Climatic traits on daily clearness and cloudiness indices
<p>Solar radiation has a crucial role in photosynthesis, evapotranspiration and other biogeochemical processes. The amount of solar radiation reaching the Earth's surface is a function of astronomical geometry and atmospheric optics. While the first is deterministic, the latter has a rand...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2021-01-01
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| Series: | Biogeosciences |
| Online Access: | https://bg.copernicus.org/articles/18/573/2021/bg-18-573-2021.pdf |
| _version_ | 1818648658081480704 |
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| author | E. Muñoz A. Ochoa |
| author_facet | E. Muñoz A. Ochoa |
| author_sort | E. Muñoz |
| collection | DOAJ |
| description | <p>Solar radiation has a crucial role in photosynthesis, evapotranspiration and other biogeochemical processes. The amount of solar radiation reaching the Earth's surface is a function of astronomical geometry and atmospheric optics. While the first is deterministic, the latter has a random behaviour caused by highly variable atmospheric components such as water and aerosols.
In this study, we use daily radiation data (1978–2014) from 37 FLUXNET sites distributed across the globe to inspect for climatic traits in the shape of the probability density function (PDF) of the clear-day (<span class="inline-formula"><i>c</i></span>) and the clearness (<span class="inline-formula"><i>k</i></span>) indices. The analysis was made for shortwave radiation (SW) at all sites and for photosynthetically active radiation (PAR) at 28 sites. We identified three types of PDF, unimodal with low dispersion (ULD), unimodal with high dispersion (UHD) and bimodal (B), with no difference in the PDF type between <span class="inline-formula"><i>c</i></span> and <span class="inline-formula"><i>k</i></span> at each site. Looking for regional patterns in the PDF type, we found that latitude, global climate zone and Köppen climate type have a weak relation and the Holdridge life a stronger relation with <span class="inline-formula"><i>c</i></span> and <span class="inline-formula"><i>k</i></span> PDF types. The existence and relevance of a second mode in the PDF can be explained by the frequency and meteorological mechanisms of rainy days. These results are a frame to develop solar radiation stochastic models for biogeochemical and ecohydrological modelling.</p> |
| first_indexed | 2024-12-17T01:21:55Z |
| format | Article |
| id | doaj.art-4e530a121d664bb88845c8c0b58acb18 |
| institution | Directory Open Access Journal |
| issn | 1726-4170 1726-4189 |
| language | English |
| last_indexed | 2024-12-17T01:21:55Z |
| publishDate | 2021-01-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Biogeosciences |
| spelling | doaj.art-4e530a121d664bb88845c8c0b58acb182022-12-21T22:08:47ZengCopernicus PublicationsBiogeosciences1726-41701726-41892021-01-011857358410.5194/bg-18-573-2021Climatic traits on daily clearness and cloudiness indicesE. MuñozA. Ochoa<p>Solar radiation has a crucial role in photosynthesis, evapotranspiration and other biogeochemical processes. The amount of solar radiation reaching the Earth's surface is a function of astronomical geometry and atmospheric optics. While the first is deterministic, the latter has a random behaviour caused by highly variable atmospheric components such as water and aerosols. In this study, we use daily radiation data (1978–2014) from 37 FLUXNET sites distributed across the globe to inspect for climatic traits in the shape of the probability density function (PDF) of the clear-day (<span class="inline-formula"><i>c</i></span>) and the clearness (<span class="inline-formula"><i>k</i></span>) indices. The analysis was made for shortwave radiation (SW) at all sites and for photosynthetically active radiation (PAR) at 28 sites. We identified three types of PDF, unimodal with low dispersion (ULD), unimodal with high dispersion (UHD) and bimodal (B), with no difference in the PDF type between <span class="inline-formula"><i>c</i></span> and <span class="inline-formula"><i>k</i></span> at each site. Looking for regional patterns in the PDF type, we found that latitude, global climate zone and Köppen climate type have a weak relation and the Holdridge life a stronger relation with <span class="inline-formula"><i>c</i></span> and <span class="inline-formula"><i>k</i></span> PDF types. The existence and relevance of a second mode in the PDF can be explained by the frequency and meteorological mechanisms of rainy days. These results are a frame to develop solar radiation stochastic models for biogeochemical and ecohydrological modelling.</p>https://bg.copernicus.org/articles/18/573/2021/bg-18-573-2021.pdf |
| spellingShingle | E. Muñoz A. Ochoa Climatic traits on daily clearness and cloudiness indices Biogeosciences |
| title | Climatic traits on daily clearness and cloudiness indices |
| title_full | Climatic traits on daily clearness and cloudiness indices |
| title_fullStr | Climatic traits on daily clearness and cloudiness indices |
| title_full_unstemmed | Climatic traits on daily clearness and cloudiness indices |
| title_short | Climatic traits on daily clearness and cloudiness indices |
| title_sort | climatic traits on daily clearness and cloudiness indices |
| url | https://bg.copernicus.org/articles/18/573/2021/bg-18-573-2021.pdf |
| work_keys_str_mv | AT emunoz climatictraitsondailyclearnessandcloudinessindices AT aochoa climatictraitsondailyclearnessandcloudinessindices |