<p>The average conditions of the <a href="https://en.wikipedia.org/wiki/Indonesian_Throughflow" rel="noreferrer">Indonesian Throughflow</a> (ITF) are well-represented by the top figure.
The transport varies significantly throughout the year. One main driver of the change in transport magnitude is the Monsoon. During the <a href="https://en.wikipedia.org/wiki/Monsoon#Australia" rel="noreferrer">Indo-Australian Monsoon</a> (November-February), westerly winds partly counteract the ITF transport, especially in the upper part of the water column. During the <a href="https://en.wikipedia.org/wiki/Monsoon#Southwest_monsoon" rel="noreferrer">Southwest Monsoon</a> (June-August), southeasterly winds over Indonesia drive additional flow through the ITF. In the transition months, downwelling favorable winds in the eastern Indian Ocean increase sea level in the southwest part of the ITF region, reducing the pressure gradient from the Pacific into the Indian Ocean and causing a minimum ITF transport. The sporadic eastward current in the Indian Ocean is referred to as the <a href="https://doi.org/10.1126/science.181.4096.262" rel="noreferrer">Wyrtki jet</a>.</p>
<p>During times of reduced ITF transport, reversals of the ITF can occurred, especially in some of the smaller branches like the flow through Lombok Strait. The caused of these reversals is usually associated with specific weather systems. For example, <a href="https://doi.org/10.1175/JPO-D-11-0120.1" rel="noreferrer">Shinoda et al. (2012)</a> showed an episode of flow reversal during May 2004.  The development of a northward current anomaly can be seen in the sea surface height and current anomaly map.</p>
<p><a href="https://i.sstatic.net/DPEnz.jpg" rel="noreferrer"><img src="https://i.sstatic.net/DPEnz.jpg" alt="Shinoda et al. 2012 Figure 5d" /></a>
Sea Surface Height (shading; m) and upper-ocean (average over 50–250-m depths) velocity (vectors) anomalies during 9–30 May 2004 relative to the mean of April–June 2004. Source <a href="https://doi.org/10.1175/JPO-D-11-0120.1" rel="noreferrer">Shinoda et al. (2012)</a>.</p>

CC BY-SA 4.0
2023-01-10T02:45:46.040Z
thanks for such a detailed answer! Also wanted to ask if ITF is deep water flow. I thought that windy.com represents only current on the surface. My suggestion was that two pictures in my question represent different levels of water - depth for ITF and surface current generated by local winds.
pacman
CC BY-SA 4.0
2023-01-10T04:34:14.357Z
@pacman, you have to be careful with windy's currents. They misrepresent the information they are providing: https://community.windy.com/topic/5848/currents-wrong-data
arkaia
CC BY-SA 4.0
2023-01-03T14:10:48.403Z
2023-01-03T14:10:48.403Z
arkaia
<p>According to <a href="https://en.wikipedia.org/wiki/Indonesian_Throughflow" rel="nofollow noreferrer">Wikipedia</a>, Indonesian Throughflow passes Lombok Strait from north to south bringing water mass from the Pacific Ocean to the Indian Ocean.
<a href="https://i.sstatic.net/v3zFU.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/v3zFU.png" alt="enter image description here" /></a></p>
<p>But when I the checked currents map on <a href="https://www.windy.com/-8.773/115.725?currents,-8.673,115.611,10" rel="nofollow noreferrer">windy.com</a> I found that current's direction is opposite - from south to north. So how can it be explained?</p>
<p><a href="https://i.sstatic.net/ec4p2.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/ec4p2.jpg" alt="enter image description here" /></a></p>

