Tidally Induced Variations of PMC Ice Water Content Using a Data Assimilation System
Abstract
Polar mesospheric clouds (PMCs) respond sensitively to small changes in the ambient conditions of the upper mesosphere, including temperature variations over the diurnal cycle. To this end, we employ the Advanced-Level Physics High-Altitude (ALPHA) prototype of the Navy Operational Global Atmospheric Prediction System (NOGAPS). NOGAPS-ALPHA assimilates satellite temperature observations from the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) on the NASA TIMED satellite and the Microwave Limb Sounder (MLS) on the NASA Aura satellite as well as water vapor observations from MLS from the ground to ~90 km altitude. NOGAPS-ALPHA was run for the northern 2007 summer in a continuous 6-hourly forecast-assimilation update cycle in order to produce synoptic “nowcasts” of the global atmosphere. We assemble the NOGAPS-ALPHA results in local time and latitude for temperature, water vapor and vertical winds and use them to drive the one-dimensional Community Aerosol and Radiation Model for Atmospheres (CARMA) over the diurnal cycle. We find that near 69° N the temperature at PMC altitudes has a predominantly diurnal variation with an amplitude of ~4 K, which controls the local time dependence of the vertically integrated PMC ice mass density or ice water content (IWC). We compare the IWC to concurrent PMC observations and discuss the implications to analysis of multi-satellite observations that are locked in local time. We will pay particular attention to how and why the diurnal variation of IWC changes with latitude.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2009
- Bibcode:
- 2009AGUFMSA41A1585S
- Keywords:
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- 0305 ATMOSPHERIC COMPOSITION AND STRUCTURE / Aerosols and particles;
- 0320 ATMOSPHERIC COMPOSITION AND STRUCTURE / Cloud physics and chemistry;
- 3315 ATMOSPHERIC PROCESSES / Data assimilation;
- 3389 ATMOSPHERIC PROCESSES / Tides and planetary waves