Retrieval of foreign-broadened water vapor continuum coefficients from emitted spectral radiance in the H_2O rotational band from 240 to 590 cm^-1

Serio, Carmine; Masiello, Guido; Esposito, Francesco; Girolamo, Paolo Di; Iorio, Tatiana Di; Palchetti, Luca; Bianchini, Giovanni; Muscari, Giovanni; Pavese, G.; Rizzi, Rolando; Carli, B.; Cuomo, V.

doi:10.1364/oe.16.015816

Cited by 47 publications

(54 citation statements)

References 19 publications

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“…Also, note that the derivative matrix (7), is a N L by N matrix, where N L is the number of atmospheric layers. For more details on the properties of the jacobian with respect to the continuum absorption see, e.g., Serio et al (2008b). If we vary the wave number dependent density function by the constant value δf we should observe a bias in temperature, δT given by Figure 17b shows the results for the case where we vary the continuum density function by −10% and −90% respectively.…”

Section: Spectroscopic Parameters: the Co 2 Continuummentioning

confidence: 99%

The use of IASI data to identify systematic errors in the ECMWF forecasts of temperature in the upper stratosphere

2011

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Abstract. Since data from the Infrared Atmospheric Sounding Interferometer (IASI) became available in 2007, a number of papers have appeared in the literature which have reported relatively large discrepancies between IASI spectra and forward calculations in the centre of the CO 2 Q-branch at 667 cm −1 . In this paper we show that these discrepancies are primarily due to errors in the temperature profiles used in the forward calculations. In particular, we have used forecasts of temperature profiles from the European Centre for MediumRange Weather Forecasts (ECMWF) to demonstrate that, for the case study considered in this paper, these profiles are affected by systematic errors of the order of ≈10 K at the level of the stratopause. To derive the magnitude and the spatial location of the systematic errors in the temperature profile, we have carried out forward/inverse calculations for a number of clear-sky, daytime, IASI tropical soundings over the sea. The forward calculations have been performed using atmospheric state vectors which have been obtained either from the direct inversion of the IASI radiances or from space-time co-located profiles derived from radiosonde observations and from the ECMWF model. To rule out any effect due to the accuracy of the forward model, we have performed the forward calculations using two independent models. The sensitivity of the temperature biases to the variability of the CO 2 profile and to spectroscopy errors has also been studied.

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Section: Spectroscopic Parameters: the Co 2 Continuummentioning

confidence: 99%

The use of IASI data to identify systematic errors in the ECMWF forecasts of temperature in the upper stratosphere

2011

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“…Radiative closure exercises have successfully been used to evaluate and improve line-by-line radiative transfer models for many years [e.g., Serio et al, 2008;Turner et al, 2004;Tobin et al, 1999]. However, adequate evaluation using groundbased observations requires that the atmospheric transmissivity be significantly larger than zero (i.e., >5%).…”

Section: Introductionmentioning

confidence: 99%

Ground‐based high spectral resolution observations of the entire terrestrial spectrum under extremely dry conditions

Turner¹,

Mlawer²,

Bianchini³

et al. 2012

Geophysical Research Letters

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[1] A field experiment was conducted in northern Chile at an altitude of 5.3 km to evaluate the accuracy of line-by-line radiative transfer models in regions of the spectrum that are typically opaque at sea level due to strong water vapor absorption. A suite of spectrally resolved radiance instruments collected simultaneous observations that, for the first time ever, spanned the entire terrestrial thermal spectrum (i.e., from 10 to 3000 cm À1 , or 1000 to 3.3 mm). These radiance observations, together with collocated water vapor and temperature profiles, are used to provide an initial evaluation of the accuracy of water vapor absorption in the farinfrared of two line-by-line radiative transfer models. These initial results suggest that the more recent of the two models is more accurate in the strongly absorbing water vapor pure rotation band. This result supports the validity of the Turner et al. (2012) study that demonstrated that the use of the more recent water vapor absorption model in climate simulations resulted in significant radiative and dynamical changes in the simulation relative to the older water vapor model. , et al. (2012), Ground-based high spectral resolution observations of the entire terrestrial spectrum under extremely dry conditions, Geophys.

