diff --git a/Project.toml b/Project.toml
index 2af3d7b..f346e24 100644
--- a/Project.toml
+++ b/Project.toml
@@ -16,7 +16,7 @@ RelocatableFolders = "05181044-ff0b-4ac5-8273-598c1e38db00"
 [compat]
 Aqua = "0.8.9"
 CSV = "0.10"
-CommonDataModel = "0.3"
+CommonDataModel = "0.4"
 Compat = "4.10"
 Dates = "1"
 DiskArrays = "0.3, 0.4"
diff --git a/src/Instruments/IASI/VariableExtra.jl b/src/Instruments/IASI/VariableExtra.jl
index 5d46ba7..8c4de9a 100644
--- a/src/Instruments/IASI/VariableExtra.jl
+++ b/src/Instruments/IASI/VariableExtra.jl
@@ -28,7 +28,7 @@ function CDM.variable(
 
         T = eltype(disk_array)
         N = ndims(disk_array)
-        return MetopVariable{T, N, R}(ds, disk_array, varname)
+        return MetopVariable{T, N, R, typeof(disk_array)}(ds, disk_array, varname)
     else
         return default_variable(ds, varname)
     end
@@ -106,7 +106,7 @@ function CDM.variable(
         data_array = getfield(gaird, varname)
         T = eltype(data_array)
         N = ndims(data_array)
-        return MetopVariable{T, N, R}(ds, data_array, varname)
+        return MetopVariable{T, N, R, typeof(data_array)}(ds, data_array, varname)
     end
 
     return default_variable(ds, varname)
diff --git a/src/InterfaceDataModel/variable.jl b/src/InterfaceDataModel/variable.jl
index 5c0731d..eb46c41 100644
--- a/src/InterfaceDataModel/variable.jl
+++ b/src/InterfaceDataModel/variable.jl
@@ -7,9 +7,9 @@
 `MetopVariable` wraps an `AbstractArray` so it can be used with `MetopDataset`. 
 The data array is normally `AbstractMetopDiskArray`.
 """
-struct MetopVariable{T, N, R} <: CDM.AbstractVariable{T, N}
+struct MetopVariable{T, N, R, A <: AbstractArray{T, N}} <: CDM.AbstractVariable{T, N}
     parent::MetopDataset{R}
-    data_array::AbstractArray{T, N}
+    data_array::A
     field_name::Symbol
 end
 
@@ -80,7 +80,7 @@ function default_variable(ds::MetopDataset{R}, varname::CDM.SymbolOrString) wher
     T = eltype(disk_array)
     N = ndims(disk_array)
 
-    return MetopVariable{T, N, R}(ds, disk_array, varname)
+    return MetopVariable{T, N, R, typeof(disk_array)}(ds, disk_array, varname)
 end
 
 function default_dimnames(v::MetopVariable{T, N, R}) where {T, N, R}
@@ -130,12 +130,21 @@ function CDM.attrib(v::MetopVariable, name::CDM.SymbolOrString)
 end
 
 Base.size(v::MetopVariable) = size(v.data_array)
+Base.parent(v::MetopVariable) = v.data_array
 
-### get index 
-function Base.getindex(v::MetopVariable, indices...)
-    checkbounds(v, indices...)
-    return getindex(v.data_array, indices...)
+function DiskArrays.readblock!(v::MetopVariable{T, N, R, <:DiskArrays.AbstractArray},
+        aout,
+        indexes::Vararg{OrdinalRange, N}) where {T, N, R}
+    return DiskArrays.readblock!(parent(v), aout, indexes...)
 end
+
+function DiskArrays.readblock!(v::MetopVariable{T, N},
+        aout,
+        indexes::Vararg{OrdinalRange, N}) where {T, N}
+    aout .= getindex(parent(v), indexes...)
+    return nothing
+end
+
 # fix ambiguity
 Base.getindex(v::MetopVariable, n::CDM.CFStdName) = getindex(v::CDM.AbstractVariable, n)
 function Base.getindex(v::MetopVariable, name::CDM.SymbolOrString)
diff --git a/src/MetopDatasets.jl b/src/MetopDatasets.jl
index a308c1a..135b3e8 100644
--- a/src/MetopDatasets.jl
+++ b/src/MetopDatasets.jl
@@ -7,7 +7,7 @@ using Dates: DateFormat, Day, Millisecond, Microsecond, format
 import CommonDataModel as CDM
 import CSV
 import Dates: DateTime
-import Base: size, keys, close, getindex
+import Base: size, keys, close, getindex, parent
 import DiskArrays
 using Compat: @compat
 using PrecompileTools: @setup_workload, @compile_workload
@@ -36,7 +36,7 @@ Returns path to folder storing reduced test data. Note that the test data is dow
 the first time the function it called.
 """
 get_test_data_artifact() = joinpath(
-    LazyArtifacts.artifact"test_data_MetopDatasets", "reduced_data")
+        LazyArtifacts.artifact"test_data_MetopDatasets", "reduced_data")
 
 export MetopDataset