Why Operational Meteorologists Need More Satellite Soundings

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Accuracy of Geophysical Parameters Derived from AIRS/AMSU as a Function of Fractional Cloud Cover

AIRS was launched on EOS Aqua on May 4,2002, together with AMSU A and HSB, to form a next generation polar orbiting infrared and microwave atmospheric sounding system. The primary products of AIRS/AMSU are twice daily global fields of atmospheric temperature-humidity profiles, ozone profiles, sea/land surface skin temperature, and cloud related parameters including OLR. The sounding goals of AIRS are to produce 1 km tropospheric layer mean temperatures with an rms error of 1K, and layer precipitable water with an rms error of 20%, in cases with up to 80% effective cloud cover. The basic theory used to analyze AIRS/AMSU/HSB data in the presence of clouds, called the at-launch algorithm, was described previously. Pre-launch simulation studies using this algorithm indicated that these results should be achievable. Some modifications have been made to the at-launch retrieval algorithm as described in this paper. Sample fields of parameters retrieved from AIRS/AMSU/HSB data are presented and validated as a function of retrieved fractional cloud cover. As in simulation, the degradation of retrieval accuracy with increasing cloud cover is small. HSB failed in February 2005, and consequently HSB channel radiances are not used in the results shown in this paper. The AIRS/AMSU retrieval algorithm described in this paper, called Version 4, become operational at the Goddard DAAC in April 2005 and is being used to analyze near-real time AIRS/AMSU data. Historical AIRS/AMSU data, going backwards from March 2005 through September 2002, is also being analyzed by the DAAC using the Version 4 algorithm

TOI-1338 : TESS' first transiting circumbinary planet

Funding: Funding for the DPAC has been provided by national institutions, in particular, the institutions participating in the Gaia Multilateral Agreement. W.F.W. and J.A.O.thank John Hood Jr. for his generous support of exoplanet research at SDSU. Support was also provided and acknowledged through NASA Habitable Worlds grant 80NSSC17K0741 and NASA XRP grant 80NSSC18K0519. This work is partly supported by NASA Habitable Worlds grant 80NSSC17K0741. This material is based upon work supported by the National Science Foundation Graduate Research Fellowship Program under grant No.(DGE-1746045). A.H.M.J.T. has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No. 803193/BEBOP) and from a Leverhulme Trust Research Project grant No. RPG-2018-418. A.C. acknowledges support by CFisUC strategic project (UID/FIS/04564/2019).We report the detection of the first circumbinary planet (CBP) found by Transiting Exoplanet Survey Satellite (TESS). The target, a known eclipsing binary, was observed in sectors 1 through 12 at 30 minute cadence and in sectors 4 through 12 at 2 minute cadence. It consists of two stars with masses of 1.1 M⊙ and 0.3 M⊙ on a slightly eccentric (0.16), 14.6 day orbit, producing prominent primary eclipses and shallow secondary eclipses. The planet has a radius of ∼6.9 R⊕ and was observed to make three transits across the primary star of roughly equal depths (∼0.2%) but different durations—a common signature of transiting CBPs. Its orbit is nearly circular (e ≍ 0.09) with an orbital period of 95.2 days. The orbital planes of the binary and the planet are aligned to within ∼1°. To obtain a complete solution for the system, we combined the TESS photometry with existing ground-based radial-velocity observations in a numerical photometric-dynamical model. The system demonstrates the discovery potential of TESS for CBPs and provides further understanding of the formation and evolution of planets orbiting close binary stars.Publisher PDFPeer reviewe

Current Challenges in the Remote Sounding of the Earth

This workshop will focus on the topic of remote sounding of the Earth’s atmosphere using modern space-borne hyperspectral infrared (e.g., AIRS, IASI, CrIS) and microwave (e.g., AMSU, MHS, ATMS) instruments to extract information about the Earth’s atmosphere. This workshop will have three major sections. The first section will be a conceptual introduction to the mathematical methods of sounding, that is, radiative transfer and inversion (a.k.a. retrieval) of observations. The 2nd section will highlight the NOAA-Unique Combined Atmospheric Processing System (NUCAPS) and the Community Long-term Infrared Microwave Coupled Atmospheric Product System (CLIMCAPS) to illustrate the value and limitations of modern operational products and our ability to validate and utilize them. The 3rd section will focus on the lessons-learned over the last decade and some thoughts on a path forward for new sounding instruments and capabilities. The over-arching goal of this workshop is to stimulate discussion on how we, as a community, can improve the use of sounding for greater societal benefit. Each section will consist of a ~30 minute presentation followed by ~30 minutes of discussion

Evaluating Satellite Sounding Temperature Observations for Cold Air Aloft Detection

Cold Air Aloft (CAA) can impact commercial flights when cold air descends below 12,192 m (40,000 ft) and temperatures drop dramatically. A CAA event is identified when air temperature falls below −65 °C, which decreases fuel efficiency and poses a safety hazard. This manuscript assesses the performance of the National Oceanic and Atmospheric Administration Unique Combined Atmospheric Processing System (NUCAPS) in detecting CAA events using sounders on polar-orbiting satellites. We compare NUCAPS air temperature profiles with those from Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) for January–March 2018. Of 1311 collocated profiles, 236 detected CAA. Our results showed that NUCAPS correctly detects CAA in 48.1% of profiles, while 17.2% are false positives and 34.7% are false negatives. To identify the reason for these detection states, we used a logistic regression trained on NUCAPS diagnostic parameters. We found that cloud cover can impact the skill even at higher vertical levels. This work indicates that a CAA-specific quality flag is feasible and may be useful to help forecasters to diagnose NUCAPS in real-time. Furthermore, the inclusion of an additional sounder data source (e.g., NOAA-20) may increase CAA forecast accuracy. Cloud scenes change rapidly, so additional observations provide more opportunities for correct detection

