The diurnal variability of precipitable water vapor derived from GPS tropospheric path delays over the Eastern Mediterranean

Ziv, Shlomi Ziskin; Yair, Yoav; Alpert, Pinhas; Uzan, Leenes; Reuveni, Yuval

doi:10.1016/j.atmosres.2020.105307

Cited by 14 publications

(16 citation statements)

References 46 publications

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“…Furthermore, these improvements may be associated with the frontal Mediterranean Sea Breeze (MSB) due to the fact, that the highest improvements are along the coastline, Jordan Rift Valley and the Dead Sea. The MSB propagates from the coastline eastward inland combined with northern winds enhancement due to Coriolis force, which brings moisture inland as recently suggested by Ziskin et al [54], and observed (using in-situ and ground remote-sensing) and simulated using WRF model by Kunin et al [55]. The initialization times cover the period between 03:00-15:00 LT.…”

Section: Discussionmentioning

confidence: 73%

On the Potential of Improving WRF Model Forecasts by Assimilation of High-Resolution GPS-Derived Water-Vapor Maps Augmented with METEOSAT-11 Data

2020

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Improving the accuracy of numerical weather predictions remains a challenging task. The absence of sufficiently detailed temporal and spatial real-time in-situ measurements poses a critical gap regarding the proper representation of atmospheric moisture fields, such as water vapor distribution, which are highly imperative for improving weather predictions accuracy. The estimated amount of the total vertically integrated water vapor (IWV), which can be derived from the attenuation of global positioning systems (GPS) signals, can support various atmospheric models at global, regional, and local scales. Currently, several existing atmospheric numerical models can estimate the IWV amount. However, they do not provide accurate results compared with in-situ measurements such as radiosondes. Here, we present a new strategy for assimilating 2D IWV regional maps estimations, derived from combined GPS and METEOSAT satellite imagery data, to improve Weather Research and Forecast (WRF) model predictions accuracy in Israel and surrounding areas. As opposed to previous studies, which used point measurements of IWV in the assimilation procedure, in the current study, we assimilate quasi-continuous 2D GPS IWV maps, combined with METEOSAT-11 data. Using the suggested methodology, our results indicate an improvement of more than 30% in the root mean square error (RMSE) of WRF forecasts after assimilation relative standalone WRF, when both are compared to the radiosonde measured data near the Mediterranean coast. Moreover, significant improvements along the Jordan Rift Valley and Dead Sea Valley areas are obtained when compared to 2D IWV regional maps estimations. Improvements in these areas suggest the impact of the assimilated high resolution IWV maps, with initialization times which coincide with the Mediterranean Sea Breeze propagation from the coastline to highland stations, as the distance to the Mediterranean Sea shore, along with other features, dictates its arrival times.

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Section: Discussionmentioning

confidence: 73%

On the Potential of Improving WRF Model Forecasts by Assimilation of High-Resolution GPS-Derived Water-Vapor Maps Augmented with METEOSAT-11 Data

2020

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“…Ziskin Ziv et al . (2021) used the same SOI‐APN stations to study the PWV diurnal variations in the EM region. We use the same methodology as in Ziskin Ziv et al .…”

Section: Methodsmentioning

confidence: 99%

“…Similar to Ziskin Ziv et al . (2021), we start with downloading the daily RINEX files from the SOPAC/Garner GPS archive (http://garner.ucsd.edu/). We then process the daily RINEX files using NASA's JPL GipsyX (Bertiger et al ., 2020) software.…”

Section: Methodsmentioning

confidence: 99%

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Long‐term variability and trends of precipitable water vapour derived from GPS tropospheric path delays over the Eastern Mediterranean

Ziv

Alpert

Reuveni

2021

Intl Journal of Climatology

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The precipitable water vapour (PWV) of 21 Global Navigation Satellite System (GNSS) ground receivers from the Survey Of Israel Active Permanent Network (SOI-APN) in the Eastern Mediterranean area are processed and analysed. We focus on the annual cycles, inter-annual variations and long-term trends. The PWV monthly mean values peak during September-October where October has the highest variability for all stations. PWV values reach minimum level during February-March where Apr is the least variable month for most stations. Generally, the PWV variability decreases with station height. Additionally, harmonic analysis indicates that the annual mode's amplitude decreases with station height. In contrast, the semi-annual mode's accounting for the sub-annual variance increases with station height. The PWV monthly mean anomalies are consistent among all the stations suggesting a common regional driver. Furthermore, a comparison between the PWV station average anomalies and the regional mean anomalies from the ERA5 reanalysis shows a strong correlation with r = 0.95. In addition, a correlation coefficient of r = 0.72 was found with the regional mean moisture flux anomalies at 750 hPa taken from ERA5 and the station average PWV anomalies, thus implying that horizontal moisture flow accounts for most of the inter-annual variability. However, the significance of the 750 hPa pressure level requires future investigation. For the long-term analysis, we find an increasing regional mean trend of 0.5 mm Á decade −1 for the entire data period (1997-2019) as compared to 1 mm Á decade −1 for the last decade (2010-2019) suggesting a recent accelerated moistening of the Eastern Mediterranean region.

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“…Here, the PWV data were extracted from 21 GPS ground stations belonging to the Survey of Israel Active Permanent Network (SOI-APN). For a more detailed description of the methodology, see Ziskin Ziv et al [23,24]. Six daily values are presented below.…”

Section: Estimation Of Precipitable Water Vapor (Pwv)mentioning

confidence: 99%

Impacts of Non-Local versus Local Moisture Sources on a Heavy (and Deadly) Rain Event in Israel

et al. 2021

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Motivated by poor forecasting of a deadly convective event within the Levant, the factor separation technique was used to investigate the impact of non-local versus local moisture sources on simulated precipitation and lightning rates in central and southern Israel on 25 and 26 April 2018. Both days saw unusually heavy rains, and it was hypothesized that antecedent precipitation on 25 April contributed to the development of deadly flooding late morning on the 26th, as well as strong lightning and heavy rains later the same day. Antecedent precipitation led to an increase in the precipitable water content and an overall increase in instability as measured by the Convective Available Potential Energy (CAPE). The deadly flood occurred in the area of the Tzafit river gorge (hereafter, Tzafit river), about 25 km southeast of the city of Dimona, a semi-arid region in the northeastern Negev desert. The heavy rains and strong lightning occurred throughout the Levant with local peaks in the vicinity of Jerusalem. Factor separation conducted in model simulations showed that local ground moisture sources had a large impact on the CAPE and subsequent precipitation and lightning rates in the area of Jerusalem, while non-local moisture sources enabled weak convection to occur over broad areas, with particularly strong convection in the area of the Tzafit river. The coupled impact of both moisture sources also led to localized enhanced areas of convective activity. The results suggest that forecast models for the Levant should endeavor to incorporate an accurate depiction of soil moisture to predict convective rain, especially during the typically drier spring-time season.

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The diurnal variability of precipitable water vapor derived from GPS tropospheric path delays over the Eastern Mediterranean

Cited by 14 publications

References 46 publications

On the Potential of Improving WRF Model Forecasts by Assimilation of High-Resolution GPS-Derived Water-Vapor Maps Augmented with METEOSAT-11 Data

On the Potential of Improving WRF Model Forecasts by Assimilation of High-Resolution GPS-Derived Water-Vapor Maps Augmented with METEOSAT-11 Data

Long‐term variability and trends of precipitable water vapour derived from GPS tropospheric path delays over the Eastern Mediterranean

Impacts of Non-Local versus Local Moisture Sources on a Heavy (and Deadly) Rain Event in Israel

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