scholarly journals Applicability of GRACE and GRACE-FO for monitoring water mass changes of the Aral Sea and the Caspian Sea

2020 ◽  
Vol 26 (2) ◽  
pp. 443-453
Author(s):  
Lorant Földváry ◽  
Victor Statov ◽  
Nizamatdin Mamutov
Keyword(s):  
Gravity Field ◽  
Caspian Sea ◽  
Large Scale ◽  
Aral Sea ◽  
Water Volume ◽  
Satellite Mission ◽  
The Caspian Sea ◽  
Gravity Fields ◽  
Range Rate ◽  
Sea Area

The GRACE gravity satellite mission has provided monthly gravity field solutions for about 15 years enabling a unique opportunity to monitor large scale mass variation processes. By the end of the GRACE, the GRACE-FO mission was launched in order to continue the time series of monthly gravity fields. The two missions are similar in most aspects apart from the improved intersatellite range rate measurements, which is performed with lasers in addition to microwaves. An obvious demand for the geoscientific applications of the monthly gravity field models is to understand the consistency of the models provided by the two missions. This study provides a case-study related consistency investigation of GRACE and GRACE-FO monthly solutions for the Aral Sea region. As the closeness of the Caspian Sea may influence the monthly mass variations of the Aral Sea, it has also been involved in the investigations. According to the results, GRACE-FO models seem to continue the mass variations of the GRACE period properly, therefore their use jointly with GRACE is suggested. Based on the justified characteristics of the gravity anomaly by water volume variations in the case of the Aral Sea, GRACE models for the period March–June 2017 are suggested to be neglected. Though the correlation between water volume and monthly gravity field variations is convincing in the case of the Aral Sea, no such a correlation for the Caspian Sea could have been detected, which suggests to be the consequence of other mass varying processes, may be related to the seismicity of the Caspian Sea area.

scholarly journals Gravity field of Sarmatia according to satellite data (model EIGEN-6S2) and its interpretation

2021 ◽  
Vol 43 (3) ◽  
pp. 47-63
Author(s):  
O. A. Chornaya ◽  
T. P. Yegorova
Keyword(s):  
Gravity Field ◽  
Satellite Data ◽  
Large Scale ◽  
Donets Basin ◽  
Field Pattern ◽  
Satellite Mission ◽  
The Caspian Sea ◽  
Tectonic Zone ◽  
The North ◽  
Free Air

The paper presents a brief overview of satellite observations of the CHAMP, GRACE and GOCE missions to study the Earth’s global gravity field, and the used mathematical apparatus in the form of an expansion of the geopotential in spherical harmonics. The application of satellite data in various fields of Earth Sciences is considered. As a basic global model of the Earth’s gravity field based on satellite data we used the EIGEN-6S2 model [Rudenko et al, 2014] that combines satellite mission data GRACE and GOCE, and also uses satellite data of LAGEOUS laser ranging.  On its basis, the gravity field of Sarmatia was analyzed using the Free Air anomalies, Bouguer anomalies, the second radial derivative of the geopotential and the geoid heights. The geological units of Sarmatia and its surroundings are most clearly manifested in the Free Air anomalies and in the distribution of the second derivative of the geopotential, showing differences in the gravity field pattern of the Ukrainian Shield, the Voronezh Massif, and the Pripyat-Dnieper-Donets basin (PDDB) with characteristic anomalies of the general northwest strike. The continuation of the PDDB in a southeastern direction through the Karpinsky Swell to the northern part of the Caspian Sea confirms the existence of an extended ancient tectonic zone of the Sarmato-Turanian lineament. The geoid within Sarmatia shows in general a regional west-east gradient change from +40 m in the west to -10 m in the east. Such large-scale geoid changes are determined by the Sarmatia position between two global geoid anomalies — the maximum of the North Atlantic and the minimum of the Indian Ocean.

scholarly journals Neolithic developments in the Gorgan Plain, south-east of the Caspian Sea

Antiquity ◽  
2017 ◽  
Vol 91 (358) ◽  
Author(s):  
Kourosh Roustaei ◽  
Jebrael Nokandeh
Keyword(s):  
Caspian Sea ◽  
Large Scale ◽  
The Caspian Sea ◽  
North East ◽  
Ceramic Assemblages

Until about two decades ago, the Neolithic of north-east Iran was known only from a few brief excavation reports: the sites of Yarim Tappeh (Stronach 1972) and Turang Tappeh (Deshayes 1967) on the Gorgan Plain, and preliminary reports of large-scale excavations at the twin mound of Sang-e Chakhmaq in the southern foothills of the eastern Alborz Mountains (e.g. Masuda 1984). In the absence of absolute chronologies, these sites were dated by ceramic assemblages to the sixth millennium BC, and were considered to relate to the so-called ‘Jeitun Culture’ of southern Turkmenistan (Figure 1; Roustaei 2016a).

