A review of sources of systematic errors and uncertainties in observations  and simulations at 183 GHz

Brogniez, Hélène; English, Stephen; Mahfouf, Jean‐François; Behrendt, Andreas; Berg, Wesley; Boukabara, Sid; Buehler, Stefan A.; Chambon, Philippe; Gambacorta, Antonia; Geer, Alan; Ingram, William; Kursinski, E. R.; Matricardi, Marco; Odintsova, T.A.; Payne, Vivienne H.; Thorne, Peter; Tretyakov, M.Yu.; Wang, Junhong

doi:10.5194/amt-9-2207-2016

Cited by 46 publications

(35 citation statements)

References 67 publications

(65 reference statements)

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“…However, Bobryshev et al () show that carefully matching radiosonde profiles with satellite observations (e.g., using only radiosonde profiles with less than 15 km horizontal drift) and also using cloud masks from visible satellite instruments can potentially reduce the differences between the simulated and observed Tbs. However, the biases shown for water vapor channels in Figure as well as in other studies, for example, Bobryshev et al () and Brogniez et al (), are still considerably larger than the biases shown in Figure for the temperature sounding channels.…”

Section: Double Difference Techniquesupporting

confidence: 44%

Performance of Radiative Transfer Models in the Microwave Region

et al. 2020

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We compared two fast radiative transfer models, Community Radiative Transfer Model (CRTM) and Radiative Transfer for TIROS Operational Vertical Sounder (RTTOV), with the LBL model Atmospheric Radiative Transfer Simulator (ARTS). We used the measurements from Advanced Technology Microwave Sounder (ATMS) and the Global Precipitation Measurement Microwave Imager (GMI) for evaluation of the radiative transfer models. The models in comparison with the observations and each other performed very well with a mean difference less than 0.5 K for the temperature sounding channels operating near the oxygen absorption band at 60 GHz. There was a difference of up to 1 K among the models as well as compared with the observations for humidity sounding channels operating around water vapor absorption line at 183 GHz. The mean difference between the simulations and observations was up to 6 K for surface sensitive channels. Water vapor and surface sensitive channels also showed to be more sensitive than the temperature sounding channels to the spectroscopy models used to calculate the absorption coefficients. There was a small difference, less than 0.1 K, between brightness temperatures calculated using traditional boxcar and actual Sensor or Spectral Response Functions, except for a difference of 0.25 K for ATMS Channel 6. Double difference technique showed about 1 K difference between water vapor channels from ATMS instruments onboard N20 and National Polar‐orbiting Partnership (NPP). However, comparison of a new version of ATMS/NPP observations recently generated using an enhanced calibration algorithm with ATMS/N20 observations showed that the differences between the two instruments are less than 0.5 K after improving the ATMS/NPP calibration.

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Section: Double Difference Techniquesupporting

confidence: 44%

Performance of Radiative Transfer Models in the Microwave Region

et al. 2020

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“…These were reduced by almost an order of magnitude via amplitude ratioing with the calibration tone [Kursinski et al, 2016]. Residual amplitude scintillations may be the largest source of random error in the least square fits.…”

Section: Sources Of Uncertainty and Validation Of Resultsmentioning

confidence: 99%

“…These results support the prediction that an ATOMMS system in LEO would be a major advance toward achieving the fundamental satellite observing system goals of very high vertical 25 resolution, all-weather temperature and water vapor sounding with very small random and absolute uncertainties, across the entire globe in support of weather prediction, climate monitoring and the quantitative constraints on process needed to improve models. A mission design concept using a constellation of very small ATOMMS satellites using cubesat technology is given in Kursinski et al, 2016. ATOMMS has the potential to provide global observations from space that approach, and in some ways exceed, the performance of sondes.…”

Section: Discussionmentioning

confidence: 99%

Retrieval of Water Vapor using Ground-based Observations from a Prototype ATOMMS Active cm- and mm- Wavelength Occultation Instrument

