Abstract:The coverage and quality of remotely sensed upper-tropospheric moisture parameters have improved considerably with the deployment of a new generation of operational geostationary meteorological satellites: GOES-8/9 and GMS-5. The GOES-8/9 water vapor imaging capabilities have increased as a result of improved radiometric sensitivity and higher spatial resolution. The addition of a water vapor sensing channel on the latest GMS permits nearly global viewing of upper-tropospheric water vapor (when joined with GOE… Show more
“…While the large target window allows other unwanted noisy structures enter into the search domain, too small window increases false alarms (Bresky et al, 2012). Conventionally, wind guess (WG) information supplements this exercise and to set the coordinates of smaller windows in the latter image before matching (Velden et al, 1997;Bedka and Mecikalski, 2005;Bresky et al, 2012). In the present study, the horizontal wind climatology discussed in Sect.…”
Section: Tracking the Target Cloud And The Estimation Of CMVmentioning
confidence: 93%
“…The retrieval techniques improved from a simple cross correlation analysis in the beginning (Izawa and Fujita, 1969;Leese et al, 1971;Hubert and Whitney, 1971) to those involving very advanced photogrammetry and satellite imagery analysis in recent times for obtaining CMVs with higher precision (Schmetz et al, 1993;Velden et al, 1997;Kishtawal et al, 2009;Deb et al, 2015;Kaur et al, 2014 and references therein). First level unrefined knowledge about a cloud element can be obtained from the cloud top temperatures, retrieved by Thermal infrared (IR) channel.…”
Abstract. The paper explores the possibility of implementing an advanced photogrammetric technique, generally employed for satellite measurements, on airglow imager, a ground-based remote sensing instrument primarily used for upper atmospheric studies, measurements of clouds for the extraction of cloud motion vectors (CMVs). The major steps involved in the algorithm remain the same, including image processing for better visualization of target elements and noise removal, identification of target cloud, setting a proper search window for target cloud tracking, estimation of cloud height, and employing 2-D cross-correlation to estimate the CMVs. Nevertheless, the implementation strategy at each step differs from that of satellite, mainly to suit airglow imager measurements. For instance, climatology of horizontal winds at the measured site has been used to fix the search window for target cloud tracking. The cloud height is estimated very accurately, as required by the algorithm, using simultaneous collocated lidar measurements. High-resolution, both in space and time (4 min), cloud imageries are employed to minimize the errors in retrieved CMVs. The derived winds are evaluated against MST radar-derived winds by considering it as a reference. A very good correspondence is seen between these two wind measurements, both showing similar wind variation. The agreement is also found to be good in both the zonal and meridional wind velocities with RMSEs < 2.4 m s −1 . Finally, the strengths and limitations of the algorithm are discussed, with possible solutions, wherever required.
