diff --git a/map2map/args.py b/map2map/args.py
index 31c1625..768dd35 100644
--- a/map2map/args.py
+++ b/map2map/args.py
@@ -28,6 +28,9 @@ def add_common_args(parser):
     parser.add_argument('--scale-factor', default=1, type=int,
             help='input upsampling factor for super-resolution purpose, in '
             'which case crop and pad will be taken at the original resolution')
+    parser.add_argument('--noise-chan', default=0, type=int,
+            help='input noise channels to produce the output stochasticity, '
+            'if the input does not completely determines the output')
 
     parser.add_argument('--model', required=True, type=str,
             help='model from .models')
diff --git a/map2map/data/fields.py b/map2map/data/fields.py
index 32d13b2..08cde15 100644
--- a/map2map/data/fields.py
+++ b/map2map/data/fields.py
@@ -27,11 +27,13 @@ class FieldDataset(Dataset):
     in which case `crop`, `pad`, and other spatial attributes will be taken
     at the original resolution.
 
+    Noise channels can be concatenated to the input.
+
     `cache` enables data caching.
     `div_data` enables data division, useful when combined with caching.
     """
     def __init__(self, in_patterns, tgt_patterns, in_norms=None, tgt_norms=None,
-            augment=False, crop=None, pad=0, scale_factor=1,
+            augment=False, crop=None, pad=0, scale_factor=1, noise_chan=0,
             cache=False, div_data=False, rank=None, world_size=None,
             **kwargs):
         in_file_lists = [sorted(glob(p)) for p in in_patterns]
@@ -88,6 +90,10 @@ class FieldDataset(Dataset):
                 "only support integer upsampling"
         self.scale_factor = scale_factor
 
+        assert isinstance(noise_chan, int) and noise_chan >= 0, \
+                "only support integer noise channels"
+        self.noise_chan = noise_chan
+
         self.cache = cache
         if self.cache:
             self.in_fields = {}
@@ -139,6 +145,11 @@ class FieldDataset(Dataset):
             for norm, x in zip(self.tgt_norms, tgt_fields):
                 norm(x)
 
+        if self.noise_chan > 0:
+            in_fields.append(
+                torch.randn((self.noise_chan,) + in_fields[0].shape[1:],
+                    dtype=torch.float32))
+
         in_fields = torch.cat(in_fields, dim=0)
         tgt_fields = torch.cat(tgt_fields, dim=0)
 
diff --git a/map2map/models/patchgan.py b/map2map/models/patchgan.py
index 74a59af..df57afa 100644
--- a/map2map/models/patchgan.py
+++ b/map2map/models/patchgan.py
@@ -8,10 +8,10 @@ class PatchGAN(nn.Module):
         super().__init__()
 
         self.convs = nn.Sequential(
-            ConvBlock(in_chan, 64, seq='CA'),
+            ConvBlock(in_chan, 32, seq='CA'),
+            ConvBlock(32, 64, seq='CBA'),
             ConvBlock(64, 128, seq='CBA'),
-            ConvBlock(128, 256, seq='CBA'),
-            nn.Conv3d(256, out_chan, 1)
+            nn.Conv3d(128, out_chan, 1)
         )
 
     def forward(self, x):
diff --git a/map2map/test.py b/map2map/test.py
index a7a5dbb..2c086d4 100644
--- a/map2map/test.py
+++ b/map2map/test.py
@@ -26,7 +26,7 @@ def test(args):
     in_chan, out_chan = test_dataset.in_chan, test_dataset.tgt_chan
 
     model = getattr(models, args.model)
-    model = model(sum(in_chan), sum(out_chan))
+    model = model(sum(in_chan) + args.noise_chan, sum(out_chan))
     criterion = getattr(torch.nn, args.criterion)
     criterion = criterion()
 
diff --git a/map2map/train.py b/map2map/train.py
index d476a96..75d5378 100644
--- a/map2map/train.py
+++ b/map2map/train.py
@@ -84,7 +84,7 @@ def gpu_worker(local_rank, args):
     in_chan, out_chan = train_dataset.in_chan, train_dataset.tgt_chan
 
     model = getattr(models, args.model)
-    model = model(sum(in_chan), sum(out_chan))
+    model = model(sum(in_chan) + args.noise_chan, sum(out_chan))
     model.to(args.device)
     model = DistributedDataParallel(model, device_ids=[args.device],
             process_group=dist.new_group())
@@ -247,6 +247,8 @@ def train(epoch, loader, model, criterion, optimizer, scheduler,
 
         # generator adversarial loss
         if args.adv:
+            if args.noise_chan > 0:
+                input = input[:, :-args.noise_chan]  # remove noise channels
             if args.cgan:
                 if hasattr(model, 'scale_factor') and model.scale_factor != 1:
                     input = F.interpolate(input,
@@ -340,6 +342,8 @@ def validate(epoch, loader, model, criterion, adv_model, adv_criterion, args):
             epoch_loss[0] += loss.item()
 
             if args.adv:
+                if args.noise_chan > 0:
+                    input = input[:, :-args.noise_chan]  # remove noise channels
                 if args.cgan:
                     if hasattr(model, 'scale_factor') and model.scale_factor != 1:
                         input = F.interpolate(input,