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Maps (in • N Latitude and • E Longitude coordinates) of Polarization Corrected Temperature (PCT) at 37 GHz (a) and 89 GHz (b), and Brightness Temperature (BT) at 166 GHz (V polarization) (c) for the MCS of 20 September 2014 over the Adriatic Sea. The black line indicates the position of the vertical cross-section shown in Figure 2. The colorbar refers to the PCT and BT values.
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Since early March 2014, the NASA/JAXA Global Precipitation Measurement-Core Observatory (GPM-CO) satellite has allowed analysis of precipitation systems around the globe, thanks to the capabilities of the GPM Microwave Imager (GMI) and Dual-Frequency Precipitation Radar (DPR). In this work, we demonstrate how GPM-CO measurements obtained from 4 yea...
Contexts in source publication
Context 1
... example of the effectiveness of PCTs to identify convection over land and sea is provided for an intense MCS, that hit Emilia-Romagna region (Italy), causing extensive and intense rainfall and floods in several river basins and then moved to the Adriatic Sea and the coasts of Croatia, between 14 and 20 September 2014. Figure 1a-c show the maps of the 37 GHz PCT, the 89 GHz PCT, both obtained from Equation (1), and the BT at 166 GHz (V polarization), respectively, for the GMI overpass on 20 September 2014 over the Adriatic Sea. The most intense region of the storm interested by deep convection are well highlighted by the marked PCT depressions compared to the warm background in Figure 1a,b, while the radiatively cold sea surface that would be visible in the BT images, is not contaminating the scene. ...
Context 2
... 1a-c show the maps of the 37 GHz PCT, the 89 GHz PCT, both obtained from Equation (1), and the BT at 166 GHz (V polarization), respectively, for the GMI overpass on 20 September 2014 over the Adriatic Sea. The most intense region of the storm interested by deep convection are well highlighted by the marked PCT depressions compared to the warm background in Figure 1a,b, while the radiatively cold sea surface that would be visible in the BT images, is not contaminating the scene. In particular, the low values reached in the convective core confirm the extremely intense nature of the system, with minimum values of PCT at 37 GHz and 89 GHz of 135 K and 68 K, respectively. ...
Context 3
... values are comparable to the values reported by Marra et al. [7] for an extremely intense hailstorm occurred near Naples, Italy, on 5 September 2015, and are compatible with the presence of large and high density precipitating ice particles (hail) and strong updrafts. On the other hand, 166 GHz (V pol) BT shows the large extension of the system, including the anvil, with an extended area of cold brightness temperatures compared to the warm background, due to scattering from ice particles in the stratiform region, and lower values in correspondence to the convective cores ( Figure 1c). The strength of the convection is also well depicted by a vertical cross section of DPR Ku-band measured reflectivity (reported in Figure 2 in correspondence of the black lines of Figure 1a-c). ...
Context 4
... the other hand, 166 GHz (V pol) BT shows the large extension of the system, including the anvil, with an extended area of cold brightness temperatures compared to the warm background, due to scattering from ice particles in the stratiform region, and lower values in correspondence to the convective cores ( Figure 1c). The strength of the convection is also well depicted by a vertical cross section of DPR Ku-band measured reflectivity (reported in Figure 2 in correspondence of the black lines of Figure 1a-c). In addition, the BTs measured by GMI within the considered scan line are also reported. ...
Context 5
... noisy trend with large oscillations in the curves are due to the low number of available cases, especially for the hailstorms over the sea. A similar behavior is found in the monthly distribution of potential hailstorms detected with the two criteria (DPR-based and GMI-based) reported in Figure 10. The trends are similar, with largest percentage of hailstorms (up to 25%) in the summer over land, and in the fall over sea. ...
Context 6
... geographical distribution and seasonality of overshooting top events and hailstorms are shown in Figure 11a,b. In addition, in this case, the behavior is similar to what already observed for all deep convection PFs detected using different proxies. ...
Context 7
... similarities in diurnal and seasonal behaviors can be considered as a sanity check of the procedures and methodologies adopted in the deep convection PF analysis. , the percentages of the volumetric precipitation associated with the OPFs and hailstorms in each season (normalized to total volumetric precipitation associated with all PFs for each season), are shown in Figure 12a,b. Both types of events contribute to the total precipitation (considering what satellite observes at the time of overpass) mostly during the fall in conjunction with the southward shift of the storms (also triggered over the sea by the thermal air-sea contrast), with similar contributions over land and over sea. ...
