diff --git a/src/jop_prop2DAcoTTIDenQ_DEO2_FDTD.jl b/src/jop_prop2DAcoTTIDenQ_DEO2_FDTD.jl
index 37b0e78..96e0d7a 100644
--- a/src/jop_prop2DAcoTTIDenQ_DEO2_FDTD.jl
+++ b/src/jop_prop2DAcoTTIDenQ_DEO2_FDTD.jl
@@ -51,8 +51,16 @@ function JetProp2DAcoTTIDenQ_DEO2_FDTD(;
             i += 1
         end
     end
-    passive_modelset["sinθ"] = isempty(θ) ? zeros(Float32, size(values(active_modelset)[1])) : sin.(convert(Array{Float32}, θ));
-    passive_modelset["cosθ"] = isempty(θ) ? ones(Float32, size(values(active_modelset)[1])) : cos.(convert(Array{Float32}, θ));
+
+    # 2022.11.03 
+    #   - these angles are input in degrees
+    #   - θ is TTI symmetry tilt, input specified in degrees from vertical axis (+z)
+    # 
+    # Tilt (φ) 
+    #   if measured from +z in a right handed coordinate system must be transformed to 
+    #   +z in our left handed coordinate system: φ_lhs = - φ_rhs
+    passive_modelset["sinθ"] = isempty(θ) ? zeros(Float32, size(values(active_modelset)[1])) : sin.(convert(Array{Float32}, deg2rad.(-1 .* θ)));
+    passive_modelset["cosθ"] = isempty(θ) ? ones(Float32,  size(values(active_modelset)[1])) : cos.(convert(Array{Float32}, deg2rad.(-1 .* θ)));
     @assert length(active_modelset) > 0
 
     # active and passive wavefields (an active wavefield is serialized to disk)
@@ -220,6 +228,10 @@ Parameters that are *not* passed to the constructor are assumed to be **active**
 of the model that the operator acts on, stored as a 3D array with the following indices: 
 `[Z coord][X coord][Active Parameter]`
 
+## TTI Symmetry Axes
+This angle is input in degrees, specified as described below
+  - θ (tilt) opening angle from vertical axis (+z) in right hand coordinate system (z upward)
+
 # Examples
 
 ## Model and acquisition geometry setup
diff --git a/src/jop_prop3DAcoTTIDenQ_DEO2_FDTD.jl b/src/jop_prop3DAcoTTIDenQ_DEO2_FDTD.jl
index b2f5e65..6df14fc 100644
--- a/src/jop_prop3DAcoTTIDenQ_DEO2_FDTD.jl
+++ b/src/jop_prop3DAcoTTIDenQ_DEO2_FDTD.jl
@@ -61,10 +61,23 @@ function JetProp3DAcoTTIDenQ_DEO2_FDTD(;
             i += 1
         end
     end
-    passive_modelset["sinθ"] = isempty(θ) ? zeros(Float32, size(values(active_modelset)[1])) : sin.(convert(Array{Float32}, θ))
-    passive_modelset["cosθ"] = isempty(θ) ? ones(Float32, size(values(active_modelset)[1])) : cos.(convert(Array{Float32}, θ))
-    passive_modelset["sinϕ"] = isempty(ϕ) ? zeros(Float32, size(values(active_modelset)[1])) : sin.(convert(Array{Float32}, ϕ))
-    passive_modelset["cosϕ"] = isempty(ϕ) ? ones(Float32, size(values(active_modelset)[1])) : cos.(convert(Array{Float32}, ϕ))
+
+    # 2022.11.03 
+    #   - these angles are input in degrees
+    #   - θ is TTI symmetry tilt, input specified in degrees from vertical axis (+z)
+    #   - φ is TTI symmetry azimuth, input specified in "compass angle": degrees clockwise from north (+y)
+    # 
+    # Tilt (φ) 
+    #   if measured from +z in a right handed coordinate system must be transformed to 
+    #   +z in our left handed coordinate system: φ_lhs = - φ_rhs
+    # 
+    # Azimuth (θ) 
+    #   must be transformed from compass angle (clockwise from north or +y) 
+    passive_modelset["sinθ"] = isempty(θ) ? zeros(Float32, size(values(active_modelset)[1])) : sin.(convert(Array{Float32}, deg2rad.(-1 .* θ)));
+    passive_modelset["cosθ"] = isempty(θ) ? ones(Float32,  size(values(active_modelset)[1])) : cos.(convert(Array{Float32}, deg2rad.(-1 .* θ)));
+    passive_modelset["sinϕ"] = isempty(ϕ) ? zeros(Float32, size(values(active_modelset)[1])) : sin.(convert(Array{Float32}, deg2rad.(90 .- ϕ)));
+    passive_modelset["cosϕ"] = isempty(ϕ) ? ones(Float32,  size(values(active_modelset)[1])) : cos.(convert(Array{Float32}, deg2rad.(90 .- ϕ)));
+
     @assert length(active_modelset) > 0
 
     # active and passive wavefields (an active wavefield is serialized to disk)
@@ -240,6 +253,11 @@ Parameters that are *not* passed to the constructor are assumed to be **active**
 of the model that the operator acts on, stored as a 3D array with the following indices: 
 `[Z coord][X coord][Active Parameter]`
 
+## TTI Symmetry Axes
+These angles are input in degrees, specified as described below
+  - θ (tilt) opening angle from vertical axis (+z) in right hand coordinate system (z upward)
+  - φ (azim) opening angle clockwise from "north" or +y axies in right hand coordinate system (z upward)
+
 # Examples
 
 ## Model and acquisition geometry setup