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Feasibility Study on Measuring Atmospheric CO2 in Urban Areas Using Spaceborne CO2-IPDA LIDAR. REMOTE SENSING 2018. [DOI: 10.3390/rs10070985] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Ground-Based Remote Sensing of Volcanic CO2 Fluxes at Solfatara (Italy)—Direct Versus Inverse Bayesian Retrieval. REMOTE SENSING 2018. [DOI: 10.3390/rs10010125] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Han G, Xu H, Gong W, Ma X, Liang A. Simulations of a multi-wavelength differential absorption lidar method for CO 2 measurement. APPLIED OPTICS 2017; 56:8532-8540. [PMID: 29091636 DOI: 10.1364/ao.56.008532] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Accepted: 09/24/2017] [Indexed: 06/07/2023]
Abstract
The increase of greenhouse gas is one of the most important factors leading to global climate change. Differential absorption lidar (DIAL) is considered to be the tool with the most potential to measure CO2 remotely. However, it is difficult to obtain accurate CO2 retrievals and determine carbon fluxes with the traditional dual-wavelength differential absorption inversion method, which is characterized by a low signal-to-noise ratio (SNR). Therefore, a multi-wavelength differential absorption inversion framework is proposed in this work. Based on the measurement of the absorption optical depths (ODs) of a single line at 30 different wavelengths, we tried to minimize the differences between the simulated and measured absorption ODs through an iterative process, which consisted of forward simulation and reverse inversion processes. The retrievals are determined when an optimal solution is obtained. The simulation experiments show that the precision of the nonuniform sampling wavelength method is better than that of the dual-wavelength method. The precision of the proposed method was improved by more than 60% for an SNR of 30-40 dB compared to the traditional method. Furthermore, the average error of this method is about 1/9th the traditional method.
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Shibata Y, Nagasawa C, Abo M. Development of 1.6 μm DIAL using an OPG/OPA transmitter for measuring atmospheric CO 2 concentration profiles. APPLIED OPTICS 2017; 56:1194-1201. [PMID: 28158133 DOI: 10.1364/ao.56.001194] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
An experiment for the measurement of atmospheric CO2 vertical profiles up to a 7 km altitude was successfully conducted using a 1.6 μm ground-based differential absorption Lidar developed by Tokyo Metropolitan University. To achieve a high pulse repetition rate, large power output, and high frequency stabilization, we developed a new 1.6 μm Lidar system using an optical parametric generator (OPG) transmitter. Unlike the previous system's transmitter, OPG does not need a resonator. We amplified its output with two optical parametric amplifiers. We validated our system against an in situ sensor and found the difference between their CO2 concentration measurements to be 0.06 ppm.
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Ai X, Pérez-Serrano A, Quatrevalet M, Nock RW, Dahnoun N, Ehret G, Esquivias I, Rarity JG. Analysis of a random modulation single photon counting differential absorption lidar system for space-borne atmospheric CO 2 sensing. OPTICS EXPRESS 2016; 24:21119-21133. [PMID: 27607715 DOI: 10.1364/oe.24.021119] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The ability to observe the Earth's carbon cycles from space provides scientists an important tool to analyze climate change. Current proposed systems are mainly based on pulsed integrated path differential absorption lidar, in which two high energy pulses at different wavelengths interrogate the atmosphere sequentially for its transmission properties and are back-scattered by the ground. In this work an alternative approach based on random modulation single photon counting is proposed and analyzed; this system can take advantage of a less power demanding semiconductor laser in intensity modulated continuous wave operation, benefiting from a better efficiency, reliability and radiation hardness. Our approach is validated via numerical simulations considering current technological readiness, demonstrating its potential to obtain a 1.5 ppm retrieval precision for 50 km averaging with 2.5 W average power in a space-borne scenario. A major limiting factor is the ambient shot noise, if ultra-narrow band filtering technology could be applied, 0.5 ppm retrieval precision would be attainable.
