Reply to “Comments on ‘On the Choice of Average Solar Zenith Angle’’’
The solar zenith angle controls local insolation and also affects the partitioning of insolation into planetary reflection, atmospheric absorption, and surface absorption. Because of this role of the solar zenith angle in modulating albedo, Cronin and others have proposed that insolation weighting s...
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| Format: | Article |
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American Meteorological Society
2018
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| Online Access: | http://hdl.handle.net/1721.1/114583 https://orcid.org/0000-0002-7807-2878 |
| _version_ | 1811097150820450304 |
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| author | Cronin, Timothy Wallace |
| author2 | Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences |
| author_facet | Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences Cronin, Timothy Wallace |
| author_sort | Cronin, Timothy Wallace |
| collection | MIT |
| description | The solar zenith angle controls local insolation and also affects the partitioning of insolation into planetary reflection, atmospheric absorption, and surface absorption. Because of this role of the solar zenith angle in modulating albedo, Cronin and others have proposed that insolation weighting should be used to determine the solar zenith angle when a single-angle calculation is used to represent a spatial or temporal average of solar fluxes. A comment by Li claims instead that daytime weighting is optimal, and that insolation weighting leads to serious errors, but this claim is based on a severe misinterpretation of the method proposed by Cronin. With any method of zenith angle averaging, both the solar constant and the zenith angle are free parameters, but their product-the mean insolation-must be held constant. Li fails to hold insolation constant when comparing different methods of zenith angle averaging and, thus, obtains large but spurious "errors." This paper attempts to clarify the method proposed by Cronin and tabulates the insolation-weighted solar zenith angle and solar constant that should be used as a function of latitude for annual-average radiative transfer on a planet with Earth's obliquity and a circular orbit. Keywords: Albedo; Cloud forcing; Radiative transfer |
| first_indexed | 2024-09-23T16:55:09Z |
| format | Article |
| id | mit-1721.1/114583 |
| institution | Massachusetts Institute of Technology |
| last_indexed | 2024-09-23T16:55:09Z |
| publishDate | 2018 |
| publisher | American Meteorological Society |
| record_format | dspace |
| spelling | mit-1721.1/1145832022-09-29T22:26:41Z Reply to “Comments on ‘On the Choice of Average Solar Zenith Angle’’’ Cronin, Timothy Wallace Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences Cronin, Timothy Wallace The solar zenith angle controls local insolation and also affects the partitioning of insolation into planetary reflection, atmospheric absorption, and surface absorption. Because of this role of the solar zenith angle in modulating albedo, Cronin and others have proposed that insolation weighting should be used to determine the solar zenith angle when a single-angle calculation is used to represent a spatial or temporal average of solar fluxes. A comment by Li claims instead that daytime weighting is optimal, and that insolation weighting leads to serious errors, but this claim is based on a severe misinterpretation of the method proposed by Cronin. With any method of zenith angle averaging, both the solar constant and the zenith angle are free parameters, but their product-the mean insolation-must be held constant. Li fails to hold insolation constant when comparing different methods of zenith angle averaging and, thus, obtains large but spurious "errors." This paper attempts to clarify the method proposed by Cronin and tabulates the insolation-weighted solar zenith angle and solar constant that should be used as a function of latitude for annual-average radiative transfer on a planet with Earth's obliquity and a circular orbit. Keywords: Albedo; Cloud forcing; Radiative transfer 2018-04-06T13:57:29Z 2018-04-06T13:57:29Z 2017-05 2017-02 2018-03-30T17:49:03Z Article http://purl.org/eprint/type/JournalArticle 0022-4928 1520-0469 http://hdl.handle.net/1721.1/114583 Cronin, Timothy W. “Reply to “Comments on ‘On the Choice of Average Solar Zenith Angle’’’.” Journal of the Atmospheric Sciences 74, 5 (May 2017): 1677–1680 © 2017 American Meteorological Society https://orcid.org/0000-0002-7807-2878 http://dx.doi.org/10.1175/JAS-D-16-0335.1 Journal of the Atmospheric Sciences Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. application/pdf American Meteorological Society American Meteorological Society |
| spellingShingle | Cronin, Timothy Wallace Reply to “Comments on ‘On the Choice of Average Solar Zenith Angle’’’ |
| title | Reply to “Comments on ‘On the Choice of Average Solar Zenith Angle’’’ |
| title_full | Reply to “Comments on ‘On the Choice of Average Solar Zenith Angle’’’ |
| title_fullStr | Reply to “Comments on ‘On the Choice of Average Solar Zenith Angle’’’ |
| title_full_unstemmed | Reply to “Comments on ‘On the Choice of Average Solar Zenith Angle’’’ |
| title_short | Reply to “Comments on ‘On the Choice of Average Solar Zenith Angle’’’ |
| title_sort | reply to comments on on the choice of average solar zenith angle |
| url | http://hdl.handle.net/1721.1/114583 https://orcid.org/0000-0002-7807-2878 |
| work_keys_str_mv | AT cronintimothywallace replytocommentsononthechoiceofaveragesolarzenithangle |