Data

The main sources of quantitative spatial data to examine MCs are satellite observations and fields of geophysical parameters retrieved from measurements conducted by various satellite sensors. The MCs were detected by screening wide swath mode ASAR archive images acquired over the Northwest Pacific in 2002-2007. The images were downloaded from an ESA web site (http://eoli.esa.int/). They represent the so-called quick look (QL) images and have the strongly reduced spatial and radiometric resolution. In spite of this they are valuable source of information on the features of spatial organization of the cyclones, the location of their centers, the areas of high surface winds, wind direction, the presence of sea ice. The ASAR precision processed images (PRI) have a spatial resolution of 75 x 75 m in wide swath mode that allowed studying the fine details of surface wind. The ASAR images cover the Japan, Okhotsk and Bering seas and the northwest Pacific Ocean between 40-62° N and 130-180° E. More than 3,000 QL and 320 PRI images are now in our database. SAR images of the MCs in different stage of development were selected for the study.

Each ASAR image of MC covering it completely or partly was compared with the microwave brightness temperatures measured by Aqua AMSR-E and ADEOS-II AMSR provided by EORC JAXA (http://sharaku.eorc.jaxa.jp/AMSR/index_ e.htm/), with QuikSCAT-derived wind speed fields downloaded from website http://manati.wwb.noaa.gov/quikscat/ as well as with the Aqua and Terra MODIS visible and thermal infrared (IR) images downloaded from web site http://rapidfire. sci.gsfc.nasa.gov/, and the NOAA AVHRR images available from several web sites. Satellite images were compared also with the surface analysis maps and ice condition maps of the Japan Meteorological Agency (AMS).

Detailed quantitative analysis of structure and parameters of MCs was carried out to demonstrate the high potential of the present satellite sensors providing quantitative information on various marine weather systems. The presence of growing quantitative data can be used in the future for construction of more reliable climatology of MCs, which will allow estimating fields of atmospheric water vapor, cloud liquid water, sea surface wind, impact of wind field on the sea surface, etc. Earlier climatological compilations were based or on satellite visible/ IR images showing only cloud structure (Yarnal and Henderson 1989; Harold et al. 1999) or on Re-Analysis dataset (ERA-40) that permits to reveal predominantly the large MCs (Condron et al. 2006; Kolstad 2006).

Was this article helpful?

0 0

Post a comment