Radio-Occultation based Monthly Gridded Dry Temperature, Bending Angles, and Refractivities

Introduction

Radio occultation uses observed radio wave bending angles from global navigation satellite systems (including GPS and GLONASS) to derive atmospheric properties.  The resulting derived profiles provide a high-accuracy, high vertical resolution, limited footprint, product featuring atmospheric variables such as dry temperature and refractivity. For more detailed information please refer to https://www.cosmic.ucar.edu/what-we-do/gnss-radio-occultation

This gridded, monthly mean dataset is constructed through merging 13 radio occultation (RO) profile datasets provided by the COSMIC Data Analysis and Archive Center (CDAAC) and subsequently gridding into a monthly 5°x10° product. All valid (non-bad flagged) profiles from each mission were incorporated. All tropopause calculations were carried out independently from CDAAC calculations and were derived either directly from the profile data (Cold Point Tropopause), or from the gridded dry temperature product (Lapse Rate, Potential Temperature Gradient).

Specifications

Included datasets: 

Gridded Resolution:

• 5° Latitude, 10° Longitude, 200 m Vertical for Dry Temperature
• 5° Latitude Zonal Mean, 200 m Vertical for Bending Angle and Refractivity
• 5° Latitude, 10° Longitude for tropopause parameters

Variables included:

• Dry Temperature, (Temp), 10 – 40 km
• Bending Angle, (Bend_ang), 0 – 60 km
• Refractivity, (Ref), 0 – 60 km
• Tropopause Parameters
  • Cold Point Temperature (cpt)  (for latitudes 30 N - 30 S), Calculated Using Profiles
  • Lapse Rate Tropopause  (lapse_rate), Calculated Using Gridded Dry Temperature
  • Potential Temperature Gradient Tropopause (ptgt), Calculated Using Gridded Dry Temperature

Data Timeframe: March 2002 – September 2025