scholarly journals OFFERINGS OF HUNNIC-TYPE ARTIFACTS IN STONE ENCLOSURES AT ALTYNKAZGAN, THE EASTERN CASPIAN REGION

2018 ◽  
Vol 46 (2) ◽  
pp. 68-78
Author(s):  
A. E. Astafyev ◽  
E. S. Bogdanov
Keyword(s):  
Caspian Sea ◽  
Historical Records ◽  
Caspian Region ◽  
North Caucasus ◽  
The Caspian Sea ◽  
Land Bridge ◽  
The Third ◽  
Area North ◽  
Sea Area ◽  
Mangyshlak Peninsula

In 2014–2015, nine enclosures built of stone slabs were excavated at Altynkazgan on the Mangyshlak Peninsula, Republic of Kazakhstan. Inside them, remains of offering ceremonies were found: vessels dug into the ground, altars made of limestone blocks, and pits for offerings. In one of these, we found a richly decorated bridle, in another, a belt set of inlaid golden plaques, and in the third, remains of a saddle (silver plates and other items). The entire assemblage has numerous parallels among the 5th and 6th century fi nds from the northern Black Sea area, North Caucasus, and the Volga basin. Ritual burial of a “golden” belt, a bridle, and a ceremonial saddle indicate an advanced cult that included offerings of prestigious belongings of a horseman. These rituals were introduced by Iranian-speaking nomads who had migrated to the eastern Caspian region during the Hunnic raids to Iran in the 5th century. At that time, owing to the regressive phase of the Caspian Sea, the semi-desert northern Caspian coast was connected with Mangyshlak by a land bridge. Our hypotheses are supported by both historical records and modern geomorphological studies of the Caspian Sea.

ON THE CONNECTION BETWEEN LEVEL FLUCTUATIONS IN THE CASPIAN SEA AND THE ARAL SEA

1975 ◽  
Vol 16 (4) ◽  
pp. 231-239
Author(s):  
S. A. Mayeva ◽  
A. N. Kosarev ◽  
Ye. G. Mayev
Keyword(s):  
Caspian Sea ◽  
Aral Sea ◽  
The Caspian Sea

Assessment of ERA-Interim Reanalysis Data Quality for the Caspian Sea Area

2020 ◽  
Vol 45 (9) ◽  
pp. 650-657
Author(s):  
G. S. Dyakonov ◽  
R. A. Ibrayev ◽  
P. O. Shishkova
Keyword(s):  
Data Quality ◽  
Caspian Sea ◽  
Reanalysis Data ◽  
The Caspian Sea ◽  
Sea Area

scholarly journals SLR, GRACE and Swarm Gravity Field Determination and Combination

2019 ◽  
Vol 11 (8) ◽  
pp. 956 ◽  
Author(s):  
Ulrich Meyer ◽  
Krzysztof Sosnica ◽  
Daniel Arnold ◽  
Christoph Dahle ◽  
Daniela Thaller ◽  
...  
Keyword(s):  
Mass Transport ◽  
Gravity Field ◽  
Large Scale ◽  
Mass Gain ◽  
Normal Equation ◽  
Polar Regions ◽  
Swarm Satellites ◽  
Gravity Fields ◽  
Long Time ◽  
Gravity Field Determination

Satellite gravimetry allows for determining large scale mass transport in the system Earth and to quantify ice mass change in polar regions. We provide, evaluate and compare a long time-series of monthly gravity field solutions derived either by satellite laser ranging (SLR) to geodetic satellites, by GPS and K-band observations of the GRACE mission, or by GPS observations of the three Swarm satellites. While GRACE provides gravity signal at the highest spatial resolution, SLR sheds light on mass transport in polar regions at larger scales also in the pre- and post-GRACE era. To bridge the gap between GRACE and GRACE Follow-On, we also derive monthly gravity fields using Swarm data and perform a combination with SLR. To correctly take all correlations into account, this combination is performed on the normal equation level. Validating the Swarm/SLR combination against GRACE during the overlapping period January 2015 to June 2016, the best fit is achieved when down-weighting Swarm compared to the weights determined by variance component estimation. While between 2014 and 2017 SLR alone slightly overestimates mass loss in Greenland compared to GRACE, the combined gravity fields match significantly better in the overlapping time period and the RMS of the differences is reduced by almost 100 Gt. After 2017, both SLR and Swarm indicate moderate mass gain in Greenland.

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