Near Real Time Data for CLIMODE Cruises

Kathryn Kelly APL/University of Washington

Three remotely sensed data sets will be retrieved, processed and sent to the ship investigators each day during the Fall and Winter cruises for the CLIMODE project. The data sets include sea surface temperature, sea surface height and near surface wind vectors. The data are 'near real time' (nrt), which is different than research quality data. The nrt data are available in a few hours, but don't necessarily have the quality control of the research data. We will not be archiving the nrt data, but will of course archive the research quality data for the use of CLIMODE PI's. The shipboard investigators will receive *.mat type files each day for use in matlab along with *.m files (sent prior to cruise) to access and plot the data.

Near real time Sea Surface Temperature measured March 1, 2005 with microwave radiometers aboard the TRMM and Aqua satellites, courtesy of Remote Sensing Systems. The data from the two satellites are merged by optimal interpolation (Reynolds and Smith, 1994) and are on a 1/4 degree grid. Contours of 17.5 and 18.5C are overlaid. The diamond is a surface met mooring and the stars are moored profilers.

1) Sea surface temperature (SST) is measured with microwave radiometers which can see the surface through clouds. There will be a one day delay in sending it to the ship. Data will be downloaded early afternoon (Pacific time) to get the previous day's data. The units are degrees Celcius. The data are on a 1/4 degree grid.

Near real time Sea Surface Height map from ten days worth of data up to March 1, 2005. Anomaly data measured from the Jason and Geosat Follow on (GFO) altimeters, courtesy of Colorado Center for Astrodynamics Research, (CCAR). The mean SSH field was developed by Kathryn Kelly and Shenfu Dong at the University of Washington from Topex/Poseidon plus Hydrobase data (http://ultrasat.apl.washington.edu/kkelly/natl). The units are meters.The diamond is a surface met mooring and the stars are moored profilers.

2) Sea surface height (SSH) anomalies are measured from altimeters. Ten days or so of data are collected to make an anomaly map to which we add a mean. The anomaly maps will be downloaded early afternoon to get the latest data in the map. A moving window of about ten days worth of data is used. The units are meters. The data are on a 1/4 degree grid.

Near real time 10m wind vectors measured March 1, 2005 from the a) ascending passes and b) descending passes of the the SeaWinds scatterometer on the QuikSCAT satellite, courtesy of Remote Sensing Systems. Data mapped onto 1/4 degree grid. Units are m/s. Data are removed if rain is flagged and wind speed is less than 10m/s. The diamond is a surface met mooring and the stars are moored profilers.

3) Near surface wind vectors are measured with a scatterometer. There will be a one day delay in sending the data to the ship. The previous day's data will be downloaded early afternoon as with the other datasets. The units are meters/second, in a neutrally stratified atmosphere at 10 meters height. The wind direction follows the oceanographic convention, where 0 degrees is blowing towards the North and 90 degrees is blowing towards the East. The data are separated into ascending and descending swaths to preclude overlap. We eliminate low wind speed data (<10m/s) when the rain flag is positive. We will also include approximate minute of the day (gmt) of the scatterometer overpass with the data.

4) Example of a derived Product:
Satellite-based, microwave sensors are providing all weather views of both currents (arrows) and sea surface temperature (SST,colors). Here is an image of the Gulf Stream and the surface (geostrophic) currents in a region where it leaves the coast near Cape Hatteras. The current map is based on 10 days of altimeter data, while the SST is from a single day (matlab code available from T.Joyce).

5) Sample matlab routines and data

Please send comments, clarifications and data requests to Suzanne Dickinson, Kathryn Kelly's assistant (suzanne@apl.washington.edu)