Construction and Uncertainty Estimation of a Satellite‐Derived Total Precipitable Water Data Record Over the World's Oceans

Mears, C. A.; Smith, Derrick W.; Ricciardulli, Lucrezia; Wang, Junhong; Huelsing, Hannah K.; Wentz, F. J.

doi:10.1002/2018ea000363

Cited by 28 publications

(24 citation statements)

References 29 publications

(37 reference statements)

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“…They noted that this systematic difference not necessarily reflects the true difference between rainy skies and cloudy skies. Recently, [28] estimated this bias at 15 GNSS stations to be on average −0.12 kg/m 2 . They speculate that this bias might be larger in rainier cases.…”

Section: Discussion Based On Case Studies and Instantaneous Datamentioning

confidence: 99%

The GEWEX Water Vapor Assessment: Overview and Introduction to Results and Recommendations

et al. 2019

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To date, a large variety of water vapour data records from satellite and reanalysis are available. It is key to understand the quality and uncertainty of these data records in order to fully exploit these records and to avoid data being employed incorrectly or misinterpreted. Therefore, it is important to inform users on accuracy and limitations of these data records based on consistent inter-comparisons carried out in the framework of international assessments. Addressing this challenge is the major objective of the Global Water and Energy Exchanges (GEWEX) water vapor assessment (G-VAP) which was initiated by the GEWEX Data and Assessments Panel (GDAP).Here, an overview of G-VAP objectives and an introduction to the results from G-VAP's first phase are given. After this overview, a summary of available data records on water vapour and closely related variables and a short introduction to the utilized methods are presented. The results from inter-comparisons, homogeneity testing and inter-comparison of trend estimates, achieved within G-VAP's first phase are summarized. The conclusions on future research directions for the wider community and for G-VAP's next phase are outlined and recommendations have been formulated.For instance, a key recommendation is the need for recalibration and improved inter-calibration of radiance data records and subsequent reprocessing in order to increase stability and to provide uncertainty estimates. This need became evident from a general disagreement in trend estimates (e.g., trends in TCWV ranging from −1.51 ± 0.17 kg/m 2 /decade to 1.22 ± 0.16 kg/m 2 /decade) and the presence of break points on global and regional scale. It will be a future activity of G-VAP to reassess the stability of updated or new data records and to assess consistency, i.e., the closeness of data records given their uncertainty estimates. aimed at the consolidation of the G-VAP strategy and the technical implementation. Results from these workshops and feedback from GDAP were used to establish the G-VAP assessment plan. G-VAP organises annual workshops to provide opportunities for (i) presenting state-of-the-art of water vapour retrievals and products, (ii) discussion of results from inter-comparisons exercises and quantifying the sources of observed differences, and (iii) providing recommendations for future directions and roadmap. It was consensus at the G-VAP workshops to continue G-VAP beyond the finalisation of the World Climate Research Programme (WCRP) report on G-VAP, with support from GDAP. Details of the future of G-VAP were discussed and agreed upon at the 7th workshop in October 2017. The assessment plan and minutes from the G-VAP workshops are available at http://gewex-vap.org/?page_id=19 and partly workshop summaries have been published in the GEWEX News (see http://www.gewex.org/resources/gewex-news/).Prior to analysis, an inventory of available satellite and reanalysis data records has been carried out and made available online at http://gewex-vap.org/?pageid=13. A subset of these data rec...

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Section: Discussion Based On Case Studies and Instantaneous Datamentioning

confidence: 99%

The GEWEX Water Vapor Assessment: Overview and Introduction to Results and Recommendations

et al. 2019

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“…This leads to a higher portion of local aerosols in the atmosphere that can serve as cloud condensation nuclei and foster cloud formation and cloud optical properties. Furthermore, a positive trend in water vapor was found on the coast of tropical oceans in West Africa from satellite data (Mears et al, 2018), which would reduce the GHI at the surface.…”

Section: Temporal Analysismentioning

confidence: 95%

Photovoltaic power potential in West Africa using long-term satellite data

et al. 2020

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Abstract. This paper addresses long-term historical changes in solar irradiance in West Africa (3 to 20∘ N and 20∘ W to 16∘ E) and the implications for photovoltaic systems. Here, we use satellite irradiance (Surface Solar Radiation Data Set – Heliosat, Edition 2.1 – SARAH-2.1) and temperature data from a reanalysis (ERA5) to derive photovoltaic yields. Based on 35 years of data (1983–2017), the temporal and regional variability as well as long-term trends in global and direct horizontal irradiance are analyzed. Furthermore, a detailed time series analysis is undertaken at four locations. According to the high spatial resolution SARAH-2.1 data record (0.05∘×0.05∘), solar irradiance is largest (up to a 300 W m−2 daily average) in the Sahara and the Sahel zone with a positive trend (up to 5 W m−2 per decade) and a lower temporal variability (<75 W m−2 between 1983 and 2017 for daily averages). In contrast, the solar irradiance is lower in southern West Africa (between 200 W m−2 and 250 W m−2) with a negative trend (up to −5 W m−2 per decade) and a higher temporal variability (up to 150 W m−2). The positive trend in the north is mostly connected to the dry season, whereas the negative trend in the south occurs during the wet season. Both trends show 95 % significance. Photovoltaic (PV) yields show a strong meridional gradient with the lowest values of around 4 kWh kWp−1 in southern West Africa and values of more than 5.5 kWh kWp−1 in the Sahara and Sahel zone.

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“…Satellites essentially observe the entire Earth each day, providing excellent geographic coverage, but whose radiances provide bulk-layer atmospheric measurements only. There are some key adjustments that are required too, and the methods adopted by different teams lead to the range in the results (Haimberger et al 2012;Po-Chedley et al 2015;Mears and Wentz 2016; see also Figs. A2.7 and A2.9).…”

Section: ) Tropospheric Temperature-jr Christy C a Mears S Pomentioning

confidence: 99%

“…A2.14). TCWV estimates are available from satellite-borne microwave radiometers over ocean (Mears et al 2018); from COSMIC; Metop-A,-B, and -C; and COSMIC2 GPS-RO (Global Positioning System-Radio Occultation) over land and ocean (Ho et al 2010a(Ho et al ,b, 2020Teng et al 2013;Huang et al 2013;Ho et al 2020, submitted to Remote Sens. ); and from ground-based Global Navigation Satellite System (GNSS) stations (Bock and Parracho 2019;Bock 2019).…”

Section: S39mentioning

confidence: 99%