Midsummer stratospheric NO2 at latitude 45°S

1979 ◽  
Vol 57 (8) ◽  
pp. 1110-1117 ◽  
Author(s):  
A. W. Harrison
Keyword(s):  
New Zealand ◽  
Nitrogen Dioxide ◽  
Zenith Angle ◽  
Solar Zenith Angle ◽  
Absorption Bands ◽  
Ozone Absorption ◽  
Vertical Column ◽  
The Mean

Ground based measurements of stratospheric nitrogen dioxide during morning and evening twilight have been made at Lauder, New Zealand, 169°40′E longitude and 45°04′S latitude during January and February 1979. The analysis shows that ozone absorption overlying the nitrogen dioxide absorption bands cannot be ignored. After correcting for ozone absorption the mean vertical column abundance of nitrogen dioxide was found to be 2.9 × 1015 cm−2 (evening, solar zenith angle = 90°) and 1.1 × 1015 cm−2 (morning, solar zenith angle = 90°).

scholarly journals Effects of solar flares on the ionosphere as shown by the dynamics of ionograms recorded in Europe and South Africa

2019 ◽  
Vol 37 (4) ◽  
pp. 747-761 ◽  
Author(s):  
Veronika Barta ◽  
Gabriella Sátori ◽  
Kitti Alexandra Berényi ◽  
Árpád Kis ◽  
Earle Williams
Keyword(s):  
South Africa ◽  
Zenith Angle ◽  
Solar Flares ◽  
Solar Zenith Angle ◽  
Low Latitude ◽  
Systematic Analysis ◽  
Radio Wave Absorption ◽  
The Mean ◽  
Qualitative Measure ◽  
Solar Flare Effects

Abstract. We have investigated the solar flare effects on ionospheric absorption with the systematic analysis of ionograms measured at midlatitude and low-latitude ionosonde stations under different solar zenith angles. The lowest recorded ionosonde echo, the minimum frequency (fmin, a qualitative proxy for the “nondeviative” radio wave absorption occurring in the D-layer), and the dfmin parameter (difference between the value of the fmin and the mean fmin for reference days) have been considered. Data were provided by meridionally distributed ionosonde stations in Europe and South Africa during eight X- and M-class solar flares in solar cycle 23. Total and partial radio fade-out was experienced at every ionospheric station during intense solar flares (> M6). The duration of the total radio fade-out varied between 15 and 150 min and it was highly dependent on the solar zenith angle of the ionospheric stations. Furthermore, a solar-zenith-angle-dependent enhancement of the fmin (2–9 MHz) and dfmin (1–8 MHz) parameters was observed at almost every station. The fmin and dfmin parameters show an increasing trend with the enhancement of the X-ray flux. Based on our results, the dfmin parameter is a good qualitative measure for the relative variation of the “nondeviative” absorption, especially in the case of the less intense solar flares, which do not cause total radio fade-out in the ionosphere (class < M6).

scholarly journals Validation of Ozone Monitoring Instrument (OMI) ozone profiles and stratospheric ozone columns with Microwave Limb Sounder (MLS) measurements

2010 ◽  
Vol 10 (5) ◽  
pp. 2539-2549 ◽  
Author(s):  
X. Liu ◽  
P. K. Bhartia ◽  
K. Chance ◽  
L. Froidevaux ◽  
R. J. D. Spurr ◽  
...  
Keyword(s):  
Zenith Angle ◽  
Solar Zenith Angle ◽  
Stratospheric Ozone ◽  
Random Noise ◽  
Ozone Monitoring Instrument ◽  
Middle Latitudes ◽  
Upper Limits ◽  
The Mean ◽  
Standard Deviations ◽  
Ozone Column

Abstract. We validate OMI ozone profiles between 0.22–215 hPa and stratospheric ozone columns down to 215 hPa (SOC215) against v2.2 MLS data from 2006. The validation demonstrates convincingly that SOC can be derived accurately from OMI data alone, with errors comparable to or smaller than those from current MLS retrievals, and it demonstrates implicitly that tropospheric ozone column can be retrieved accurately from OMI or similar nadir-viewing ultraviolet measurements alone. The global mean biases are within 2.5% above 100 hPa and 5–10% below 100 hPa; the standard deviations of the differences (1σ) are 3.5–5% between 1–50 hPa, 6–9% above 1 hPa and 8–15% below 50 hPa. OMI shows some latitude and solar zenith angle dependent biases, but the mean biases are mostly within 5% and the standard deviations are mostly within 2–5% except for low altitudes and high latitudes. The excellent agreement with MLS data shows that OMI retrievals can be used to augment the validation of MLS and other stratospheric ozone measurements made with even higher vertical resolution than that for OMI. OMI SOC215 shows a small bias of −0.6% with a standard deviation of 2.8%. When compared as a function of latitude and solar zenith angle, the mean biases are within 2% and the standard deviations range from 2.1 to 3.4%. Assuming 2% precision for MLS SOC215, we deduce that the upper limits of random-noise and smoothing errors for OMI SOC215 range from 0.6% in the southern tropics to 2.8% at northern middle latitudes.

