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Geoffrey C. Toon - One of the best experts on this subject based on the ideXlab platform.
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improved ftir retrieval strategy for hcfc 22 chclf 2 comparisons with in situ and satellite datasets with the support of models and determination of its long term trend above jungfraujoch
Atmospheric Chemistry and Physics, 2019Co-Authors: Maxime Prignon, Christian Servais, Geoffrey C. Toon, Martin K. Vollmer, Simon Chabrillat, Daniele Minganti, Simon Odoherty, G P Stiller, Emmanuel MahieuAbstract:Abstract. Hydrochlorofluorocarbons (HCFCs) are the first, but temporary, substitution products for the strong ozone-depleting chlorofluorocarbons (CFCs). HCFC consumption and production are currently regulated under the Montreal Protocol on Substances that Deplete the Ozone Layer and their emissions have started to stabilize or even decrease. As HCFC-22 ( CHClF2 ) is by far the most abundant HCFC in today's atmosphere, it is crucial to continue to monitor the evolution of its atmospheric concentration. In this study, we describe an improved HCFC-22 retrieval strategy from ground-based high-resolution Fourier transform infrared (FTIR) Solar Spectra recorded at the high-altitude scientific station of Jungfraujoch, the Swiss Alps, 3580 m a.m.s.l. (above mean sea level). This new strategy distinguishes tropospheric and lower-stratospheric partial columns. Comparisons with independent datasets, such as the Advanced Global Atmospheric Gases Experiment (AGAGE) and the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS), supported by models, such as the Belgian Assimilation System for Chemical ObErvation (BASCOE) and the Whole Atmosphere Community Climate Model (WACCM), demonstrate the validity of our tropospheric and lower-stratospheric long-term time series. A trend analysis on the datasets used here, now spanning 30 years, confirms the last decade's decline in the HCFC-22 growth rate. This updated retrieval strategy can be adapted for other ozone-depleting substances (ODSs), such as CFC-12. Measuring or retrieving ODS atmospheric concentrations is essential for scrutinizing the fulfilment of the globally ratified Montreal Protocol.
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using a speed dependent voigt line shape to retrieve o 2 from total carbon column observing network Solar Spectra to improve measurements of xco 2
Atmospheric Measurement Techniques, 2019Co-Authors: Joseph Mendonca, Geoffrey C. Toon, Kimberly Strong, Debra Wunch, David A Long, Joseph T Hodges, Vincent T Sironneau, J E FranklinAbstract:Abstract. High-resolution, laboratory, absorption Spectra of the a 1 Δ g ← X 3 Σ g - oxygen ( O2 ) band measured using cavity ring-down spectroscopy were fitted using the Voigt and speed-dependent Voigt line shapes. We found that the speed-dependent Voigt line shape was better able to model the measured absorption coefficients than the Voigt line shape. We used these line shape models to calculate absorption coefficients to retrieve atmospheric total columns abundances of O2 from ground-based Spectra from four Fourier transform spectrometers that are a part of the Total Carbon Column Observing Network (TCCON). Lower O2 total columns were retrieved with the speed-dependent Voigt line shape, and the difference between the total columns retrieved using the Voigt and speed-dependent Voigt line shapes increased as a function of Solar zenith angle. Previous work has shown that carbon dioxide ( CO2 ) total columns are better retrieved using a speed-dependent Voigt line shape with line mixing. The column-averaged dry-air mole fraction of CO2 ( XCO2 ) was calculated using the ratio between the columns of CO2 and O2 retrieved (from the same Spectra) with both line shapes from measurements taken over a 1-year period at the four sites. The inclusion of speed dependence in the O2 retrievals significantly reduces the air mass dependence of XCO2 , and the bias between the TCCON measurements and calibrated integrated aircraft profile measurements was reduced from 1 % to 0.4 %. These results suggest that speed dependence should be included in the forward model when fitting near-infrared CO2 and O2 Spectra to improve the accuracy of XCO2 measurements.
