Firstly, thanks so much for the work you do to create and maintain the IBTrACS data, we rely on it greatly for identifying cyclonic and non-cyclonic distributions for metocean criteria. We are still in the process of updating our scripts to deal fully with the v3 data and I have a few questions. We use the extended csv data for all stations (rather than just the WMO sanctioned ones) and are interested in trying to make the wind speeds more consistent between stations for plotting and comparison with model data.
1. Regarding Latitude and Longitude, what are the different sources for Latitude (deg_north), Longitude (deg_east) versus Latitude_for_mapping (degrees_north), Longitude_for_mapping (degrees_east)? Looking back at v02 data, the previous lat/lon correspond to the mapping versions. I thought one might be the average of all stations and the other the average of only the WMO-sanctioned but this doesn't seem to be the case.
2. Under the FAQ of 'Why does IBTrACS differ from HURDAT (or data from other agencies)?' for v02r01 and earlier, it is stated that JTWC provides data as 1-minute and (for v02) winds were converted to 10-min using a factor of 0.88. Is it right however that the MSW is calculated from 10-min means, but the individual agency data provided is not corrected to 10-min means? For example, comparing v02 and v03 data for JTWC_SH for storm INGRID in March 2005 shows that the wind speeds are the same, even though the v03 winds should be 1-min means, therefore v02 winds for JTWC_SH are also 1-min means.
Also it states that the IBTrACS maximum sustained winds (MSW) is an average from all available agencies, but surely MSW_max is the maximum of all available agencies? This is what it appears to be (and if so, we will calculate something similar from the v03 data once we do some corrections).
3. Are the winds in ds824.1 presented as 1-min means? I couldn't find this information on the IBTrACS website or elsewhere. Also what about the Neumann dataset, ATCF, mlc_natl (not sure what this is anyway?), NCDC's DSI-9635 and DSI-9636?
4. More data is occasionally available for some cyclones at <6hr resolution (i.e. on the 3-hrly intervals). However there is lat and lon and WMO max wind, there doesn't seem to be any information from any of the centers, even WMO ones! For example INGRID has a record 06-Mar-2005 03:00 with a Wind(WMO) of 45kts but nothing in the subsequent columns. Why is this, and where do the numbers come from for lat/lon and Wind(WMO)?
Sorry for all the questions! But it will be extremely helpful in knowing the difference in what we were plotting previously and what we want to plot with the v03 data.
Many thanks.
Kind Regards,
Fugro GEOS Ltd.
Dr Hazel Grant
Senior Oceanographer
T +44 (0)1491 820533 | F +44 (0)1491 820599
h.g...@fugro.com | www.fugro.com
Fugro House, Hithercroft Road, Wallingford, OX10 9RB, UK
Company Registration No. 2985431 | VAT No. GB 655 4756 06
What are the original wind averages of the following datasets:The Neumann dataset, ds824.1 , ATCF, and NCDC's DSI-9635 and DSI-9636.
We are also very interested in the following, but it's not so vital:Regarding Latitude and Longitude, what are the different sources for Latitude (deg_north), Longitude (deg_east) versus Latitude_for_mapping (degrees_north), Longitude_for_mapping (degrees_east)?
Meteorologist, Center for Weather and Climate
NOAA National Centers for Environmental Information
formerly NOAA’s National Climatic Data Center