Context 8
... example of the effectiveness of PCTs to identify convection over land and sea is provided for an intense MCS, that hit Emilia-Romagna region (Italy), causing extensive and intense rainfall and floods in several river basins and then moved to the Adriatic Sea and the coasts of Croatia, between 14 and 20 September 2014. Figure 1a-c show the maps of the 37 GHz PCT, the 89 GHz PCT, both obtained from Equation (1), and the BT at 166 GHz (V polarization), respectively, for the GMI overpass on 20 September 2014 over the Adriatic Sea. The most intense region of the storm interested by deep convection are well highlighted by the marked PCT depressions compared to the warm background in Figure 1a,b, while the radiatively cold sea surface that would be visible in the BT images, is not contaminating the scene. ...
Context 9
... 1a-c show the maps of the 37 GHz PCT, the 89 GHz PCT, both obtained from Equation (1), and the BT at 166 GHz (V polarization), respectively, for the GMI overpass on 20 September 2014 over the Adriatic Sea. The most intense region of the storm interested by deep convection are well highlighted by the marked PCT depressions compared to the warm background in Figure 1a,b, while the radiatively cold sea surface that would be visible in the BT images, is not contaminating the scene. In particular, the low values reached in the convective core confirm the extremely intense nature of the system, with minimum values of PCT at 37 GHz and 89 GHz of 135 K and 68 K, respectively. ...
Context 10
... values are comparable to the values reported by Marra et al. [7] for an extremely intense hailstorm occurred near Naples, Italy, on 5 September 2015, and are compatible with the presence of large and high density precipitating ice particles (hail) and strong updrafts. On the other hand, 166 GHz (V pol) BT shows the large extension of the system, including the anvil, with an extended area of cold brightness temperatures compared to the warm background, due to scattering from ice particles in the stratiform region, and lower values in correspondence to the convective cores ( Figure 1c). The strength of the convection is also well depicted by a vertical cross section of DPR Ku-band measured reflectivity (reported in Figure 2 in correspondence of the black lines of Figure 1a-c). ...
Context 11
... the other hand, 166 GHz (V pol) BT shows the large extension of the system, including the anvil, with an extended area of cold brightness temperatures compared to the warm background, due to scattering from ice particles in the stratiform region, and lower values in correspondence to the convective cores ( Figure 1c). The strength of the convection is also well depicted by a vertical cross section of DPR Ku-band measured reflectivity (reported in Figure 2 in correspondence of the black lines of Figure 1a-c). In addition, the BTs measured by GMI within the considered scan line are also reported. ...
Context 12
... noisy trend with large oscillations in the curves are due to the low number of available cases, especially for the hailstorms over the sea. A similar behavior is found in the monthly distribution of potential hailstorms detected with the two criteria (DPR-based and GMI-based) reported in Figure 10. The trends are similar, with largest percentage of hailstorms (up to 25%) in the summer over land, and in the fall over sea. ...
Context 13
... geographical distribution and seasonality of overshooting top events and hailstorms are shown in Figure 11a,b. In addition, in this case, the behavior is similar to what already observed for all deep convection PFs detected using different proxies. ...
Context 14
... similarities in diurnal and seasonal behaviors can be considered as a sanity check of the procedures and methodologies adopted in the deep convection PF analysis. , the percentages of the volumetric precipitation associated with the OPFs and hailstorms in each season (normalized to total volumetric precipitation associated with all PFs for each season), are shown in Figure 12a,b. Both types of events contribute to the total precipitation (considering what satellite observes at the time of overpass) mostly during the fall in conjunction with the southward shift of the storms (also triggered over the sea by the thermal air-sea contrast), with similar contributions over land and over sea. ...
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... The PCT values at 89 GHz locate the DC cores among the top 1% DC intensity class derived over a 4-year period in the Mediterranean region (Hourngir et al., 2021). The PCT at 37 GHz allows also to detect the precipitation areas, evidenced by a cooling with respect to the background (Fig. 4a), which are confirmed by low values of the difference between the TB at vertical (V) and horizontal (H) polarization channels at 37 GHz (ΔTB 37GHz ) shown in Fig. 4b. ...
