Analysis of changes in air temperature in Russia and empirical forecast for the first quarter of the 21st century     

O. A. Anisimov  V. A. Lobanov  S. A. Reneva 《Russian Meteorology and Hydrology》2007,32(10):620-626

Changes in air temperature in administrative districts of the Russian Federation are studied. The in-regional homogeneity of modern climate changes is estimated based on several criteria for the first half of the 20th century and for the next period. The relation between regional changes in mean annual and seasonal temperatures and global air temperature is considered, and an empirical forecast for one or two decades is suggested to be made on its basis. Empirical regional forecasts of a rate of changes in mean annual air temperature are compared with the calculation results from five general circulation models.  相似文献   

Modern climate-related changes in heat supply,moistening, and productivity of the agrosphere in Russia     

O. D. Sirotenko  G. V. Gruza  E. Ya. Rankova  E. V. Abashina  V. N. Pavlova 《Russian Meteorology and Hydrology》2007,32(8):538-546

Climate changes observed in recent decades are analyzed, and the respective climate-related tendencies of changes in heat supply, moistening, and productivity of the agrosphere that determine the natural resourse of potential Russia are determined. The grain crop yield trends are used additionally as climate change indicators. It is shown that climate changes observed in the last 30 years promote the increase in potential agriculture productivity in most of the Russian Federation, where not less than 85% of agricultural products are produced. At the same time, the increase in climate aridity is observed in several regions of Siberia and Chernozem Center, which results in a reduced productivity of agriculture.  相似文献   

Clear-sky aerosol radiative forcing effects based on multi-site AERONET observations over Europe     

S. Gonzi  O. Dubovik  D. Baumgartner  E. Putz 《Meteorology and Atmospheric Physics》2007,96(3-4):277-291

Summary One of the great unknowns in climate research is the contribution of aerosols to climate forcing and climate perturbation. In this study, retrievals from AERONET are used to estimate the direct clear-sky aerosol top-of-atmosphere and surface radiative forcing effects for 12 multi-site observing stations in Europe. The radiative transfer code sdisort in the libRadtran environment is applied to accomplish these estimations. Most of the calculations in this study rely on observations which have been made for the years 1999, 2000, and 2001. Some stations do have observations dating back to the year of 1995. The calculations rely on a pre-compiled aerosol optical properties database for Europe. Aerosol radiative forcing effects are calculated with monthly mean aerosol optical properties retrievals and calculations are presented for three different surface albedo scenarios. Two of the surface albedo scenarios are generic by nature bare soil and green vegetation and the third relies on the ISCCP (International Satellite Cloud Climatology Project) data product. The ISCCP database has also been used to obtain clear-sky weighting fractions over AERONET stations. The AERONET stations cover the area 0° to 30° E and 42° to 52° N. AERONET retrievals are column integrated and this study does not make any seperation between the contribution of natural and anthropogenic components. For the 12 AERONET stations, median clear-sky top-of-atmosphere aerosol radiative forcing effect values for different surface albedo scenarios are calculated to be in the range of −4 to −2 W/m². High median radiative forcing effect values of about −6 W/m² were found to occur mainly in the summer months while lower values of about −1 W/m² occur in the winter months. The aerosol surface forcing also increases in summer months and can reach values of −8 W/m². Individual stations often have much higher values by a factor of 2. The median top-of-atmosphere aerosol radiative forcing effect efficiency is estimated to be about −25 W/m² and their respective surface efficiency is around −35 W/m². The fractional absorption coefficient is estimated to be 1.7, but deviates significantly from station to station. In addition, it is found that the well known peak of the aerosol radiative forcing effect at a solar zenith angle of about 75° is in fact the average of the peaks occurring at shorter and longer wavelengths. According to estimations for Central Europe, based on mean aerosol optical properties retrievals from 12 stations, the critical threshold of the aerosol single scattering albedo, between cooling and heating in the presence of an aerosol layer, is close between 0.6 and 0.76.  相似文献   

Initial CHIP He I Observations of Solar Limb Activity     

MacQueen  R. M.  Blankner  J. G.  Elmore  D. F.  Lecinski  A. R.  White  O. R. 《Solar physics》1998,182(1):97-105

A new instrument capable of 3-min time resolution full-disk and limb observations in the Hei 1083 nm spectral line has been in operation at the High Altitude Observatory's Mauna Loa Solar Observatory (MLSO) since April 1996. We discuss instrument capabilities and performance and present some initial observations of limb activity from the first year of instrument operation. We compare limb Hei and Hα observations of quiescent and active prominences, comment on the role of Doppler shifts in interpreting the Hei observations, and illustrate the use of disk/limb Hei observations of a CME-associated eruptive filament in mass-ejection studies.  相似文献   

