The Stratospheric Diurnal Cycle in COSMIC GPS Radio Occultation Data: Scientific Applications

Abstract

The diurnal cycle throughout the stratosphere is analyzed by applying Bayesian interpolation to Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) Global Positioning System radio occultation (RO) data and three scientific applications of the analysis are introduced. First, the migrating thermal tides are analyzed with unprecedented accuracy and precision, with an uncertainty in the analysis of the vertically propagating tides ranging from 0.1 in the lower stratosphere to 0.6 K in the upper stratosphere for an individual month of RO data and with an uncertainty in a 10‐year climatological diurnal cycle a factor of 10 less. Moreover, the midlatitude trapped tide is found to be smaller than what is produced by an atmospheric model and lags the model in phase, a likely consequence of a faulty parameterization of eddy diffusivity in the upper stratosphere. Second, a clear signal of solar cycle influence on the diurnal cycle is evident in this analysis, but whether the cause is the systematic bias of ionospheric residual associated with RO retrieval or it is an actual atmospheric phenomenon is less clear. Third, RO satellites and missions that obtain inadequate coverage of the diurnal cycle will be biased by under‐sampling it, whether or not subsampling weather forecasts is used to removal sampling error. The analysis of the diurnal cycle in COSMIC RO data can be used to diagnose the systematic sampling error incurred by incomplete coverage of the diurnal cycle, which is of the order of 0.2 K for a Metop‐based RO climatology.

Influences of Different Factors on Gravity Wave Activity in the Lower Stratosphere of the Indian Region

“…Satellite observations, which are valuable complements to traditional ground-based Remote Sens. 2024, 16, 761 2 of 20 and field observations, can provide global information about the spatial and temporal distributions of GWs and make it possible to provide some constraints on the parameterization of GW activity in GCMs [13].…”

“…The vertical resolution of RO temperature profiles ranges from 100 m in the lower troposphere to 1.4 km in the upper stratosphere. The RO temperature profiles generally have errors of less than 0.4 K in the upper troposphere and lower stratosphere (UTLS) [14][15][16], which are ideal data sources for the study of GWs in this altitude region [2,[17][18][19].…”

“…The six satellites of COSMIC-2 were deployed in 24 • inclination parking orbits at an altitude of about 550 km [21,22], each of which carries an advanced Tri-GNSS RO System instrument (TGRS) developed by the National Aeronautics and Space Administration's Jet Propulsion Laboratory [23]. COSMIC-2 is the successor to the highly successful COSMIC mission, whose products have improved global weather forecasts and supported hundreds of scientific studies of weather, climate, and space weather [2,16,[24][25][26]. After the COSMIC-2 mission is fully operational, it will observe about 5000 RO events per day at middle and low latitudes of 40 • S-40 • N. Compared to COSMIC, which can only observe the global positioning system (GPS) RO events, COSMIC-2 can observe both the GPS and the global navigation satellite system (GLONASS) RO events, and the performance of the RO receivers has been improved substantially [20,21,27].…”