Daniel H. DeSlover

An Intercomparison of Microphysical Retrieval Algorithms for Upper-Tropospheric Ice Clouds

The large horizontal extent, with its location in the cold upper troposphere, and ice composition make cirrus clouds important modulators of the Earths radiation budget and climate. Cirrus cloud microphysical properties are difficult to measure and model because they are inhomogeneous in nature and their ice crystal size distribution and habit are not well characterized. Accurate retrievals of cloud properties are crucial for improving the representation of cloud-scale processes in largescale models and for accurately predicting the Earths future climate. A number of passive and active remote sensing retrieval algorithms exist for estimating the microphysical properties of upper-tropospheric clouds. We believe significant progress has been made in the evolution of these retrieval algorithms in the last decade; however, there is room for improvement. Members of the Atmospheric Radiation Measurement (ARM) program Cloud Properties Working Group are involved in an intercomparison of optical depth τ and ice ...

A Methodology for Measuring Cirrus Cloud Visible-to-Infrared Spectral Optical Depth Ratios

Abstract Knowledge of cirrus cloud optical depths is necessary to understand the earth’s current climate and to model the cloud radiation impact on future climate. Cirrus clouds, depending on the ratio of their shortwave “visible” to longwave “infrared” optical depth, can act to either cool or warm the planet. In this study, visible-to-infrared cirrus cloud optical depth ratios were measured using ground-based lidar and Fourier transform spectrometry. A radiosonde temperature profile combined with the 0.532-μm-high spectral resolution lidar vertical cloud optical depth profile provided an effective weighting to the cloud radiance measured by the interferometer. This allowed evaluation of cirrus cloud optical depths in 18 infrared microwindows between water vapor absorption lines within the 800–1200-cm−1 infrared atmospheric window. The data analysis was performed near the peak solar and terrestrial emission regions, which represent the effective radiative cloud forcing efficiency of the given cloud sample...

Infrared land surface remote sensing using high spectral resolution aircraft observations

Abstract A method for emissivity–temperature separation using high spectral resolution infrared observations is presented. An additional constraint is available with high spectral resolution observations that allow for the determination of an effective surface temperature and effective surface emissivity spectrum appropriate for advanced atmospheric temperature and water vapor sounders. The method is illustrated using observations from a high altitude aircraft over a ground truth site in North Central Oklahoma, USA.

Validation of aircraft-measured land surface emissivity

This paper evaluates the performance of two techniques currently under development for use in the future validation of AIRS surface emissivity measurements over the Southern Great Plains Atmospheric Radiation Measurement site in Oklahoma, USA. The first technique involves a simultaneous retrieval of atmospheric temperature and water vapor, sruface skin temperature, and surface emissivity using a statistical approach; the second, a relative retrieval of the relative surface emissivity from spectral radiance observations between gaseous absorption lines. High spectral resolution upwelling radiance measurements from the aircraft-based NPOESS Atmospheric Sounder Testbed-Interferometer (NAST-I) obtained during the ARM/FIRE Water Vapor Experiment 2000 and Chesapeake Lighthouse and Aircraft Measurements for Satellites 2001 were used to compare each method. Surface truth was provided by ground-based Atmospheric Emitted Radiance Interferometer measurements.

Infrared land surface remote sensing using high spectral resolution observations

This study presents a new technique for the separation of land surface infrared emissivity and surface skin temperature using high spectral resolution infrared observations. High spectral resolution observations of upwelling radiance at 20 km altitude were obtained by the Scanning High-resolution Interferometer Sounder (S-HIS) aboard the NASA ER-2 aircraft during the TX-2001 experiment. These aircraft observations are used in conjunction with complementary ground-based observations of downwelling radiance at the surface to estimate the surface skin temperature and absolute emissivity for a region in north central Oklahoma, USA. Coincident MODIS Airborne Simulator (MAS) observations are used to quantify the land surface variability within the S-HIS scene in the vicinity of the DOE ARM Southern Great Plain central facility. Ground truth data is presented from a ground based Scanning Atmospheric Emitted Radiance Interferometer. This remote sensing technique has application to satellite based observations from the NASA AIRS, the NPOESS CrIS, the EUMETSAT IASI, and the NASA GIFTS instruments.

