Contributions of Cretaceous Quiet Zone natural remanent magnetization to Magsat anomalies in the Southwest Indian Ocean

1994 ◽  
Vol 99 (B6) ◽  
pp. 11923-11936 ◽  
Author(s):  
Lawrence G. Fullerton ◽  
Herbert V. Frey ◽  
James H. Roark ◽  
Herman H. Thomas
Keyword(s):  
Indian Ocean ◽  
Remanent Magnetization ◽  
Natural Remanent Magnetization ◽  
Southwest Indian Ocean

scholarly journals Circulation pattern controls of wet days and dry days in Free State, South Africa

2021 ◽  
Author(s):  
Chibuike Chiedozie Ibebuchi
Keyword(s):  
South Africa ◽  
Indian Ocean ◽  
Atmospheric Circulation ◽  
Southern Africa ◽  
Austral Summer ◽  
Free State ◽  
Austral Spring ◽  
Study Region ◽  
Southwest Indian Ocean ◽  
South Indian

AbstractAtmospheric circulation is a vital process in the transport of heat, moisture, and pollutants around the globe. The variability of rainfall depends to some extent on the atmospheric circulation. This paper investigates synoptic situations in southern Africa that can be associated with wet days and dry days in Free State, South Africa, in addition to the underlying dynamics. Principal component analysis was applied to the T-mode matrix (variable is time series and observation is grid points at which the field was observed) of daily mean sea level pressure field from 1979 to 2018 in classifying the circulation patterns in southern Africa. 18 circulation types (CTs) were classified in the study region. From the linkage of the CTs to the observed rainfall data, from 11 stations in Free State, it was found that dominant austral winter and late austral autumn CTs have a higher probability of being associated with dry days in Free State. Dominant austral summer and late austral spring CTs were found to have a higher probability of being associated with wet days in Free State. Cyclonic/anti-cyclonic activity over the southwest Indian Ocean, explained to a good extent, the inter-seasonal variability of rainfall in Free State. The synoptic state associated with a stronger anti-cyclonic circulation at the western branch of the South Indian Ocean high-pressure, during austral summer, leading to enhanced low-level moisture transport by southeast winds was found to have the highest probability of being associated with above-average rainfall in most regions in Free State. On the other hand, the synoptic state associated with enhanced transport of cold dry air, by the extratropical westerlies, was found to have the highest probability of being associated with (winter) dryness in Free State.

Natural remanent magnetization studies of a layered Breccia Boulder from the lunar highland region

The Moon ◽  
1975 ◽  
Vol 14 (3-4) ◽  
pp. 473-481 ◽  
Author(s):  
S. K. Banerjee ◽  
G. Swits
Keyword(s):  
Remanent Magnetization ◽  
Natural Remanent Magnetization ◽  
Highland Region

Current-controlled, abyssal microtopography and sedimentation in Mozambique Basin, southwest Indian Ocean

1980 ◽  
Vol 34 (3-4) ◽  
pp. 171-206 ◽  
Author(s):  
Venkatarathnam Kolla ◽  
Stephen Eittreim ◽  
Lawrence Sullivan ◽  
John A Kostecki ◽  
Lloyd H Burckle
Keyword(s):  
Indian Ocean ◽  
Southwest Indian Ocean

scholarly journals Acquisition of Natural Remanent Magnetization for Dirt-Snow Containing Rock Dust.

