No abstract

Lake levels in the Qinghai-Tibet Plateau (QTP) provide valuable records for climate change studies. We use two decades of measurements (January 1993-December 2014) from the TOPEX/Poseidon (T/P)-family satellite altimeters (T/P, Jason-1 and -2) to detect lake level variations at 23 lakes along their repeat ground tracks every 10 days. We employ an optimal processing technique to obtain quality measurements, including outlier detection, averaging and filtering. The lake level accuracies are improved by subwaveform retracking. Jason-1 delivers few measurements after waveform retracking and a cluster classification at most lakes. From January 1993 to December 2014, most lake levels in eastern Tibet rose, while those in western Tibet declined. In Qinghai, lake levels dropped before 2005 and then rose afterwards, coinciding with the measure in 2005 that protects the Qinghai ecosystem (e.g., grassland conservation). The overall pattern of lake level change in the QTP is largely affected by monsoons and lake locations. Most lake levels show clear annual and inter-annual oscillations. Certain lakes show alternating level highs and lows in the same seasons and varying amplitudes of annual oscillations due to lake level changes. We detect a sudden rise of lake level by 7 m caused by floods, varying lake level trends associated with the 1997-98 El Niño and other factors, and persistently rising and declining lake levels associated with the long-term precipitation trends in the QTP. The T/P-family satellites will continue to monitor lake levels here as long as the sea level monitoring program lasts, collecting a long-term climate record at highlands echoing sea level change.

The first borate carbonate UV nonlinear optical material Pb7O(OH)3(CO3)3(BO3) was hydrothermally synthesized, which features a (3,9)-connected IrSi3-like structure constructed by Pb7O(OH)3(BO3) units and carbonates. This compound exhibits a large second-harmonic generation (SHG) response about 4.5 times that of KH2PO4 (KDP), attributed to synergistic interactions between the stereoeffect of the Pb(II) cations and coparallel BO3 and CO3 triangles groups.

powder: The rutile TiO 2 powder was prepared using a procedure similar to the reported method (Ref. S1). In a typical synthesis, an aqueous solution of