An assessment of the consistency between satellite measurements of upper tropospheric water vapor

Chung, Eunhyea; Soden, Brian J.; Huang, Xianglei; Shi, Lei; John, Viju O.

doi:10.1002/2015jd024496

Cited by 16 publications

(27 citation statements)

References 52 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The vertical distance of 1 km implies an air temperature difference of about 6.5 K on average in the upper troposphere, and this explains that an average T 12 of about the same value is found in the radiative transfer calculations. A similar (average) correction of 8 K has been derived by Shi and Bates (2011) and used by Chung et al (2016). Now the question arises of how characteristics of humidity profiles are reflected in the brightness temperature differences.…”

Section: Discussion Of Radiative Transfer Resultsmentioning

confidence: 98%

See 1 more Smart Citation

Intercalibration between HIRS/2 and HIRS/3 channel 12 based on physical considerations

2018

View full text Add to dashboard Cite

Abstract. High-resolution Infrared Radiation Sounder (HIRS) brightness temperatures at channel 12 (T 12 ) can be used to assess the water vapour content of the upper troposphere. The transition from HIRS/2 to HIRS/3 in 1999 involved a shift in the central wavelength of channel 12 from 6.7 to 6.5 µm, causing a discontinuity in the time series of T 12 . To understand the impact of this change in the measured brightness temperatures, we have performed radiative transfer calculations for channel 12 of HIRS/2 and HIRS/3 instruments, using a large set of radiosonde profiles of temperature and relative humidity from three different sites. Other possible changes within the instrument, apart from the changed spectral response function, have been assumed to be of minor importance, and in fact, it was necessary to assume as a working hypothesis that the spectral and radiometric calibration of the two instruments did not change during the relatively short period of their common operation. For each radiosonde profile we performed two radiative transfer calculations, one using the HIRS/2 channel response function of NOAA 14 and one using the HIRS/3 channel response function of NOAA 15, resulting in negative differences of T 12 (denoted as T 12 := T 12/15 − T 12/14 ) ranging between −12 and −2 K. Inspection of individual profiles for large, medium and small values of T 12 pointed to the role of the mid-tropospheric humidity. This guided us to investigate the relation between T 12 and the channel 11 brightness temperatures which are typically used to detect signals from the mid-troposphere. This allowed us to construct a correction for the HIRS/3 T 12 , which leads to a pseudo-channel 12 brightness temperature as if a HIRS/2 instrument had measured it. By applying this correction we find an excellent agreement between the original HIRS/2 T 12 and the HIRS/3 data inferred from the correction method with R = 0.986. Upper-tropospheric humidity (UTH) derived from the pseudo HIRS/2 T 12 data compared well with that calculated from intersatellite-calibrated data, providing independent justification for using the two intercalibrated time series (HIRS/2 and HIRS/3) as a continuous HIRS time series for long-term UTH analyses.

show abstract

Section: Discussion Of Radiative Transfer Resultsmentioning

confidence: 98%

“…The intercalibrated time series was used for several studies (e.g. Gierens et al, 2014;Chung et al, 2016). Yet problems remained in the lower tail of the distribution of brightness temperatures, that is, at the lowest values of brightness temperatures, as has been detected by Gierens and Eleftheratos (2017, in the following cited as GE17).…”

Section: Introductionmentioning

confidence: 99%

Intercalibration between HIRS/2 and HIRS/3 channel 12 based on physical considerations

2018

View full text Add to dashboard Cite

show abstract

“…The first phase of G-VAP concluded in 2017 with a report to the World Climate Research Programme (WCRP) [4]. Many related research works and assessments have advanced our understanding of water vapor measurements from satellite sensors and their general advantages and limitations for climate applications; see, for example, [5][6][7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Assessing the Pattern Differences between Satellite-Observed Upper Tropospheric Humidity and Total Column Water Vapor during Major El Niño Events