1991 ◽  
Vol 43 (10) ◽  
pp. 803-811 ◽  
Author(s):  
Minoru FUNAKI ◽  
Hideo SAKAI
Keyword(s):  
Remanent Magnetization ◽  
Natural Remanent Magnetization ◽  
Rock Dust

scholarly journals Effect of deep convection on the tropical tropopause layer composition over the southwest Indian Ocean during austral summer

2020 ◽  
Vol 20 (17) ◽  
pp. 10565-10586
Author(s):  
Stephanie Evan ◽  
Jerome Brioude ◽  
Karen Rosenlof ◽  
Sean M. Davis ◽  
Holger Vömel ◽  
...  
Keyword(s):  
Water Vapor ◽  
Indian Ocean ◽  
Tropical Cyclones ◽  
Austral Summer ◽  
Lagrangian Model ◽  
Southwest Indian Ocean ◽  
Tropical Tropopause Layer ◽  
Tropical Tropopause ◽  
Tropopause Region ◽  
The Impact

Abstract. Balloon-borne measurements of cryogenic frost-point hygrometer (CFH) water vapor, ozone and temperature and water vapor lidar measurements from the Maïdo Observatory on Réunion Island in the southwest Indian Ocean (SWIO) were used to study tropical cyclones' influence on tropical tropopause layer (TTL) composition. The balloon launches were specifically planned using a Lagrangian model and Meteosat-7 infrared images to sample the convective outflow from tropical storm (TS) Corentin on 25 January 2016 and tropical cyclone (TC) Enawo on 3 March 2017. Comparing the CFH profile to Aura's Microwave Limb Sounder's (MLS) monthly climatologies, water vapor anomalies were identified. Positive anomalies of water vapor and temperature, and negative anomalies of ozone between 12 and 15 km in altitude (247 to 121 hPa), originated from convectively active regions of TS Corentin and TC Enawo 1 d before the planned balloon launches according to the Lagrangian trajectories. Near the tropopause region, air masses on 25 January 2016 were anomalously dry around 100 hPa and were traced back to TS Corentin's active convective region where cirrus clouds and deep convective clouds may have dried the layer. An anomalously wet layer around 68 hPa was traced back to the southeast Indian Ocean where a monthly water vapor anomaly of 0.5 ppmv was observed. In contrast, no water vapor anomaly was found near or above the tropopause region on 3 March 2017 over Maïdo as the tropopause region was not downwind of TC Enawo. This study compares and contrasts the impact of two tropical cyclones on the humidification of the TTL over the SWIO. It also demonstrates the need for accurate balloon-borne measurements of water vapor, ozone and aerosols in regions where TTL in situ observations are sparse.

scholarly journals Paleomagnetic secular variation for a 21,000-year sediment sequence from Cascade Lake, north-central Brooks Range, Arctic Alaska

2021 ◽  
Author(s):  
Douglas P. Steen ◽  
Joseph S. Stoner ◽  
Jason P. Briner ◽  
Darrell S. Kaufman
Keyword(s):  
Secular Variation ◽  
Remanent Magnetization ◽  
Sediment Cores ◽  
Natural Remanent Magnetization ◽  
Companion Paper ◽  
Angular Deviation ◽  
Arctic Alaska ◽  
Geomagnetic Field Models ◽  
Paleomagnetic Secular Variation ◽  
Radiometric Ages

Abstract. Two > 5-m-long sediment cores from Cascade Lake (68.38° N, 154.60° W), Arctic Alaska, were analyzed to quantify their paleomagnetic properties over the past 21,000 years. Alternating-field demagnetization of the natural remanent magnetization, anhysteretic remanent magnetization, isothermal remanent magnetization, and hysteresis experiments reveal a strong, well-defined characteristic remanent magnetization carried by a low coercivity magnetic component that increases up core. Maximum angular deviation values average < 2°, and average inclination values are within 4° of the geocentric axial dipole prediction. Radiometric ages based on 210Pb and 14C were used to correlate the major inclination features of the resulting paleomagnetic secular variation (PSV) record with those of other regional PSV records, including two geomagnetic field models and the longer series from Burial Lake, located 200 km to the west. Following around 6 ka (cal BP), the ages of PSV fluctuations in Cascade Lake begin to diverge from those of the regional records, reaching a maximum offset of about 2000 years at around 4 ka. Several correlated cryptotephra ages from this section (reported in a companion paper by Davies et al., this volume) support the regional PSV-based chronology and indicate that some of the 14C ages at Cascade Lake are variably too old.

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