Estimation of Turbulent Kinetic Energy Dissipation Rate in the Bottom Boundary Layer of the Pearl River Estuary

A structure function approach is applied to estimate the turbulent kinetic energy （TKE） dissipation rate in the bottom boundary layer of the Pearl River Estuary （PRE）. Simultaneous measurements with an acoustic Doppler velocimeter （ADV） supplied independent data for the verification of the structure function method. The results show that, 1） the structure function approach is reliable and successfully applied method to estimate the TKE dissipation rate. The observed dissipation rates range between 8.3 ×10^-4 W/kg and 4.9× 10^-6 W/kg in YM01 and between 3.4×10^-4 W/kg and 4.8×10^-7 W/kg in YM03, respectively, while exhibiting a strong quarter-diurnal variation. 2） The balance between the shear production and viscous dissipation is better achieved in the straight river. This first-order balance is significantly broken in the estuary by non-shear production/dissipation due to wave-induced fluctuations.

Robust Solution for Boundary Layer Height Detections with Coherent Doppler Wind Lidar

Although coherent Doppler wind lidar(CDWL)is promising in detecting boundary layer height(BLH),differences between BLH results are observed when different CDWL measurements are used as tracers.Here,a robust solution for BLH detections with CDWL is proposed and demonstrated:mixed layer height(MLH)is retrieved best from turbulent kinetic energy dissipation rate(TKEDR),while stable boundary layer height(SBLH)and residual layer height(RLH)can be retrieved from carrier-to-noise ratio(CNR).To study the cause of the BLH differences,an intercomparison experiment is designed with two identical CDWLs,where only one is equipped with a stability control subsystem.During the experiment,it is found that the CNR could be distorted by instrument instability because the coupling efficiency from free-space to the polarization-maintaining fiber of the telescope is sensitive to the surrounding environment.In the ML,a bias up to 2.13 km of the MLH from CNR is found,which is caused by the CNR deviation.In contrast,the MLH from TKEDR is robust as long as the accuracy of wind is guaranteed.In the SBL(RL),the CNR is found capable to retrieve SBLH and RLH simultaneously and robustly.This solution is tested during an observation period over one month.Statistical analysis shows that the root-mean-square errors(RMSE)in the MLH,SBLH,and RLH are 0.28 km,0.23 km,and 0.24 km,respectively.

Residue determination ofβ-cyfluthrin and imidacloprid as mix formulation in/on chickpea(Cicer arietinum)pods and soil and its risk assessment

OBJECTIVES:A field experiment was conducted at Agricultural Research Station for irrigated crops at Thasara,Anand Agricultural University,Anand,to study the dissipation and risk assessment ofβ-cyfluthrin and imidacloprid as combination product in/on chickpea.MATERIALS AND METHODS:Solomon 300 OD comprising 9 per centβ-cyfluthrin and 21 per cent imidacloprid was foliar sprayed at the doses of 18+42g a.i.ha−1(standard dose)and 36+84g a.i.ha−1(double dose).Totally three sprays were made at an interval of 1 week starting from fruiting stage.RESULTS AND DISCUSSIONS:The residues ofβ-cyfluthrin estimated using gas chromatograph with electron capture detector(GC-ECD)showed an initial deposit of 0.16 and 0.27μg g−1 in standard and double doses,respectively.The residues for corresponding doses persisted till 7th and 10th day after application and reached below determination level of 0.01μg g−1 on the 10th and 15th day,respectively.Imidacloprid was estimated using high performance liquid chromatography(HPLC)and showed initial deposits of 1.22 and 2.7μg g−1 in standard and double doses,respectively.Its levels reached below the determination level(0.01μg g−1)on the 15th day in green pods.Statistical analysis of dissipation kinetics showed thatβ-cyfluthrin followed zero-order kinetics in standard dose with half-life of 7.27 days.In double dose,the dissipation kinetics followed first-order kinetics with half-life of 9 days.Imidacloprid followed first-order kinetics in both the doses with half-life of 6.7 and 7.7 days.CONCLUSIONS:A pre-harvest interval(PHI)of 15 days is suggested.Theoretical risk assessment calculated as hazard quotient was less than 1,rendering the use of combination product as safe-provided proper PHI is followed.