Calibration of the Pyranometer Sensitivity Using the Integrating Sphere     

Bu-Yo Kim  Kyu-Tae Lee  Il-Sung Zo  Sang-Ho Lee  Hyun-Seok Jung  Se-Hun Rim  Jeong-Pil Jang 《Asia-Pacific Journal of Atmospheric Sciences》2018,54(4):639-648

The pyranometer for observing the solar radiation reaching the surface of the earth is manufactured by various companies around the world. The sensitivity of the pyranometer at the observatory is required to be properly controlled based on the reference value of the World Radiometric Center (WRC) and the observatory environment; otherwise, the observational data may be subject to a large error. Since the sensitivity of the pyranometer can be calibrated in an indoor or outdoor calibration, this study used a CSTM-USS-4000C Integrating Sphere by Labsphere Inc. (USA) to calibrate the sensitivity of CMP22 pyranometer by Kipp&Zonen Inc. (Netherlands). Consequently, the factory sensitivity of CMP22 was corrected from 8.68 μV·(Wm^?2)^?1 to 8.98 μV·(Wm^?2)^?1, and the result from the outdoor calibration according to the observatory environment was 8.90 μV·(Wm^?2)^?1. After the indoor calibration of the pyranometer sensitivity, the root mean square error (RMSE) of the observational data at the observatory on a clear day without clouds (July 13, 2017) was 7.11 Wm^?2 in comparison to the reference pyranometer. After the outdoor calibration of the pyranometer sensitivity based on these results, the RMSE of the observational data was 1.74 Wm^?2 on the same day. Periodic inspections are required because the decrease of sensitivity over time is inevitable in the pyranometer data produced at the observatory. The initial sensitivity after indoor calibration (8.98 μV·(Wm^?2)^?1) is important, and the sensitivity after outdoor calibration (8.90 μV·(Wm^?2)^?1) can be compared to the data at the Baseline Surface Radiation Network (BSRN) or can be used for various studies and daily applications.  相似文献   

Taking correlations into account: a diagonal correlation model     

Kermarrec  Gaël  Schön  Steffen 《GPS Solutions》2017,21(4):1895-1906

GPS Solutions - The true covariance matrix of the GPS phase observations is unknown and has to be assumed or estimated. The variance of the least-squares residuals was empirically shown to have an...  相似文献   

The Impact of Landscape Fragmentation on Atmospheric Flow: A Wind-Tunnel Study     

Christopher Poëtte  Barry Gardiner  Sylvain Dupont  Ian Harman  Margi Böhm  John Finnigan  Dale Hughes  Yves Brunet 《Boundary-Layer Meteorology》2017,163(3):393-421

Landscape discontinuities such as forest edges play an important role in determining the characteristics of the atmospheric flow by generating increased turbulence and triggering the formation of coherent tree-scale structures. In a fragmented landscape, consisting of surfaces of different heights and roughness, the multiplicity of edges may lead to complex patterns of flow and turbulence that are potentially difficult to predict. Here, we investigate the effects of different levels of forest fragmentation on the airflow. Five gap spacings (of length approximately 5h, 10h, 15h, 20h, 30h, where h is the canopy height) between forest blocks of length 8.7h, as well as a reference case consisting of a continuous forest after a single edge, were investigated in a wind tunnel. The results reveal a consistent pattern downstream from the first edge of each simulated case, with the streamwise velocity component at tree top increasing and turbulent kinetic energy decreasing as gap size increases, but with overshoots in shear stress and turbulent kinetic energy observed at the forest edges. As the gap spacing increases, the flow appears to change monotonically from a flow over a single edge to a flow over isolated forest blocks. The apparent roughness of the different fragmented configurations also decreases with increasing gap size. No overall enhancement of turbulence is observed at any particular level of fragmentation.  相似文献   

Validate global mapping of internal lunar magnetic field     

Mohamed Sharif Berguig  Mohamed Hamoudi  Jean Louis Lemouël  Yves Cohen 《Arabian Journal of Geosciences》2013,6(4):1063-1072