scholarly journals Validation of Ozone Monitoring Instrument (OMI) ozone profiles and stratospheric ozone columns with Microwave Limb Sounder (MLS) measurements

2009 ◽  
Vol 9 (6) ◽  
pp. 24913-24943 ◽  
Author(s):  
X. Liu ◽  
P. K. Bhartia ◽  
K. Chance ◽  
L. Froidevaux ◽  
R. J. D. Spurr ◽  
...  
Keyword(s):  
Zenith Angle ◽  
Solar Zenith Angle ◽  
Stratospheric Ozone ◽  
Random Noise ◽  
Ozone Monitoring Instrument ◽  
Middle Latitudes ◽  
Upper Limits ◽  
The Mean ◽  
Standard Deviations ◽  
Ozone Column

Abstract. We validate OMI ozone profiles between 0.22–215 hPa and stratospheric ozone columns down to 215 hPa (SOC215) against v2.2 MLS data from 2006. The validation demonstrates convincingly that SOC can be derived accurately from OMI data alone, with errors comparable to or smaller than those from current MLS retrievals, and it demonstrates implicitly that tropospheric ozone column can be retrieved accurately from OMI or similar nadir-viewing ultraviolet measurements alone. The global mean biases are within 2.5% above 100 hPa and 5–10% below 100 hPa; the standard deviations (1σ) are 3.5–5% between 1–50 hPa, 6–9% above 1 hPa and 8–15% below; 50 hPa. OMI shows some latitude and solar zenith angle dependent biases, but the mean biases are mostly within 5% and the standard deviations are mostly within 2–5% except for low altitudes and high latitudes. The excellent agreement with MLS data shows that OMI retrievals can be used to augment the validation of MLS and other stratospheric ozone measurements made with even higher vertical resolution than that for OMI. OMI SOC215 shows a small bias of −0.6% with a standard deviation of 2.8%. When compared as a function of latitude and solar zenith angle, the mean biases are within 2% and the standard deviations range from 2.1 to 3.4%. Assuming 2% precision for MLS SOC215, we deduce that the upper limits of random-noise and smoothing errors for OMI SOC215 range from 0.6% in the southern tropics to 2.8% at northern middle latitudes.

scholarly journals Generalizing Cloud Overlap Treatment to Include Solar Zenith Angle Effects on Cloud Geometry

2007 ◽  
Vol 64 (6) ◽  
pp. 2116-2125 ◽  
Author(s):  
Adrian M. Tompkins ◽  
Francesca Di Giuseppe
Keyword(s):  
Zenith Angle ◽  
Large Scale ◽  
Solar Zenith Angle ◽  
Forecast Model ◽  
Simple Extension ◽  
Scale Models ◽  
Field Geometry ◽  
The Mean ◽  
The Impact ◽  
First Time

Shortwave radiative transfer depends on the cloud field geometry as viewed from the direction of the sun. To date, the radiation schemes of large-scale models only consider a zenith view of the cloud field, and the apparent change in the cloud geometry with decreasing solar zenith angle is neglected. A simple extension to an existing cloud overlap scheme is suggested to account for this for the first time. It is based on the assumption that at low sun angles, the overlap between cloud elements is random for an unscattered photon. Using cloud scenes derived from radar retrievals at two European sites, it is shown that the increase of the apparent cloud cover with a descending sun is reproduced very well with the new scheme. Associated with this, there is a marked reduction in the mean radiative biases averaged across all solar zenith angles with respect to benchmark calculations. The scheme is implemented into the ECMWF global forecast model using imposed sea surface temperatures, and while the impact on the radiative statistics is significant, the feedback on the large-scale dynamics is minimal.

scholarly journals A new numerical model to compute photolysis rates and solar heating with anisotropic scattering in spherical geometry

1996 ◽  
Vol 14 (1) ◽  
pp. 80-97 ◽  
Author(s):  
M. Balluch
Keyword(s):  
Numerical Model ◽  
Zenith Angle ◽  
Solar Zenith Angle ◽  
Spherical Geometry ◽  
Anisotropic Scattering ◽  
Solar Heating ◽  
Isotropic Scattering ◽  
Heating Rates ◽  
Vertical Column ◽  
Photolysis Rates

