diff --git a/polar2grid/readers/avhrr_l1b_aapp.py b/polar2grid/readers/avhrr_l1b_aapp.py
index 59019496..673ae314 100644
--- a/polar2grid/readers/avhrr_l1b_aapp.py
+++ b/polar2grid/readers/avhrr_l1b_aapp.py
@@ -53,11 +53,15 @@
 from __future__ import annotations
 
 from argparse import ArgumentParser, _ArgumentGroup
+import logging
 from typing import Optional
 
-from satpy import DataQuery
+from satpy import DataQuery, Scene
 
 from ._base import ReaderProxyBase
+from ..core.script_utils import ExtendConstAction
+
+logger = logging.getLogger(__name__)
 
 FILTERS = {
     "day_only": {
@@ -95,6 +99,25 @@ class ReaderProxy(ReaderProxyBase):
 
     is_polar2grid_reader = True
 
+    def __init__(self, scn: Scene, user_products: list[str]):
+        self._modified_aliases = PRODUCT_ALIASES.copy()
+
+        try:
+            # they specified --normalized-radiances
+            user_products.remove("normalized_radiances")
+            apply_sunz = False
+        except ValueError:
+            apply_sunz = True
+
+        modifiers = ("sunz_corrected",) if apply_sunz else ()
+        for chan_name in ["1", "2", "3a", "band1_vis", "band2_vis", "band3a_vis"]:
+            if modifiers:
+                logger.debug(f"Using visible channel modifiers: {modifiers}")
+            self._modified_aliases[chan_name] = DataQuery(
+                name=chan_name, calibration="reflectance", modifiers=modifiers
+            )
+        super().__init__(scn, user_products)
+
     def get_default_products(self) -> list[str]:
         """Get products to load if users hasn't specified any others."""
         return VIS_PRODUCTS + IR_PRODUCTS
@@ -105,7 +128,7 @@ def get_all_products(self) -> list[str]:
 
     @property
     def _aliases(self) -> dict[str, DataQuery]:
-        return PRODUCT_ALIASES
+        return self._modified_aliases
 
 
 def add_reader_argument_groups(
@@ -119,4 +142,11 @@ def add_reader_argument_groups(
     """
     if group is None:
         group = parser.add_argument_group(title="AVHRR L1b AAPP Reader")
+    group.add_argument(
+        "--normalized-radiances",
+        dest="products",
+        action=ExtendConstAction,
+        const=["normalized_radiances"],
+        help="Do not apply '/ cos(SZA)' when loading visible bands.",
+    )
     return group, None
diff --git a/polar2grid/readers/mersi2_l1b.py b/polar2grid/readers/mersi2_l1b.py
index 462e650f..71b303ad 100644
--- a/polar2grid/readers/mersi2_l1b.py
+++ b/polar2grid/readers/mersi2_l1b.py
@@ -98,9 +98,15 @@
 from __future__ import annotations
 
 from argparse import ArgumentParser, _ArgumentGroup
+import logging
 from typing import Optional
 
+from satpy import Scene, DataQuery
+
 from ._base import ReaderProxyBase
+from ..core.script_utils import ExtendConstAction
+
+logger = logging.getLogger(__name__)
 
 ALL_BANDS = [str(x) for x in range(1, 26)]
 ALL_ANGLES = ["solar_zenith_angle", "solar_azimuth_angle", "sensor_zenith_angle", "sensor_azimuth_angle"]
@@ -127,6 +133,23 @@ class ReaderProxy(ReaderProxyBase):
 
     is_polar2grid_reader = True
 
+    def __init__(self, scn: Scene, user_products: list[str]):
+        self._modified_aliases = PRODUCT_ALIASES.copy()
+
+        try:
+            # they specified --normalized-radiances
+            user_products.remove("normalized_radiances")
+            apply_sunz = False
+        except ValueError:
+            apply_sunz = True
+
+        modifiers = ("sunz_corrected",) if apply_sunz else ()
+        for chan_num in range(1, 20):
+            if modifiers:
+                logger.debug(f"Using visible channel modifiers: {modifiers}")
+            self._modified_aliases[f"{chan_num}"] = DataQuery(name=f"{chan_num}", modifiers=modifiers)
+        super().__init__(scn, user_products)
+
     def get_default_products(self) -> list[str]:
         """Get products to load if users hasn't specified any others."""
         return DEFAULT_PRODUCTS
@@ -137,11 +160,20 @@ def get_all_products(self) -> list[str]:
 
     @property
     def _aliases(self) -> dict:
-        return PRODUCT_ALIASES
+        return self._modified_aliases
 
 
 def add_reader_argument_groups(
     parser: ArgumentParser, group: Optional[_ArgumentGroup] = None
 ) -> tuple[Optional[_ArgumentGroup], Optional[_ArgumentGroup]]:
     """Add reader-specific command line arguments to an existing argument parser."""
-    return None, None
+    if group is None:
+        group = parser.add_argument_group(title="MERSI-2 L1B Reader")
+    group.add_argument(
+        "--normalized-radiances",
+        dest="products",
+        action=ExtendConstAction,
+        const=["normalized_radiances"],
+        help="Do not apply '/ cos(SZA)' when loading visible bands.",
+    )
+    return group, None