2018

Self Cite

View full text Add to dashboard Cite

As part of the activities for the Global Energy and Water Exchanges (GEWEX) water vapor assessment project, the consistency of satellite-observed upper tropospheric humidity (UTH) and total column water vapor (TCWV) is examined. The examination is focused on their respective patterns during major El Niño events. The analysis shows that the two datasets, consisting of one measurement of vertically averaged relative humidity in the upper troposphere and one of absolute water vapor integrated over the atmospheric vertical column with dominant contribution from the lower troposphere, are consistent over the equatorial central-eastern Pacific, both showing increases of water vapor during major El Niño events as expected. However, the magnitude of drying in the TCWV field over the western Pacific is much weaker than that of moistening over the central-eastern Pacific, while the UTH field exhibits equivalent magnitude of drying and moistening. Furthermore, the drying in the UTH field covers larger areas in the tropics. The difference in their patterns results in an opposite phase in the time series during a major El Niño event when a tropical average is taken. Both UTH and TCWV are closely correlated with major climate indices. However, they have significantly different lag correlations with the Niño 3.4 index in both the sign (positive or negative) and lag time over tropical oceans.

show abstract

“…A similar (average) correction of 8 K has been derived by Shi and Bates (2011) and used by Chung et al (2016). Now the question arises how characteristics of humidity profiles are reflected in the brightness temperature differences.…”

mentioning

confidence: 98%

“…The 10 intercalibrated time series was used for several studies (e.g. Gierens et al, 2014;Chung et al, 2016). Yet problems remained in the lower tail of the distribution of brightness temperatures, that is, at the lowest values of brightness temperatures, as has been detected by Gierens and Eleftheratos (2017, …”

mentioning

confidence: 99%

Intercalibration between HIRS/2 and HIRS/3 channel 12 based on physical considerations

Gierens¹,

Eleftheratos²,

Sausen³

2017

Preprint

View full text Add to dashboard Cite

Abstract. HIRS brightness temperatures at channel 12 (T 12 ) can be used to assess the water vapour content of the upper troposphere. The transition from HIRS/2 to HIRS/3 in 1999 involved a shift in the central wavelength of channel 12 from 6.7 µm to 6.5 µm causing a discontinuity in the time series of T 12 . To understand the impact of this change in the measured brightness temperatures, we have performed radiative transfer calculations for channel 12 of HIRS/2 and HIRS/3 instruments, using a large set of radiosonde profiles of temperature and relative humidity from three different sites. For each radiosonde profile we 5 performed two radiative transfer calculations, one using the HIRS/2 channel response function of NOAA 14 and one using the HIRS/3 channel response function of NOAA 15, resulting in negative differences of T 12 (denoted as ∆T 12 := T 12/15 − T 12/14 ) ranging between −12 K and −2 K. Inspection of individual profiles for large, medium and small values of ∆T 12 pointed to the role of the middle tropospheric humidity. This guided us to investigate the relation between ∆T 12 and the channel 11 brightness temperatures which are typically used to detect signals from the middle troposphere. This allowed us to construct a correction 10 for the HIRS/3 T 12 , a correction that leads to a pseudochannel 12 brightness temperature such as if a HIRS/2 instrument had measured it. By applying this correction we find an excellent agreement between the original HIRS/2 T 12 and the HIRS/3 data inferred from the correction method with R = 0.986. Upper tropospheric humidity (UTH) derived from the pseudoHIRS/2 T 12 data compared well with that calculated from intersatellite-calibrated data, confirming that the two intercalibrated time series (HIRS/2 and HIRS/3) can be fairly combined to form a continuous HIRS time series for long term UTH analyses.

show abstract

An assessment of the consistency between satellite measurements of upper tropospheric water vapor

Cited by 16 publications

References 52 publications

Intercalibration between HIRS/2 and HIRS/3 channel 12 based on physical considerations

Intercalibration between HIRS/2 and HIRS/3 channel 12 based on physical considerations

Assessing the Pattern Differences between Satellite-Observed Upper Tropospheric Humidity and Total Column Water Vapor during Major El Niño Events

Intercalibration between HIRS/2 and HIRS/3 channel 12 based on physical considerations

Contact Info

Product

Resources

About