Updating argo tutorial to use float dt

Author: erikvansebille

docs/user_guide/examples/tutorial_Argofloats.ipynb

@@ -30,54 +30,44 @@
     "driftdepth = 1000  # maximum depth in m\n",
     "maxdepth = 2000  # maximum depth in m\n",
     "vertical_speed = 0.10  # sink and rise speed in m/s\n",
-    "cycletime = (\n",
-    "    10 * 86400\n",
-    ")  # total time of cycle in seconds  # TODO update to \"timedelta64[s]\"\n",
+    "cycletime = 10 * 86400  # total time of cycle in seconds\n",
     "drifttime = 9 * 86400  # time of deep drift in seconds\n",
     "\n",
     "\n",
     "def ArgoPhase1(particles, fieldset):\n",
-    "    dt = particles.dt / np.timedelta64(1, \"s\")  # convert dt to seconds\n",
-    "\n",
     "    def SinkingPhase(p):\n",
     "        \"\"\"Phase 0: Sinking with vertical_speed until depth is driftdepth\"\"\"\n",
-    "        p.dz += vertical_speed * dt\n",
+    "        p.dz += vertical_speed * particles.dt\n",
     "        p.cycle_phase = np.where(p.z + p.dz >= driftdepth, 1, p.cycle_phase)\n",
     "        p.dz = np.where(p.z + p.dz >= driftdepth, driftdepth - p.z, p.dz)\n",
     "\n",
     "    SinkingPhase(particles[particles.cycle_phase == 0])\n",
     "\n",
     "\n",
     "def ArgoPhase2(particles, fieldset):\n",
-    "    dt = particles.dt / np.timedelta64(1, \"s\")  # convert dt to seconds\n",
-    "\n",
     "    def DriftingPhase(p):\n",
     "        \"\"\"Phase 1: Drifting at depth for drifttime seconds\"\"\"\n",
-    "        p.drift_age += dt\n",
+    "        p.drift_age += particles.dt\n",
     "        p.cycle_phase = np.where(p.drift_age >= drifttime, 2, p.cycle_phase)\n",
     "        p.drift_age = np.where(p.drift_age >= drifttime, 0, p.drift_age)\n",
     "\n",
     "    DriftingPhase(particles[particles.cycle_phase == 1])\n",
     "\n",
     "\n",
     "def ArgoPhase3(particles, fieldset):\n",
-    "    dt = particles.dt / np.timedelta64(1, \"s\")  # convert dt to seconds\n",
-    "\n",
     "    def SecondSinkingPhase(p):\n",
     "        \"\"\"Phase 2: Sinking further to maxdepth\"\"\"\n",
-    "        p.dz += vertical_speed * dt\n",
+    "        p.dz += vertical_speed * particles.dt\n",
     "        p.cycle_phase = np.where(p.z + p.dz >= maxdepth, 3, p.cycle_phase)\n",
     "        p.dz = np.where(p.z + p.dz >= maxdepth, maxdepth - p.z, p.dz)\n",
     "\n",
     "    SecondSinkingPhase(particles[particles.cycle_phase == 2])\n",
     "\n",
     "\n",
     "def ArgoPhase4(particles, fieldset):\n",
-    "    dt = particles.dt / np.timedelta64(1, \"s\")  # convert dt to seconds\n",
-    "\n",
     "    def RisingPhase(p):\n",
     "        \"\"\"Phase 3: Rising with vertical_speed until at surface\"\"\"\n",
-    "        p.dz -= vertical_speed * dt\n",
+    "        p.dz -= vertical_speed * particles.dt\n",
     "        p.temp = fieldset.thetao[p.time, p.z, p.lat, p.lon]\n",
     "        p.cycle_phase = np.where(p.z + p.dz <= fieldset.mindepth, 4, p.cycle_phase)\n",
     "        p.dz = np.where(\n",
@@ -100,8 +90,7 @@
     "\n",
     "\n",
     "def ArgoPhase6(particles, fieldset):\n",
-    "    dt = particles.dt / np.timedelta64(1, \"s\")  # convert dt to seconds\n",
-    "    particles.cycle_age += dt  # update cycle_age"
+    "    particles.cycle_age += particles.dt  # update cycle_age"
    ]
   },
   {
@@ -211,11 +200,7 @@
     "x = ds_particles[\"lon\"][:].squeeze()\n",
     "y = ds_particles[\"lat\"][:].squeeze()\n",
     "z = ds_particles[\"z\"][:].squeeze()\n",
-    "time = (\n",
-    "    (ds_particles[\"time\"][:].squeeze() - fieldset.time_interval.left).astype(float)\n",
-    "    / 1e9\n",
-    "    / 86400\n",
-    ")  # convert time to days\n",
+    "time = ds_particles[\"time\"][:].squeeze()\n",
     "temp = ds_particles[\"temp\"][:].squeeze()"
    ]
   },