All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 145 12 3
PDF Downloads 17 2 1

Initialization and Validation of a Simulation of Cirrus Using FIRE-II Data

D.L. WestphalNaval Research Laboratory, Monterey, California

Search for other papers by D.L. Westphal in
Current site
Google Scholar
PubMed
Close
,
S. KinneNASA/Ames Research Center, Moffet Field, California

Search for other papers by S. Kinne in
Current site
Google Scholar
PubMed
Close
,
P. PilewskieNASA/Ames Research Center, Moffet Field, California

Search for other papers by P. Pilewskie in
Current site
Google Scholar
PubMed
Close
,
J.M. AlvarezNASA/Langley Research Center, Hampton, Virginia

Search for other papers by J.M. Alvarez in
Current site
Google Scholar
PubMed
Close
,
P. MinnisNASA/Langley Research Center, Hampton, Virginia

Search for other papers by P. Minnis in
Current site
Google Scholar
PubMed
Close
,
D.F. YoungNASA/Langley Research Center, Hampton, Virginia

Search for other papers by D.F. Young in
Current site
Google Scholar
PubMed
Close
,
S.G. BenjaminNOAA/FSL, Boulder, Colorado

Search for other papers by S.G. Benjamin in
Current site
Google Scholar
PubMed
Close
,
W.L. EberhardNOAA/ETL, Boulder, Colorado

Search for other papers by W.L. Eberhard in
Current site
Google Scholar
PubMed
Close
,
R.A. KropfliNOAA/ETL, Boulder, Colorado

Search for other papers by R.A. Kropfli in
Current site
Google Scholar
PubMed
Close
,
S.Y. MatrosovNOAA/ETL, Boulder, Colorado

Search for other papers by S.Y. Matrosov in
Current site
Google Scholar
PubMed
Close
,
J.B. SniderNOAA/ETL, Boulder, Colorado

Search for other papers by J.B. Snider in
Current site
Google Scholar
PubMed
Close
,
T.A. UttalNOAA/ETL, Boulder, Colorado

Search for other papers by T.A. Uttal in
Current site
Google Scholar
PubMed
Close
,
A.J. HeymsfieldNCAR, Boulder, Colorado

Search for other papers by A.J. Heymsfield in
Current site
Google Scholar
PubMed
Close
,
G.G. MacePennsylvania State University, University Park, Pennsylvania

Search for other papers by G.G. Mace in
Current site
Google Scholar
PubMed
Close
,
S.H. MelfiNASA/Goddard Space Flight Center, Greenbelt, Maryland

Search for other papers by S.H. Melfi in
Current site
Google Scholar
PubMed
Close
,
D.O'C. StarrNASA/Goddard Space Flight Center, Greenbelt, Maryland

Search for other papers by D.O'C. Starr in
Current site
Google Scholar
PubMed
Close
, and
J.J. SodenNOAA/GFDL, Princeton, New Jersey

Search for other papers by J.J. Soden in
Current site
Google Scholar
PubMed
Close
Full access

Abstract

Observations from a wide variety of instruments and platforms are used to validate many different aspects of a three-dimensional mesoscale simulation of the dynamics, cloud microphysics, and radiative transfer of a cirrus cloud system observed on 26 November 1991 during the second cirrus field program of the First International Satellite Cloud Climatology Program (ISCCP) Regional Experiment (FIRE-II) located in southeastern Kansas. The simulation was made with a mesoscale dynamical model utilizing a simplified bulk water cloud scheme and a spectral model of radiative transfer. Expressions for cirrus optical properties for solar and infrared wavelength intervals as functions of ice water content and effective particle radius are modified for the midlatitude cirrus observed during FIRE-II and are shown to compare favorably with explicit size-resolving calculations of the optical properties. Rawinsonde, Raman lidar, and satellite data are evaluated and combined to produce a time–height cross section of humidity at the central FIRE-II site for model verification. Due to the wide spacing of rawinsondes and their infrequent release, important moisture features go undetected and are absent in the conventional analyses. The upper-tropospheric humidities used for the initial conditions were generally less than 50% of those inferred from satellite data, yet over the course of a 24-h simulation the model produced a distribution that closely resembles the large-scale features of the satellite analysis. The simulated distribution and concentration of ice compares favorably with data from radar, lidar, satellite, and aircraft. Direct comparison is made between the radiative transfer simulation and data from broadband and spectral sensors and inferred quantities such as cloud albedo, optical depth, and top-of-the-atmosphere 11-µm brightness temperature, and the 6.7-µm brightness temperature. Comparison is also made with theoretical heating rates calculated using the rawinsonde data and measured ice water size distributions near the central site. For this case study, and perhaps for most other mesoscale applications, the differences between the observed and simulated radiative quantities are due more to errors in the prediction of ice water content, than to errors in the optical properties or the radiative transfer solution technique.

Abstract

Observations from a wide variety of instruments and platforms are used to validate many different aspects of a three-dimensional mesoscale simulation of the dynamics, cloud microphysics, and radiative transfer of a cirrus cloud system observed on 26 November 1991 during the second cirrus field program of the First International Satellite Cloud Climatology Program (ISCCP) Regional Experiment (FIRE-II) located in southeastern Kansas. The simulation was made with a mesoscale dynamical model utilizing a simplified bulk water cloud scheme and a spectral model of radiative transfer. Expressions for cirrus optical properties for solar and infrared wavelength intervals as functions of ice water content and effective particle radius are modified for the midlatitude cirrus observed during FIRE-II and are shown to compare favorably with explicit size-resolving calculations of the optical properties. Rawinsonde, Raman lidar, and satellite data are evaluated and combined to produce a time–height cross section of humidity at the central FIRE-II site for model verification. Due to the wide spacing of rawinsondes and their infrequent release, important moisture features go undetected and are absent in the conventional analyses. The upper-tropospheric humidities used for the initial conditions were generally less than 50% of those inferred from satellite data, yet over the course of a 24-h simulation the model produced a distribution that closely resembles the large-scale features of the satellite analysis. The simulated distribution and concentration of ice compares favorably with data from radar, lidar, satellite, and aircraft. Direct comparison is made between the radiative transfer simulation and data from broadband and spectral sensors and inferred quantities such as cloud albedo, optical depth, and top-of-the-atmosphere 11-µm brightness temperature, and the 6.7-µm brightness temperature. Comparison is also made with theoretical heating rates calculated using the rawinsonde data and measured ice water size distributions near the central site. For this case study, and perhaps for most other mesoscale applications, the differences between the observed and simulated radiative quantities are due more to errors in the prediction of ice water content, than to errors in the optical properties or the radiative transfer solution technique.

Save