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improving the retrieval of xco 2 from total carbon columnnetwork Solar Spectra
Atmospheric Measurement Techniques Discussions, 2018Co-Authors: Joseph Mendonca, Geoffrey C. Toon, Kimberly Strong, Debra Wunch, David A Long, Joseph T Hodges, Vincent T Sironneau, J E FranklinAbstract:Abstract. High-resolution absorption Spectra of the a 1 ∆ g ←X 3 Σ g − O 2 band measured using cavity ring-down spectroscopy were fitted using the Voigt and speed-dependent Voigt line shapes. We found that the speed-dependent Voigt line shape was better able to model the measured absorption coefficients than the Voigt line shape. Total columns of O 2 were retrieved from ground-based high-resolution absorption Spectra from four Total Carbon Column Observing Network (TCCON) sites using both Voigt and speed-dependent Voigt line shapes to calculate absorption coefficients. A lower O 2 concentration was retrieved with the speed-dependent Voigt line shape, with the difference increasing as a function of Solar zenith angle. CO 2 total columns were also retrieved from the same Spectra using a Voigt line shape and speed-dependent Voigt with line mixing. The column-averaged dry-air mole fraction of CO 2 (XCO 2 ) was calculated using the CO 2 and O 2 columns retrieved with both line shapes from measurements made over a one-year period at the four sites and compared. The inclusion of speed dependence reduces the airmass dependence of XCO 2 . The TCCON empirical airmass correction factor for XCO 2 derived from a year of measurements from TCCON sites at Darwin, Lamont, and Park Falls for XCO 2 improved from −0.0071±0.0057 to −0.0012±0.0054 when speed dependence was included. XCO 2 retrieved with the Voigt and speed-dependent Voigt line shapes was compared to aircraft profiles measured at 13 TCCON sites. The bias between the TCCON measurements and the integrated aircraft profile measurements was reduced from 0.9897±0.0005 to 1.0041±0.0005 for XCO 2 retrieved with the Voigt and speed-dependent Voigt line shapes respectively. These results suggest that speed dependence should be included in the forward model when fitting near-infrared CO 2 and O 2 Spectra to improve the accuracy of XCO 2 measurements.
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Retrieval of HCFC-142b (CH3CClF2) from ground-based high-resolution infrared Solar Spectra: Atmospheric increase since 1989 and comparison with surface and satellite measurements
Journal of Quantitative Spectroscopy and Radiative Transfer, 2017Co-Authors: Emmanuel Mahieu, Benoît Bovy, Bernard Lejeune, Christian Servais, Geoffrey C. Toon, Peter F. Bernath, Chris D. Boone, Kaley A. Walker, Stefan Reimann, Martin K. VollmerAbstract:Abstract We have developed an approach for retrieving HCFC-142b (CH 3 CClF 2 ) from ground-based high-resolution infrared Solar Spectra, using its ν 7 band Q branch in the 900–906 cm −1 interval. Interferences by HNO 3 , CO 2 and H 2 O have to be accounted for. Application of this approach to observations recorded within the framework of long-term monitoring activities carried out at the northern mid-latitude, high-altitude Jungfraujoch station in Switzerland (46.5°N, 8.0°E, 3580 m above sea level) has provided a total column times series spanning the 1989 to mid-2015 time period. A fit to the HCFC-142b daily mean total column time series shows a statistically-significant long-term trend of (1.23±0.08×10 13 molec cm −2 ) per year from 2000 to 2010, at the 2-σ confidence level. This corresponds to a significant atmospheric accumulation of (0.94±0.06) ppt (1 ppt=1/10 12 ) per year for the mean tropospheric mixing ratio, at the 2− σ confidence level. Over the subsequent time period (2010–2014), we note a significant slowing down in the HCFC-142b buildup. Our ground-based FTIR (Fourier Transform Infrared) results are compared with relevant data sets derived from surface in situ measurements at the Mace Head and Jungfraujoch sites of the AGAGE (Advanced Global Atmospheric Gases Experiment) network and from occultation measurements by the ACE-FTS (Atmospheric Chemistry Experiment-Fourier Transform Spectrometer) instrument on-board the SCISAT satellite.
