scholarly journals A method for comparing properties of cirrus clouds in global climate models with those retrieved from IR sounder satellite observations

2010 ◽  
Vol 19 (6) ◽  
pp. 577-589 ◽  
Author(s):  
Johannes Hendricks ◽  
Andreas Falb ◽  
Claudia J. Stubenrauch ◽  
Claudia Emde
Keyword(s):  
Climate Models ◽  
Global Climate ◽  
Global Climate Models ◽  
Satellite Observations ◽  
Cirrus Clouds

scholarly journals Cirrus clouds in a global climate model with a statistical cirrus cloud scheme

2009 ◽  
Vol 9 (4) ◽  
pp. 16607-16682 ◽  
Author(s):  
M. Wang ◽  
J. E. Penner
Keyword(s):  
Climate Models ◽  
Climate Model ◽  
Global Climate ◽  
Global Climate Model ◽  
Circulation Model ◽  
Global Climate Models ◽  
Cirrus Clouds ◽  
Cirrus Cloud ◽  
Ice Crystal ◽  
Low Level

Abstract. A statistical cirrus cloud scheme that accounts for mesoscale temperature perturbations is implemented into a coupled aerosol and atmospheric circulation model to better represent both cloud fraction and subgrid-scale supersaturation in global climate models. This new scheme is able to better simulate the observed probability distribution of relative humidity than the scheme that was implemented in an older version of the model. Heterogeneous ice nuclei (IN) are shown to affect not only high level cirrus clouds through their effect on ice crystal number concentration but also low level liquid clouds through the moistening effect of settling and evaporating ice crystals. As a result, the change in the net cloud forcing is not very sensitive to the change in ice crystal concentrations associated with heterogeneous IN because changes in high cirrus clouds and low level liquid clouds tend to cancel. Nevertheless, the change in the net radiative flux at the top of the atmosphere due to changes in IN is still large because of changes in the greenhouse effect of water vapor caused by the changes in ice crystal number concentrations. Changes in the magnitude of the assumed mesoscale temperature perturbations by 25% alter the ice crystal number concentrations and radiative fluxes by an amount that is similar to that from a factor of 10 change in the heterogeneous IN number concentrations.

Sensitivity of resolved gravity wave momentum fluxes on different background separation methods in a high resolution simulation.

2020 ◽  
Author(s):  
Zuzana Procházková ◽  
Petr Šácha ◽  
Aleš Kuchař ◽  
Petr Pišoft ◽  
Christopher Kruse
Keyword(s):  
High Resolution ◽  
Climate Models ◽  
Global Climate ◽  
Internal Gravity Waves ◽  
Complex Problem ◽  
Global Climate Models ◽  
Satellite Observations ◽  
Detection Methods ◽  
Spatial And Temporal Scales ◽  
Resolution Model

<p>Internal gravity waves (GWs) and their interaction with the atmospheric circulation present a complex problem for global climate models (GCMs) due to a variety of spatial and temporal scales involved. GWs and their effects in GCMs are parameterized by employing various simplifications and restrictions<br>(propagation, spectrum). Also, our incomplete knowledge of the GW properties in the real atmosphere complicates the situation. Global (satellite) observations of the GW activity are spatiotemporally sparse, making the quantification of the GW interaction with the circulation hardly possible. Recently, atmospheric models capable of resolving most of the GW spectrum have been emerging due to the increasing performance of computing systems. It is increasingly acknowledged that a combination of various types of observations with dedicated high-resolution, GW resolving, simulations has a potential to provide the most precise information about GWs. This combination will allow us to better understand the uncertainty of satellite observations of GW activity, which in turn will be used to develop new GW parameterizations or in development of GW resolving models.<br>In this study, we will analyze sensitivity of GW momentum flux and its divergence on background separation (and other GW detection) methods and approximations (Boussinesq, anelastic) used in the formulas. We analyze data from high-resolution model simulations produced for an observing system simulation experiment of the ISSI team "New Quantitative Constraints on Orographic GW Stress and Drag" (to be introduced in an invited presentation by Ch. Kruse).</p>

scholarly journals Discrepancies with satellite observations in the spatial structure of global precipitation as derived from global climate models

2018 ◽  
Vol 144 (S1) ◽  
pp. 419-435 ◽  
Author(s):  
Francisco J. Tapiador ◽  
Andrés Navarro ◽  
Alfonso Jiménez ◽  
Raúl Moreno ◽  
Eduardo García‐Ortega
Keyword(s):  
Spatial Structure ◽  
Climate Models ◽  
Global Climate ◽  
Global Climate Models ◽  
Satellite Observations ◽  
Global Precipitation

scholarly journals Evaluation of the Warm Rain Formation Process in Global Models with Satellite Observations

2015 ◽  
Vol 72 (10) ◽  
pp. 3996-4014 ◽  
Author(s):  
Kentaroh Suzuki ◽  
Graeme Stephens ◽  
Alejandro Bodas-Salcedo ◽  
Minghuai Wang ◽  
Jean-Christophe Golaz ◽  
...  
Keyword(s):  
Climate Models ◽  
Global Climate ◽  
Global Climate Models ◽  
Satellite Observations ◽  
Dimensional Model ◽  
One Dimensional ◽  
Warm Rain ◽  
Stratiform Clouds ◽  
The One ◽  
Rain Formation

