Determination of direct normal irradiance including circumsolar radiation in climate/NWP models
Bibliographic record
Abstract
An issue in the determination of the direct component of solar radiation involving the circumsolar contribution in numerical weather prediction (NWP) and climate models is discussed. The direct solar radiation has multiple definitions in different applications, but this ambiguity has not always been clearly identified and has therefore sometimes caused confusion. The confusion arises from a fact that the photons that are scattered into the direct solar beam path by atmospheric particles are no different from the non‐scattered photons travelling in the same direction. Therefore there is a question whether these scattered photons should be included in the direct flux calculation or whether they should be excluded. Different definitions of the direct solar radiation in a wide range of applications have been discussed by Blanc et al. (2014). We further discuss it in terms of its relation to NWP and climate models. The short‐wave radiation schemes used in NWP and climate models can be classified into two groups: those that calculate the direct solar radiation without including scattering contributions and those which include the scattering contribution in terms of the delta‐Eddington approximation. We assess the two treatments by comparing modelled direct solar radiation with observations. It is found that the use of delta‐Eddington scaling results in positive errors in the direct solar flux at the surface, while neglecting the delta‐scaling leads to negative errors. The important result is that the positive error from using the delta‐Eddington scaling is at least 1 order of magnitude larger than the absolute negative error due to neglecting it. In order to include properly the scattering contribution in the direct flux calculation, a simple parametrization for dust aerosol is developed which can be used to consider the scattering contribution due to the particular case of dust aerosol to the direct solar radiation within the circumsolar region.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".