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first identification of the a1δg x3σg electric quadrupole transitions of oxygen in Solar and laboratory Spectra
Journal of Quantitative Spectroscopy & Radiative Transfer, 2010Co-Authors: Iouli E Gordon, S Kassi, A Campargue, Geoffrey C. ToonAbstract:Abstract Electric quadrupole transitions in the a 1 Δ g – X 3 Σ g − band of 16O2 near 1.27 μm are reported for the first time. They were first detected in atmospheric Solar Spectra acquired with a ground-based Fourier transform spectrometer (FTS) in Park Falls, WI. Subsequently high-sensitivity CW—cavity ring down spectroscopy (CW-CRDS) experiments were carried out at Grenoble University in the 7717–7917 cm−1 region in order to provide quantitative intensity information for the electric quadrupole transitions. Measured intensities were used as input data for the calculation of the complete list of electric quadrupole transitions with ΔJ=±2, ±1 and 0. The calculation was carried out for the intermediate coupling case and assuming that these transitions are possible only through mixing of the Ω=0 component of the ground electronic state and b 1 Σ g + state induced by spin–orbit coupling. The calculated line list agrees well with experimental measurements and was used to improve the residuals of the fitted Solar atmospheric spectrum. Emission probability for the electric quadrupole band was determined to be (1.02±0.10)×10−6 s−1.
W Z Shen - One of the best experts on this subject based on the ideXlab platform.
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perovskite c si monolithic tandem Solar cells under real Solar Spectra improving energy yield by oblique incident optimization
Journal of Physical Chemistry C, 2019Co-Authors: Tun Wang, Jiayuan Wang, W Z ShenAbstract:Many research groups have noticed the performance of rapidly developed perovskite/silicon monolithic tandem Solar cells (TSCs) under a real situation, but they overlook the short current density mi...
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perovskite c si monolithic tandem Solar cells under real Solar Spectra improving energy yield by oblique incident optimization
The Journal of Physical Chemistry, 2019Co-Authors: Tun Wang, Jiayuan Wang, W Z ShenAbstract:Many research groups have noticed the performance of rapidly developed perovskite/silicon monolithic tandem Solar cells (TSCs) under a real situation, but they overlook the short current density mismatch of two subcells at different times in a day and the spectrum variation at different latitudes. Here, we have systematically analyzed the efficiency losses and proposed an optimization scheme by combination of the experiment and simulation relying on reliable experimental data in a year. We have verified the simulated absorptance Spectra varying with incident angle θ to substitute the external quantum efficiency Spectra, which makes the optimization at oblique incidence possible. More importantly, we have further calculated and expanded the optimized current losses and energy output enhancement in perovskite/silicon monolithic TSCs to all latitudes. This work can serve as a practical guidance for the design of perovskite/silicon monolithic TSCs with the best annual energy output at different latitudes in the world.
Emmanuel Mahieu - One of the best experts on this subject based on the ideXlab platform.
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improved ftir retrieval strategy for hcfc 22 chclf 2 comparisons with in situ and satellite datasets with the support of models and determination of its long term trend above jungfraujoch
Atmospheric Chemistry and Physics, 2019Co-Authors: Maxime Prignon, Christian Servais, Geoffrey C. Toon, Martin K. Vollmer, Simon Chabrillat, Daniele Minganti, Simon Odoherty, G P Stiller, Emmanuel MahieuAbstract:Abstract. Hydrochlorofluorocarbons (HCFCs) are the first, but temporary, substitution products for the strong ozone-depleting chlorofluorocarbons (CFCs). HCFC consumption and production are currently regulated under the Montreal Protocol on Substances that Deplete the Ozone Layer and their emissions have started to stabilize or even decrease. As HCFC-22 ( CHClF2 ) is by far the most abundant HCFC in today's atmosphere, it is crucial to continue to monitor the evolution of its atmospheric concentration. In this study, we describe an improved HCFC-22 retrieval strategy from ground-based high-resolution Fourier transform infrared (FTIR) Solar Spectra recorded at the high-altitude scientific station of Jungfraujoch, the Swiss Alps, 3580 m a.m.s.l. (above mean sea level). This new strategy distinguishes tropospheric and lower-stratospheric partial columns. Comparisons with independent datasets, such as the Advanced Global Atmospheric Gases Experiment (AGAGE) and the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS), supported by models, such as the Belgian Assimilation System for Chemical ObErvation (BASCOE) and the Whole Atmosphere Community Climate Model (WACCM), demonstrate the validity of our tropospheric and lower-stratospheric long-term time series. A trend analysis on the datasets used here, now spanning 30 years, confirms the last decade's decline in the HCFC-22 growth rate. This updated retrieval strategy can be adapted for other ozone-depleting substances (ODSs), such as CFC-12. Measuring or retrieving ODS atmospheric concentrations is essential for scrutinizing the fulfilment of the globally ratified Montreal Protocol.