Ward

Kursinski²,

Otárola

et al. 2017

Preprint

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Abstract.A fundamental goal of satellite weather and climate observations is profiling the atmosphere with in situ-like precision and resolution with absolute accuracy and unbiased, all-weather, global coverage. While GPS radio occultation (RO) has come perhaps closest in terms of profiling the gas state from orbit, it does not provide sufficient information to simultaneously profile water vapor and temperature. We have been developing the Active Temperature, Ozone and Moisture Microwave Spectrometer (ATOMMS) RO system that probes the 22 and 183 GHz water vapor absorption lines to 20 simultaneously profile temperature and water vapor from the lower troposphere to the mesopause. Using an ATOMMS instrument prototype between two mountaintops, we have demonstrated its ability to penetrate through water vapor, clouds and rain up to optical depths of 17 (7 orders of magnitude reduction in signal power) and still isolate the vapor absorption line spectrum to retrieve water vapor with a precision better than 1%. This demonstration represents a key step toward an orbiting ATOMMS system for weather, climate and constraining processes. 25

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“…SAPHIR channels in the 183 GHz band are capable of probing the atmospheric humidity from the surface to the tropopause. However, some research studies have shown a discrepancy between observed and radiative transfer model‐simulated brightness temperatures in the 183 GHz band, with increasing differences towards the wings of the line (Brogniez et al, ; Kursinski et al, ). Hence, assimilation of channel 6 of SAPHIR using the radiative transfer model RTTOV‐9 (Saunders, ) used in present study may result in an error in the vertical extent of the layers which this channel influences.…”

Section: Saphir: Instrument Detailsmentioning

confidence: 99%

Megha‐tropiques SAPHIR radiances in a hybrid 4D‐Var data assimilation system: Study of forecast impact

Kumar

Rani

George

et al. 2018

Quart J Royal Meteoro Soc

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Assimilation of microwave humidity channels from various satellites plays a key role in numerical weather prediction (NWP), especially over the Tropics. This article examines various characteristics and the impact of assimilation of Megha‐Tropiques SAPHIR (Sondeur Atmosphérique du Profil ďHumidité Intertropicale par Radiométrie) microwave radiances on model forecasts along with that of other similar microwave humidity sensors. A hybrid 4D‐Var scheme is used for assimilation of these observations, and forecasts are carried out using an advanced global atmospheric model, National Centre for Medium Range Weather Forecasting (NCMRWF) Unified Model (NCUM). The impact of SAPHIR radiances along with similar kinds of sensors have been studied using adjoint‐based Forecast Sensitivity to Observations (FSO) and Observing System Experiments (OSEs). The lowest altitude peaking channel of SAPHIR (183 ± 11 GHz) has the highest beneficial impact on the forecast compared to other channels of the same instrument and other similar instruments on board other satellites. FSO experiments show SAPHIR and Microwave Humidity Sounder (MHS) observations complement each other by having the higher beneficial impact in the lower and upper troposphere, respectively. The other microwave humidity sounders have less or negligible impact in comparison to SAPHIR/MHS, both globally and over the Indian region. An OSE shows that SAPHIR radiances assimilation influences the humidity and wind forecast of the tropical troposphere, while its impact on temperature is negligible.

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A review of sources of systematic errors and uncertainties in observations and simulations at 183 GHz

Cited by 46 publications

References 67 publications

Performance of Radiative Transfer Models in the Microwave Region

Performance of Radiative Transfer Models in the Microwave Region

Retrieval of Water Vapor using Ground-based Observations from a Prototype ATOMMS Active cm- and mm- Wavelength Occultation Instrument

Megha‐tropiques SAPHIR radiances in a hybrid 4D‐Var data assimilation system: Study of forecast impact

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A review of sources of systematic errors and uncertainties in observations and simulations at 183 GHz

Cited by 46 publications

References 67 publications

Performance of Radiative Transfer Models in the Microwave Region

Performance of Radiative Transfer Models in the Microwave Region

Retrieval of Water Vapor using Ground-based Observations from a Prototype ATOMMS Active cm- and mm- Wavelength Occultation Instrument

Megha‐tropiques SAPHIR radiances in a hybrid 4D‐Var data assimilation system: Study of forecast impact

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A review of sources of systematic errors and uncertainties in observations and simulations at 183 GHz