P. Rasch - Academia.edu (original) (raw)

Papers by P. Rasch

The 2010 International Joint Conference on Neural Networks (IJCNN), 2010

A novel approach based on the neural network (NN) technique is formulated and used for developmen... more A novel approach based on the neural network (NN) technique is formulated and used for development of a NN ensemble stochastic convection parameterization for numerical climate and weather prediction models. This fast parameterization is built based on data from Cloud Resolving Model (CRM) simulations initialized with TOGA-COARE data. CRM emulated data are averaged and projected onto the General Circulation Model

To address issues specifically related to the interaction between chemistry and climate, a new in... more To address issues specifically related to the interaction between chemistry and climate, a new initiative, "Atmospheric Chemistry and Climate Initiative" (AC&amp;C), has been started up under the auspices of WCRP- SPARC (Stratospheric Processes and Their Role in Climate) and IGBP-IGAC (International Global Atmospheric Chemistry Project). The goal of AC&amp;C is to improve our understanding of the processes involved in atmospheric

Environmental Research Letters, 2014

Black carbon in snow (BCS) simulated in the Community Atmosphere Model (CAM5) is evaluated agains... more Black carbon in snow (BCS) simulated in the Community Atmosphere Model (CAM5) is evaluated against measurements over Northern China and the Arctic, and its sensitivity to atmospheric deposition and two parameters that affect post-depositional enrichment is explored. Improvements in atmospheric BC transport and deposition significantly reduce the biases (by a factor of two) in the estimation of BCS concentration over both Northern China and the Arctic. Further sensitivity simulations using the improved CAM5 indicate that the melt-water scavenging efficiency (MSE) parameter plays an important role in regulating BC concentrations in the Arctic through the post-depositional enrichment, which not only drastically changes the amplitude but also shifts the seasonal cycle of the BCS concentration and its radiative forcing in the Arctic. The impact of the snow aging scaling factor (SAF) on BCS shows more complex latitudinal and seasonal dependence, and overall impact of SAF is much smaller than that of MSE. The improvements of BC transport and deposition in CAM5 have a stronger influence on BCS than perturbations of the two snow model parameters in Northern China.

cienciaescolar.net

... 1 Pacific Northwest National Laboratory, 902 Battelle Boulevard, PO Box 999, MSIN K9-34, Rich... more ... 1 Pacific Northwest National Laboratory, 902 Battelle Boulevard, PO Box 999, MSIN K9-34, Richland, WA, 99352 (philip.rasch@pnl.gov) 2 ... Summary The geo-engineering idea we are investigating is to increase, in a controlled way, the albedos of shallow oceanic clouds, by ...

Journal of Climate, 2008

A simulation of the present-day climate by the Community Climate System Model version 3 (CCSM3) t... more A simulation of the present-day climate by the Community Climate System Model version 3 (CCSM3) that uses a Finite Volume (FV) numerical method for solving the equations governing the atmospheric dynamics is presented. The simulation is compared to observations and to the well-documented simulation by the standard CCSM3, which uses the Eulerian spectral method for the atmospheric dynamics. The atmospheric component in the simulation herein uses a 1° latitude × 1.25° longitude grid, which is a slightly finer resolution than the T85-grid used in the spectral transform. As in the T85 simulation, the ocean and ice models use a nominal 1-degree grid. Although the physical parameterizations are the same and the resolution is comparable to the standard model, substantial testing and slight retuning were required to obtain an acceptable control simulation. There are significant improvements in the simulation of the surface wind stress and sea surface temperature. Improvements are also seen ...

The MOPITT (Measurements Of Pollution In The Troposphere) instrument on board the NASA Terra sate... more The MOPITT (Measurements Of Pollution In The Troposphere) instrument on board the NASA Terra satellite has beet taking measurements of tropospheric carbon monoxide since March of 2000. MOPITT measurements provide a unique opportunity to better understand surface sources and sinks of carbon monoxide. Such task, however, is made difficult due to chemical interactions of carbon monoxide with OH and other

Page 1. NCAR/TN-285+STR NCAR TECHNICAL NOTE June 1987 Description of NCAR Community Climate Model... more Page 1. NCAR/TN-285+STR NCAR TECHNICAL NOTE June 1987 Description of NCAR Community Climate Model (CCM1) David L. Williamson Jeffrey T. Kiehl V. Ramanathan Robert E. Dickinson James J. Hack CLIMATE AND GLOBAL DYNAMICS DIVISION ...

Atmospheric Ozone as a Climate Gas, 1995

Geoscientific Model Development Discussions, 2011

. A modal aerosol module (MAM) has been developed for the Community Atmosphere Model version 5 (C... more . A modal aerosol module (MAM) has been developed for the Community Atmosphere Model version 5 (CAM5), the atmospheric component of the Community Earth System Model version 1 (CESM1). MAM is capable of simulating the aerosol size distribution and both internal and external mixing between aerosol components, treating numerous complicated aerosol processes and aerosol physical, chemical and optical properties in a physically based manner. Two MAM versions were developed: a more complete version with seven lognormal modes (MAM7), and a version with three lognormal modes (MAM3) for the purpose of long-term (decades to centuries) simulations. Major approximations in MAM3 include assuming immediate mixing of primary organic matter (POM) and black carbon (BC) with other aerosol components, merging of the MAM7 fine dust and fine sea salt modes into the accumulation mode, merging of the MAM7 coarse dust and coarse sea salt modes into the single coarse mode, and neglecting the explicit treatment of ammonia and ammonium cycles. Simulated sulfate and secondary organic aerosol (SOA) mass concentrations are remarkably similar between MAM3 and MAM7 as most (~90%) of these aerosol species are in the accumulation mode. Differences of POM and BC concentrations between MAM3 and MAM7 are also small (mostly within 10%) because of the assumed hygroscopic nature of POM, so that much of the freshly emitted POM and BC is wet-removed before mixing internally with soluble aerosol species. Sensitivity tests with the POM assumed to be hydrophobic and with slower aging increase the POM and BC concentrations, especially at high latitudes (by several times). The mineral dust global burden differs by 10% and sea salt burden by 30–40% between MAM3 and MAM7 mainly due to the different size ranges for dust and sea salt modes and different standard deviations of the log-normal size distribution for sea salt modes between MAM3 and MAM7. The model is able to qualitatively capture the observed geographical and temporal variations of aerosol mass and number concentrations, size distributions, and aerosol optical properties. However, there are noticeable biases, e.g., simulated sulfate and mineral dust concentrations at surface over the oceans are too low. Simulated BC concentrations are significantly lower than measurements in the Arctic. There is a low bias in modeled aerosol optical depth on the global scale, especially in the developing countries. There biases in aerosol simulations clearly indicate the need for improvements of aerosol processes (e.g., emission fluxes of anthropogenic aerosols and precursor gases in developing countries, boundary layer nucleation) and properties (e.g., primary aerosol emission size, POM hygroscopicity). In addition the critical role of cloud properties (e.g., liquid water content, cloud fraction) responsible for the wet scavenging of aerosol is highlighted.