摘要:

We report several observations of the Lα interplanetary emission recorded by a photometer flown in 1977 on board the soviet spacecraft Prognoz‐5. The Prognoz scans sampled emission in a plane perpendicular to the sun‐spacecraft line and also traversed the Lα maximum emission region (MER), a region centered a few AU from the Sun on the upstream interstellar‐flow axis. These scans reveal the existence of a 10% decrease in intensity centered near the ecliptic plane and about 30° wide. All the dips form a new feature of the interplanetary emission, a “groove” aligned approximately with the ecliptic plane. This groove is present only near the upwind direction, and is interpreted as the result of enhanced ionisation of interstellar H by charge‐exchange with the solar wind in a sheet of approximately 30° width in latitude around the average position of the neutral sheet, at this time o

ISSN:0094-8276    

DOI:10.1029/96GL03475

年代:1996

数据来源: WILEY

摘要:

A novel method is described for reconstruction of two‐dimensional current‐layer structures from measurements taken by a single spacecraft traversing the layer. In its present form, the method is applicable only to 2D magneto‐hydrostatic structures that are passively convected past the observing spacecraft. It is tested on a magnetopause crossing of the tangential‐discontinuity type by the spacecraft AMPTE/IRM. The magnetic structures recovered include a magnetic island located between two X‐type nulls as well as a magnetic ‘worm hole’ through which a bundle of weak magnetic flux appears to connect the magnetosphere and the

ISSN:0094-8276    

DOI:10.1029/96GL03573

年代:1996

数据来源: WILEY

摘要:

Indian MST radar at Gadanki (13.5°N, 79.2°E, 12.5° dip) was operated during July/August 1994, to observe the 3‐m scale size field aligned irregularities associated with the lower E region. Irregularity structure was studied by using height‐time variation of the echo intensity and weighted mean Doppler velocity. In this paper results of three diurnal cycles of observation are presented. Field perpendicular echoes were observed both during daytime and nighttime. A layered irregularity structure extending down to altitude below 86 Km was seen during the nighttime. The daytime structure showed a narrow echoing region with significant downward slope. Doppler velocity was in the range of 20–50 ms−1, both during day and night and was, in general, consistent with the slope of scattering structure observed in the height‐time‐i

ISSN:0094-8276    

DOI:10.1029/96GL02625

年代:1996

数据来源: WILEY

摘要:

On February 26, 1995, during a NASA sponsored mission to Peru to study red sprites and blue jets, the instrumented Westwind 2 jet aircraft encountered spectacular St. Elmo's fire from the wing pods, tail and nose while flying through a cloud at an altitude of 13.83 km (45,376 ft). The phenomenon was captured on low light level monochromatic and color television systems aboard the aircraft, and its spectrum was recorded on a low light level TV spectrograph with response from 395.0 to 750.0 nm. The cameras and spectrograph also recorded scattered intra‐cloud lightning and a possible lightning discharge near, or to, the aircraft. The spectrum of St. Elmo's fire was primarily the second (2nd) positive bands of N2. The data were consistent with a population of electrons having relatively low energy (<18 eV

ISSN:0094-8276    

DOI:10.1029/96GL03621

年代:1996

数据来源: WILEY

摘要:

Horizontal magnetic field variations in the frequency range of the Earth‐ionosphere cavity resonances are observed at Silberborn, Germany, simultaneous with 19 sprite‐associated lightning flashes in the midwestern United States, on July 15, 1995. The measured horizontal magnetic intensities are linearly related to the horizontal magnetic intensities of slow tails of radio atmospherics which were simultaneously recorded at Palmer Station, Antarctica. Enhancement of the Earth‐ionosphere cavity resonances is verified by spectral analysis, and the measured arrival azimuths are in agreement with the expected orientation of the Poynting vector along the great‐circle path. The estimated accuracy of the arrival azimuth determination is on the order

ISSN:0094-8276    

DOI:10.1029/96GL03538

年代:1996

数据来源: WILEY

摘要:

