Liu et al. (2025) Radar First Echo Detection With Spaceborne Precipitation Radars

⚠️ Warning: This summary was generated from the abstract only, as the full text was not available.

Identification

• Journal: Journal of Geophysical Research Atmospheres
• Year: 2025
• Date: 2025-12-10
• Authors: Chuntao Liu, Earle Williams
• DOI: 10.1029/2025jd045191

Research Groups

The abstract does not explicitly list specific research groups, labs, or departments, but the study utilizes data from the Global Precipitation Mission and Tropical Rainfall Measurement Mission satellites.

Short Summary

This study identifies and characterizes "first echoes" in fresh growing clouds using 26 years of satellite Ku-band radar observations, revealing three distinct altitude-related modes in the tropics linked to different microphysical processes, environmental conditions, and aerosol types.

Objective

• To identify and characterize radar "first echoes" in fresh growing clouds using satellite Ku-band radar observations.
• To investigate the altitude-related modes of these "first echoes" in the tropics and their relationships with microphysical processes, environmental conditions, and aerosol types.

Study Configuration

• Spatial Scale: Tropics (global coverage by GPM/TRMM, analysis focused on tropics).
• Temporal Scale: 26 years.

Methodology and Data

• Models used: ERA5 reanalysis (for cloud base height and total column water vapor).
• Data sources: Ku band radars onboard Global Precipitation Mission (GPM) and Tropical Rainfall Measurement Mission (TRMM) satellites (26-year observations).

Main Results

• Three altitude-related modes of "first echoes" are identified in the tropics:
  • Shallow mode: At 1.5–2 km altitude, mainly from warm rain growth via rapid coalescence. Predominant over ocean with more sea salt aerosols.
  • Mid mode: Between 0 °C and -7 °C (approximately 4-6 km altitude), mainly over land and coastal regions. Explained by enhanced radar reflectivity from ice particles through heterogeneous ice nucleation at warmer temperatures, followed by active riming. Associated with moist (ice-supersaturated) environments and large smoke/sulfate aerosol concentrations.
  • Deep mode: Between -12 °C and -25 °C (approximately 7-10 km altitude), frequently found over both land and ocean. Often involved with large dust aerosol concentrations.
• Approximately 12% of isolated echoes, mainly over desert regions, could be remnants of dissipating precipitation (virga).
• Cloud base height and total column water vapor derived from ERA5 reanalysis are positively related to "first echo" height.
• Mid mode first echoes are more likely found in a moist (ice-supersaturated) environment, which is favorable for crystal growth following heterogeneous ice nucleation.

Contributions

• Provides a comprehensive 26-year observational characterization of radar "first echoes" in the tropics using satellite Ku-band data.
• Identifies and describes three distinct altitude-related modes of "first echoes" (shallow, mid, deep) and links them to specific microphysical processes (warm rain, heterogeneous ice nucleation/riming) and environmental conditions.
• Establishes relationships between "first echo" height and cloud base height, total column water vapor, and different aerosol types (sea salt, smoke, sulfate, dust).
• Offers insights into the initial stages of precipitation formation across various tropical environments.

Funding

The abstract does not provide information on funding projects, programs, or reference codes.

Citation

@article{Liu2025Radar,
  author = {Liu, Chuntao and Williams, Earle},
  title = {Radar First Echo Detection With Spaceborne Precipitation Radars},
  journal = {Journal of Geophysical Research Atmospheres},
  year = {2025},
  doi = {10.1029/2025jd045191},
  url = {https://doi.org/10.1029/2025jd045191}
}