Cosmic-Ray Decreases and Interplanetary Disturbances During the Solar Magnetic Polarity Reversal in Solar Cycle 20     

Ifedili  S. O. 《Solar physics》1998,180(1-2):487-493

Using the cosmic-ray intensity data recorded with ground-based monitors at Mt. Washington and Deep River, and with cosmic-ray telescopes on Pioneer 8 and 9 spacecraft as well as the 2-hour averages of the IMF (magnitude and direction) and the solar wind bulk speed and density at 1 AU, the cosmic-ray decreases and interplanetary disturbances, that occurred during the period of solar magnetic polarity reversal in solar cycle 20, were investigated.We observed a two-step Forbush decrease on 22–23 November 1969, and a Forbush decrease on 26 November 1969, which are respectively consistent with the model of Barnden (1973), and of Parker (1963) and Barnden (1973). Only one Forbush decrease event was observed in December 1969, a period during which there was a solar magnetic polarity reversal; the Forbush decrease was attributed to a long-lived corotating high-speed solar wind stream. This is indicative that at heliolongitudes from 43° E to 70° W of S–E radial, covered by the observations, the solar magnetic polarity reversal in solar cycle 20 was not carried by, nor related to, individual transient structures, and that the reversal most probably evolved gradually.  相似文献   

Large-Scale Electric Fields in Solar Flare Regions     

M. I. Pudovkin  S. A. Zaitseva  N. O. Shumilov  C.-V. Meister 《Solar physics》1998,178(1):125-136

A method of separating electric field in the flare region in the potential and vortex (induced) parts is discussed. According to the proposed model, the motion of flare ribbons from the central line of the flare region is caused by the vortex component of the coronal electric field, while the motion of bright spots within the flare region towards the central line is driven by the potential component of that field. The intensity of both the components of the flare region electric field is estimated to equal approximately 1–3 V cm^–1, which provides the input of the electromagnetic energy into the active region at a rate of about 10¹⁰ erg cm^–2 s^–1.  相似文献   

On the Power Distribution of Solar p MODES     

H-Y. Chang  D. O. Gough 《Solar physics》1998,181(2):251-263

We present a simple idealized model of stochastically forced solar oscillations, and compare the distribution function of energy, averaged over 12-hour intervals, with that of low-degree solar modes. We find that the simulated energy distribution is similar to the observations, except at extremely high energy.  相似文献   

The Determination of the Reduction Factor for Sunspot Observations and its Variation with Meteorological Parameters     

Altas  L.  Düzgelen  A.  Barlas  O. 《Solar physics》1998,178(2):267-270

Sunspot observations performed at Kandilli Observatory and the Earthquake Research Institute (KOERI) in cycle 21 (between January 1976 and December 1986) were investigated to obtain the reduction factors. The dependence of the reduction factors on the meteorological parameters and on the seeing conditions has been analysed and their relationship to these parameters is discussed here.  相似文献   

Cluster–subcluster mergers and the formation of narrow-angle tailed radio sources     

M. Bliton    E. Rizza    J. O. Burns    F. N. Owen  & M. J. Ledlow 《Monthly notices of the Royal Astronomical Society》1998,301(3):609-625

We examine the ROSAT PSPC X-ray properties of a sample of 15 Abell clusters containing 23 narrow-angle tailed (NAT) radio galaxies. We find that clusters with NATs show a significantly higher level of substructure than a similar sample of radio-quiet clusters, indicating that NAT radio sources are preferentially located in dynamically complex systems. Also, the velocity distribution of the NAT galaxies is similar to that of other cluster members; these velocities are inadequate for producing the ram pressure necessary to bend the radio jets. We therefore propose a new model for NAT formation, in which NATs are associated with dynamically complex clusters undergoing merger events. The U -shaped NAT morphology is produced in part by the merger-induced bulk motion of the ICM bending the jets.  相似文献   

X-ray observations of distant Abell clusters     

E. Rizza  J. O. Burns  M. J. Ledlow  F. N. Owen  W. Voges  & M. Bliton 《Monthly notices of the Royal Astronomical Society》1998,301(2):328-342

We present results from a ROSAT HRI study of 11 distant ( z  ∼ 0.2–0.3) Abell clusters. We have performed a morphological analysis to search for and quantify substructure in the clusters. About 70 per cent of the sample shows significant evidence of substructure in the form of centroid shift or obvious X-ray clumps. We examine the clusters for the presence of cooling flows, and determine the physical properties of the ICM by deprojecting the HRI data. Nine of the clusters have central cooling times less than the age of the system, in agreement with fractions determined from nearby, X-ray-bright samples. Additional PSPC results are presented for four clusters in the sample, and ASCA results for six clusters. The temperatures and metallicities for these distant clusters appear to be consistent with nearby clusters of similar richness.  相似文献