Line-by-line model development in support of the JCSDA PI – Eli Mlawer (AER) Co-PI – Vivienne Payne (JPL) AER contributors – Matt Alvarado, Karen Cady-Pereira, Jean-Luc Moncet, Gennady Uymin, Dan Gombos, and Alan Lipton Joint Center for Satellite Data Assimilation Workshop June 5, 2013 Copyright 2013, Supported by JCSDA external research program through NASA contract NNH11CD78C – “Maintaining High Quality Spectroscopy for the Community Radiative Transfer Model”

Satellite data assimilation depends on accurate IR spectroscopy –Reducing uncertainties in spectroscopic line parameters and continua is critical to improving the use of satellite data in numerical weather prediction (NWP) and climate models. JCSDA Community Radiative Transfer Model (CRTM) is trained using AER line-by-line models –Both OPTRAN-based CRTM and new version developed with AER’s OSS approach Two LBL models – LBLRTM and MonoRTM (Clough et al., 2005)  Line-by-Line Radiative Transfer Model (LBLRTM) For general applications, consistent physics for all spectral regions from MW to UV Reference standard for model intercomparisons in the thermal IR (e.g., CCMVal, CIRC) Basis of retrieval algorithms for IASI, TES,...  Monochromatic Radiative Transfer Model (MonoRTM) For applications requiring higher accuracy (e.g. narrow channels such as in microwave)  Spectroscopic Input to AER’s LBL Models AER’s line parameter database - Built from HITRAN with selected upgrades MT_CKD continuum model –Includes water vapor continuum model derived from field and lab measurements; used by most RT codes JCSDA and Line-by-Line Modeling at AER

Release of LBLRTM_v12.2 –Upgrades to CO 2, O 2, spectroscopy –Over 300 downloads from AER RT Model webpage (rtweb.aer.com) Validation studies –Recent spectroscopic updates to LBLRTM using IASI measurements Alvarado et al., ACPD, 2013 –Spectroscopy related to mid/upper tropospheric water vapor Results from high-altitude (5300 m) field campaign in Chile - RHUBC Ongoing project – upgrade of features in MonoRTM –Broadening of O 2 lines by H 2 O Recent Developments in AER’s LBL Modeling

Recent Updates to LBLRTM Spectroscopy CO 2 -First order line coupling parameter (P-,Q-, and R-branches) computed using database of Lamouroux et al. (2010) -Lines between 5970 cm -1 and 6400 cm -1 were updated based on the work of Devi et al. (2007a, 2007b) O 2 -Adopted recent HITRAN linelist update (replacement of HITRAN 2008 list) -Quadrupole linelist of Gordon et al. (2010) was adopted ( cm -1 ) Model release – LBLRTM_v12.2 Released in November Spectroscopy updates, increased use of structures, bug fixes,... -Widely downloaded by community

Improvement due to new O 2 linelist Evaluated using spectra measured by Bruker FTS in Lamont, OK - Part of the Total Carbon Column Observing Network (TCCON) - Measures from cm -1 with 0.02 cm -1 resolution - Analysis included 75 cases from various seasons, zenith angles, aerosol and H 2 O loadings Wavenumber (cm -1 ) December 20, 2009, SZA = 70°

Improvement due to new O 2 linelist Wavenumber (cm -1 ) HITRAN 2008 linesNew Linelist December 20, 2009, SZA = 70°

Recent Updates to LBLRTM Spectroscopy CO 2 -First order line coupling parameter (P-,Q-, and R-branches) computed using positions and intensities in Lamouroux et al. (2010) -Lines between 5970 cm -1 and 6400 cm -1 were updated based on the work of Devi et al. (2007a, 2007b) O 2 -Adopted recent HITRAN linelist update (replacement of HITRAN 2008 list) -Quadrupole linelist of Gordon et al. (2010) was adopted ( cm -1 ) Model release – LBLRTM_v12.2 Released in November Spectroscopy updates, increased use of structures, bug fixes,... -Widely downloaded by community

AER RT Model Downloads for 5/20-5/31 Includes downloads from NIST, Harvard, UMBC, Caltech, U. Idaho, 2 U.S. private companies, Canada, Austria, Pakistan, Belgium

Rigorous validation of recent spectroscopic updates to LBLRTM against a global dataset of 120 near-nadir measurements from IASI. The performance of LBLRTM v12.1 is compared to a previous version (LBLRTM v9.4+) to test the impact of the latest updates to the line parameters and the CO 2 and H 2 O continua (including the addition of P- and R-branch line coupling for CO 2 ) - Alvarado et al., ACPD (2013) Validation Study of LBLRTM vs. IASI

