Papers by Antonia Gambacorta
Journal of Geophysical Research: Atmospheres, 2014
This paper presents the retrieval algorithm of nitrous oxide (N 2 O) using the Atmospheric Infrar... more This paper presents the retrieval algorithm of nitrous oxide (N 2 O) using the Atmospheric Infrared Sounder (AIRS) on EOS/Aqua, its validation using aircraft measurements, and one possible application for monitoring the global N 2 O annual trend from 2003 to 2013. The results demonstrate that AIRS is sensitive to N 2 O in the middle to upper troposphere, with the peak vertical sensitivity between 200 and 750 hPa and the sensitivity in the tropics larger than in the high-latitude regions. The degrees of freedom of the N 2 O retrieval are mostly between 1.0 and 1.5. Validation using the aircraft measurement profiles by the High-Performance Instrumented Airborne Platform for Environmental Research Pole-to-Pole Observations program over the Pacific Ocean indicated that the retrieval RMS error is mostly less than 8 ppb (or~2.1%). One important feature is that the variability of N 2 O from AIRS is more than 2 times than that of the aircraft measurements in the lower troposphere. In agreement with surface measurements, a nearly linear trend of N 2 O can be obtained based on limited AIRS data of 1 day in 15 May in each year from 2003 to 2013, and the increase rate of N 2 O is about 0.72 ppb yr À1 . This algorithm will be implemented in AIRS operational retrieval system, enabling the derivation of the N 2 O for over 20 years using the AIRS, the Infrared Atmospheric Sounding Interferometer, and the Cross-track Infrared Sounder. Such a unique product will be complementary to currently sparse ground-based observations for monitoring the N 2 O trend associated with climate change.
Enhanced validation of satellite derived sounding products using reference and dedicated radiosondes
2014 United States National Committee of URSI National Radio Science Meeting (USNC-URSI NRSM), 2014
Journal of Geophysical Research: Atmospheres, 2014
The Cross-track Infrared Sounder (CrIS) and the Advanced Technology Microwave Sounder (ATMS) inst... more The Cross-track Infrared Sounder (CrIS) and the Advanced Technology Microwave Sounder (ATMS) instruments aboard the Suomi National Polar-orbiting Partnership satellite provide high-quality hyperspectral infrared and microwave observations to retrieve atmospheric vertical temperature and moisture profiles (AVTP and AVMP) and many other environmental data records (EDRs). The official CrIS and ATMS EDR algorithm, together called the Cross-track Infrared and Microwave Sounding Suite (CrIMSS), produces EDR products on an operational basis through the interface data processing segment. The CrIMSS algorithm group is to assess and ensure that operational EDRs meet beta and provisional maturity requirements and are ready for stages 1-3 validations. This paper presents a summary of algorithm optimization efforts, as well as characterization and validation of the AVTP and AVMP products using the European Centre for Medium-Range Weather Forecasts (ECMWF) analysis, the Atmospheric Infrared Sounder (AIRS) retrievals, and conventional and dedicated radiosonde observations. The global root-mean-square (RMS) differences between the CrIMSS products and the ECMWF show that the AVTP is meeting the requirements for layers 30-300 hPa (1.53 K versus 1.5 K) and 300-700 hPa (1.28 K versus 1.5 K). Slightly higher RMS difference for the 700 hPa-surface layer (1.78 K versus 1.6 K) is attributable to land and polar profiles. The AVMP product is within the requirements for 300-600 hPa (26.8% versus 35%) and is close in meeting the requirements for 600 hPa-surface (25.3% versus 20%). After just one year of maturity, the CrIMSS EDR products are quite comparable to the AIRS heritage algorithm products and show readiness for stages 1-3 validations.
A Cross-Comparison of The NOAA/NESDIS AIRS, IASI and CrIS Operational Channel Selections: Methodology and Information Content
Imaging and Applied Optics, 2011
ABSTRACT We present a cross-comparison of the NOAA/NESDIS operational channel selection for AIRS,... more ABSTRACT We present a cross-comparison of the NOAA/NESDIS operational channel selection for AIRS, IASI and CrIS. The focus of this study is on the channel selection methodology and the final information content in the three systems.