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Retrieval of HCFC-142b (CH3CClF2) from ground-based high-resolution infrared Solar Spectra: Atmospheric increase since 1989 and comparison with surface and satellite measurements
Journal of Quantitative Spectroscopy and Radiative Transfer, 2017Co-Authors: Emmanuel Mahieu, Benoît Bovy, Bernard Lejeune, Christian Servais, Geoffrey C. Toon, Peter F. Bernath, Chris D. Boone, Kaley A. Walker, Stefan Reimann, Martin K. VollmerAbstract:Abstract We have developed an approach for retrieving HCFC-142b (CH 3 CClF 2 ) from ground-based high-resolution infrared Solar Spectra, using its ν 7 band Q branch in the 900–906 cm −1 interval. Interferences by HNO 3 , CO 2 and H 2 O have to be accounted for. Application of this approach to observations recorded within the framework of long-term monitoring activities carried out at the northern mid-latitude, high-altitude Jungfraujoch station in Switzerland (46.5°N, 8.0°E, 3580 m above sea level) has provided a total column times series spanning the 1989 to mid-2015 time period. A fit to the HCFC-142b daily mean total column time series shows a statistically-significant long-term trend of (1.23±0.08×10 13 molec cm −2 ) per year from 2000 to 2010, at the 2-σ confidence level. This corresponds to a significant atmospheric accumulation of (0.94±0.06) ppt (1 ppt=1/10 12 ) per year for the mean tropospheric mixing ratio, at the 2− σ confidence level. Over the subsequent time period (2010–2014), we note a significant slowing down in the HCFC-142b buildup. Our ground-based FTIR (Fourier Transform Infrared) results are compared with relevant data sets derived from surface in situ measurements at the Mace Head and Jungfraujoch sites of the AGAGE (Advanced Global Atmospheric Gases Experiment) network and from occultation measurements by the ACE-FTS (Atmospheric Chemistry Experiment-Fourier Transform Spectrometer) instrument on-board the SCISAT satellite.
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long term evolution in the tropospheric concentration of chlorofluorocarbon 12 ccl2f2 derived from high Spectral resolution infrared Solar absorption Spectra retrieval and comparison with in situ surface measurements
Journal of Quantitative Spectroscopy & Radiative Transfer, 2005Co-Authors: C P Rinsland, Aaron Goldman, Emmanuel Mahieu, S Wood, Rodolphe Zander, Linda S Chiou, James W Hannigan, J W ElkinsAbstract:Abstract The average tropospheric volume mixing ratios of chlorofluorocarbon 12 (CCl2F2) have been retrieved from high-Spectral resolution ground-based infrared Solar-absorption Spectra recorded from March 1982 to October 2003 with the McMath Fourier transform spectrometer at the US National Solar Observatory facility on Kitt Peak in southern Arizona (31.9°N, 111.6°W, 2.09 km altitude). The retrievals are based on fits to the unresolved ν 8 band Q-branches near 922 cm - 1 using the SFIT2 retrieval algorithm. The annual increase rate was equal to ( 16.88 ± 1.37 ) parts per trillion ( 10 - 12 ) by volume at the beginning of the time series, March 1982, or ( 4.77 ± 0.04 ) % , 1 sigma, declining progressively to ( 2.49 ± 1.24 ) parts per trillion, by volume at the end, October 2003, or ( 0.46 ± 0.24 ) % , 1 sigma. Average tropospheric mixing ratios from the Solar Spectra have been compared with average surface flask and in situ sampling measurements from the Climate Monitoring and Diagnostics Laboratory (CMDL) station at Niwot Ridge, CO, (USA) (40.0°N, 105.5°W, 3013 m altitude). The average ratio and standard deviation of the monthly means of the retrieved tropospheric mixing ratios relative to the CMDL surface mixing ratios is ( 1.01 ± 0.03 ) for the overlapping time period. Both datasets demonstrate the progressive impact of the Montreal protocol and its strengthening amendments on the trend of CCl2F2, though a tropospheric decrease has yet to be observed.