IASI Closure Study Methodology Schematic of the retrieval procedure. The dashed arrows show additional retrievals performed to assess the consistency of CO 2 in the IASI spectral range. 120 clear-sky, nighttime, over ocean IASI profiles (a subset of Matricardi, 2009) - minimize potential errors from clouds, surface emissivity, and NLTE effects. Systematic spectral residuals after retrievals indicate errors in the spectroscopy. A priori profiles: Temperature: ECMWF adjusted between 10 mbar and 0.1 mbar (Masiello et al., 2011). H 2 O: ECMWF model. O 3 : ECMWF model scaled by OMI. CO 2, N 2 O, CH 4, and CO: Aura TES climatology

The addition of P- and R-branch line coupling improved performance in the  2 band of CO 2 IASI Scan #754 Mean Residuals LBLRTM v12.1 Mean Residuals LBLRTM v9.4+

The spectroscopy updates alter the temperature profiles retrieved using the  2 band Right: Mean and std. dev. of the differences between the temperature profiles retrieved with LBLRTM v12.1 and v9.4+. Only the cases that converged for all four model/band combinations are included.

Updates to the MT_CKD continuum have improved performance at the  3 bandhead IASI Scan #754 Mean Residuals LBLRTM v12.1 Mean Residuals LBLRTM v9.4+ Note that green ν 3 region was not used in temperature retrievals here

The  2 and  3 temperature retrievals in LBLRTM v12.1 are remarkably consistent. Mean and std. dev. of the differences between the retrieved temperature profiles. Right panel: the  2 retrieval was smoothed with the  3 averaging kernel and retrieval(Rodgers and Connor, 2003).

Residuals in the H 2 O  2 band are improved, especially in P-branch IASI Scan #754 Mean Residuals LBLRTM v12.1 Mean Residuals LBLRTM v9.4+

Residuals in the H 2 O  2 band are improved, especially in P-branch

Updated H 2 O spectroscopy in LBLRTM v12.1 impacts retrieved H 2 O profiles Right: Mean and std. dev. of the ratio between the H 2 O profiles retrieved with LBLRTM v12.1 and v9.4+. Only the 122 cases that converged for temperature and H 2 O in both models are included.

Residuals in the 616 JCSDA assimilated IASI channels are substantially improved IASI Scan #754 Mean Residuals LBLRTM v12.1 Mean Residuals LBLRTM v9.4+

Conclusions from Alvarado et al. The improved CO 2 spectroscopy in LBLRTM v12.1 can alter the retrieved temperature profiles by 0.5 K or more. The LBLRTM v12.1 CO 2 spectroscopy is remarkably consistent between the CO 2  2 and  3 bands. –Systematic residuals remain in the  2 Q-branches and at the  3 bandhead. The H 2 O spectroscopy is improved in both the P- and R- branches of the  2 band in LBLRTM v12.1, but significant systematic residuals remain. –Using a more realistic, vertically-varying HDO profile may reduce the P-branch mean residuals for scans with high water vapor. Existing satellite- and ground-based observations can validate most, but not all, infrared spectroscopy of interest.

Spectral Cooling Rate Profiles in the Infrared for MLS Far-Infrared

Infrared Transmittance

Scientific Motivation for Radiative Heating in Underexplored Bands Campaigns (RHUBC) Radiative heating/cooling in the mid-troposphere modulates the vertical motions of the atmosphere –This heating/cooling occurs primarily in water vapor absorption bands that are opaque at the surface - essentially unvalidated Approximately 40% of the OLR comes from the far-IR –Until recently, the observational tools were not available to evaluate the accuracy of the far-IR radiative transfer models Upper troposphere radiative processes are critical in understanding the radiative balance of the tropical tropopause layer and the transport of air into the stratosphere These processes need to be parameterized accurately in climate simulations (GCMs)

RHUBC Campaigns Main objective: Use radiative closure to reduce uncertainties in H 2 O spectroscopy (H 2 O continuum absorption model, line parameters (e.g. strengths, widths)) RHUBC-I ARM North Slope of Alaska (Barrow) February - March 2007 ~80 radiosondes launched 2 far-IR/IR interferometers Microwave radiometers for PWV RHUBC-II Cerro Toco (~5350 m), Atacama, Chile August - October far-IR / IR interferometers ~100 radiosondes, extremely low PWV 1 microwave radiometer for PWV 1 sub-millimeter FTS

RHUBC Precipitable Water Vapor (PWV) Values For reference, PWV for US Standard atmosphere is 14.3 mm.

