Advanced search    

Search: authors:"Bjorn Stevens"

10 papers found.
Use AND, OR, NOT, +word, -word, "long phrase", (parentheses) to fine-tune your search.

The Atlantic ITCZ bias in CMIP5 models

Angela Cheska Siongco Cathy Hohenegger Bjorn Stevens 0 ) C. Hohenegger B. Stevens Max Planck Institute for Meteorology , Bundesstrasse 53, 20146 Hamburg , Germany Precipitation over the tropical

Using aquaplanets to understand the robust responses of comprehensive climate models to forcing

Idealized climate change experiments using fixed sea-surface temperature are investigated to determine whether zonally symmetric aquaplanet configurations are useful for understanding climate feedbacks in more realistic configurations. The aquaplanets capture many of the robust responses of the large-scale circulation and hydrologic cycle to both warming the sea-surface temperature ...

Climate feedback efficiency and synergy

Earth’s climate sensitivity to radiative forcing induced by a doubling of the atmospheric CO2 is determined by feedback mechanisms, including changes in atmospheric water vapor, clouds and surface albedo, that act to either amplify or dampen the response. The climate system is frequently interpreted in terms of a simple energy balance model, in which it is assumed that individual ...

Assessment of different metrics for physical climate feedbacks

We quantify the feedbacks from the physical climate system on the radiative forcing for idealized climate simulations using four different methods. The results differ between the methods and differences are largest for the cloud feedback. The spatial and temporal variability of each feedback is used to estimate the averaging scale necessary to satisfy the feedback concept of one ...

Revealing differences in GCM representations of low clouds

Aquaplanet configurations of four atmospheric general circulation models (GCMs) are compared with standard, Earth-like configurations and observations. The focus here is on tropical, low-level clouds, which have been identified as important for estimates of climate sensitivity. Investigating the distribution of the monthly mean vertical velocity and lower-tropospheric stability, ...

Observing and Modeling Earth’s Energy Flows

Bjorn Stevens 0 Stephen E. Schwartz 0 0 S. E. Schwartz Atmospheric Sciences Division, Brookhaven National Laboratory , Upton, NY 11973, USA This article reviews, from the authors' perspective

Structure and Dynamical Influence of Water Vapor in the Lower Tropical Troposphere

In situ, airborne and satellite measurements are used to characterize the structure of water vapor in the lower tropical troposphere—below the height, \(z_*,\) of the triple-point isotherm, \(T_*.\) The measurements are evaluated in light of understanding of how lower-tropospheric water vapor influences clouds, convection and circulation, through both radiative and thermodynamic ...

Mechanisms and Model Diversity of Trade-Wind Shallow Cumulus Cloud Feedbacks: A Review

Shallow cumulus clouds in the trade-wind regions are at the heart of the long standing uncertainty in climate sensitivity estimates. In current climate models, cloud feedbacks are strongly influenced by cloud-base cloud amount in the trades. Therefore, understanding the key factors controlling cloudiness near cloud-base in shallow convective regimes has emerged as an important ...

Study of low-order numerical effects in the two-dimensional cloud-top mixing layer

Eckhard Dietze Juan Pedro Mellado Bjorn Stevens Heiko Schmidt Large-eddy simulation (LES) has been extensively used as a tool to understand how various processes contribute to the dynamics of the

Two-fluid formulation of the cloud-top mixing layer for direct numerical simulation

A mixture fraction formulation to perform direct numerical simulations of a disperse and dilute two-phase system consisting of water liquid and vapor in air in local thermodynamic equilibrium using a two-fluid model is derived and discussed. The goal is to understand the assumptions intrinsic to this simplified but commonly employed approach for the study of two-layer buoyancy ...