... In fact, the areas with PCT values at 89 GHz ≤240 K and TB values at 183 ± 7 GHz ≤260 K, respectively, indicate the presence of ice hydrometeors. These values correspond to the 4 th intensity class (accounting for 10% lowest PCT values) of the DC feature classification provided by Hourngir et al. (2021). This confirms a weakening of the convective activity with respect to the previous phase when the PCT values fall in the 3 rd intensity class (accounting for 1% lowest PCT values). ...
The present work analyzes the synoptic, thermodynamic, and microphysics characteristics of two Mediterranean cyclones that occurred in February–March 2023. The analysis is mainly carried out through the use of passive microwave (PMW) satellite measurements, which allow us to follow the cyclones’ evolution and state whether Helios and Juliette can be considered as Mediterranean tropical-like cyclones (i.e., medicanes). Both cyclones show a very similar evolution, with a low-stratospheric warm air anomaly during the development phase, followed by the development of a warm anomaly in the low− /mid-troposphere. This feature is often observed in
medicanes (e.g., Qendresa, Zorbas), except for few cases (i.e., Medicane Ianos, which shows a warm core (WC) development clearly driven by diabatic processes without a preliminary warming signal in the lower stratosphere and upper troposphere). The analysis carried out highlights that, while Helios maintains this setting through its
whole lifetime, Juliette undergoes tropical transition in the final stage of its evolution. As opposed to most medicane cases, the PMW precipitation microphysics diagnostics shows the predominance of shallow clouds, with almost total absence of ice hydrometeors and deep convection in the proximity of the WC center (i.e., within
100 km radius) for Helios and during the initial stage of Juliette. PMW radiometry provides strong indication that diabatic heating plays a role in the WC development when the onset of deep convection features is identified in the proximity of the Juliette cyclone center. Moreover, the PMW cloud-top height product does not show a closed
cloud-free eye for Helios, while it is observed for the final stage of Juliette as often happens during medicanes’ mature phase. Therefore, we deem that while Helios can be labeled as a warm seclusion, Juliette can be included in the tropical-like cyclone category.
... The PCT values at 89 GHz locate the DC cores among the top 1% DC intensity class derived over a 4-year period in the Mediterranean region (Hourngir et al., 2021). The PCT at 37 GHz allows also to detect the precipitation areas, evidenced by a cooling with respect to the background (Fig. 4a), which are confirmed by low values of the difference between the TB at vertical (V) and horizontal (H) polarization channels at 37 GHz (ΔTB 37GHz ) shown in Fig. 4b. ...
... In fact, the areas with PCT values at 89 GHz ≤240 K and TB values at 183 ± 7 GHz ≤260 K, respectively, indicate the presence of ice hydrometeors. These values correspond to the 4 th intensity class (accounting for 10% lowest PCT values) of the DC feature classification provided by Hourngir et al. (2021). This confirms a weakening of the convective activity with respect to the previous phase when the PCT values fall in the 3 rd intensity class (accounting for 1% lowest PCT values). ...
The precipitation characteristics of tropical cyclone (TC) formed over the Arabian Sea during the onset phase of the Indian summer monsoon (i.e., late‐May and early‐June months) and in the post‐monsoon season were investigated during the period from 2014 to 2021 using the Global Precipitation Measurement (GPM) satellite level 2 V07 data. For the cyclonic precipitation, 2‐D frequency distribution between liquid water content (LWC) and non‐liquid water content, that is, ice water content (IWC) shows significant variation with the rain type and season. A large proportion of rain droplets are within the LWC (IWC) range of 0–800 (0–350) g/m² for the stratiform precipitation of TCs in both seasons. The average value of the mass‐weighted mean diameter (Dm), for the stratiform and convective precipitation at 2 km above the mean sea level in the monsoon (post‐monsoon) season is 1.29 (1.27) mm and 1.47 (1.31) mm, respectively. A gradual decrease in the normalized intercept parameters (Nw) is found to occur with an increase in Dm, irrespective of cloud type and season. There is an enormously high concentration of supercooled liquid and ice particles observed above the melting layer during the convection precipitation in both seasons. In the stratiform cyclonic cloud, the contribution of the collision‐coalescence and breaking‐up process is about 36.62% (47.58%) and 52.52% (41.52%) during the monsoon (post‐monsoon) season. However, the collision‐coalescence process (63.45% in monsoon and 70.2% in post‐monsoon) is acting as dominating microphysical process in the convective precipitation as compared to the break‐up process.