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Wagner GA, Plusquellic DF. Ground-based, integrated path differential absorption LIDAR measurement of CO 2, CH 4, and H 2O near 1.6 μm. APPLIED OPTICS 2016; 55:6292-6310. [PMID: 27534472 DOI: 10.1364/ao.55.006292] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
A ground-based, integrated path, differential absorption light detection and ranging (IPDA LIDAR) system is described and characterized for a series of nighttime studies of CO2, CH4, and H2O. The transmitter is based on an actively stabilized, continuous-wave, single-frequency external-cavity diode laser (ECDL) operating from 1.60 to 1.65 μm. The fixed frequency output of the ECDL is microwave sideband tuned using an electro-optical phase modulator driven by an arbitrary waveform generator and filtered using a confocal cavity to generate a sequence of 123 frequencies separated by 300 MHz. The scan sequence of single sideband frequencies of 600 ns duration covers a 37 GHz region at a spectral scan rate of 10 kHz (100 μs per scan). Simultaneously, an eye-safe backscatter LIDAR system at 1.064 μm is used to monitor the atmospheric boundary layer. IPDA LIDAR measurements of the CO2 and CH4 dry air mixing ratios are presented in comparison with those from a commercial cavity ring-down (CRD) instrument. Differences between the IPDA LIDAR and CRD concentrations in several cases appear to be well correlated with the atmospheric aerosol structure from the backscatter LIDAR measurements. IPDA LIDAR dry air mixing ratios of CO2 and CH4 are determined with fit uncertainties of 2.8 μmol/mol (ppm) for CO2 and 22 nmol/mol (ppb) for CH4 over 30 s measurement periods. For longer averaging times (up to 1200 s), improvements in these detection limits by up to 3-fold are estimated from Allan variance analyses. Two sources of systematic error are identified and methods to remove them are discussed, including speckle interference from wavelength decorrelation and the seed power dependence of amplified spontaneous emission. Accuracies in the dry air retrievals of CO2 and CH4 in a 30 s measurement period are estimated at 4 μmol/mol (1% of ambient levels) and 50 nmol/mol (3%), respectively.
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Campbell JF, Lin B, Nehrir AR, Harrison FW, Obland MD. High-resolution CW lidar altimetry using repeating intensity-modulated waveforms and Fourier transform reordering. OPTICS LETTERS 2014; 39:6078-6081. [PMID: 25361160 DOI: 10.1364/ol.39.006078] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
An interpolation method is described for range measurements of high precision and altimetry using repeating intensity-modulated continuous wave (IM-CW) lidar waveforms, where the range is determined by means of a cross-correlation between the digital form of the transmitted signal and the digitized return signal collected by the lidar receiver. This method uses reordering of the array elements in the frequency domain to convert a repeating synthetic pulse signal to single highly interpolated pulse. The computation of this processing is marginally greater than the correlation itself, as it only involves reordering of the correlation in the frequency domain, which makes it possible to implement this in a real time application. It is shown through theoretical arguments and flight-testing that this is a viable method for high-speed interpolated range measurements. Standard deviation is 0.75 m over water with only 350 mw of transmitted power at 2600 m.
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Campbell JF, Lin B, Nehrir AR. Advanced sine wave modulation of continuous wave laser system for atmospheric CO(2) differential absorption measurements. APPLIED OPTICS 2014; 53:816-829. [PMID: 24663259 DOI: 10.1364/ao.53.000816] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2013] [Accepted: 12/18/2013] [Indexed: 06/03/2023]
Abstract
In this theoretical study, modulation techniques are developed to support the Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) mission. A continuous wave (CW) lidar system using sine waves modulated by maximum length (ML) pseudo-noise (PN) codes is described for making simultaneous online/offline differential absorption measurements. Amplitude and phase-shift keying (PSK) modulated intensity modulation (IM) carriers, in addition to a hybrid-pulse technique are investigated, which exhibit optimal autocorrelation properties. A method is presented to bandwidth limit the ML sequence based on a filter implemented in terms of Jacobi theta functions, which does not significantly degrade the resolution or introduce sidelobes as a means of reducing aliasing and IM carrier bandwidth.