Transmission in the Infrared

Uncertainty in the WV Continuum in Far-IR 1 st Principles SHEBA RHUBC-I

Far-infrared Spectroscopy of the Troposphere (FIRST) PI - Marty Mlynczak, NASA-LaRC Michelson interferometer cm -1 (resolution ~0.64 cm -1 ) Radiation Explorer in the Far Infrared (REFIR) Italian collaboration (RHUBC lead - Luca Palchetti) Fourier Transform Spectrometer cm -1 (resolution ~0.50 cm -1 ) Smithsonian Astrophysical Observatory FTS PI - Scott Paine 300 GHz – 3.5 THz (3 GHz resolution) U. Cologne HATPRO 7 channels from GHz, 7 channels from GHz Atmospheric Emitted Radiance Interferometer (AERI) ARM Instrument developed at U. Wisconsin cm -1 (resolution ~0.5 cm -1 ) RHUBC-II Instruments

Spectral Observations 170 GHz (5.6 cm -1 ) to 3 µm (3000 cm -1 ) SAO FTS (Smithsonian) FIRST (NASA/LaRC) REFIR (Italy) AERI (UW) First ever measurement of the entire infrared spectrum from 3 to 1780 μm!

Improving Sonde H 2 O Profiles Sonde H 2 O values have known accuracy issues Other measurements can be used to improve sonde profiles -Vaisala RS92 H 2 O correction derived using e.g. frost-point hygrometer Miloshevich et al. (2009) - may not apply to RHUBC sondes Sonde too moist Sonde too dry RHUBC-II PWV

Improving Sonde H 2 O Profiles Sonde H 2 O values have known accuracy issues Other measurements can be used to improve sonde profiles -Vaisala RS92 H 2 O correction derived using e.g. frost-point hygrometer Miloshevich et al. (2009) - may not apply to RHUBC sondes Analysis from ARM SGP: IR radiative closure improved after sonde H 2 O profile scaled to agree with PWV retrieved from MW radiometer (22 GHz line) -22 GHz line too weak to provide information for RHUBC Spectroscopy of 183 GHz line has low uncertainty – Clough et al. (1973), Payne et al. (2008, 2011)

GVRP: channels centered at 170, 171, …, 183, GHz Optical Depths for PWV ~0.3 cm Approach: Retrieve water vapor profiles using GVRP measurements -Optimal estimation approach -Miloshevich et al. (2009) corrected sonde used as initial guess / prior

Water Vapor Profile Retrieval from GVRP

Impact of WV Profiles on Far-IR Radiances

RHUBC-II: Comparison with SAO-FTS (sub-mm) figure: Scott Paine

RHUBC-II: Comparison with HATPRO (μwave) all RHUBC sondes figure: Gerrit Maschwitz Impact on downwelling brightness temperature of adding O 2 isotopologue lines to default linelist Impact on upwelling (US Std)

MonoRTM upgrade Currently ongoing – release in July Objectives -Support OSS-CRTM development by making MonoRTM more modular -directly calls more LBLRTM subroutines -utilizes same binary line parameter file as LBLRTM -Add capability to utilize line broadening coefficients due to collisions from a specific molecule (when available) e.g. broadening of: CO 2 due to H 2 O; O 2 due to H 2 O in microwave -Implement speed dependent line shape -Augment default microwave linelist (as needed) -Various bug fixes

H2O broadening of O2 in microwave New measurements by Brian Drouin of JPL Paper submitted - Drouin, Payne, Oyafuso, Sung, Mlawer: “Pressure broadening of oxygen by water” Change in brightness temperature from including this effect for atmosphere with PWV = 3 cm

MonoRTM upgrade Currently ongoing – release in July Objectives -Support OSS-CRTM development by making MonoRTM more modular -directly calls more LBLRTM subroutines -utilizes same binary line parameter file as LBLRTM -Add capability to utilize line broadening coefficients due to collisions from a specific molecule (when available) e.g. broadening of: CO 2 due to H 2 O; O 2 due to H 2 O in microwave -Implement speed dependent line shape -Augment default microwave linelist (as needed) -Various bug fixes

Future work – evaluate temperature dependence of O 2 line widths Comparison of HATPRO measurements from site in Greenland with MonoRTM calculation Shows possible line width temperature dependence issue at 52.3 GHz - from Miller et al. (2013)

Acknowledgements S. A. Clough, Clough Radiation Associates Marco Matricardi, ECMWF Scott Paine, Smithsonian Astrophysical Observatory Joint Center for Satellite Data Assimilation (JCSDA) NASA Gerrit Maschwitz Dave Turner, NOAA NSSL

AERI-ER ARM Instruments for RHUBC-II GVRP MPL MFRSR Vaisala Ceilometer Radiometers Sondes Met station

Far-IR Analysis: Results 17 cases used in study; H 2 O from sondes scaled by GVR +/- 7 PWV retrieval Adjustments made to water vapor continuum and selected line widths Delamere et al., JGR, 2010 Average AERI Radiances AERI-LBLRTM Residuals Before RHUBC-I Residuals After RHUBC-I

Site location RHUBC-II, Cerro Toco, Chile