Extreme precipitation events and associated flash floods caused by synoptic cyclonic systems profoundly impact society and the environment, particularly in arid regions. This study brings forward a satellite-reanalysis-based approach to quantify extreme precipitation characteristics over the Sinai Peninsula (SiP) in Egypt from a statistical–synoptic perspective for the period of 2001–2020. With a multi-statistical approach developed in this research, SiP's wet and dry periods are determined. Using satellite observations of precipitation and a set of derived precipitation indices, we characterize the spatiotemporal variations of extreme rainfall climatologies across the SiP. Then, using the reanalysis datasets, synoptic systems responsible for the occurrence of extreme precipitation events along with the major tracks of cyclones during the wet and dry periods are described. Our results indicate that trends and spatial patterns of the rainfall events across the region are inconsistent in time and space. The highest precipitation percentiles (∼20 mm per month), frequencies (∼15 d per month with rainfall ≥10 mm d−1), standard deviations (∼9 mm month per month), and monthly ratios (∼18 %) are estimated in the northern and northeastern parts of the region during the wet period, especially in early winter; also, a substantial below-average precipitation condition (drier trend) is clearly observed in most parts except for the south. Mediterranean cyclones accompanied by the Red Sea and Persian troughs are responsible for the majority of extreme rainfall events year-round. A remarkable spatial relationship is found between SiP's rainfall and the atmospheric variables of sea level pressure, wind direction, and vertical velocity. A cyclone-tracking analysis indicates that 125 cyclones (with rainfall ≥10 mm d−1) formed within, or transferred to, the Mediterranean basin and precipitated over the SiP during wet periods compared to 31 such cyclones during dry periods. It is estimated around 15 % of cyclones with sufficient rainfall >40 mm d−1 would be capable of leading to flash floods during the wet period. This study, therefore, sheds new light on the extreme precipitation characteristics over the SiP and its association with dominant synoptic-scale mechanisms over the eastern Mediterranean region.
This study investigated the effects of interfering signals on high-altitude precipitation extraction from spaceborne precipitation radar data. Data analyses were performed on the products of the Tropical Rainfall Measuring Mission Precipitation Radar (TRMM PR) and the Global Precipitation Measurement Core Observatory Dual-Frequency Precipitation Radar (GPM DPR) to clarify the effects of removing radio interferences and mirror images, particularly focusing on deep precipitation detection. The TRMM PR acquired precipitation data up to an altitude of approximately 20 km and occasionally captured interferences from artificial radio transmissions in specific areas. Artifacts could be distinguished as isolated profiles exhibiting almost constant radar reflectivity. The number of interferences affecting the TRMM PR gradually increased during the operation period of 1998–2013. A filter was introduced to separate the observed profiles into deep storms that reach the upper observation altitude and contamination caused by radio interference. The former frequently appeared over the Sahel area, where the observation upper limits are lowest. The removal of the latter, radio interference, improved the detection accuracy of the mean precipitation at high altitudes and considerably influenced specific low-precipitation areas such as the Middle East. This spatial feature–based filter allowed us to evaluate the results of screening based on noise limits that are implemented in standard algorithms. The GPM DPR Ku-band radar product contained other unwanted echoes due to the mirror images appearing as second-trip echoes contaminating the high-altitude statistics. Such second-trip echoes constitute a major portion of the echoes observed near the highest altitudes of deep storms.
Significance Statement
Understanding the current state of separation of naturally occurring precipitation signals from artificial interference signals in spaceborne radar data at altitudes of approximately 20 km is critical for gaining a comprehensive picture of the intensity and structure of precipitation systems. In the case of the TRMM PR data, artifacts could be distinguished as isolated profiles with an almost constant radar reflectivity, and interferences gradually increased during the operation period. The removal of radio interference considerably affects the statistics of extremely deep storms. Improved algorithms and observation techniques have expanded the observation coverage associated with the GPM DPR KuPR data, but there are interferences (mirror images) that should be removed for a thorough discussion of very high-altitude precipitation.