Cross-track infrared sounder (CrIS) spectral radiance calibration and evaluations

The Cross-track Infrared Sounder (CrIS) is a high spectral resolution infrared sounder on the Suomi-NPP satellite. CrIS will compliment and extend similar data records begun by the Atmospheric Infrared Sounder (AIRS) on EOS-Aqua and by the Infrared Atmospheric Sounding Interferometer (IASI) on METOP. Primary uses of CrIS include assimilation of the radiance data into NWP models for medium range weather forecasting, retrievals of vertical profiles and temperature and water vapor, and various climate studies. Following Suomi-NPP launch on 28 October 2011, the CrIS was powered on on 20 January 2012. As part of NOAA and NASA efforts, over the past several months CIMSS/SSEC researchers have played a key role in the early checkout of the sensor including fine tuning of various calibration coefficients and characterization of the sensor’s performance.

Ground-based measurement of cirrus cloud optical properties as validation to aircraft- and satellite-based cloud studies

Ground-based Atmospheric Emitted Radiance Interferometer (AERI) and Raman Lidar measurements are used to infer cirrus cloud absorption optical depth and effective particle size. Our methodology will be discussed, and results shown for a number of contrasting cloud cases. The high spectral resolution AERI measurements allow inversion of the infrared radiative transfer equation between gaseous absorption lines (e.g., regions of minimal atmospheric emission), referred to as microwindows, to derive the cloud infrared absorption optical depth. Spectral variation in the cloud optical depth yields information on particle size and shape. A best fit of absorption optical depth to the measured absorption optical depth in each microwindow is used to determine the effective radius of particles within the cloud. Results will also be compared to simultaneous upwelling aircraft measurements.

S-HIS Dual Regression Retrieval Analysis Relating to the HS3 Field Campaign

Atmospheric state retrievals from S-HIS measurements from NASAs Global Hawk during the HS3 aircraft field campaign during the 2012 through 2014 hurricane seasons. Results will be compared to colocated AVAPS dropsonde and CPL lidar measurements--flown alongside S-HIS on the Globalhawk.

GROUND BASED RETRIEVALS OF SMALL ICE CRYSTALS AND WATER PHASE IN ARCTIC CIRRUS

The microphysical properties of cirrus clouds are uncertain due to the problem of ice particles shattering at the probe inlet upon sampling. To facilitate better estimation of small ice crystal concentrations in cirrus clouds, a new ground‐based remote sensing technique has been used in combination with in situ aircraft measurements. Data from the Mixed‐Phase Arctic Cloud Experiment (M‐PACE), conducted at the north slope of Alaska (winter 2004), have been used to test a new method for retrieving the liquid water path (LWP) and ice water path (IWP) in mixed phase clouds. The framework of the retrieval algorithm consists of the modified anomalous diffraction approximation or MADA (for mixed phase cloud optical properties), a radar reflectivity‐ice microphysics relationship and a temperature‐dependent ice particle size distribution (PSD) scheme. Cloud thermal emission measurements made by the ground‐based Atmospheric Emitted Radiance Interferometer (AERI) yield information on the total water path (TWP) while...

Comparison of cirrus cloud optical properties from ground-, aircraft-, and satellite-based measurements

Results will focus on cirrus events which occurred during the ARM FIRE Water Vapor Experiment (AFWEX 2000) and Texas 2002 (TX2002) field campaigns over the Southern Great Plains Cloud and Radiation Testbed site (Oklahoma, USA) on 8 December 2000 and 29 November 2002, respectively. Aircraft measurements were taken from the NPOESS Airborne Sounder Testbed-Interferometer (NAST-I) during AFWEX 2000 and the Scanning-High resolution Infrared Sounder (S-HIS) during TX2002. Surface measurements were acquired by the Atmospheric Emitted Radiance Interferometer (AERI), located at the Central Facility. A second AERI, operating in rapid-scan mode within the University of Wisconsin mobile AERIbago, was available during the Texas 2002 case. Spectral absorption optical depths were retrieved using the high spectral resolution infrared measurements combined with lidar measured cloud boundaries. The spectral variation in each optical depth measurement were used to infer cloud particle effective radius from a database of hexagonal column extinction calculations. Results will compare cloud optical properties from simultaneous below- and above-cloud measurements.