“…While the large target window allows other unwanted noisy structures enter into the search domain, too small window increases false alarms (Bresky et al, 2012). Conventionally, wind guess (WG) information supplements this exercise and to set the coordinates of smaller windows in the latter image before matching (Velden et al, 1997;Bedka and Mecikalski, 2005;Bresky et al, 2012). In the present study, the horizontal wind climatology discussed in Sect.…”
Section: Tracking the Target Cloud And The Estimation Of CMVmentioning
confidence: 93%
“…The retrieval techniques improved from a simple cross correlation analysis in the beginning (Izawa and Fujita, 1969;Leese et al, 1971;Hubert and Whitney, 1971) to those involving very advanced photogrammetry and satellite imagery analysis in recent times for obtaining CMVs with higher precision (Schmetz et al, 1993;Velden et al, 1997;Kishtawal et al, 2009;Deb et al, 2015;Kaur et al, 2014 and references therein). First level unrefined knowledge about a cloud element can be obtained from the cloud top temperatures, retrieved by Thermal infrared (IR) channel.…”
Abstract. The paper explores the possibility of implementing an advanced photogrammetric technique, generally employed for satellite measurements, on airglow imager, a ground-based remote sensing instrument primarily used for upper atmospheric studies, measurements of clouds for the extraction of cloud motion vectors (CMVs). The major steps involved in the algorithm remain the same, including image processing for better visualization of target elements and noise removal, identification of target cloud, setting a proper search window for target cloud tracking, estimation of cloud height, and employing 2-D cross-correlation to estimate the CMVs. Nevertheless, the implementation strategy at each step differs from that of satellite, mainly to suit airglow imager measurements. For instance, climatology of horizontal winds at the measured site has been used to fix the search window for target cloud tracking. The cloud height is estimated very accurately, as required by the algorithm, using simultaneous collocated lidar measurements. High-resolution, both in space and time (4 min), cloud imageries are employed to minimize the errors in retrieved CMVs. The derived winds are evaluated against MST radar-derived winds by considering it as a reference. A very good correspondence is seen between these two wind measurements, both showing similar wind variation. The agreement is also found to be good in both the zonal and meridional wind velocities with RMSEs < 2.4 m s −1 . Finally, the strengths and limitations of the algorithm are discussed, with possible solutions, wherever required.
“…The methods used for generating cloud and water vapour based polar AMVs using MODIS observations from the NASA Aqua and Terra satellites (Key et al 2003(Key et al , 2004Daniels et al 2004) are similar to those used with sequential infrared and water vapour band observations from the Geostationary Operational Environmental Satellites (GOES) Velden et al 1997;Le Marshall et al 2003). To generate the winds used here, infrared (11 µm) and water vapour (6.7 µm) band imagery from three sequential polar Aust.…”
“…It repetitively cycles through evaporation and condensation phases, transporting heat energy around the Earth and between the surface and the atmosphere (Solomon et al, 2010). WV in the atmosphere allows short wavelength radiation from the sun to propagate through the atmosphere, but it traps the long wavelength radiation emitted by the Earth's surface (van Vleck, 1947). This trapped radiation causes temperatures to increase.…”
Section: Introductionmentioning
confidence: 99%
“…The most common ones utilize radiosondes (Kley et al, 2000;Soden et al, 2004;Miloshevich et al, 2006), different techniques of GPS meteorology (Bevis et al, 1992(Bevis et al, , 1994Duan et al, 1996;Ware and Alber, 1997;Hagemann and Bengtsson, 2003;Vedel et al, 2004;Heise et al, 2009;Guerova et al, 2013;Hordyniec et al, 2015) or measurements from remote sensing satellites (Velden et al, 1997;Cresswell et al, 1999;Jiang et al, 2012). Radiosondes offer an essential component of the global observing system due to their extended lifetime and broad geographic coverage (Kley et al, 2000).…”
Abstract. Using GPS satellites signals, we can study different processes and coupling mechanisms that can help us understand the physical conditions in the lower atmosphere, which might lead or act as proxies for severe weather events such as extreme storms and flooding. GPS signals received by ground stations are multi-purpose and can also provide estimates of tropospheric zenith delays, which can be converted into accurate integrated water vapor (IWV) observations using collocated pressure and temperature measurements on the ground. Here, we present for the first time the use of Israel's dense regional GPS network for extracting tropospheric zenith path delays combined with near-realtime Meteosat-10 water vapor (WV) and surface temperature pixel intensity values (7.3 and 10.8 µm channels, respectively) in order to assess whether it is possible to obtain absolute IWV (kg m −2 ) distribution. The results show good agreement between the absolute values obtained from our triangulation strategy based solely on GPS zenith total delays (ZTD) and Meteosat-10 surface temperature data compared with available radiosonde IWV absolute values. The presented strategy can provide high temporal and special IWV resolution, which is needed as part of the accurate and comprehensive observation data integrated in modern data assimilation systems and is required for increasing the accuracy of regional numerical weather prediction systems forecast.
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