Could you please tell me how to initialize particles in a square grid pattern with equal spacing using a Parcels ParticleSet?

[nbuaan0211-stack]

Question

Question

I've been using start, finish, and size to initialize particles along a line, but I'm struggling to figure out how to set them up in a regular grid pattern. What is the best way to achieve a 2D grid layout in Parcels?

from datetime import timedelta
from operator import attrgetter

import matplotlib.pyplot as plt
import numpy as np
import trajan as ta
import xarray as xr
from IPython.display import HTML
from matplotlib.animation import FuncAnimation

import parcels

import cartopy.crs as ccrs
import cartopy.feature as cfeature

1.

variables={
"U":"water_u",
"V":"water_v",
}

2.

dimensions={

"lon":"lon",
"lat":"lat",
"time":"time"

}

fieldsetの作成。from_netcdf を使って読み込む

fieldset = parcels.FieldSet.from_netcdf(
filenames="/mnt/c/2019/201901*.nc",
variables=variables,
dimensions=dimensions
)

確認

print(fieldset)

#particleset作成。fieldsetを用いる
pset = parcels.ParticleSet.from_line(
fieldset=fieldset,
pclass=parcels.JITParticle,
size=10, # releasing 10 particles
start=(122.5,20 ), # releasing on a line: the start longitude and latitude
finish=(125, 22.5), # releasing on a line: the end longitude and latitude
)

print(pset)

#particlefileの作成。particlesetを用いる
output_file = pset.ParticleFile(
name="ParticelTest.zarr", outputdt=timedelta(hours=12)
)

print(output_file)

#実行
#RK4を適用し5日分5分刻みで計算する
pset.execute(
parcels.AdvectionRK4,
runtime=timedelta(days=30),
dt=timedelta(minutes=5),
output_file=output_file
)

#作成したzarrデータをxarrayで読み込む
#このデータセットを使って描画しないと
ds=xr.open_zarr("ParticelTest.zarr")

print(ds)

fig=plt.figure(figsize=(12,8))
ax=plt.axes(projection=ccrs.PlateCarree())
ax.set_extent([115, 135, 15, 35], crs=ccrs.PlateCarree())

2. 地図の機能を追加（陸地・海など）

ax.add_feature(cfeature.LAND, facecolor="white")
ax.add_feature(cfeature.OCEAN, facecolor="lightblue")
#海岸線・国境を追加
ax.coastlines(resolution="10m",linewidth=0.8)
ax.add_feature(cfeature.BORDERS,linestyle=":")

#粒子の挙動の描画
ax.plot(ds.lon.T, ds.lat.T, "-", color="blue")

開始地点をドットで強調

ax.plot(ds.lon.T.loc[0], ds.lat.T.loc[0], "o", color="red", label="Start")

#ax.pcolormesh(fieldset.U.grid.lon,fieldset.U.grid.lat,fieldset.U.data[0,:,:])

plt.xlabel("lon")
plt.ylabel("lat")

=== 緯度・経度グリッド線の追加 === 12/16

gl = ax.gridlines(
crs=ccrs.PlateCarree(),
draw_labels=True, # 数値ラベルを表示
linewidth=0.5,color="gray",alpha=0.7,linestyle="--"
)
gl.top_labels = False
gl.right_labels = False

画面に表示

plt.show()

# Paste your error message within this block

[michaeldenes]

Hi @nbuaan0211-stack , you can use the from_list() function to do this. Create a list of longitudes and latitudes using numpy, for example using meshgrid, and pass these into from_list (see https://docs.parcels-code.org/en/latest/reference/particles.html#parcels.particleset.ParticleSet.from_list)