In this work, we report a global mapping of vector lunar magnetic field based on new method of separation of internal and external fields. The magnetic measurements collected during the lifetime of lunar prospector (LP) extended mission during 1999 were strongly disturbed by the solar wind, a period which coincided with a maximum of the 23 cycle activity. The multiscale wavelength external fields were analyzed using spherical harmonic transform. The external field determined by inversion was then removed from each magnetic field component for each half orbit. To map the vector magnetic crustal anomalies, all LP magnetometer data collected at low altitudes in the three different lunar environments: (1) geomagnetic tail, (2) solar wind, and (3) geomagnetic sheath were processed using this new approach. The results obtained using these selection criteria allow us to get a global coverage of the lunar surface by the vector magnetic field at variable spacecraft low altitudes. To validate our mapping, we have developed and applied a method based on properties of potential fields functions. This method can be used to determine both horizontal north and east components using only vertical component. The validated lunar internal magnetic measurements obtained at variable spacecraft altitudes were then continued to a common altitude of 30 km using an inverse method. This mapping confirms firstly the nature of the crustal sources of lunar magnetic field and clearly shows that the strongest concentrations of anomalies are associated with high albedo and/or located antipodal to large young basins (Orientale, Serenitatis, Imbrium, and Crisium) of age about 3.9 Ga.  相似文献   

The 1995–2002 Long-Term Monitoring of Comet C/1995 O1 (HALE–BOPP) at Radio Wavelength     

Biver  Nicolas  Bockelée-Morvan  Dominique  Colom  Pierre  Crovisier  Jacques  Henry  Florence  Lellouch  Emmanuel  Winnberg  Anders  Johansson  Lars E.B.  Gunnarsson  Marcus  Rickman  Hans  Rantakyrö  Fredrik  Davies  John K.  Dent  William R.F.  Paubert  Gabriel  Moreno  Raphaël  Wink  Jörn  Despois  Didier  Benford  Dominic J.  Gardner  Matt  Lis  Dariusz C.  Mehringer  David  Phillips  Thomas G.  Rauer  Heike 《Earth, Moon, and Planets》2002,90(1-4):5-14

The bright comet Hale–Bopp provided the first opportunity to follow the outgassing rates of a number of molecular species over a large range of heliocentric distances. We present the results of our observing campaign at radio wavelengths which began in August 1995 and ended in January 2002. The observations were carried out with the telescopes of Nançay, IRAM, JCMT, CSO and, since September 1997, SEST. The lines of nine molecules (OH, CO, HCN, CH₃OH, H₂CO, H₂S, CS, CH₃CN and HNC) were monitored. CS, H₂S, H₂CO, CH₃CN were detected up to r_h= 3–4 AU from the Sun, while HCN and CH₃OH were detected up to 6 AU. CO, which is the main driver of cometary activity at heliocentric distances larger than 3–4 AU, was last detected in August 2001, at r_h= 14 AU. The gas production rates obtained from this programme contain important information on the nature of cometary ices, their thermal properties and sublimation mechanisms.Line shapes allow to measure gas expansion velocities, which, at large heliocentric distances, might be directly connected to the temperature of the nucleus surface. Inferred expansion velocity of the gas varied as r_h ^-0.4 within 7 AU from the Sun, but remained close to 0.4 km s^-1 further away. The CO spectra obtained at large r_hare strongly blueshifted and indicative of an important day-to-night asymmetry in outgassing and expansion velocity. The kinetic temperature of the coma, estimated from the relative intensities of the CH₃OH and CO lines, increased with decreasing r_h, from about 10 K at 7 AU to 110 K around perihelion.  相似文献   

Chemical Composition Diversity Among 24 Comets Observed At Radio Wavelengths     

Biver  Nicolas  Bockelée-Morvan  Dominique  Crovisier  Jacques  Colom  Pierre  Henry  Florence  Moreno  Raphaël  Paubert  Gabriel  Despois  Didier  Lis  Dariusz C. 《Earth, Moon, and Planets》2002,90(1-4):323-333

