Abstract : The atmosphere s response to the total solar eclipse of 4 December 2002 is studied using a prototype high-altitude global numerical weather prediction model (NOGAPS-ALPHA). Local reductions in solar ultraviolet (UV) radiation during the eclipse are estimated using astronomical calculations of umbral and penumbral surface trajectories and observed solar limb darkening at ~ 200-300 nm. In NOGAPS-ALPHA these UV eclipse shadows yield stratospheric radiative cooling rate footprints peaking near 27 K day 1, a value 2 3 times larger than assumed in previous modeling. Difference fields between NOGAPS-ALPHA runs with and without this eclipse forcing reveal vertically deep middle atmospheric responses, with three-dimensional horizontal structures very similar to the large-scale bow-wave response first proposed by Chimonas (1970). Such structure appears clearly only at later times when total eclipses have abated and gravity waves generated in the stratosphere have had time to propagate vertically. Bow-wave amplitudes and direct thermal cooling responses are both small (]1 K for temperature and ]2 3 m s 1 for horizontal winds), contradicting some rocketsonde measurements that suggest much larger responses near 50 60 km altitude. We also find clear evidence of a bow-wave-like response in the model s surface pressure fields, with an amplitude 0.1 0.5 hPa, while surface air temperatures in NOGAPS-ALPHA show 4 K cooling over Africa during the eclipse. Both findings are consistent with surface atmospheric data acquired during previous eclipse passages.

Middle and lower atmospheric effects of the total solar eclipse of 4 December 2002 simulated with a high-altitude global model

: The atmosphere s response to the total solar eclipse of 4 December 2002 is studied using a prototype high-altitude global numerical weather prediction model (NOGAPS-ALPHA). Local reductions in solar ultraviolet (UV) radiation during the eclipse are estimated using astronomical calculations of umbral and penumbral surface trajectories and observed solar limb darkening at ~ 200-300 nm. In NOGAPS-ALPHA these UV eclipse shadows yield stratospheric radiative cooling rate footprints peaking near 27 K day 1, a value 2 3 times larger than assumed in previous modeling. Difference fields between NOGAPS-ALPHA runs with and without this eclipse forcing reveal vertically deep middle atmospheric responses, with three-dimensional horizontal structures very similar to the large-scale bow-wave response first proposed by Chimonas (1970). Such structure appears clearly only at later times when total eclipses have abated and gravity waves generated in the stratosphere have had time to propagate vertically. Bow-wave amplitudes and direct thermal cooling responses are both small (]1 K for temperature and ]2 3 m s 1 for horizontal winds), contradicting some rocketsonde measurements that suggest much larger responses near 50 60 km altitude. We also find clear evidence of a bow-wave-like response in the model s surface pressure fields, with an amplitude 0.1 0.5 hPa, while surface air temperatures in NOGAPS-ALPHA show 4 K cooling over Africa during the eclipse. Both findings are consistent with surface atmospheric data acquired during previous eclipse passages.

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2006JD007880

Atmospheric effects of the total solar eclipse of 4 December 2002 simulated with a high-altitude global model

: The aim of the atmospheric modeling project is to predict absorption and scattering effects of the atmospheric medium on the transmission of ground target electromagnetic (EM) signatures in the spectral region 0.4-14 micrometers, for a wide range of meteorological conditions. Special attention is being given to low visibility atmospheric states which can exist under battlefield conditions. Two important related aspects of the program are the atmospheric extinction and radiative transfer models. These models will be integrated into system performance models for the evaluation of terminal homing, surveillance, and target acquisition systems. This report will describe the Atmospheric Sciences Laboratory's (ASL) single scattering model, which was developed for input to multiple scattering codes for the determination of EM extinction caused by the atmospheric aerosol. Sample applications will be made to the cases of haze and dust.

Atmospheric effects for ground target signature modeling. 3: Discussion and application of the ASL scattering model

During a solar eclipse, the Moon's shadow progressively occults a part of the Earth from the solar flux. This induces a cooling in the atmospheric layers that usually absorb the solar radiation. Since the eclipse shadow travels within the atmosphere at supersonic velocity, this cooling generates a planetary-scale bow-wave of internal gravity waves. The purpose of this article is to estimate the surface pressure fluctuations produced by the passage of the 1 August 2008 total solar eclipse and to compare these pressure fluctuations with those recorded by a temporary network of microbarographs and by the infrasound stations of the International Monitoring System. The surface pressure fluctuations expected at all the measurement sites are estimated using a linear spectral numerical model. It is shown that the cooling of both the ozonosphere and the troposphere can produce detectable pressure fluctuations at the ground surface but that the tropospheric cooling is likely to be the predominant source. Since the expected eclipse signals are in a frequency range that is highly perturbed by atmospheric tides and meteorological phenomena, the pressure fluctuations produced by these synoptic disturbances are characterized and removed from the recorded signals. Low-frequency gravity waves starting just after the passage of the eclipse are then brought to light at most measurement sites. The time-frequency characteristics of these waves are similar to those obtained from the model, which strongly suggests that these waves were produced by the passage of the 1 August 2008 solar eclipse.

https://hal.archives-ouvertes.fr/hal-00717708/document

Surface Pressure Fluctuations Produced by the Total Solar Eclipse of 1 August 2008

Response of tropical lower atmosphere to annular solar eclipse of 15 January, 2010

A partial solar eclipse (approximately 3-hour duration) occurred at Fort Sherman, Panama Canal Zone (9°20′N, 79°59′W), in the early morning hours on December 24, 1973. Five rocket-borne temperature sensors were deployed at an altitude of 60–65 km before, during, and after the eclipse. Temperatures and winds were measured as the sensors descended by parachute. Analysis of the data indicates that there was 3°–5°C cooling produced in the 50- to 52-km layer as the solar radiation was partially blocked from reaching the earth's atmosphere. Zonal wind speed was also affected at those levels from 15 m/s before the eclipse to 9 m/s during the maximum phase.

J. S. Randhawa

Papers

Partial solar eclipse effects on temperature and wind in an equatorial atmosphere