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long term trends of inorganic chlorine from ground based infrared Solar Spectra past increases and evidence for stabilization
Journal of Geophysical Research, 2003Co-Authors: C P Rinsland, Emmanuel Mahieu, Rodolphe Zander, M P Chipperfield, Nicholas B Jones, A Goldman, Jill Anderson, James M Russell, P Demoulin, Justus NotholtAbstract:Long-term time series of hydrogen chloride (HCl) and chlorine nitrate (ClONO2) total column abundances has been retrieved from high Spectral resolution ground-based Solar absorption Spectra recorded with infrared Fourier transform spectrometers at nine NDSC (Network for the Detection of Stratospheric Change) sites in both Northern and Southern Hemispheres. The data sets span up to 24 years and most extend until the end of 2001. The time series of Cl-y (defined here as the sum of the HCl and ClONO2 columns) from the three locations with the longest time-span records show rapid increases until the early 1990s superimposed on marked day-to-day, seasonal and inter-annual variability. Subsequently, the buildup in Cl-y slows and reaches a broad plateau after 1996, also characterized by variability. A similar time evolution is also found in the total chlorine concentration at 55 km altitude derived from Halogen Occultation Experiment (HALOE) global observations since 1991. The stabilization of inorganic chlorine observed in both the total columns and at 55 km altitude indicates that the near-global 1993 organic chlorine (CCly) peak at the Earth's surface has now propagated over a broad altitude range in the upper atmosphere, though the time lag is difficult to quantify precisely from the current data sets, due to variability. We compare the three longest measured time series with two-dimensional model calculations extending from 1977 to 2010, based on a halocarbon scenario that assumes past measured trends and a realistic extrapolation into the future. The model predicts broad Cl-y maxima consistent with the long-term observations, followed by a slow Cl-y decline reaching 12-14% relative to the peak by 2010. The data reported here confirm the effectiveness of the Montreal Protocol and its Amendments and Adjustments in progressively phasing out the major man-related perturbations of the stratospheric ozone layer, in particular, the anthropogenic chlorine-bearing source gases. (Less)
Martin K. Vollmer - One of the best experts on this subject based on the ideXlab platform.
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improved ftir retrieval strategy for hcfc 22 chclf 2 comparisons with in situ and satellite datasets with the support of models and determination of its long term trend above jungfraujoch
Atmospheric Chemistry and Physics, 2019Co-Authors: Maxime Prignon, Christian Servais, Geoffrey C. Toon, Martin K. Vollmer, Simon Chabrillat, Daniele Minganti, Simon Odoherty, G P Stiller, Emmanuel MahieuAbstract:Abstract. Hydrochlorofluorocarbons (HCFCs) are the first, but temporary, substitution products for the strong ozone-depleting chlorofluorocarbons (CFCs). HCFC consumption and production are currently regulated under the Montreal Protocol on Substances that Deplete the Ozone Layer and their emissions have started to stabilize or even decrease. As HCFC-22 ( CHClF2 ) is by far the most abundant HCFC in today's atmosphere, it is crucial to continue to monitor the evolution of its atmospheric concentration. In this study, we describe an improved HCFC-22 retrieval strategy from ground-based high-resolution Fourier transform infrared (FTIR) Solar Spectra recorded at the high-altitude scientific station of Jungfraujoch, the Swiss Alps, 3580 m a.m.s.l. (above mean sea level). This new strategy distinguishes tropospheric and lower-stratospheric partial columns. Comparisons with independent datasets, such as the Advanced Global Atmospheric Gases Experiment (AGAGE) and the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS), supported by models, such as the Belgian Assimilation System for Chemical ObErvation (BASCOE) and the Whole Atmosphere Community Climate Model (WACCM), demonstrate the validity of our tropospheric and lower-stratospheric long-term time series. A trend analysis on the datasets used here, now spanning 30 years, confirms the last decade's decline in the HCFC-22 growth rate. This updated retrieval strategy can be adapted for other ozone-depleting substances (ODSs), such as CFC-12. Measuring or retrieving ODS atmospheric concentrations is essential for scrutinizing the fulfilment of the globally ratified Montreal Protocol.