CC BY-SA 4.0
2023-01-02T17:25:55.410Z
The Wiki diagram only shows the average flow ! Temporary reversals of the flow are therefore nothing unusual.
Weiss
CC BY-SA 4.0
2023-01-03T01:46:37.897Z
does it mean that reversal in 180 degree for oceanic flow are ok?
pacman
CC BY-SA 4.0
2023-01-04T09:21:13.810Z
arakiri did answer your question much better than me
Weiss
CC BY-SA 4.0
2023-01-10T04:34:20.950Z
@pacman, you have to be careful with windy's currents. They misrepresent the information they are providing: https://community.windy.com/topic/5848/currents-wrong-data
arkaia
<oceanography><ocean-currents>
Indonesian Throughflow and currents map
pacman
# Indonesian Throughflow and currents map

(Asked by: username_0 on 2023-01-02)

According to [Wikipedia](https://en.wikipedia.org/wiki/Indonesian_Throughflow), Indonesian Throughflow passes Lombok Strait from north to south bringing water mass from the Pacific Ocean to the Indian Ocean.
[![enter image description here](https://i.sstatic.net/v3zFU.png)](https://i.sstatic.net/v3zFU.png)

But when I the checked currents map on [windy.com](https://www.windy.com/-8.773/115.725?currents,-8.673,115.611,10) I found that current's direction is opposite - from south to north. So how can it be explained?

[![enter image description here](https://i.sstatic.net/ec4p2.jpg)](https://i.sstatic.net/ec4p2.jpg)

**Tags:** oceanography, ocean-currents

> **Comments:**
> **username_1**: The Wiki diagram only shows the average flow ! Temporary reversals of the flow are therefore nothing unusual.  
> **username_0**: does it mean that reversal in 180 degree for oceanic flow are ok?  
> **username_1**: arakiri did answer your question much better than me  
> **username_2**: @username_0, you have to be careful with windy's currents. They misrepresent the information they are providing: https://community.windy.com/topic/5848/currents-wrong-data  

---

## 1 answers

### Answer by username_2 on 2023-01-03. Score: 6 | Accepted answer

The average conditions of the [Indonesian Throughflow](https://en.wikipedia.org/wiki/Indonesian_Throughflow) (ITF) are well-represented by the top figure.
The transport varies significantly throughout the year. One main driver of the change in transport magnitude is the Monsoon. During the [Indo-Australian Monsoon](https://en.wikipedia.org/wiki/Monsoon#Australia) (November-February), westerly winds partly counteract the ITF transport, especially in the upper part of the water column. During the [Southwest Monsoon](https://en.wikipedia.org/wiki/Monsoon#Southwest_monsoon) (June-August), southeasterly winds over Indonesia drive additional flow through the ITF. In the transition months, downwelling favorable winds in the eastern Indian Ocean increase sea level in the southwest part of the ITF region, reducing the pressure gradient from the Pacific into the Indian Ocean and causing a minimum ITF transport. The sporadic eastward current in the Indian Ocean is referred to as the [Wyrtki jet](https://doi.org/10.1126/science.181.4096.262).

During times of reduced ITF transport, reversals of the ITF can occurred, especially in some of the smaller branches like the flow through Lombok Strait. The caused of these reversals is usually associated with specific weather systems. For example, [Shinoda et al. (2012)](https://doi.org/10.1175/JPO-D-11-0120.1) showed an episode of flow reversal during May 2004. The development of a northward current anomaly can be seen in the sea surface height and current anomaly map.

[![Shinoda et al. 2012 Figure 5d](https://i.sstatic.net/DPEnz.jpg)](https://i.sstatic.net/DPEnz.jpg)
Sea Surface Height (shading; m) and upper-ocean (average over 50–250-m depths) velocity (vectors) anomalies during 9–30 May 2004 relative to the mean of April–June 2004. Source [Shinoda et al. (2012)](https://doi.org/10.1175/JPO-D-11-0120.1).

> **Comments:**
> **username_0**: thanks for such a detailed answer! Also wanted to ask if ITF is deep water flow. I thought that windy.com represents only current on the surface. My suggestion was that two pictures in my question represent different levels of water - depth for ITF and surface current generated by local winds.  
> **username_2**: @username_0, you have to be careful with windy's currents. They misrepresent the information they are providing: https://community.windy.com/topic/5848/currents-wrong-data  

---

