scholarly journals Vertical gradient of stratiform radar reflectivity below the bright band from the Tropics to the extratropical latitudes seen by GPM

2018 ◽  
Vol 144 (S1) ◽  
pp. 165-175 ◽  
Author(s):  
Kazuki Kobayashi ◽  
Shoichi Shige ◽  
Munehisa K. Yamamoto
Keyword(s):  
Vertical Gradient ◽  
Radar Reflectivity ◽  
Bright Band ◽  
The Tropics

Lightning Frequency and Microphysical Properties of Precipitating Clouds over the Western North Pacific during Winter as Derived from TRMM Multisensor Observations

2007 ◽  
Vol 135 (6) ◽  
pp. 2226-2241 ◽  
Author(s):  
Yasu-Masa Kodama ◽  
Haruna Okabe ◽  
Yukie Tomisaka ◽  
Katsuya Kotono ◽  
Yoshimi Kondo ◽  
...  
Keyword(s):  
North Pacific ◽  
Western North Pacific ◽  
Large Scale ◽  
Tropical Rainfall Measuring Mission ◽  
Radar Reflectivity ◽  
Phase Layer ◽  
Convective Clouds ◽  
Microphysical Properties ◽  
The Tropics ◽  
Precipitating Clouds

Abstract Tropical Rainfall Measuring Mission observations from multiple sensors including precipitation radar, microwave and infrared radiometers, and a lightning sensor were used to describe precipitation, lightning frequency, and microphysical properties of precipitating clouds over the midlatitude ocean. Precipitation over midlatitude oceans was intense during winter and was often accompanied by frequent lightning. Case studies over the western North Pacific from January and February 2000 showed that some lightning occurred in deep precipitating clouds that developed around cyclones and their attendant fronts. Lightning also occurred in convective clouds that developed in regions of large-scale subsidence behind extratropical cyclones where cold polar air masses were strongly heated and moistened from below by the ocean. The relationships between lightning frequency and the minimum polarization corrected temperature (PCT) at 37 and 85 GHz and the profile of the maximum radar reflectivity resembled relationships derived previously for cases in the Tropics. Smaller lapse rates in the maximum radar reflectivity above the melting level indicate vigorous convection that, although shallow and relatively rare, was as strong as convection over tropical oceans. Lightning was most frequent in systems for which the minimum PCT at 37 GHz was less than 260 K. Lightning and PCT at 85 GHz were not as well correlated as lightning and PCT at 37 GHz. Thus, lightning was frequent in convective clouds that contained many large hydrometeors in the mixed-phase layer, because PCT is more sensitive to large hydrometeors at 37 than at 85 GHz. The relationship between lightning occurrence and cloud-top heights derived from infrared observations was not straightforward. Microphysical conditions that support lightning over the midlatitude ocean in winter were similar to conditions in the Tropics and are consistent with Takahashi’s theory of riming electrification.

scholarly journals Testing Passive Microwave-based Hail Retrievals using GPM DPR Ku-band Radar

2020 ◽  
Author(s):  
Sarah D. Bang ◽  
Daniel J. Cecil
Keyword(s):  
High Latitude ◽  
Radar Reflectivity ◽  
Passive Microwave ◽  
Subtropical High ◽  
Tropopause Height ◽  
Regional Bias ◽  
Radar Measurements ◽  
The Tropics ◽  
Ku Band

AbstractSeveral studies in the literature have developed approaches to diagnose hail storms from satellite-borne passive-microwave imagery and build nearly global climatologies of hail. This paper uses spaceborne Ku-band radar measurements to validate several passive-microwave approaches. We assess the retrievals based on how tightly they constrain the radar reflectivity at -20°C, and how this measured radar reflectivity aloft varies geographically. The algorithm which combines Minimum 19-GHz polarization corrected temperature (PCT) with a 37-GHz PCT depression normalized by tropopause height constrains the radar reflectivity most tightly, and gives the least appearance of regional biases. A retrieval based on a 19- GHz PCT threshold of 261K also produces tightly clustered profiles of radar reflectivity, with little regional bias. An approach using regionally-adjusted Minimum 37-GHz PCT performs relatively well, but our results indicate it may overestimate hail in some subtropical and midlatitude regions. A threshold applied to the Minimum 37-GHz PCT (≤ 230K), without any scaling by region or probability of hail, overestimates hail in the tropics and underestimates beyond the tropics. For all retrieval approaches, storms identified as having hail tended to have radar reflectivity profiles that are consistent with general expectations for hailstorms (reflectivity > 50 dBZ below the 0°C level, and > 40 dBZ extending far above 0°C). Profiles from oceanic regions tended to have more rapidly decreasing reflectivity with height than profiles from other regions. Subtropical, high latitude, and high terrain land profiles had the slowest decreases of reflectivity with height.

