Addition to Baseline Observing System Experiment Impacts from N19-AMSU/MHS, SNPP-ATMS, and Aqua-AIRS using the NCEP Global Data Assimilation System

Addition to baseline Observing System Experiments (OSEs), during two seasons are used to quantify the contributions made to the forecast quality by adding specific satellite sensors to a conventional data only or baseline experiment. The impacts are measured by comparing the analysis and the forecast results from an assimilation-forecast system using only conventional data types (Baseline) to the baseline plus individual sensors. The sensors being tested include the Advanced Microwave Sounding Unit/ Microwave Humidity Sensor (AMSU/MHS) from NOAA-19, the Advanced Technology Microwave Sounder (ATMS) from the Suomi NPOES Preparatory Project (SNPP), and the Atmospheric Infrared Sounder (AIRS) from Aqua.

For these observing system experiments, forecast results are compared through 168 h for periods covering more than a month during both the summer and winter seasons of each hemisphere. The assimilation –forecast system used for these experiments is the National Centers for Environmental Prediction (NCEP) Global Data Assimilation System (GDAS) and the Global Forecast System (GFS). The May 2012 version of the GDAS/GFS, at a resolution of T574L64 will be used. The first 15 days are ignored to allow the GDAS/GFS to adjust to the new data volume. Impact statistics are derived from the 45 days following the adjustment period. Anomaly correlations (ACs) of extratropical geopotential heights by hemisphere, root-mean-square (RMS) errors of winds in the tropics, forecast impacts (FIs), and hurricane track forecasts are evaluated for experiments run during both seasons.