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A New Laser Based Approach for Measuring Atmospheric Greenhouse Gases. REMOTE SENSING 2013. [DOI: 10.3390/rs5126284] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Lin B, Ismail S, Wallace Harrison F, Browell EV, Nehrir AR, Dobler J, Moore B, Refaat T, Kooi SA. Modeling of intensity-modulated continuous-wave laser absorption spectrometer systems for atmospheric CO(2) column measurements. APPLIED OPTICS 2013; 52:7062-7077. [PMID: 24217721 DOI: 10.1364/ao.52.007062] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2013] [Accepted: 09/08/2013] [Indexed: 06/02/2023]
Abstract
The focus of this study is to model and validate the performance of intensity-modulated continuous-wave (IM-CW) CO(2) laser absorption spectrometer (LAS) systems and their CO(2) column measurements from airborne and satellite platforms. The model accounts for all fundamental physics of the instruments and their related CO(2) measurement environments, and the modeling results are presented statistically from simulation ensembles that include noise sources and uncertainties related to the LAS instruments and the measurement environments. The characteristics of simulated LAS systems are based on existing technologies and their implementation in existing systems. The modeled instruments are specifically assumed to be IM-CW LAS systems such as the Exelis' airborne multifunctional fiber laser lidar (MFLL) operating in the 1.57 μm CO(2) absorption band. Atmospheric effects due to variations in CO(2), solar radiation, and thin clouds, are also included in the model. Model results are shown to agree well with LAS atmospheric CO(2) measurement performance. For example, the relative bias errors of both MFLL simulated and measured CO(2) differential optical depths were found to agree to within a few tenths of a percent when compared to the in situ observations from the flight of 3 August 2011 over Railroad Valley (RRV), Nevada, during the summer 2011 flight campaign. In addition, the horizontal variations in the model CO(2) differential optical depths were also found to be consistent with those from MFLL measurements. In general, the modeled and measured signal-to-noise ratios (SNRs) of the CO(2) column differential optical depths (τd) agreed to within about 30%. Model simulations of a spaceborne IM-CW LAS system in a 390 km dawn/dusk orbit for CO(2) column measurements showed that with a total of 42 W of transmitted power for one offline and two different sideline channels (placed at different locations on the side of the CO(2) absorption line), the accuracy of the τd measurements for surfaces similar to the playa of RRV, Nevada, will be better than 0.1% for 10 s averages. For other types of surfaces such as low-reflectivity snow and ice surfaces, the precision and bias errors will be within 0.23% and 0.1%, respectively. Including thin clouds with optical depths up to 1, the SNR of the τd measurements with 0.1 s integration period for surfaces similar to the playa of RRV, Nevada, will be greater than 94 and 65 for sideline positions placed +3 and +10 pm, respectively, from the CO(2) line center at 1571.112 nm. The CO(2) column bias errors introduced by the thin clouds are ≤0.1% for cloud optical depth ≤0.4, but they could reach ∼0.5% for more optically thick clouds with optical depths up to 1. When the cloud and surface altitudes and scattering amplitudes are obtained from matched filter analysis, the cloud bias errors can be further reduced. These results indicate that the IM-CW LAS instrument approach when implemented in a dawn/dusk orbit can make accurate CO(2) column measurements from space with preferential weighting across the mid to lower troposphere in support of a future ASCENDS mission.
