Precipitation Top Height Research Articles

Diurnal cycles of rain storms over South China during the presummer rainy season

The variation characteristics of rain storms (RSs) are closely related to complex internal physical processes and external dynamic and thermodynamic conditions. Using a 17-year observational rainfall dataset from the Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR), the diurnal cycles of various RS characteristics and their responses to the South China Sea Summer Monsoon (SCSSM) are investigated in South China (SC) during the presummer rainy season (PSRS). Before SCSSM outbreaks, the RSs in the western inland region of SC (WSC) have stronger precipitation intensities and convective features due to orographic lifting, especially at night, while those in the eastern inland region of SC (ESC) have higher RS occurrence frequencies with higher moisture transport, especially in the afternoon. The onset of the SCSSM leads to abundant moisture and sufficient convective available potential energy over the entire SC area, resulting in significant increases in the occurrence frequency, convective fraction, and precipitation top height of RSs. In the WSC, the weakened upward motion and smaller convective inhibition limit RS development, resulting in weaker rainfall intensity. In the ESC, a particularly unstable atmosphere and enhanced low-level moisture transport in the afternoon lead to a larger three-dimensional size, more active convection, and greater precipitation intensity in the RSs. These results offer fresh insight into the diurnal variation in rainfall during the PSRS and can be effectively used to evaluate numerical model simulations.

Life Cycle of Precipitating Cloud Systems from Synergistic Satellite Observations: Evolution of Macrophysical Properties and Precipitation Statistics from Geostationary Cloud Tracking and GPM Active and Passive Microwave Measurements

Abstract Observations of clouds and precipitation in the microwave domain from the active dual-frequency precipitation radar (DPR) and the passive Global Precipitation Measurement (GPM) Microwave Imager (GMI) onboard the GPM Core Observatory satellite are used in synergy with cloud tracking information derived from infrared imagery from the GOES-13 and Meteosat-7 geostationary satellites for analysis of the life cycle of precipitating cloud systems, in terms of temporal evolution of their macrophysical characteristics, in several oceanic and continental regions of the tropics. The life cycle of each one of the several hundred thousand cloud systems tracked during the 2-yr (2015–16) analysis period is divided into five equal-duration stages between initiation and dissipation. The average cloud size, precipitation intensity, precipitation top height, and convective and stratiform precipitating fractions are documented at each stage of the life cycle for different cloud categories (based upon lifetime duration). The average life cycle dynamics is found remarkably homogeneous across the different regions and is consistent with previous studies: systems peak in size around midlife; precipitation intensity and convective fraction tend to decrease continuously from the initiation stage to the dissipation. Over the three continental regions, Amazonia (AMZ), central Africa (CAF), and Sahel (SAH), at the early stages of clouds’ life cycle, precipitation estimates from the passive GMI instrument are systematically found to be 15%–40% lower than active radar estimates. By highlighting stage-dependent biases in state-of-the-art passive microwave precipitation estimates over land, we demonstrate the potential usefulness of cloud tracking information for improving retrievals and suggest new directions for the synergistic use of geostationary and low-Earth-orbiting satellite observations.

Microphysics of Summer Precipitation Over Yangtze‐Huai River Valley Region in China Revealed by GPM DPR Observation

AbstractUtilizing the measurements and retrievals from the Global Precipitation Measurement dual‐frequency precipitation radar data during the summer of 2014–2020, this study analyzes the precipitation microphysics for summer rainfall over the Yangtze‐Huai River Valley (YHRV) region in China with respect to the precipitation efficiency index (PEI). The results show that the mean near‐surface rain rate and PEI for convective precipitation are generally larger than that for stratiform precipitation. There are larger raindrops in near‐surface rainfall for convective precipitation than that for stratiform precipitation. The High PEI precipitation is characterized by the larger ratio of convective precipitation samples compared to that for the other two categories of precipitation. The mean mass‐weighted mean diameter (Dm) of the near‐surface raindrops increase along with the precipitation top height (PTH) in Moderate PEI precipitation for convective and stratiform precipitating clouds. The larger PEI indicates the larger occurrence of the heavy raindrops and strong radar echoes near the ground. The growth process of raindrops falling below the melting layer in the High PEI precipitation is dominated by collision‐coalescence while the collisional break up is the dominant process below the melting layer in Low PEI precipitation. It is further verified that the microphysical characteristics and mechanisms of summer rainfall over the YHRV region are similar to that of precipitation derived from tropical cyclones over the ocean during the monsoon period.

