Control of wind strength and frequency in the Aral Sea basin during the late Holocene

Changing content of detrital input in laminated sediments traced by XRF scanning and microfacies analyses reflect prominent variations in sedimentation processes in the Aral Sea. A high-resolution record of titanium from a core retrieved in the northwestern Large Aral Sea allows a continuous reconstruction of wind strength and frequency in western Central Asia for the past 1500 yr. During AD 450-700, AD 1210-1265, AD 1350-1750 and AD 1800-1975, detrital inputs (bearing titanium) are high, documenting an enhanced early spring atmospheric circulation associated with an increase in intensity of the Siberian High pressure system over Central Asia. In contrast, lower titanium content during AD 1750-1800 and AD 1980-1985 reflects a diminished influence of the Siberian High during early spring with a reduced atmospheric circulation. A moderate circulation characterizes the time period AD 700-1150. Unprecedented weakened atmospheric circulation over western Central Asia are inferred during ca. AD 1180-1210 and AD 1265-1310 with a considerable decrease in dust storm frequency, sedimentation rates, lamination thickness and detrital inputs (screened at 40-μm resolution). Our results are concurrent with changes in the intensity of the Siberian High during the past 1400 yr as reported in the GISP2 Ice Core from Greenland. © 2007 University of Washington

Dry and Humid Periods Reconstructed from Tree Rings in the Former Territory of Sogdiana (Central Asia) and Their Socio-economic Consequences over the Last Millennium

One of the richest societies along the Silk Road developed in Sogdiana, located in present-day Tajikistan, Uzbekistan, and Kyrgyzstan. This urban civilisation reached its greatest prosperity during the golden age of the Silk Road (sixth to ninth century ce). Rapid political and economic changes, accelerated by climatic variations, were observed during last millennium in this region. The newly developed tree-ring-based reconstruction of precipitation for the pastmillennium revealed a series of dry and wet stages. During the Medieval Climate Anomaly (MCA), two dry periods occurred (900–1000 and 1200–1250), interrupted by a phase of wetter conditions. Distinct dry periods occurred around 1510–1650, 1750–1850, and 1920–1970, respectively. The juniper tree-ring record of moisture changes revealed that major dry and pluvial episodes were consistent with those indicated by hydroclimatic proxy data from adjacent areas. These climate fluctuations have had longand short term consequences for human history in the territory of former Sogdiana

Period of Yaz-II: stages and chronology

The archaeological site of Yaz depe was excavated over 50 years ago by V.M. Masson, and has been a reference point for the Iron Age — Yaz-I, Yaz-II and Yaz-III — in Central Asia since then. At that time it was dated to the middle of the 2nd to the beginning of the 1st Millennium BC In the early 1970s monuments of this period were discovered near the modern settlement of Bandykhan, southern Uzbekistan. Work there was renewed by a joint Uzbek-German team, starting in 2005, which gave new results for understanding the pottery evolution of the Yaz-I to III periods and allowed a subdivision of the Yaz-II period into phases A and B. Radiocarbon analyses of samples from stratigraphic context also give these periods absolute ages 10th–8th Century BC for Yaz-IIA and 7th–6th Century for Yaz-IIB. These new materials and dates are published here. In the concluding remarks the general historical context is presented, with a discussion of the Frada revolt which was crushed by the Achaemenid Empire, as is known from ancient texts. We also remark the Kavi kingdom and its connections to Zoroastrian chronology and tradition, which falls into this period. In our opinion the Yaz-II distribution coincides with the Iranian World — the «Arjan-Vaichakh», whose northern border is given by the Hissar mountain range with their well-known enemies — the legendary Turan

Control of wind strength and frequency in the Aral Sea basin during the late Holocene

Changing content of detrital input in laminated sediments traced by XRF scanning and microfacies analyses reflect prominent variations in sedimentation processes in the Aral Sea. A high-resolution record of titanium from a core retrieved in the northwestern Large Aral Sea allows a continuous reconstruction of wind strength and frequency in western Central Asia for the past 1500 yr. During AD 450-700, AD 1210-1265, AD 1350-1750 and AD 1800-1975, detrital inputs (bearing titanium) are high, documenting an enhanced early spring atmospheric circulation associated with an increase in intensity of the Siberian High pressure system over Central Asia. In contrast, lower titanium content during AD 1750-1800 and AD 1980-1985 reflects a diminished influence of the Siberian High during early spring with a reduced atmospheric circulation. A moderate circulation characterizes the time period AD 700-1150. Unprecedented weakened atmospheric circulation over western Central Asia are inferred during ca. AD 1180-1210 and AD 1265-1310 with a considerable decrease in dust storm frequency, sedimentation rates, lamination thickness and detrital inputs (screened at 40-μm resolution). Our results are concurrent with changes in the intensity of the Siberian High during the past 1400 yr as reported in the GISP2 Ice Core from Greenland. © 2007 University of Washington