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Campbell JF. Nonlinear swept frequency technique for CO2 measurements using a CW laser system. APPLIED OPTICS 2013; 52:3100-3107. [PMID: 23669780 DOI: 10.1364/ao.52.003100] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2013] [Accepted: 03/26/2013] [Indexed: 06/02/2023]
Abstract
A system using a nonlinear multiswept sine wave is described, which employs multichannel multiswept orthogonal waves, to separate channels and make multiple, simultaneous online/offline CO(2) measurements. An analytic expression and systematic method for determining the orthogonal frequencies for the unswept, linear swept, and nonlinear swept cases is presented. It is shown that one may reduce sidelobes of the autocorrelation function while preserving cross channel orthogonality, for thin cloud rejection.
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Johnson W, Repasky KS, Carlsten JL. Micropulse differential absorption lidar for identification of carbon sequestration site leakage. APPLIED OPTICS 2013; 52:2994-3003. [PMID: 23669765 DOI: 10.1364/ao.52.002994] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2012] [Accepted: 03/29/2013] [Indexed: 06/02/2023]
Abstract
A scanning differential absorption lidar (DIAL) instrument for identification of carbon dioxide leaks at carbon sequestration sites has been developed and initial data has been collected at Montana State University. The laser transmitter uses two tunable discrete mode laser diodes operating in the continuous-wave mode with one locked to the online absorption wavelength and the other operating at the offline wavelength. Two in-line fiber optic switches are used to switch between online and offline operation. After the fiber optic switch, an acousto-optic modulator is used to generate a pulse train used to injection seed an erbium-doped fiber amplifier to produce eye-safe laser pulses with maximum pulse energies of 66 μJ, a pulse repetition frequency of 15 kHz, and an operating wavelength of 1.571 μm. The DIAL receiver uses a 28 cm diameter Schmidt-Cassegrain telescope to collect that backscattered light, which is then monitored using a photomultiplier tube module operating in the photon counting mode. The DIAL has measured carbon dioxide profiles from 1 to 2.5 km with 60 min temporal averaging. Comparisons of DIAL measurements with a Licor LI-820 gas analyzer point sensor have been made.
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Affiliation(s)
- William Johnson
- Physics Department, EPS Room 264, Montana State University, Bozeman, Montana 59717, USA
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Dobler JT, Harrison FW, Browell EV, Lin B, McGregor D, Kooi S, Choi Y, Ismail S. Atmospheric CO2 column measurements with an airborne intensity-modulated continuous wave 1.57 μm fiber laser lidar. APPLIED OPTICS 2013; 52:2874-2892. [PMID: 23669700 DOI: 10.1364/ao.52.002874] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Accepted: 02/23/2013] [Indexed: 06/02/2023]
Abstract
The 2007 National Research Council (NRC) Decadal Survey on Earth Science and Applications from Space recommended Active Sensing of CO(2) Emissions over Nights, Days, and Seasons (ASCENDS) as a midterm, Tier II, NASA space mission. ITT Exelis, formerly ITT Corp., and NASA Langley Research Center have been working together since 2004 to develop and demonstrate a prototype laser absorption spectrometer for making high-precision, column CO(2) mixing ratio measurements needed for the ASCENDS mission. This instrument, called the multifunctional fiber laser lidar (MFLL), operates in an intensity-modulated, continuous wave mode in the 1.57 μm CO(2) absorption band. Flight experiments have been conducted with the MFLL on a Lear-25, UC-12, and DC-8 aircraft over a variety of different surfaces and under a wide range of atmospheric conditions. Very high-precision CO(2) column measurements resulting from high signal-to-noise ratio (>1300) column optical depth (OD) measurements for a 10 s (~1 km) averaging interval have been achieved. In situ measurements of atmospheric CO(2) profiles were used to derive the expected CO(2) column values, and when compared to the MFLL measurements over desert and vegetated surfaces, the MFLL measurements were found to agree with the in situ-derived CO(2) columns to within an average of 0.17% or ~0.65 ppmv with a standard deviation of 0.44% or ~1.7 ppmv. Initial results demonstrating ranging capability using a swept modulation technique are also presented.
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