Journal of Geophysical Research: Atmospheres, 2012
1] Accurate environmental satellite observations and calculations of top-of-atmosphere infrared (... more 1] Accurate environmental satellite observations and calculations of top-of-atmosphere infrared (IR) spectral radiances are required for the accurate retrieval of environmental data records (EDRs), including atmospheric vertical temperature and moisture profiles. For this reason it is important that systematic differences between observations and calculations under well-characterized conditions be minimal, and because most sensors must scan the earth surface to facilitate global coverage, this should include unbiased agreement over the range of zenith angles encountered. This paper investigates the "clear-sky observations" commonly used in such analyses, which include "cloud-masked" data (as is typical from imagers), as well as "cloud-cleared radiances" (as is typical from hyper/ultraspectral sounders). Here we derive simple physical conceptual models to examine quantitatively the longwave IR brightness temperature sensitivity arising from the increasing probability of cloudy fields-of-view with zenith angle, or alternatively from increased slant-path through an aerosol layer. To model the angular effect of clouds, we apply previously derived probability of clear line-of-sight (PCLoS) models for single-layer broken opaque clouds. We then generalize this approach to account for the impact of high, semitransparent (non-opaque) cold clouds, by deriving analytical expressions for the mean slant-paths through each of the idealized shapes under consideration. Our sensitivity analyses suggest that contamination by residual clouds and/or aerosols within clear-sky observations can have a measurable concave-up impact (i.e., an increasing positive bias symmetric over the scanning range) on the angular agreement of hypothetical "observations" with "calculations." The magnitudes are typically on the order of couple tenths of a Kelvin or more depending on the residual absolute cloud fraction and optical depth (i.e., the degree of cloud contamination), the residual aerosol optical depth (i.e., the degree of aerosol contamination), the temperature difference between the surface and the residual cloud/aerosol layers, and the shape and vertical aspect ratio of the clouds. Citation: Nalli, N. R., C. D. Barnet, E. S. Maddy, and A. Gambacorta (2012), On the angular effect of residual clouds and aerosols in clear-sky infrared window radiance observations: Sensitivity analyses,
Journal of Atmospheric and Oceanic Technology, 2011
High spatial resolution measurements from the Advanced Very High Resolution Radiometer (AVHRR) on... more High spatial resolution measurements from the Advanced Very High Resolution Radiometer (AVHRR) on the Meteorological Operation (MetOp)-A satellite that are collocated to the footprints from the Infrared Atmospheric Sounding Interferometer (IASI) on the satellite are exploited to improve and quality control cloud-cleared radiances obtained from the IASI. For a partial set of mostly ocean MetOp-A orbits collected on 3 October 2010 for latitudes between 708S and 758N, these cloud-cleared radiances and clear-sky subpixel AVHRR measurements within the IASI footprint agree to better than 0.25-K root-mean-squared difference for AVHRR window channels with almost zero bias. For the same dataset, surface skin temperatures retrieved using the combined AVHRR, IASI, and Advanced Microwave Sounding Unit (AMSU) cloudclearing algorithm match well with ECMWF model surface skin temperatures over ocean, yielding total uncertainties #1.2 K for scenes with up to 97% cloudiness.
Geophysical Research Letters, 2012
An Experiment Using High Spectral Resolution CrIS Measurements for Atmospheric Trace Gases: Carbon Monoxide Retrieval Impact Study
IEEE Geoscience and Remote Sensing Letters, 2000
ABSTRACT We perform a demonstration experiment using the National Oceanic Atmospheric Administrat... more ABSTRACT We perform a demonstration experiment using the National Oceanic Atmospheric Administration Unique Cross-track Infrared Sounder (CrIS)/Advanced Technology Microwave Sounder Processing System to assess the improvement on trace gas retrievals upon switching to high spectral resolution CrIS radiance measurements (0.625 $hbox{cm}^{-1}$). The focus of this study is carbon monoxide retrievals. The experimental high spectral resolution CO retrievals show a remarkable improvement, of almost up to one order of magnitude in the degree of freedom of the signal, with respect to the low-resolution mode. Furthermore, high-resolution CO retrievals show similar skill with respect to existing CO operational products from the Atmospheric InfraRed Sounder, Atmospheric Sounder Interferometer, and Measurements of Pollution In The Troposphere instruments, both in terms of spatial variability and degrees of freedom. The results of this research provide evidence to support the need for high spectral resolution CrIS measurements. This is a fundamental prerequisite in guaranteeing continuity to the CO afternoon orbit monitoring as part of a multisatellite uniformly integrated long-term data record of atmospheric trace gases.
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Papers by Antonia Gambacorta