Showing papers on "Solar constant published in 2005"

The Total Irradiance Monitor (TIM): Science Results

Abstract: The solar observations from the Total Irradiance Monitor (TIM) are discussed since the SOlar Radiation and Climate Experiment (SORCE) launch in January 2003. The TIM measurements clearly show the background disk-integrated solar oscillations of generally less than 50 parts per million (ppm) amplitude over the ∼2 ppm instrument noise level. The total solar irradiance (TSI) from the TIM is about 1361 W/m2, or 4–5 W/m2 lower than that measured by other current TSI instruments. This difference is not considered an instrument or calibration error. Comparisons with other instruments show excellent agreement of solar variability on a relative scale. The TIM observed the Sun during the extreme activity period extending from late October to early November 2003. During this period, the instrument recorded both the largest short-term decrease in the 25-year TSI record and also the first definitive detection of a solar flare in TSI, from which an integrated energy of roughly (6± 3)×1032 ergs from the 28 October 2003 X17 flare is estimated. The TIM has also recorded two planets transiting the Sun, although only the Venus transit on 8 June 2004 was definitive.

The Geostationary Earth Radiation Budget Project

Abstract: This paper reports on a new satellite sensor, the Geostationary Earth Radiation Budget (GERB) experiment. GERB is designed to make the first measurements of the Earth's radiation budget from geostationary orbit. Measurements at high absolute accuracy of the reflected sunlight from the Earth, and the thermal radiation emitted by the Earth are made every 15 min, with a spatial resolution at the subsatellite point of 44.6 km (north–south) by 39.3 km (east–west). With knowledge of the incoming solar constant, this gives the primary forcing and response components of the top-of-atmosphere radiation. The first GERB instrument is an instrument of opportunity on Meteosat-8, a new spin-stabilized spacecraft platform also carrying the Spinning Enhanced Visible and Infrared (SEVIRI) sensor, which is currently positioned over the equator at 3.5°W. This overview of the project includes a description of the instrument design and its preflight and in-flight calibration. An evaluation of the instrument performan...

On the response of the O(1S) dayglow emission rate to the Sun's energy input: An empirical model deduced from WINDII/UARS global measurements

Abstract: [1] More than 520,000 emission rate profiles of the O(1S) dayglow (557.7 nm, the atomic oxygen green line) were measured by the Wind Imaging Interferometer (WINDII) on the Upper Atmospheric Research Satellite (UARS) during 1991–1997, providing an unprecedented and unique resource for studying the O(1S) emission layer, its related physics and chemistry, and the response of the mesosphere and thermosphere to the solar input. The daytime O(1S) emission is one of the most remarkable and persistent phenomena in the Earth's atmosphere between 80 and 280 km. The emission has two components, peaking at 140–180 km and 94–104 km. WINDII measurements show that both components are sensitively correlated with the Sun in the sense that (1) for a given day, the peak emission rates in both the F-region and the E-region increase with increasing cosine of the solar zenith angle, the height of the peak emission rate in the F-region decreases with increasing peak emission rate but that in the E-region does not have a clear relationship with the peak emission rate; (2) both the peak emission rate and its height in the F-region as well in the E-region increase with increasing solar irradiance, i.e., they follow the solar cycle. For the first time an empirical model of the green line emission rate and height of the peak emission are derived from WINDII global measurements over six years as functions of the solar zenith angle and the solar irradiance using the daily solar F10.7 cm flux as a proxy. This model provides a baseline for the unperturbed daytime green line emission for any time and any location. Owing to the direct effect of the solar zenith angle, the emission rate is symmetrical with respect to local noon; and globally, it is symmetrical with respect to the equator at equinox, and is much larger in the summer hemisphere than in the winter hemisphere at solstice. As a result, for a constant solar irradiance, the emission rate has an annual oscillation at mid and high latitudes, and a semiannual oscillation at the equator. In the solar cycle 22, for an overhead Sun, the max/min ratio of the F10.7 cm flux is about four, and the max/min ratio of the integrated O(1S) emission rate is about three. Some unsolved problems regarding the mechanism of the green line emission are reported.

Measurements of the Solar Radius in Antalya between 2001–2003

Abstract: The results of the solar radius measurements from February 2001 to November 2003 with the solar astrolabe at the TUBITAK National Observatory are presented. The mean semi-diameter for the period, corrected for systematic effects such as the Fried parameter and the zenith distance, is found to be 959.29 ± 0.01 arc sec. A comparison of the monthly averages of the solar radius with the monthly means of sunspot numbers shows that the semi-diameter of the Sun increases with an amplitude of 0.017 arc sec per year in opposite phase with solar cycle 23.

