AIRS/AMSU/HSB validation

Fetzer, Eric J.; McMillin, Larry M.; Tobin, David C.; Aumann, Hartmut H.; Gunson, M. R.; McMillan, W. W.; Hagan, Denise E.; Hofstadter, Mark; Yoe, James G.; Whiteman, David N.; Barnes, John; Bennartz, Ralf; Vömel, H.; Walden, Von P.; Newchurch, M. J.; Minnett, Peter J.; Atlas, Robert; Schmidlin, F. J.; Olsen, E. T.; Goldberg, Mitchell D.; Zhou, Sisong; Ding, HanJung; Smith, William L.; Revercomb, Henry E.

doi:10.1109/tgrs.2002.808293

Cited by 115 publications

(97 citation statements)

References 47 publications

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“…Most efforts to validate satellite and model estimates of precipitable water over Africa are hindered due to lack of GPS and other ground-based atmospheric observing systems as well as large data gaps (e.g. Fetzer et al, 2003;King et al, 2003;Bock et al, 2007a).…”

Section: G Mengistu Tsidu Et Al: Precipitable Water Vapourmentioning

confidence: 99%

Observations of precipitable water vapour over complex topography of Ethiopia from ground-based GPS, FTIR, radiosonde and ERA-Interim reanalysis

2015

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Abstract. Water vapour is one of the most important greenhouse gases. Long-term changes in the amount of water vapour in the atmosphere need to be monitored not only for its direct role as a greenhouse gas but also because of its role in amplifying other feedbacks such as clouds and albedo. In recent decades, monitoring of water vapour on a regular and continuous basis has become possible as a result of the steady increase in the number of deployed global positioning satellite (GPS) ground-based receivers. However, the Horn of Africa remained a data-void region in this regard until recently, when some GPS ground-receiver stations were deployed to monitor tectonic movements in the Great Rift Valley. This study seizes this opportunity and the installation of a Fourier transform infrared spectrometer (FTIR) at Addis Ababa to assess the quality and comparability of precipitable water vapour (PWV) from GPS, FTIR, radiosonde and interim ECMWF Re-Analysis (ERA-Interim) over Ethiopia. The PWV from the three instruments and the reanalysis show good correlation, with correlation coefficients in the range from 0.83 to 0.92. On average, GPS shows the highest PWV followed by FTIR and radiosonde observations. ERAInterim is higher than all measurements with a bias of 4.6 mm compared to GPS. The intercomparison between GPS and ERA-Interim was extended to seven other GPS stations in the country. Only four out of eight GPS stations included simultaneous surface pressure observations. Uncertainty in the model surface pressure of 1 hPa can cause up to 0.35 mm error in GPS PWV. The gain obtained from using observed surface pressure in terms of reducing bias and strengthening correlation is significant but shows some variations among the GPS sites. The comparison between GPS and ERA-Interim PWV over the seven other GPS stations shows differences in the magnitude and sign of bias of ERA-Interim with respect to GPS PWV from station to station. This feature is also prevalent in diurnal and seasonal variabilities. The spatial variation in the relationship between the two data sets is partly linked to variation in the skill of the European Centre for Medium-Range Weather Forecasts (ECMWF) model over different regions and seasons. This weakness in the model is related to poor observational constraints from this part of the globe and sensitivity of its convection scheme to orography and land surface features. This is consistent with observed wet bias over some highland stations and dry bias over few lowland stations. The skill of ECMWF in reproducing realistic PWV varies with time of the day and season, showing large positive bias during warm and wet summer at most of the GPS sites.

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Section: G Mengistu Tsidu Et Al: Precipitable Water Vapourmentioning

confidence: 99%

Observations of precipitable water vapour over complex topography of Ethiopia from ground-based GPS, FTIR, radiosonde and ERA-Interim reanalysis

2015

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“…No data is available if the retrieval detects sufficiently opaque cloud (the surface temperature deviates from what is expected based on correlative data). We use AIRS level-2 data retrievals (version 3.0;Fetzer et al 2003) with an effective vertical resolution of 1-3 km (Susskind et al 2003). Horizontal resolution is approximately 45 ϫ 45 km (nine pixels of 15 ϫ 15 km each), and there are on the order of 300 000 AIRS profiles per day.…”