A Version 7 algorithm and calibration have been applied to the 14.5 year Nimbus 7 TOMS ozone record (1978–1993). The ozone retrieval algorithm has been significantly improved for cloudy conditions and for high solar zenith angles, and the radiative transfer used in the algorithm is more accurate. New calibration techniques have been used that produce a very stable data set even after 1990 when TOMS degradation became significant. TOMS ozone now agrees with average ozone from an ensemble of 30 northern hemisphere ground stations (Dobsons and Brewers) to within ±1% throughout most of the 14.5 year record. The time‐dependent drift relative to Dobson is 0.29% per decade through the end of the data record. There is almost no solar zenith angle dependence in the comparison for angles below about 80°, but data should be used with caution for larger solar zenith angles. There is also a residual total ozone dependence in the TOMS‐Dobson difference, of about 1% per

ISSN:0094-8276    

DOI:10.1029/96GL03539

年代:1996

数据来源: WILEY

摘要:

Ozone measurements from the Nimbus 7 TOMS instrument, which operated from November 1978 through early May 1993, have been extended through December 1994 using data from the TOMS instrument on‐board the Russian Meteor 3 satellite. Both TOMS data records have recently been recalibrated, and then reprocessed using the Version 7 retrieval algorithm. Long‐term trend estimates obtained from a multiple regression analysis show ozone losses in the extended data record similar to those reported in previous studies using Version 6 TOMS and SBUV data, and ground‐based Dobson data. Ozone continues to decline through the end of 1994, with the most significant ozone losses occurring in the high southern latitudes during October (−20% per decade) and in the northern mid‐ to high‐latitudes during March/April (−6 to −8% per decade). There is no significant ozone trend in the tropics. Annual‐average trends derived from the Nimbus 7 Version 7 data are 0–2.5% per decade less negative than those derived over the same time period u

ISSN:0094-8276    

DOI:10.1029/96GL03540

年代:1996

数据来源: WILEY

摘要:

The stratospheric winters 1994/1995 and 1995/1996 were both extremely cold. The temperature (T) fell below that necessary for type 1 polar stratospheric cloud formation (195 K at 50 hPa) on many consecutive days in each winter and occasionally reached values low enough for ice cloud formation. The meteorological situation each winter was quite different. Both seasons were cold throughout Dec and Jan. In 1995 a dynamical warming event increasedTin the latter part of Feb but a further cold spell occurred in early Mar. In contrast, the polar vortex remained well developed until early Mar 1996, whenTincreased rapidly. While both winters were extremely cold at 50 hPa, the polar vortex was deeper in Feb 1996 when extremely lowToccurred over large areas at 30 hPa.

ISSN:0094-8276    

DOI:10.1029/96GL03614

年代:1996

数据来源: WILEY

摘要:

The Lorentz‐Lorenz relation is used to estimate the refractive index of aqueous H2SO4/HNO3solutions (5–70 wt%) for wavelengths from the near‐ultraviolet to the near‐infrared (0.35–2 µm) and for temperatures from 370 K to stratospheric temperatures (185 K). The molecular refractivities of the involved species are based on data of the binary solutions at room temperature. For the extrapolation to low temperatures, a careful estimate of the density of the ternary solutions has been performed. The accuracy of the model predictions is estimated to be bett

ISSN:0094-8276    

DOI:10.1029/96GL03581

年代:1996

数据来源: WILEY

摘要:

Multichannel radiometer measurements of a newly formed contrail taken from a NASA ER‐2 aircraft over northern Oklahoma during the FIRE Cirrus‐II experiment are used in a split‐window retrieval of the contrail's particle size and optical depth. The effect of horizontal inhomogeneity in an underlying cirrus layer on the contrail retrieval is studied through the use of multi‐dimensional radiative transfer model simulations. Estimates of the contrail's effective radius are significantly smaller (5–7 µm) than those in the underlying cirrus (21 µm). The effect of horizontal inhomogeneity in the underlying cirrus on contrail particle size and optical depth retrievals is generally smaller than the corresponding effects of particle shape or spectral variations in surface emissivity on the retrievals. The differences in particle size retrievals are 10 percent or less as a result of the inhomogeneity, while they are from 10 to 40 percent for ice cylinders, and range from 1 to 40 percent for ice spheroids. Horizontal inhomogeneity affected the optical depth retrievals by only one or two percent, while surface emissivity variations affected the retrievals by 12 to 24 percent, and particle shape produced differences as large a

ISSN:0094-8276    

DOI:10.1029/96GL03645

年代:1996

数据来源: WILEY