On the response of the atomic oxygen red line emission rates to the Sun's energy input: an empirical model deduced from WINDII/UARS global measurements

Abstract: In a previous paper by Zhang and Shepherd, an empirical model for the peak volume emission rate (Vp) and the integrated volume emission rate of the O(1D) (630 nm) dayglow was deduced from more than 130,000 daytime emission rate profiles observed by the Wind Imaging Interferometer (WINDII) on the Upper Atmospheric Research Satellite (UARS) during 1991-1995. In the model, the emission rates are given as functions of the solar zenith angle (χ) and solar irradiance using the F10.7 cm flux as a proxy. This paper extends the daytime empirical model into the twilight zone and includes the height of the peak emission rate and the width of the emission layer. For a given day, the O(1D) emission layer during both daytime and twilight-time is found to be sensitive to the solar zenith angle when solar irradiance is treated as a constant. Positive linear relationships are found between the daytime emission rate and cos1/eχ at χ < 87° the twilight-time emission rate and cos(χ+0.25)1.8 at 87° less than or equal to χ less than or equal to 104.5°, and the width of the emission layer and cosχ at χ < 87°. A negative linear relationship is found between the peak emission rate and its height at χ < 104.5°. In the long-term, the emission layer varies according to the solar cycle in that both the emission rate and the height of the emission layer increase with increasing solar irradiance. The empirical model provides the peak volume emission rate and its height, and the integrated emission rate, for both daytime and twilight zones, and the width of the daytime emission layer as functions of the solar zenith angle and solar irradiance using F10.7, E10.7, and Lyman-β as proxies. The profiles of the volume emission rate and global morphology of the red line emission therefore can be constructed using the model. Effects of solar storms, and physical precesses and photochemical reactions other than that due to the direct solar energy deposition in the thermosphere can be derived by comparing to the model.

The direct solar influence on climate: modeling the lower atmosphere

Abstract: A set of ensemble experiments has been run focusing on the Dalton minimum to identify the individual contributions of solar variability, volcanism, greenhouse gas concentration changes and the combination of these forcing on climate. Additionally an idealized experiment has been carried out, where a sinusoidal forcing corresponding to the period of the Gleissberg-cycle, which led to the Dalton minimum, has been prescribed. Both, the volcanic and the solar forcing contribute to the global cooling during the Dalton minimum. The volcanic forcing, however, plays the major role for the global mean temperature. The temperature rise due to the greenhouse gases concentration increase counteracts this cooling only marginally. For the European region significant reduction of the solar constant (in the range of the imposed volcanic forcing) shift the NAO into the negative phase, thus enhancing the cooling over Europe. The experimental setup, which does not allow to take the volcanic aerosol forcing directly into consideration does not produce the winter warming in the years directly after the volcanic eruptions which has been seen in other modeling studies. In the idealized experiment the temperature follows the forcing with a lag of 4 to 6 years, which close to the observed value of 7 years. The MOC also reacts to the variations in the solar forcing. The pattern of the idealized response is only in the midand high latitudes similar to the one of the GHG experiments.

Summer Land-surface Radiation Characteristic over Longzhong Region of Loess Plateau, China

Abstract: The land-surface radiation characteristic over semi-arid region of the Loess Plateau is analyzed based on the radiation data observed at Dingxi Arid Meteorology and Ecological Environment Experimental Station. It is showed that the radiant intensity is very high and the maximum of instantaneous global radiation is beyond \{1 000\} W\5m~(-2), sometimes beyond solar constant in summer. The ratio of the daily average global radiation during spring wheat growth to one on a clear day is between 0.6 and 0.8, and the ratio of the daily net radiation between 0.4 and 0.6, and likewise over bare soil. In other words, it means that the cloud and rainfall can make great influence on land-surface radiation. In addition, the fluctuation of the mean daily albedo is high and the maximum and the minimum is 0.24 and 0.11 respectively during experiment. It is because the water droplet adhering to the leaf of wheat that causes the increasing of the albedo and the increasing of wind speed can induce considerable variation of the albedo. In short, the daily albedo under different types of synoptic conditions shows as different characteristic because of integrated affect which caused by soil water content, synoptic conditions and solar altitude angle.

Solar-energy jet-type refrigerator

Abstract: A refrigerator of solar energy jet type is composed of insulation layer, jet mouth, energy accumulator , solar constant temperature cavity , temperature controlled electromagnetic disc , condenser , mixing chamber , automatic jet , wire , light pipe receiver , frame for fixing light pipe , evaporator , relay control panel , fan , spiral wall in cavity and transfusion pipe . It features connecting light pipe receiver to energy accumulator in series for forming outdoor energy receiver and setting solar constant temperature cavity connected with condenser at top and mixing chamber at bottom in energy accumulator.

Does Solar Irradiance Caused the Time Shifting of Termination-II?

Abstract: The Orbital theory presumes that the solar irradiance was constant during geological periods of time. Recent studies demonstrated that this presumption is not precise. Direct satellite measurements of the solar constant demonstrated that it varies with time as much as 0.4% during the observation time span (Hickey et al., 1980), but there are experimental data suggesting that it varied much greater during geological periods. Stuiver & Braziunas (1989) demonstrated that longer solar cycles are more than one order of magnitude stronger, than the solar cycles covered by direct measurements. Increasing of the ice volume and the related sea level change during glaciations produces changes in the inertial moment of the Earth and resulting changes in the speed of Earth’s rotation (Tenchov et al., 1993). Orbital variations cause also some deformation of the solid Earth and redistribution of the Ocean masses (Morner, 1983). In result theoretical Milankovich curves can be used only for qualitative reference. For quantitative correlation it is necessary to use experimental records of the solar insolation, because they contain also variations of the solar irradiance and number of others not covered by the Orbital theory.