开始使用#
本文介绍如何使用 cedarkit 工具栈为 CMA-MESO 数据绘制中国区域 2 米温度填充图。
首先加载需要使用的包,包括:
数据结构相关:pandas
数据准备工具库:reki
绘图工具库:cedarkit.maps
绘图板:
Panel
底图布局:
EastAsiaMapDomain
填充图样式:
ContourStyle
颜色表:
get_ncl_colormap
地图包:
set_default_map_package
import pandas as pd
from reki.data_finder import find_local_file
from reki.format.grib.eccodes import load_field_from_file
from cedarkit.maps.style import ContourStyle
from cedarkit.maps.chart import Panel
from cedarkit.maps.domains import EastAsiaMapDomain
from cedarkit.maps.colormap import get_ncl_colormap
from cedarkit.maps.map import set_default_map_package
设置绘图的数据参数。绘制 CMA-MESO 2024 年 4 月 1 日 00 时次 024 时效的 2 米温度场。
system_name = "CMA-MESO"
data_type = "cma_meso_3km/grib2/orig"
start_time = pd.to_datetime("2024-04-01 00:00:00")
forecast_time = pd.to_timedelta("24h")
加载数据#
获取 GRIB2 文件目录
file_path = find_local_file(
data_type,
start_time=start_time,
forecast_time=forecast_time,
)
file_path
PosixPath('/g3/COMMONDATA/OPER/CEMC/MESO_3KM/Prod-grib/2024040100/ORIG/rmf.hgra.2024040100024.grb2')
加载 2 米温度场。这里直接使用 ecCodes 内置的要素名 2t
t_2m_field = load_field_from_file(
file_path,
parameter="2t",
) - 273.15
t_2m_field
<xarray.DataArray '2t' (latitude: 1671, longitude: 2501)> Size: 33MB array([[-0.71931641, -0.75931641, -0.80931641, ..., -4.16931641, -2.87931641, -2.95931641], [-3.65931641, -3.66931641, -2.27931641, ..., -6.91931641, -6.31931641, -3.72931641], [-3.54931641, -3.58931641, -0.85931641, ..., -7.60931641, -7.47931641, -3.43931641], ..., [26.60068359, 26.60068359, 26.59068359, ..., 25.80068359, 25.79068359, 25.97068359], [26.59068359, 26.60068359, 26.59068359, ..., 25.78068359, 25.78068359, 26.00068359], [26.59068359, 26.59068359, 26.60068359, ..., 25.78068359, 25.79068359, 25.97068359]]) Coordinates: time datetime64[ns] 8B 2024-04-01 step timedelta64[ns] 8B 1 days valid_time datetime64[ns] 8B 2024-04-02 heightAboveGround int64 8B 2 * latitude (latitude) float64 13kB 60.1 60.07 60.04 ... 10.03 10.0 * longitude (longitude) float64 20kB 70.0 70.03 70.06 ... 145.0 145.0
配置#
定义填充图层次
t_2m_level = [-24, -20, -16, -12, -8, -4, 0, 4, 8, 12, 16, 20, 24, 28, 32]
定义填充图颜色表。色表来自 cedarkit-maps 内置的 NCL 色表文件 BlAqGrYeOrReVi200.rgb。
color_index = [2, 12, 22, 32, 42, 52, 62, 72, 82, 92, 102, 112, 122, 132, 142, 152]
t_2m_color_map = get_ncl_colormap("BlAqGrYeOrReVi200", index=color_index)
定义填充图样式
t_2m_style = ContourStyle(
colors=t_2m_color_map,
levels=t_2m_level,
fill=True,
)
使用 CEMC 地图包
注:如果没有安装 cemc-meda-data 包,可以注释改行代码,直接使用默认地图包
set_default_map_package("cedarkit.maps.map.cemc")
'cedarkit.maps.map.cemc'
绘图#
创建中国区域底图布局
domain = EastAsiaMapDomain()
创建绘图板,绘制等值线,设置标题,添加颜色条
panel = Panel(domain=domain)
panel.plot(t_2m_field, style=t_2m_style)
domain.set_title(
panel=panel,
graph_name="2m Temperature (C)",
system_name=system_name,
start_time=start_time,
forecast_time=forecast_time,
)
domain.add_colorbar(panel=panel, style=t_2m_style)
panel.show()