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Solar-J and Cloud-J models version 7.6c

Citation

Prather, Michael; Hsu, Juno (2019), Solar-J and Cloud-J models version 7.6c, v2, UC Irvine Dash, Dataset, https://doi.org/10.7280/D1096P

Abstract

This dataset includes the models (fortran code, matlab code, data) used to simulate the heating and photolysis rates in a spherical atmosphere.  Both Solar-J v7.5 and Cloud-J v7.3c have been published previously, but with the publication of Prather and Hsu, "A round Earth for climate models" in PNAS (2019) both models have been merged in terms of overlapping subroutines and both now include option for (0) a flat-Earth atmosphere, (1) solar ray tracing through a spherical atmosphere, (2) refracted solar rays in a spherical atmosphere, and (3) a geometically expanding spherical atmosphere that includes the extra area, volumen and mass for a spherical hydrostatic atmosphere.  

"Sunlight drives the Earth's weather, climate, chemistry and biosphere.  Recent efforts to improve solar heating codes in climate models focused on more accurate treatment of the absorption spectrum or fractional clouds.  A mostly forgotten assumption in climate models is that of a flat-Earth atmosphere.  Spherical atmospheres intercept 2.5 W m-2 more sunlight and heat the climate by an additional 1.5 W m-2 globally.  Such a systematic shift, being comparable to the radiative forcing change from preindustrial to present, is likely to produce a discernible climate shift that would alter a model's skill in simulating current climate.  Regional heating errors, particularly at high latitudes, are several times larger.  Unlike flat atmospheres, constituents in a spherical atmosphere, such as clouds and aerosols, alter the total amount of energy received by the Earth.  To calculate the net cooling of aerosols in a spherical framework, one must count the increases in both incident and reflected sunlight, thus reducing the aerosol effect by 10-14% relative to using just the increase in reflected.  Simple fixes to the current flat-earth climate models can correct much of this oversight, although some inconsistencies will remain."

 

Early climate and weather models, constrained by computing resources, made numerical approximations on modeling the real world.  One process, the radiative transfer of sunlight through the atmosphere, has always been a costly component.  As computational ability expanded, these models added resolution, processes, and numerical methods to reduce errors and become the Earth system models that we use today.  While many of the original approximations have since been improved, one -- that the Earth's surface and atmosphere are flat – remains in current models.  Correcting from flat to spherical atmospheres leads to regionally differential solar heating at rates comparable to the climate forcing by greenhouse gases and aerosols.  In addition, spherical atmospheres change how we evaluate the aerosol direct radiative forcing.

 

 

Methods

This dataset includes two models that were coded and tested by Juno Hsu and Michael Prather (UC Irvine). Solar-J is the code version that can be implemented incliamte model to calculate soalr heating rates.  Cloud-J here is a stanalone code that can be integrated into a chemistry-transport model (CTM) or more encompassing earth system model (ESM).  Cloud-J is a superset of the Fast-J code that has been implemented in many CTMs.  The included meteorological datasets are meant to be replaced with the users own; the other data tables are based on underlying laboratory or atmospheric data or fundamental physics or previous model development

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Usage Notes

Both Solar-J and Cloud-J modells included here should be able to run a standalone codes and reproduce the included output data.  The data and code are documented inline at some level, as well as inthe publications.

Funding

NASA HQ MAP, Award: NNX13AL12G

DOE BER, Award: DE-SC0012536

DOE LLNL E3SM, Award: B628407

References