Retrieval of Atmospheric and Surface Parameters from AIRS/AMSU/HSB Data Under Cloudy Conditions

New state of the art methodology is described to analyze AIRS/AMSU/HSB data in the presence of multiple cloud formations. The methodology forms the basis for the AIRS Science Team algorithm which will be used to analyze AIRS/AMSU/HSB data on EOS Aqua. The cloud clearing methodology requires no knowledge of the spectral properties of the clouds. The basic retrieval methodology is general and extracts the maximum information from the radiances, consistent with the channel noise covariance matrix. The retrieval methodology minimizes the dependence of the solution on the first guess field and the first guess error characteristics. Results are shown for AIRS Science Team simulation studies with multiple cloud formations. These simulation studies imply that clear column radiances can be reconstructed under partial cloud cover with an accuracy comparable to single spot channel noise in the temperature and water vapor sounding regions, temperature soundings can be produced under partial cloud cover with RMS errors on the order of, or better than, 1deg K in 1 km thick layers from the surface to 700 mb, 1 km layers from 700 mb to 300 mb, 3 km layers from 300 mb to 30 mb, and 5 km layers from 30 mb to 1 mb, and moisture profiles can be obtained with an accuracy better than 20% absolute errors in 1 km layers from the surface to nearly 200 mb

Evaluating the Value of CrIS Shortwave-Infrared Channels in Atmospheric-Sounding Retrievals

The Cross-track Infrared Sounder (CrIS), in low Earth orbit since 2011, makes measurements of the top of atmosphere radiance for input into data assimilation (DA) systems as well as the retrieval of geophysical state variables. CrIS measurements have 2211 narrow infrared channels ranging between 650 and 2550 cm−1 (~3.9–15.4 μm) and capture the variation in profiles of atmospheric temperature, water vapor, and numerous trace gas species. DA systems derive atmospheric temperature by assimilating CO2-sensitive channels in the CrIS longwave (LW) band (650–1095 cm−1). Here, we investigate if CO2-sensitive channels in the shortwave (SW) band (2155–2550 cm−1) can similarly be applied. We first evaluated the information content of the CrIS bands followed by an assessment of the performance degradation of retrievals due to the loss of individual CrIS bands. We found that temperature profile retrievals derived from the CrIS SW band were statistically both well-behaved and as accurate as a retrieval utilizing the CrIS LW band. The one caveat, however, is that the higher CrIS instrument noise in the SW band limited its performance under certain conditions. We conclude with a discussion on the implications our results have for channel selection in retrieval and DA systems as well as the design of future space instruments

An anomaly correlation skill score for the evaluation of the performance of hyperspectral infrared sounders

With the availability of very accurate six hour forecasts, the metric of accuracy alone for the evaluation of the performance of a retrieval system can produce misleading results: the retrievals may be statistically accurate, but be of little value compared to the accurate forecast. A useful characterization of the quality of a retrieval system and its potential to contribute to an improved weather forecast is its skill, which we define as the ability to make retrievals of geophysical parameters which are closer to the truth than the six hour forecast. We illustrate retrieval skill using one day of AMSU-A and AIRS data with three different retrieval algorithms. In the spirit of achieving global retrievals under clear and cloudy conditions, we evaluated retrieval accuracy and skill for 90% of the covered area. Two of the three algorithms meet the 1 K/1 km "RAOB quality" accuracy requirement and have skill between 900 and 150 hPa, but none have skill between the surface and 900 hPa. AIRS was launched on the EOS Aqua spacecraft in May 2002 into a 705 km polar sun-synchronous orbit with accurately maintained 1:30 PM ascending node. Essentially un-interrupted data are freely available since September 2002.United Sates Air Force (contract FA8721-05-C-0002)National Aeronautics and Space Administratio

Seven Years’ Observation of Mid-Upper Tropospheric Methane from Atmospheric Infrared Sounder

The Atmospheric Infrared Sounder (AIRS) on EOS/Aqua platform provides a measurement of global methane (CH4) in the mid-upper troposphere since September, 2002. As a thermal infrared sounder, the most sensitivity of AIRS to atmospheric CH4 is in the mid-upper troposphere with the degree of freedom of ~1.0. Validation of AIRS CH4 product versus thousands of aircraft profiles (convolved using the AIRS averaging kernels) demonstrates that its RMS error (RMSE) is mostly less than 1.5%, and its quality is pretty stable from 2003 to 2009. For scientific analysis of the spatial and temporal variation of mid-upper tropospheric CH4 (MUT-CH4) in the High Northern Hemisphere (HNH), it is more valuable to use the AIRS retrieved CH4 in a layer of about 100 hPa below tropopause (“Representative Layer”) than in a fixed pressure layer. Further analysis of deseasonalized time-series of AIRS CH4 in both a fixed pressure layer and the “Representative Layer” of AIRS (only for the HNH) from 2003 to 2009 indicates that, similar to the CH4 in the marine boundary layer (MBL) that was found to increase in 2007–2008, MUT-CH4 was also observed to have a recent increase but the most significant increase occurred in 2008. MUT-CH4 continued to increase in 2009, especially in the HNH. Moreover, the trend of MUT-CH4 from 2006 to 2008 is lower than the trend of CH4 in the MBL by 30–40% in both the southern hemisphere and HNH. This delay for the MUT-CH4 increase of about one year than CH4 in the MBL as well as the smaller increase trend for MUT-CH4 suggest that surface emission is likely a major driver for the recent CH4 increase. It is also found that the seasonal cycle of MUT-CH4 is different from CH4 in the MBL due to the impact of transport, in addition to the surface emission and the photochemical loss