Abstract This study examines the warm rain formation process over the global ocean in global climate models. Methodologies developed to analyze CloudSat and Moderate Resolution Imaging Spectroradiometer (MODIS) satellite observations are employed to investigate the cloud-to-precipitation process of warm clouds and are applied to the model results to examine how the models represent the process for warm stratiform clouds. Despite a limitation of the present study that compares the statistics for stratiform clouds in climate models with those from satellite observations, including both stratiform and (shallow) convective clouds, the statistics constructed with the methodologies are compared between the models and satellite observations to expose their similarities and differences. A problem common to some models is that they tend to produce rain at a faster rate than is observed. These model characteristics are further examined in the context of cloud microphysics parameterizations using a simplified one-dimensional model of warm rain formation that isolates key microphysical processes from full interactions with other processes in global climate models. The one-dimensional model equivalent statistics reproduce key characteristics of the global model statistics when corresponding autoconversion schemes are assumed in the one-dimensional model. The global model characteristics depicted by the statistics are then interpreted as reflecting behaviors of the autoconversion parameterizations adopted in the models. Comparisons of the one-dimensional model with satellite observations hint at improvements to the formulation of the parameterization scheme, thus offering a novel way of constraining key parameters in autoconversion schemes of global models.

scholarly journals Properties of mid-latitude cirrus cloud from surface Ka-band radar observations during 2014–2017

2020 ◽  
Author(s):  
Juan Huo ◽  
Yufang Tian ◽  
Xue Wu ◽  
Congzheng Han ◽  
Bo Liu ◽  
...  
Keyword(s):  
Summer Monsoon ◽  
Climate Models ◽  
Global Climate ◽  
Winter Monsoon ◽  
Global Climate Models ◽  
Cirrus Clouds ◽  
Cirrus Cloud ◽  
Formation And Evolution ◽  
The Mean

Abstract. The physical properties and radiative role of cirrus clouds remain one of the uncertainties in the Earth–atmosphere system. In this study, we present a detailed analysis of cirrus properties based on four years of surface millimetre wavelength radar measurements in Beijing, China, where summer monsoon from the ocean and winter monsoon from the continent prevails alternately, resulting in various cirrus clouds. More than 6600 cirrus clusters were studied to quantify the properties of cirrus clouds, such as the height, optical depth and horizontal extent, which can serve as a reference for parameterization and characterization in global climate models. In addition, comparison between cirrus clusters formed under summer monsoon and winter monsoon indicates the different formation and evolution mechanisms of cirrus. Statistically, the temperature of more than 90 % of cirrus bins are below −15 °C. The dependence of the radar reflectivity of cirrus particles on the height and temperature was also observed in this study, indicating that the reflectivity of cirrus bins increases (decreases) as the temperature (height) increases. In addition, it was found that there is a strong linear relationship between the mean reflectivity and the cirrus cloud depth. Due to various synoptic circumstances, the cirrus clouds in summer are warmer, higher, and thicker, with larger reflectivity than that in winter; in particular, the mean cloud-top height of cirrus clouds in summer is 2.5 km higher than that in winter. It was found that most cirrus clusters in winter are likely to be the in situ origin type cirrus but some cirrus clusters in summer are the in situ origin cirrus and others are the liquid origin type cirrus.

Using the learnings of machine learning to distill cloud controlling environmental regimes from satellite observations

2021 ◽  
Author(s):  
Alyson Douglas ◽  
Philip Stier
Keyword(s):  
Climate Models ◽  
Global Climate ◽  
Controlling Factors ◽  
Global Climate Models ◽  
Satellite Observations ◽  
Cloud Formation ◽  
Future Projections ◽  
Cloud Properties ◽  
Environmental Regimes ◽  
Well Model

<div> <div> <div> <div> <p>Cloud processes are the leading source of uncertainty in our current global climate models. Therefore understanding cloud formation, lifetime, and decay remains pivotal in order to reduce uncertainty in our global climate models future projections. Exploiting over ten years of satellite observations, the relationships between cloud properties and environmental factors, including aerosols, can be better understood and clustered into environmental regimes. We cluster regimes based on the regional strength of the relationships between the environment and cloud properties revealed using a random forest. Numerous processes, such as stratocumulus to cumulus transitions, may be constrained by the environmental regimes revealed by our analysis. Our results show that depending on the region, aerosol and the environment work to determine the baseline cloud properties. These observation based regimes can be compared to regimes derived from global climate models to understand how well model parameterizations capture the cloud controlling factors.</p> </div> </div> </div> </div>

Extreme Events in High Resolution CMCC Regional and Global Climate Models

2011 ◽  
Author(s):  
Enrico Scoccimarro ◽  
Silvio Gualdi ◽  
Antonella Sanna ◽  
Edoardo Bucchignani ◽  
Myriam Montesarchio
Keyword(s):  
High Resolution ◽  
Extreme Events ◽  
Climate Models ◽  
Global Climate ◽  
Global Climate Models
Sign in / Sign up

Export Citation Format

Share Document