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Crossovers Nadir

[2]:

from casys.readers import CLSTableReader

from casys import CasysPlot, DateHandler, Field, NadirData

NadirData.enable_loginfo()

Dataset definition

[3]:

# Reader definition
table_name = "TABLE_C_J3_B_GDRD"
orf_name = "C_J3_GDRD"
cycle_number = 122
start = DateHandler.from_orf(orf_name, cycle_number, 1, pos="first")
end = DateHandler.from_orf(orf_name, cycle_number, 154, pos="last")

reader = CLSTableReader(
    name=table_name,
    date_start=start,
    date_end=end,
    orf=orf_name,
    time="time",
    longitude="LONGITUDE",
    latitude="LATITUDE",
)

# Data container definition
ad = NadirData(source=reader)

var_sla = Field(
    name="sla",
    source="ORBIT.ALTI - RANGE.ALTI - MEAN_SEA_SURFACE.MODEL.CNESCLS15",
    unit="m",
)

Definition of the statistic

Using the add_crossover_stat method:

[4]:

ad.add_crossover_stat(
    name="Crossover SLA",
    field=var_sla,
    max_time_difference="5 days",
    stats=["mean", "count"],
    temporal_stats_freq=["cycle", "day"],
)

ad.compute()

2025-05-14 10:57:57 INFO    Reading ['LONGITUDE', 'LATITUDE', 'sla', 'time']
2025-05-14 10:57:59 INFO    Computing diagnostics ['Crossover SLA']
2025-05-14 10:58:00 INFO    Computing done.

Compute

[5]:

ad.compute()

2025-05-14 10:58:00 INFO    Computing done.

Plot

Graphical display of crossovers

Display daily mean statistic on a graphic:

[6]:

sla_cross_mean_plot = CasysPlot(
    data=ad, data_name="Crossover SLA", freq="day", stat="mean"
)
sla_cross_mean_plot.show()

[6]:

../_images/examples_example_basic_Crossovers_Statistic_13_0.png

Map crossovers upon time

[7]:

cross_delta_plot = CasysPlot(data=ad, data_name="Crossover SLA", delta="time")
cross_delta_plot.show()

[7]:

../_images/examples_example_basic_Crossovers_Statistic_15_0.png

Map crossovers upon field

[8]:

cross_delta_plot = CasysPlot(data=ad, data_name="Crossover SLA", delta="field")
cross_delta_plot.show()

[8]:

../_images/examples_example_basic_Crossovers_Statistic_17_0.png

To learn more about crossovers definition, please visit this documentation page.