The NASA‐JAXA Global Precipitation Measurement mission – part II: New frontiers in precipitation science

The <scp>NASA‐JAXA</scp> Global Precipitation Measurement mission – part <scp>II</scp>: New frontiers in precipitation science

1997/98 El Niño–Induced Changes in Rainfall Vertical Structure in the East Pacific

Abstract The 1997/98 El Niño–induced changes in rainfall vertical structure in the east Pacific (EP) are investigated by using collocated Tropical Rainfall Measuring Mission (TRMM) precipitation radar (PR) and associated daily SST and 6-hourly reanalysis data during January, February, March, and April of 1998, 1999, and 2000. This study shows that there are five key parameters, that is, surface rain rate, precipitation-top height (or temperature), and precipitation growth rates at upper, middle, and low layers to define a rainfall profile, and those five key parameters are strongly influenced by both SST and large-scale dynamics. Under the influence of 1997/98 El Niño, the precipitation-top heights in the EP were systematically higher by about 1 km than those under non–El Niño conditions, while the freezing level was about 0.5 km higher. Under the constraints of rain type, surface rain rate, and the precipitation top, the shape of rainfall profile still showed significant differences: the rain growth was relatively faster in the mid-layer (−5° to +2°C isotherm) but slower in the lower layer (below +2°C isotherm) under the influence of El Niño. It is also evident that the dependence of precipitation top height on SST was stronger under large-scale decent (non–El Niño) circulations but much weaker under large-scale ascent (El Niño) circulations. The combined effect of larger vertical extent and greater growth rate in the middle layer further shifted latent heating upward as compared with the impact of horizontal changes in the rain type fractions (convective versus stratiform). Such additional latent heating shift would certainly further elevate circulation centers and strengthen the upper-layer circulation.

Properties of Precipitation and In-Cloud Vertical Motion in a Global Nonhydrostatic Aquaplanet Experiment

To gain insight into properties of in-cloud vertical motion and precipitation production in the tropics, three-dimensional outputs from an aquaplanet experiment using a 3.5-km mesh global cloud-system resolving model (GCRM) were analyzed.Probability distributions of precipitation and latent heating in the 10°N–10°S domain are evaluated in comparison with Tropical Rainfall Measurement Mission (TRMM) observations. Despite biases of generally higher precipitation top height (PTH) and deficiencies near the melting level, the model reproduced the general morphology of the precipitation and total latent heating profiles. Relationship between PTH and cloud top height (CTH) in the simulated clouds reproduced clear contrast between deep and shallow convection in active and suppressed environments, respectively. The simulated in-cloud vertical velocities were on the order of O(0.1 m s-1) in anvil clouds and O(1 m s-1) in updraft cores, as in the range of those in previous observations. Focusing on relatively strong upward motion, the maximum in-cloud vertical motion (w_max) was defined in each column. Probabilities of w_max had double peaks (z = 1–4 and 7–12 km) with minima in the middle troposphere. Vigorous upward motions most frequently occurred in the upper troposphere as the active portion of well-organized convective systems. They were often surrounded by updrafts with w_max height in the lower to middle troposphere, forming a group of updraft regions (w_max > 1 m s-1) with horizontal scale of O(10 km). In the regions of compensating subsidence, updrafts tended to be capped below the middle troposphere and small in horizontal size. In both regions the updrafts were accompanied by cold pools of their characteristic horizontal scale.Finally, time evolutions of in-cloud updrafts were analyzed to explore the roles of in-cloud updrafts at different altitude. It was found that the updrafts with w_max height in the middle troposphere produced the heaviest surface precipitation, preceded by moisture transport in the lower to middle troposphere. This suggests that middle tropospheric updrafts most efficiently produced surface precipitation through tight linkage between dynamics and cloud processes, although their occurrence was rare.

Statistical Relation between Maximum Vertical Velocity and Surface Precipitation of Tropical Convective Clouds in a Global Nonhydrostatic Aquaplanet Experiment

This study investigated the properties of heavy precipitation and its associated vertical motion in an aquaplanet experiment with a 3.5-km mesh global cloud-system resolving model (GCRM). The statistics of precipitation and vertical velocity were examined in terms of the precipitation top height (PTH) and the maximum in-cloud vertical velocity in each column (w_max) for the grid points with the top 1% and 1–10% of the surface precipitation rate (pr_sfc) in the 10°N–10°S domain. To support the findings, realistic simulation cases were also analyzed. In the columns with the top 1% (1–10%) of pr_sfc, peak frequencies of w_max height were found at z = 4–6 (1–4) km with the PTH several kilometers above that. Thermodynamic conditions were more humid and warmer in these columns than in the columns with average precipitation. These results were common to all simulation cases. Composite time evolution of convection with heavy surface precipitation was also examined for the aquaplanet experiment. The results suggest that the vigorous upward motion in the middle (lower) troposphere for columns with the top 1% (1–10%) of pr_sfc enabled efficient moisture transport from the boundary layer to the middle troposphere.