We present a comparative study on molecular abundances in comets basedon millimetre/submillimetre observations made with the IRAM 30-m,JCMT, CSO and SEST telescopes. This study concerns a sample of 24comets (6 Jupiter-family, 3 Halley-family, 15 long-period) observedfrom 1986 to 2001 and 8 molecular species (HCN, HNC, CH₃CN,CH₃OH, H₂CO, CO, CS, H₂S). HCN was detected in all comets,while at least 2 molecules were detected in 19 comets. From the sub-sample of comets for which contemporary H₂O productionrates are available, we infer that the HCN abundance relative to water variesfrom 0.08% to 0.25%. With respect to other species, HCN is the moleculewhich exhibits the lowest abundance variation from comet to comet. Therefore,production rates relative to that of HCN can be used for a comparative study ofmolecular abundances in the 19 comets. It is found that: CH₃OH/HCN varies from ≤ 9 to 64; CO/HCN varies from ≤ 24 to 180; H₂CO/HCN varies between 1.6 and 10; and H₂S/HCN varies between 1.5 and 7.6. This study does not show any clear correlation between the relative abundancesand the dynamical origins of the comets, or their dust-to-gas ratios.  相似文献   

Current climate data rescue activities in Australia     

Linden Ashcroft  Rob Allan  Howard Bridgman  Joëlle Gergis  Christa Pudmenzky  Ken Thornton 《大气科学进展》2016,33(12):1323-1324

正1.Introduction Recovering historical instrumental climate data is crucial for identifying long-term climate variability and change,putting present climate into context and constraining future climate projections(Brunet and Jones,2011).In other words,to understand the future,we need to improve our understand-  相似文献   

Seismic vulnerability assessment of urban environments in moderate-to-low seismic hazard regions using association rule learning and support vector machine methods   总被引：2，自引：2，他引：0  

Ismaël Riedel  Philippe Guéguen  Mauro Dalla Mura  Erwan Pathier  Thomas Leduc  Jocelyn Chanussot 《Natural Hazards》2015,76(2):1111-1141

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Stalactite drip-water monitoring and tracer tests approach to assess hydrogeologic behavior of karst vadose zone: case study of Han-sur-Lesse (Belgium)     

Amaël Poulain  Gaëtan Rochez  Isabelle Bonniver  Vincent Hallet 《Environmental Earth Sciences》2015,74(12):7685-7697

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U-Th-Pb and Trace Element Evaluation of Existing Titanite and Apatite LA-ICP-MS Reference Materials and Determination of 208Pb/232Th-206Pb/238U Date Discordance in Archaean Accessory Phases     

Omar Khalil Droubi  Ann M. Bauer  Chloë Bonamici  William O. Nachlas  Michael J. Tappa  Joshua M. Garber  Jesse R. Reimink 《Geostandards and Geoanalytical Research》2023,47(2):337-369

The last decade has seen a marked increase in U-Th-Pb petrochronological studies focused on titanite and apatite. This has motivated the need for detailed, phase-specific method development and well-characterised reference materials with a wide variety of ages and chemical compositions. This study presents new U-Th-Pb isotope and major-, minor- and trace-element mass fraction data for ten titanite and five apatite reference materials based on integrated EPMA, LA-ICP-MS and isotope-dilution (ID) multi-collector (MC)-ICP-MS characterisation. Cross-comparison of EPMA and LA-ICP-MS data for the same titanite reference material suite demonstrates that careful selection of EPMA primary reference materials is necessary to minimise inaccuracies. We further identify a significant X-ray interference when measuring low Ce abundances in Ti-bearing phases and outline a method for its correction. New ID-MC-ICP-MS and LA-ICP-MS data suggest tri-concordance (defined as concordant ages for the ²³⁸U-²⁰⁶Pb, ²³⁵U-²⁰⁷Pb and ²³²Th-²⁰⁸Pb decay systems) of the MKED-1 titanite reference material and demonstrate the reproducibility of ²⁰⁸Pb/²³²Th measurements in some secondary titanite reference materials. Integration of ²⁰⁸Pb/²³²Th results with U-Pb geochronology provides a meaningful tool to help interpret complex U-Th-Pb isotopic age spectra. We provide example applications of ²⁰⁸Pb/²³²Th LA-ICP-MS measurements toward interpreting Archaean titanite ages from the Acasta Gneiss Complex, Northwest Territories, Canada.  相似文献