Folks, all these D5 weather forecasts need to be revisited at day 5 as a second post to determine if they indeed had the anticipated effects on the ice (meaning an observable change in one of the direct satellite products we commonly use). Otherwise it is just a lot of hot air and rapidly depreciating hectares of forum space.
We can monitor Arctic ice change without the weather forecasts but change without attribution doesn't move our understanding forward. The weak link is not forecast accuracy but rather coupling to the ice.
This close to the solstice, insolation is putting vastly more heat into and under the ice than low conductivity air. Clouds can mitigate insolation or
make it far worse for the ice, Hyperion @ #1517 posted a rare in-depth discussion of the issues there. We've been at this far too long to still be saying 'low pressure bring clouds bring low melt'.
ESRL provides daily net energy flow maps and forecasts that have never drawn interest here. These have a model component to be sure but are have to be better than just intuiting radiative transfer.
Winds are very important to floe dispersion and hence to melt. We started looking at this cyclone situation back on June 30th (mp4 repeated below, units are wind power density), with predicted unravelling of the (exclusively Kara Tongue) ice edge and interior north of Svalbard-FJL. That seems to be gathering steam on July 1st as expected, with several more days of the same likely to follow. Here Sentinel-1AB and UH AMSR2 are used as the before and after monitoring tools as Ascat and Jaxa products are largely featureless in this region.
Jaxa is back in business! The muddy grays there do a good job at defining at-risk ice. We are seeing very rapid disintegration of sea ice concentration in the central Beaufort as well as south Kara in addition to late-stage melt on the Siberian side and inside the CAA.
Technical note: the non-contiguous color picker in gimp or photoshop though not imageJ can exploit the color complexity of Jaxa RGB. Below the fiducial gray was examined at multiple sites using the averaging capability of the picker, radius 15 and the HSV/RGB foreground value readout. The picker radius was set at 12 in the color cube after some experimentation, the selection grown 1 pxl to pick up strays, edited with the loop tool to remove land artifacts, then filled with a dimmed line pattern and flattened. The boundaries of the at-risk area are too complex to pick manually, especially for the time series necessary to mitigate passing weather artifacts.
To convey wind speeds more effectively, short bursts of nullschool (resp. windy) are captured at 3 hr intervals for five days and concatenated to a mp4 in a semi-automated manner, as described over at Dev Corner. After prediction expiry, the winds can be revisited by backing up nullschool to the required rangeH's post, minor edits: 'The situation with clouds and inbound/outbound energy fluxes is far more complicated than what you can tell by eyeballing visible and infrared Worldview imagery. Seeing cloud cover across most of the Arctic basin in true color Terra, 3-6-7 Terra, andBand 15 VIIRS cannot be interpreted as favorable to ice retention. There is only a narrow range of very small liquid water droplet cloud at that has a beneficial effect on radiation fluxes and it must be at least a kilometer up to not be subject to wind waves that are rolling it down on the ice surface.
Ice crystal clouds are unfavorable as they let in most of the high energy part of the spectrum but blocks outgoing long wave radiation. It may feel cooler to you under ice crystal cloud than a clear sky but you will sunburn just as fast. And bottom melting is likely to be enhanced. Low-level large water droplet cloud like fog or anything even a little gray, also blocks outgoing long wave, and very efficiently absorbs all incoming solar spectra but for a few narrow bands of visible spectrum.
If there is any air movement then the droplets and worse liberated vapor transfer the energy to the ice. And the absorbed spectra are re-radiated as long wave radiation, half of which get down to the surface anyway. So if it is below freezing at 850 hPa, there is no cloud cover beneficial to ice, ditto any significant air movement near surface ditto. Comparing total atmospheric column cloud water with total precipitable water shows there is far more water as vapor than cloud these days over the Arctic.
Whether directly on the ice or at altitude where the long wave can deeply penetrate the ice, this is very bad for ice as the latent heat when it condenses and later freezes is enormous. You may not feel the heat of being cooked by microwaves but you are. And you may feel cold in humid or foggy conditions when the air temp is low (but above freezing) but you are warmer, the ice is colder, so it feels warm.'