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“…We utilize an approach similar to the method proposed by Serio et al (2008), i.e., IWV is retrieved via a derivative approach using one iteration to minimize ER-AERI vs. LBLRTM spectral residuals in IWV-sensitive windows. As first-guess IWV, data from a LHATPRO microwave radiometer are used.…”

Section: A1 Retrieval Methodsmentioning

confidence: 99%

“…IWV is retrieved by minimizing ER-AERI vs. LBLRTM spectral residuals in IWV-sensitive windows. For this purpose we implemented an approach similar to the method proposed by Serio et al (2008). Details of the IWV retrieval and the procedure for the selection of suitable spectral windows are outlined in Appendix A.…”

Section: Integrated Water Vapor and Water Vapor Profilesmentioning

confidence: 99%

“…As part of the US Atmospheric Radiation Measurement (ARM) program (Ackermann and Stokes, 2003), a series of radiative closure experiments has been set up (e.g., Turner et al, 2004Turner et al, , 2012b which was complemented by the Italian ECOWAR (Earth COoling by WAter vapor Radiation) project (e.g., Bhawar et al, 2008;Bianchini et al, 2011). Various experiments have addressed the quality of (water vapor) line parameters in the FIR (Esposito et al, 2007;Delamere et al, 2010;Masiello et al, 2012), the water vapor continuum in the FIR (Tobin et al, 1999;Serio et al, 2008;Delamere et al, 2010;Liuzzi et al, 2014), and the water vapor continuum in the MIR (Turner et al, 2004;Rowe et al, 2006;Rowe and Walden, 2009). A crucial requirement for radiative closure experiments in the FIR and MIR is to select a site guaranteeing a wide range of IWV levels including the occurrence of very low IWV levels.…”

Section: Introductionmentioning

confidence: 99%

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The Zugspitze radiative closure experiment for quantifying water vapor absorption over the terrestrial and solar infrared – Part 1: Setup, uncertainty analysis, and assessment of far-infrared water vapor continuum

2016

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Abstract. Quantitative knowledge of water vapor radiative processes in the atmosphere throughout the terrestrial and solar infrared spectrum is still incomplete even though this is crucial input to the radiation codes forming the core of both remote sensing methods and climate simulations. Beside laboratory spectroscopy, ground-based remote sensing field studies in the context of so-called radiative closure experiments are a powerful approach because this is the only way to quantify water absorption under cold atmospheric conditions. For this purpose, we have set up at the Zugspitze (47.42 • N, 10.98 • E; 2964 m a.s.l.) a long-term radiative closure experiment designed to cover the infrared spectrum between 400 and 7800 cm −1 (1.28-25 µm). As a benefit for such experiments, the atmospheric states at the Zugspitze frequently comprise very low integrated water vapor (IWV; minimum = 0.1 mm, median = 2.3 mm) and very low aerosol optical depth (AOD = 0.0024-0.0032 at 7800 cm −1 at air mass 1). All instruments for radiance measurements and atmospheric-state measurements are described along with their measurement uncertainties. Based on all parameter uncertainties and the corresponding radiance Jacobians, a systematic residual radiance uncertainty budget has been set up to characterize the sensitivity of the radiative closure over the whole infrared spectral range. The dominant uncertainty contribution in the spectral windows used for far-infrared (FIR) continuum quantification is from IWV uncertainties, while T profile uncertainties dominate in the mid-infrared (MIR). Uncertainty contributions to near-infrared (NIR) radiance residuals are dominated by water vapor line parameters in the vicinity of the strong water vapor bands. The window regions in between these bands are dominated by solar Fourier transform infrared (FTIR) calibration uncertainties at low NIR wavenumbers, while uncertainties due to AOD become an increasing and dominant contribution towards higher NIR wavenumbers. Exceptions are methane or nitrous oxide bands in the NIR, where the associated line parameter uncertainties dominate the overall uncertainty.As a first demonstration of the Zugspitze closure experiment, a water vapor continuum quantification in the FIR spectral region (400-580 cm −1 ) has been performed. The resulting FIR foreign-continuum coefficients are consistent with the MT_CKD 2.5.2 continuum model and also agree with the most recent atmospheric closure study carried out in Antarctica. Results from the first determination of the NIR water vapor continuum in a field experiment are detailed in a companion paper (Reichert and Sussmann, 2016) while a novel NIR calibration scheme for the underlying FTIR measurements of incoming solar radiance is presented in another companion paper .

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Retrieval of foreign-broadened water vapor continuum coefficients from emitted spectral radiance in the H_2O rotational band from 240 to 590 cm^-1

Cited by 47 publications

References 19 publications

The use of IASI data to identify systematic errors in the ECMWF forecasts of temperature in the upper stratosphere

The use of IASI data to identify systematic errors in the ECMWF forecasts of temperature in the upper stratosphere

Ground‐based high spectral resolution observations of the entire terrestrial spectrum under extremely dry conditions

The Zugspitze radiative closure experiment for quantifying water vapor absorption over the terrestrial and solar infrared – Part 1: Setup, uncertainty analysis, and assessment of far-infrared water vapor continuum

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