Mass budgets of the Lambert, Mellor and Fisher Glaciers and basal fluxes beneath their flowbands on Amery Ice Shelf

We used in situ measurements and remote-sensing data sets to evaluate the mass budgets of the Lambert, Mellor and Fisher Glaciers and the basal melting and freezing rates beneath their flowbands on the Amery Ice Shelf. Our findings show the Lambert and Mellor Glaciers upstream of the ANARE Lambert Glacier Basin (LGB) traverse may have positive imbalances of 3.9±2.1 Gt a-1 and 2.1±2.4 Gt a-1, respectively, while the Fisher Glacier is approximately in balance. The upstream region as a whole has a positive imbalance of 5.9±4.9 Gt a-1. The three same glaciers downstream of the ANARE LGB traverse line are in negative imbalance, where the whole downstream region has a negative imbalance of -8.5±5.8 Gt a-1. Overall the mass budgets of the Lambert, Mellor, and Fisher Glaciers are close to bal-ance, and the collective three-glacier system is also nearly in balance with a mass budget of -2.6±6.5 Gt a-1. The significant positive imbalances for the interior basin upstream of the ice-movement stations established in the early 1970s (GL line) reported previously are possibly due to an overestimate of the total accumulation and an underestimate of the ice flux through the GL line. The mean melting rate is -23.0±3.5 m ice a-1 near the southern grounding line, which decreases rapidly downstream, and transitions to refreezing at around 300 km from the southern extremity of the Amery Ice Shelf. Freezing rates along the flowbands are around 0.5±0.1 to 1.5±0.2 m ice a-1. The per-centage of ice lost from the interior by basal melting beneath the flowbands is about 80%±5%. The total basal melting and refreezing beneath the three flowbands is 50.3±7.5 Gt ice a-1 and 7.0±1.1 Gt ice a-1, respectively. We find a much larger total basal melting and net melting than the results for the whole Amery Ice Shelf derived from previous modeling and oceanographic measurements.     

A Photometry Campaign for IR Geminorum in Quiescence

We report a V band photometry of the SU UMa star IR Gem at quiescence in January 2002. The observations were made with two telescopes spaced - 160° apart in longitude. Several photometric modulations have been found. One gives a period of 98.50(13) min, exactly equal to the orbital period determined spectroscopically. Two others occasionally strengthen and seem to be positive and negative superhumps with periods of 103.6(4) and 95.4(4) min, 5.2% longer and 3.1% shorter than the orbital period, respectively. A signal at - 0.6 c/d in the power spectrum is roughly consistent with the expected period of nodal precession of the disk. There is a puzzling peak at 0.21(3) c/d corresponding to the - 4.3 d sine wave seen in the raw light curve. We suspect it to be a beat frequency between the frequencies of apsidal and nodal precessions of the disk. Quasi-periodic cycles with amplitudes 0.15-0.6 mag can be seen in the light curve. The mechanism underlying this modulation is not clear.     

AN APPLICATION OF MARINE GEOMAGNETIC SURVEY TO SHALLOW SEA ENGINEERING GEOLOGY

A marine geomagnetic survey was conducted over Red Bay, a broad shallow sea area in the southern part of the Shandong Peninsula, to obtain geological information to meet the needs of an underwater engineering project. Analyses of magnetic data revealed the fault structure of the bedrock and differences in lithology. At the proposed offshore dam site, the magnetic survey results indicated the position of faults which have since been confirmed by other geophysical surveys.     

国外重要干旱区研究机构情况简介(六)

灌溉与排水国际委员会International Commission on Irrigation and Drainage(ICID)通讯地址:Central secretarist, 48 NyayaMarg, Chanakyapuri, New Delhi,11021,India Telephone:3016837,3015679 Telex:65920 ICID IN创建于1950年。研究领域:灌溉与排水,洪水控制,河道治理,土壤改良。主要探索灌溉与排水对环境和人体健康的影响。     

RELATIONSHIPS OF SOUTHERN-OSCILLATION AND OTHER LARGE-SCALE FEATURES WITH BAY OF BENGAL CYCLONES DURING THE POST-MONSOON SEASON

Relationships of three Southern Oscillations and a few other large-scale atmospheric indices, like Stratospheric Quasi-Biennial Oscillation, Northern Hemispheric surface air temperature, 50 hPa subtropical ridge position, Indian monsoon rainfall, with the movement and formation of the tropical cyclones over the Bay of Bengal during the post-monsoon season are examined. In general, these relationships are not very satisfactory. However, there is some indication that the low phase of the Southern Oscillation is associated with lower mean latitude of the tracks of cyclones.     

国际参考椭球问题

对於一切的天文工作来说,假定地球为一旋转椭球体已很足够,因为作为天文常数来说,地球大小的精度不若对於大地测量和重力测量为重要。最大的影响发生在计算月球视差之上,若地球的赤道半径增加56米,也就是赤道上重力减