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Retrieval of HCFC-142b (CH3CClF2) from ground-based high-resolution infrared Solar Spectra: Atmospheric increase since 1989 and comparison with surface and satellite measurements
Journal of Quantitative Spectroscopy and Radiative Transfer, 2017Co-Authors: Emmanuel Mahieu, Benoît Bovy, Bernard Lejeune, Christian Servais, Geoffrey C. Toon, Peter F. Bernath, Chris D. Boone, Kaley A. Walker, Stefan Reimann, Martin K. VollmerAbstract:Abstract We have developed an approach for retrieving HCFC-142b (CH 3 CClF 2 ) from ground-based high-resolution infrared Solar Spectra, using its ν 7 band Q branch in the 900–906 cm −1 interval. Interferences by HNO 3 , CO 2 and H 2 O have to be accounted for. Application of this approach to observations recorded within the framework of long-term monitoring activities carried out at the northern mid-latitude, high-altitude Jungfraujoch station in Switzerland (46.5°N, 8.0°E, 3580 m above sea level) has provided a total column times series spanning the 1989 to mid-2015 time period. A fit to the HCFC-142b daily mean total column time series shows a statistically-significant long-term trend of (1.23±0.08×10 13 molec cm −2 ) per year from 2000 to 2010, at the 2-σ confidence level. This corresponds to a significant atmospheric accumulation of (0.94±0.06) ppt (1 ppt=1/10 12 ) per year for the mean tropospheric mixing ratio, at the 2− σ confidence level. Over the subsequent time period (2010–2014), we note a significant slowing down in the HCFC-142b buildup. Our ground-based FTIR (Fourier Transform Infrared) results are compared with relevant data sets derived from surface in situ measurements at the Mace Head and Jungfraujoch sites of the AGAGE (Advanced Global Atmospheric Gases Experiment) network and from occultation measurements by the ACE-FTS (Atmospheric Chemistry Experiment-Fourier Transform Spectrometer) instrument on-board the SCISAT satellite.
Tun Wang - One of the best experts on this subject based on the ideXlab platform.
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perovskite c si monolithic tandem Solar cells under real Solar Spectra improving energy yield by oblique incident optimization
Journal of Physical Chemistry C, 2019Co-Authors: Tun Wang, Jiayuan Wang, W Z ShenAbstract:Many research groups have noticed the performance of rapidly developed perovskite/silicon monolithic tandem Solar cells (TSCs) under a real situation, but they overlook the short current density mi...
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perovskite c si monolithic tandem Solar cells under real Solar Spectra improving energy yield by oblique incident optimization
The Journal of Physical Chemistry, 2019Co-Authors: Tun Wang, Jiayuan Wang, W Z ShenAbstract:Many research groups have noticed the performance of rapidly developed perovskite/silicon monolithic tandem Solar cells (TSCs) under a real situation, but they overlook the short current density mismatch of two subcells at different times in a day and the spectrum variation at different latitudes. Here, we have systematically analyzed the efficiency losses and proposed an optimization scheme by combination of the experiment and simulation relying on reliable experimental data in a year. We have verified the simulated absorptance Spectra varying with incident angle θ to substitute the external quantum efficiency Spectra, which makes the optimization at oblique incidence possible. More importantly, we have further calculated and expanded the optimized current losses and energy output enhancement in perovskite/silicon monolithic TSCs to all latitudes. This work can serve as a practical guidance for the design of perovskite/silicon monolithic TSCs with the best annual energy output at different latitudes in the world.
