that the updated spectroscopy could improve retrievals of CH4 from satellite observations.

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.

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