Section: Data Descriptionmentioning

confidence: 99%

The Global Distribution of Supersaturation in the Upper Troposphere from the Atmospheric Infrared Sounder

et al. 2006

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Satellite data from the Atmospheric Infrared Sounder (AIRS) is analyzed to examine regions of the upper troposphere that are supersaturated: where the relative humidity (RH) is greater than 100%. AIRS data compare well to other in situ and satellite observations of RH and provide daily global coverage up to 200 hPa, though satellite observations of supersaturation are highly uncertain. The climatology of supersaturation is analyzed statistically to understand where supersaturation occurs and how frequently. Supersaturation occurs in humid regions of the upper tropical tropopause near convection 10%-20% of the time at 200 hPa. Supersaturation is very frequent in the extratropical upper troposphere, occurring 20%-40% of the time, and over 50% of the time in storm track regions below the tropopause. The annual cycle of supersaturation is consistent for the ϳ2.5 yr of data analyzed. More supersaturation is seen in the Southern Hemisphere midlatitudes, which may be attributed to higher temperature variance.

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“…According to the results of previous studies, the AIRS TPW data showed that they are wetter at low altitudes (800 hPa) and drier at higher altitudes (300~600 hPa) when compared with the results of numerical models (Pierce et al 2006), and the accuracy was about 15% within the altitude rage of 2 km from the ground surface (Divakarla et al 2006). However, since the accuracy verification results from the previous studies are focused on the tropical region (Pierce et al 2006) or Europe and the USA (Fetzer et al 2003, McMillin et al 2007, there have been no sufficient verification researches conducted specifically for the observation environment in Korea.…”

Section: Data Collection and Analytical Methodsmentioning

confidence: 94%

“…There are a number of previous studies on the accuracy verification of AIRS TPW data using radiosondes and numerical models (Fetzer et al 2003, Divakarla et al 2006, Pierce et al 2006, McMillin et al 2007). According to the results of previous studies, the AIRS TPW data showed that they are wetter at low altitudes (800 hPa) and drier at higher altitudes (300~600 hPa) when compared with the results of numerical models (Pierce et al 2006), and the accuracy was about 15% within the altitude rage of 2 km from the ground surface (Divakarla et al 2006).…”

Section: Data Collection and Analytical Methodsmentioning

confidence: 99%

Validation of the Atmospheric Infrared Sounder Water Vapor Retrievals Using Global Positioning System: Case Study in South Korea

Won¹,

Park²,

Kim³

et al. 2011

Journal of Astronomy and Space Sciences

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The atmospheric infrared sounder (AIRS) sensor loaded on the Aqua satellite observes the global vertical structure of atmosphere and enables verification of the water vapor distribution over the entire area of South Korea. In this study, we performed a comparative analysis of the accuracy of the total precipitable water (TPW) provided as the AIRS level 2 standard retrieval product by Jet Propulsion Laboratory (JPL) over the South Korean area using the global positioning system (GPS) TPW data. The analysis TPW for the period of one year in 2008 showed that the accuracy of the data produced by the combination of the Advanced Microwave Sounding Unit sensor with the AIRS sensor to correct the effect of clouds (AIRS-X) was higher than that of the AIRS IR-only data (AIRS-I). The annual means of the root mean square error with reference to the GPS data were 5.2 kg/m 2 and 4.3 kg/m 2 for AIRS-I and AIRS-X, respectively. The accuracy of AIRS-X was higher in summer than in winter while measurement values of AIRS-I and AIRS-X were lower than those of GPS TPW to some extent.

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AIRS/AMSU/HSB validation

Cited by 115 publications

References 47 publications

Observations of precipitable water vapour over complex topography of Ethiopia from ground-based GPS, FTIR, radiosonde and ERA-Interim reanalysis

Observations of precipitable water vapour over complex topography of Ethiopia from ground-based GPS, FTIR, radiosonde and ERA-Interim reanalysis

The Global Distribution of Supersaturation in the Upper Troposphere from the Atmospheric Infrared Sounder

Validation of the Atmospheric Infrared Sounder Water Vapor Retrievals Using Global Positioning System: Case Study in South Korea

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