Relationships between lightning flash rates and radar reflectivity vertical structures in thunderstorms over the tropics and subtropics

2012 ◽  
Vol 117 (D6) ◽  
pp. n/a-n/a ◽  
Author(s):  
Chuntao Liu ◽  
Daniel J. Cecil ◽  
Edward J. Zipser ◽  
Kevin Kronfeld ◽  
Roy Robertson
Keyword(s):  
Radar Reflectivity ◽  
Lightning Flash ◽  
The Tropics

scholarly journals Vertical Profiles of Radar Reflectivity Factor in Intense Convective Clouds in the Tropics

2016 ◽  
Vol 55 (5) ◽  
pp. 1277-1286 ◽  
Author(s):  
Shailendra Kumar ◽  
G. S. Bhat
Keyword(s):  
South America ◽  
Vertical Structure ◽  
Western Himalaya ◽  
Radar Reflectivity ◽  
Close Similarity ◽  
Vertical Profiles ◽  
Convective Clouds ◽  
Convective Cells ◽  
The Tropics ◽  
Reflectivity Factor

AbstractThis study is based on the analysis of 10 years of data for radar reflectivity factor Ze as derived from the TRMM Precipitation Radar (PR) measurements. The vertical structure of active convective clouds at the PR pixel scale has been extracted by defining two types of convective cells. The first one is cumulonimbus tower (CbT), which contains Ze ≥ 20 dBZ at 12-km altitude and is at least 9 km deep. The other is intense convective cloud (ICC), which belongs to the top 5% of the population of the Ze distribution at a prescribed reference height. Here two reference heights (3 and 8 km) have been chosen. Regional differences in the vertical structure of convective cells have been explored by considering 16 locations distributed across the tropics and two locations in the subtropics. The choice of oceanic locations is based on the sea surface temperature; that of the land locations is based on propensity for intense convection. One of the main findings of the study is the close similarity in the average vertical profiles of CbTs and ICCs in the mid- and lower troposphere across the ocean basins whereas differences over land areas are larger and depend on the selected reference height. The foothills of the western Himalaya, southeastern South America, and the Indo-Gangetic Plain contain the most intense CbTs; equatorial Africa, the foothills of the western Himalaya, and equatorial South America contain the most intense ICCs. Close similarity among the oceanic profiles suggests that the development of vigorous convective cells over warm oceans is similar and that understanding gained in one region is extendable to other areas.

Synoptic and Topographic Variability of Northern California Precipitation Characteristics in Landfalling Winter Storms Observed during CALJET

2006 ◽  
Vol 134 (8) ◽  
pp. 2072-2094 ◽  
Author(s):  
David E. Kingsmill ◽  
Paul J. Neiman ◽  
F. Martin Ralph ◽  
Allen B. White
Keyword(s):  
Size Distribution ◽  
Drop Size ◽  
Drop Size Distribution ◽  
Radar Reflectivity ◽  
Low Level ◽  
Bright Band ◽  
Surface Rainfall ◽  
Precipitation Characteristics ◽  
Topographic Variability ◽  
The Relationship

Abstract Observations from northern California during the California Landfalling Jets (CALJET) experiment are used to examine the mean characteristics of precipitation and their variances as functions of synoptic and topographic regimes. Ten cases involving the landfall of extratropical cyclones are analyzed with radar and rain gauge data collected at two sites: one in the coastal mountains north of San Francisco (CZD) and the other in the Central Valley just west of Sacramento (KDAX). Aside from the melting-layer bright band, the most striking feature in the 10-case composite vertical profile of radar reflectivity at CZD was a distinct change in slope about 2.5 km above the bright band. This “shoulder” is thought to represent a change in the growth rate of hydrometeors. Although the bright band was quite distinct, about one-third of the profiles in the composite did not exhibit this feature. These nonbrightband (NBB) profiles had a low-level slope where reflectivity increased with decreasing altitude, a structure suggesting that collision–coalescence was the primary growth process. The relationship between surface rainfall rate and low-level radar reflectivity implies that all profiles were composed of larger numbers of small drops than expected from a Marshall–Palmer drop size distribution, a trend that was especially apparent for NBB profiles. Synoptic variability of precipitation characteristics at CZD were examined by identifying five distinct regimes (cold sector, warm front, warm sector, cold front, and cool sector) based on a simplified conceptual model. The shoulder remained approximately 2.5 km above the bright band in each regime. Rainfall intensity was highest during the cold-frontal regime and NBB rainfall was most common during the warm-frontal, warm-sector, and cool-sector regimes. Topographic variability of precipitation characteristics was investigated by comparing results at CZD and KDAX. A shoulder structure located about 2.5 km above the bright band was also evident in the KDAX profiles, suggesting that this feature is related to large-scale dynamic, thermodynamic, and microphysical processes rather than orographic effects. The relationship between surface rainfall rate and low-level radar reflectivity near KDAX closely followed a trend expected for a Marshall–Palmer drop size distribution, implying the presence of relatively larger raindrops than observed at CZD and indicating that NBB rainfall occurs less frequently near KDAX.

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