# Transform data to a different map projection

From: Jiangfeng Wei <jwei_at_nyahnyahspammersnyahnyah>
Date: Thu, 5 Oct 2006 11:13:01 -0400

Dear all,

I want to transform a data of Lambert Conformal Format to Cylindrical Equidistant projection (regular lat/lon grid). More inflormation on this format can be found here: http://www.cdc.noaa.gov/NARR/format.html. Is there a simple way to transform it in NCL? Can I plot it in Cylindrical Equidistant projection without transforming?

The description of the Lambert Conformal Format data is:

dimensions:
time = UNLIMITED ; // (365 currently)
y = 277 ;
x = 349 ;
nbnds = 2 ;
variables:
float lat(y, x) ;
lat:long_name = "latitude coordinate" ;
lat:units = "degrees_north" ;
lat:axis = "Y" ;
lat:coordinate_defines = "point" ;
lat:standard_name = "latitude" ;
float lon(y, x) ;
lon:units = "degrees_east" ;
lon:long_name = "longitude coordinate" ;
lon:axis = "X" ;
lon:coordinate_defines = "point" ;
lon:standard_name = "longitude" ;
float x(x) ;
x:long_name = "eastward distance from southwest corner of domain in projection coordinates" ;
x:units = "m" ;
x:standard_name = "projection_x_coordinate" ;
float y(y) ;
y:long_name = "northward distance from southwest corner of domain in projection coordinates" ;
y:units = "m" ;
y:standard_name = "projection_y_coordinate" ;
int Lambert_Conformal ;
Lambert_Conformal:grid_mapping_name = "lambert_conformal_conic" ;
Lambert_Conformal:standard_parallel = 50., 50. ;
Lambert_Conformal:longitude_of_central_meridian = -107. ;
Lambert_Conformal:latitude_of_projection_origin = 50. ;
Lambert_Conformal:false_easting = 5632642.22547 ;
Lambert_Conformal:false_northing = 4612545.65137 ;
double time(time) ;
time:units = "hours since 1800-1-1 00:00:0.0" ;
time:long_name = "analysis time" ;
time:axis = "T" ;
time:standard_name = "time" ;
time:coordinate_defines = "start" ;
time:delta_t = "0000-00-01 00:00:00" ;
time:actual_range = 1569072., 1577808. ;
time:avg_period = "0000-00-01 00:00:00" ;
double time_bnds(time, nbnds) ;
time_bnds:long_name = "Time Boundaries" ;
short acpcp(time, y, x) ;
acpcp:units = "kg/m^2" ;
acpcp:long_name = "Daily accumulated convective precipitation at Surface" ;
acpcp:unpacked_valid_range = 0.f, 60.f ;
acpcp:precision = 3s ;
acpcp:actual_range = 0.000995636f, 32.766f ;
acpcp:missing_value = 32766s ;
acpcp:scale_factor = 0.001f ;
acpcp:valid_range = -32766s, 27235s ;
acpcp:_FillValue = -32767s ;
acpcp:GRIB_name = "ACPCP" ;
acpcp:GRIB_id = 63 ;
acpcp:var_desc = "convective precipitation accumulation" ;
acpcp:standard_name = "convective_precipitation_amount" ;
acpcp:level_desc = "Surface" ;
acpcp:dataset = "NARR Daily Averages" ;
acpcp:statistic = "Mean" ;
acpcp:parent_stat = "Individual Obs" ;
acpcp:grid_mapping = "Lambert_Conformal" ;
acpcp:coordinates = "lat lon" ;
acpcp:cell_methods = "time: mean (of 8 3-hourly values in one day)" ;

// global attributes:
:standardpar1 = 50. ;
:standardpar2 = 50.000001 ;
:centerlon = -107. ;
:centerlat = 50. ;
:latcorners = 1.000001f, 0.897945f, 46.3544f, 46.63433f ;
:loncorners = -145.5f, -68.32005f, -2.569891f, 148.6418f ;
:stream = "s1" ;

-----------------------------
Jiangfeng Wei
School of Earth and Atmospheric Sciences
Georgia Institute of Technology, Atlanta, Georgia 30332

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Received on Thu Oct 05 2006 - 09:13:01 MDT

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