Spectral Retrieval of Latent Heating Profiles from TRMM PR Data. Part IV: Comparisons of Lookup Tables from Two- and Three-Dimensional Cloud-Resolving Model Simulations

Abstract The spectral latent heating (SLH) algorithm was developed to estimate latent heating profiles for the Tropical Rainfall Measuring Mission Precipitation Radar (TRMM PR). The method uses TRMM PR information (precipitation-top height, precipitation rates at the surface and melting level, and rain type) to select heating profiles from lookup tables (LUTs). LUTs for the three rain types—convective, shallow stratiform, and anvil rain (deep stratiform with a melting level)—were derived from numerical simulations of tropical cloud systems from the Tropical Ocean and Global Atmosphere Coupled Ocean–Atmosphere Response Experiment (TOGA COARE) using a cloud-resolving model (CRM). The two-dimensional (2D) CRM was used in previous studies. The availability of exponentially increasing computer capabilities has resulted in three-dimensional (3D) CRM simulations for multiday periods becoming increasingly prevalent. In this study, LUTs from the 2D and 3D simulations are compared. Using the LUTs from 3D simulations results in less agreement between the SLH-retrieved heating and sounding-based heating for the South China Sea Monsoon Experiment (SCSMEX). The level of SLH-estimated maximum heating is lower than that of the sounding-derived maximum heating. This is explained by the fact that using the 3D LUTs results in stronger convective heating and weaker stratiform heating above the melting level than is the case if using the 2D LUTs. More condensate is generated in and carried from the convective region in the 3D model than in the 2D model, and less condensate is produced by the stratiform region’s own upward motion.

Spectral Retrieval of Latent Heating Profiles from TRMM PR Data. Part II: Algorithm Improvement and Heating Estimates over Tropical Ocean Regions

Abstract The spectral latent heating (SLH) algorithm was developed for the Tropical Rainfall Measuring Mission (TRMM) precipitation radar (PR) in Part I of this study. The method uses PR information [precipitation-top height (PTH), precipitation rates at the surface and melting level, and rain type] to select heating profiles from lookup tables. Heating-profile lookup tables for the three rain types—convective, shallow stratiform, and anvil rain (deep stratiform with a melting level)—were derived from numerical simulations of tropical cloud systems from the Tropical Ocean and Global Atmosphere Coupled Ocean–Atmosphere Response Experiment (TOGA COARE) utilizing a cloud-resolving model (CRM). To assess its global application to TRMM PR data, the universality of the lookup tables from the TOGA COARE simulations is examined in this paper. Heating profiles are reconstructed from CRM-simulated parameters (i.e., PTH, precipitation rates at the surface and melting level, and rain type) and are compared with the true CRM-simulated heating profiles, which are computed directly by the model thermodynamic equation. CRM-simulated data from the Global Atmospheric Research Program Atlantic Tropical Experiment (GATE), South China Sea Monsoon Experiment (SCSMEX), and Kwajalein Experiment (KWAJEX) are used as a consistency check. The consistency check reveals discrepancies between the SLH-reconstructed and Goddard Cumulus Ensemble (GCE)-simulated heating above the melting level in the convective region and at the melting level in the stratiform region that are attributable to the TOGA COARE table. Discrepancies in the convective region are due to differences in the vertical distribution of deep convective heating due to the relative importance of liquid and ice water processes, which varies from case to case. Discrepancies in the stratiform region are due to differences in the level separating upper-level heating and lower-level cooling. Based on these results, improvements were made to the SLH algorithm. Convective heating retrieval is now separated into upper-level heating due to ice processes and lower-level heating due to liquid water processes. In the stratiform region, the heating profile is shifted up or down by matching the melting level in the TOGA COARE lookup table with the observed one. Consistency checks indicate the revised SLH algorithm performs much better for both the convective and stratiform components than does the original one. The revised SLH algorithm was applied to PR data, and the results were compared with heating profiles derived diagnostically from SCSMEX sounding data. Key features of the vertical profiles agree well—in particular, the level of maximum heating. The revised SLH algorithm was also applied to PR data for February 1998 and February 1999. The results are compared with heating profiles derived by the convective–stratiform heating (CSH) algorithm. Because observed information on precipitation depth is used in addition to precipitation type and intensity, differences between shallow and deep convection are more distinct in the SLH algorithm in comparison with the CSH algorithm.

Spectral Retrieval of Latent Heating Profiles from TRMM PR Data. Part I: Development of a Model-Based Algorithm

Abstract An algorithm, the spectral latent heating (SLH) algorithm, has been developed to estimate latent heating profiles for the Tropical Rainfall Measuring Mission precipitation radar with a cloud-resolving model (CRM). Heating-profile lookup tables for the three rain types—convective, shallow stratiform, and anvil rain (deep stratiform with a melting level)—were produced with numerical simulations of tropical cloud systems in the Tropical Ocean and Global Atmosphere Coupled Ocean–Atmosphere Response Experiment. For convective and shallow stratiform regions, the lookup table refers to the precipitation-top height (PTH). For the anvil region, on the other hand, the lookup table refers to the precipitation rate at the melting level instead of PTH. A consistency check of the SLH algorithm was also done with the CRM-simulated outputs. The first advantage of this algorithm is that differences of heating profiles between the shallow convective stage and the deep convective stage can be retrieved. This is a r...