Abstract. For calculating photolysis rates and solar heating in the atmosphere, the radiation field has to be calculated very accurately. Previous investigations have shown that for large solar zenith angles a solution of the radiation equation which accounts for the Earth\\'s curvature is needed. A new simplified version of the 3D radiation equation in spherical geometry allowing for anisotropic scattering is presented. The horizontal variation of physical quantities, the variation of the solar zenith angle with different longitude and latitude for the scattering calculation for one vertical column of air and any effects of refraction are neglected. A numerical model is introduced which efficiently solves this new 3D radiation equation accurately. The effects of anisotropic scattering are shown to be very important for the directional dependence of the scattered intensity. Anisotropic scattering by aerosols and air molecules can change the intensity in certain directions by up to 180% and 25%, respectively. However, most of these changes cancel each other out when averaged over all angles, so that the effect of anisotropic scattering for large solar zenith angles on the mean intensity (actinic flux) is much smaller, i.e. less than 10%. For the heating rates, the effect of anisotropic scattering for large solar zenith angles is even smaller, being less than a few percent. Generally, the effects of anisotropic scattering and the effects of including aerosols are the larger on higher altitudes the larger the solar zenith angle is. Results of the model are shown to compare well with results of previous investigations, including the independent work of Dahlback and Stamnes. The agreement is especially good in the case of isotropic scattering by air molecules and neglecting the effects of aerosols.

scholarly journals Reply to “Comments on ‘On the Choice of Average Solar Zenith Angle’’’

2017 ◽  
Vol 74 (5) ◽  
pp. 1677-1680 ◽  
Author(s):  
Timothy W. Cronin
Keyword(s):  
Zenith Angle ◽  
Circular Orbit ◽  
Solar Zenith Angle ◽  
Solar Constant ◽  
Surface Absorption ◽  
Annual Average ◽  
The Mean ◽  
Free Parameters ◽  
Angle Calculation

Abstract 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.

Effect of solar zenith angle on satellite cloud retrievals based on O2–O2 absorption band

2021 ◽  
Vol 42 (11) ◽  
pp. 4224-4240
Author(s):  
Gyuyeon Kim ◽  
Yong-Sang Choi ◽  
Sang Seo Park ◽  
Jhoon Kim
Keyword(s):  
Absorption Band ◽  
Zenith Angle ◽  
Solar Zenith Angle

Sun-induced production of vitamin D3 throughout 1 year in tropical and subtropical regions: relationship with latitude, cloudiness, UV-B exposure and solar zenith angle

2021 ◽  
Vol 20 (2) ◽  
pp. 265-274
Author(s):  
Angela C. G. B. Leal ◽  
Marcelo P. Corrêa ◽  
Michael F. Holick ◽  
Enaldo V. Melo ◽  
Marise Lazaretti-Castro
Keyword(s):  
Zenith Angle ◽  
Vitamin D3 ◽  
Solar Zenith Angle

scholarly journals Effects of Diurnal Variations on Tropical Equilibrium States: A Two-Dimensional Cloud-Resolving Modeling Study

2007 ◽  
Vol 64 (2) ◽  
pp. 656-664 ◽  
Author(s):  
Shouting Gao ◽  
Yushu Zhou ◽  
Xiaofan Li
Keyword(s):  
Equilibrium State ◽  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Zenith Angle ◽  
Solar Zenith Angle ◽  
Diurnal Variations ◽  
Equilibrium States ◽  
Sea Surface ◽  
Two Dimensional ◽  
Time Invariant

Abstract Effects of diurnal variations on tropical heat and water vapor equilibrium states are investigated based on hourly data from two-dimensional cloud-resolving simulations. The model is integrated for 40 days and the simulations reach equilibrium states in all experiments. The simulation with a time-invariant solar zenith angle produces a colder and drier equilibrium state than does the simulation with a diurnally varied solar zenith angle. The simulation with a diurnally varied sea surface temperature generates a colder equilibrium state than does the simulation with a time-invariant sea surface temperature. Mass-weighted mean temperature and precipitable water budgets are analyzed to explain the thermodynamic differences. The simulation with the time-invariant solar zenith angle produces less solar heating, more condensation, and consumes more moisture than the simulation with the diurnally varied solar zenith angle. The simulation with the diurnally varied sea surface temperature produces a colder temperature through less latent heating and more IR cooling than the simulation with the time-invariant sea surface temperature.

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