Upper-air observations from driftsondes and dropsondes over Pacific Ocean from THORPEX Pacific Asian Regional Campaign (T-PARC)

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Tuesday, 19 January 2010: 4:15 PM
B302 (GWCC)
Junhong Wang, NCAR, Boulder, CO; and K. Young and L. Zhang

High quality, high vertical resolution upper air observations over open oceans have historically been scarce because of the limited availability of in-situ data and because available satellite data is typically low resolution, and of questionable quality. During the THORPEX Pacific Asian Regional Campaign (T-PARC), from August 1 to September 30, 2008, approximately 1900 soundings were collected over the Pacific Ocean. These include dropsondes deployed from four aircrafts and zero-pressure balloons in the stratosphere (NCAR's driftsonde system). The sounding data include profiles of pressure, temperature, humidity, wind speed and wind direction from the ocean surface to the troposphere for dropsondes, and from the surface to approximately 50 hPa for driftsondes. The data are 0.5-s vertical resolution, corresponding to ~10 m near surface and ~30 m at 50 hPa. All soundings underwent a series of vigorous quality control at NCAR. Such an unprecedented sounding dataset is valuable for studying characteristics of thermodynamic and kinematic profiles over the Pacific Ocean. Statistical analyses will be applied to the data to characterize vertical, spatial and diurnal variability of different parameters, and compare them with previous studies such as bimodality in tropical water vapor. In addition, the dataset will be used to evaluate the performance of upper-air data from four global reanalysis (RA) products, including NCEP I/II, Japanese reanalysis (JRA-25) and ERA-Interim. The uniqueness of such an evaluation is twofold. First, the T-PARC sounding data are not assimilated by any of the RAs, and thus serve as an independent data source for validating RAs. Second, the performance of upper air profiles in RAs over oceans has not been thoroughly assessed due to a lack of independent, high quality observations.